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MG MGB Technical - Kingpin Needle roller bearings upgrade
| Im thinking of upgrading to Kingpin needle roller bearings. Has anyone done this modification and found it worthwhile with the steering feel and weight having been improved? Robert |
| R J Collier |
| Robert, I'm not familiar with this modification. I assume that you are refering to replacing the sleeve bushings in the swivel axle with roller bearings. I wouldn't think that you would see much improvement in steering feel since most of the friction is on the thrust washers between the upper surface of the swivel axle and the upper trunion housing. Replacing these shims with a roller thrust bearing would help more I'd think. Going back to my street rodding past and working with early Ford solid axles, the bearing was added to the thrust surface as the weight of the cars increased over the years, it did make a significant difference in steering effort. The bushings remained basically the same between the axle and kingpin. The bearings I'm thinking about for the MG application would be similar to those shown in the McMaster-Carr catalog on page 1093. http://www.mcmaster.com/ |
| Bill Young |
| Bill I think Robert means to replace the thrust washer. The MGOC spares shop sell a rebushed stub axle with kingpin and trunnion. They also sell a version with a needle roller in place of the thrust washer, but charge a £25 premium per side ($45) for this. There is also an ebay seller that is just supplying the bearings. Those bearings from McMaster look to be very good value, although some of the washers look expensive, by comparison. Dave |
| D O'Neill |
| Bill Thanks for the info.Dave is right I have seen the bearings on ebay. If the steering is lighter it may be a worthwhile modification for the price. http://cgi.ebay.co.uk/MGB-king-pin-needle-roller-thrust-bearings_W0QQitemZ220091291865QQihZ012QQcategoryZ27380QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Robert |
| R J Collier |
| If you're already replacing the kingpins and swivel axles with refurbished pieces then the extra charge might well be worth it. I'd like to see what they use for sealing out grime from the bearings. I might have my axles machined and try to do my own conversion, as I've not seen this offered here in the States. |
| Bill Young |
| Bill I assumed that the needle bearings are a straight swap for the bronze thrust bearing which is enclosed in the top trunnion to keep dirt out. I dont think any machining is needed but perhaps someone who has fitted the needle bearings can confirm this and the benefits of the modification! Robert |
| R J Collier |
| I really don't know, just assumed that the roller bearing would be thicker than the bronze bearing. Certainly looks like this would be the case from the diagram in the Moss catalog. That's probably the reason for the price difference. |
| Bill Young |
| I would have thought that it wont take long to hammer dents in the bearing tracks, and cause notchy steering. (I could be wrong, but the pressure on those needles must be immense) See if you can find someone who has done 20,000 miles with them fitted and had no problems first. (You can always fit a larger steering wheel to reduce the effort required if you want) |
| Martin Layton |
| I have put about 10000 miles on mine, they have been great and cut down the sterring effort a lot. The king pins have sailed through the MoT every year since as well. |
| Stan Best |
| Stan I had wondered about the ingress of dirt, too. Is there anything to seal around the top of the stub axle? Bill The McMaster parts would only be around 3.5mm thick, including washers, so I don't think there would be a huge difference compared to the thrust washer. Dave |
| D O'Neill |
| Stan Did you fit just the needle bearings or did you fit the MGOC kit and if you fitted just the needle bearings are they a straight swap for the thrust washer with no machining? Martin I was starting to think "if it aint broke dont fix it" but if the MGOC are offering them, I would have thought they would be OK otherwise they would have a lot of people claiming against them.I do wonder why BL never fitted them though. Robert |
| R J Collier |
| I just put the MGOC exchange stub axles on. The only problem was poor preparation and I had to run a tap through the 4 holes that secure the splash shield. No extra seals at the top, I just pump them full of moly grease once a year. |
| Stan Best |
| Is Stan the only hands on? I would like to see these roller babies on a set of vertically shortened, by the amazing dick@mgbracing.com, stub axles. Is there no other recommender out there? I'd like to have a freer easier steering cause I'm getting fatter, need to consider a 14 or 13 inch steering wheel and the less friction freer moving rollers may just be the ticket. Can anyone else give a hands on recommendation on these rollers? Vic |
| vem myers |
| If you're getting fatter, you need a 10 in steering wheel, wide sticky tires - and go do a lot of tight space parking! FRM |
| FR Millmore |
| FR, I tried that, but all I got was bursitis in my shoulders. I'm thinking about this more for my midget than the MGA which is using B uprights, but it would be nice on both. We've got a swap meet coming up, I'll try to get some measurments on the bronze pieces and see if any machine work would be required. I went back to the McMaster listing and they spec the load rating on these at around 3000 pounds, so I wouldn't think that Martin's fears would be much of a problem. |
| Bill Young |
| Static load is not an issue, hammering is, and I don't know what the balance point may be. Certainly you cannot get away with fitting a needle thrust unit on the non hardened steel bits, as I've seen done. The combined thickness of the bronze washer(.180-.188) and the two steel spacer washers (.052 -.069 each) is about .284-.326. A bit could be gained by machining either the top trunnion or the swivel axle top, but remember that the final dimension is set by tightening the top trunnion down onto the shoulder on the pin. This calls for shims/spacers to fit around the top of the pin above the shoulder (since you've eliminated the selective thrust washers), and a bit can be gained here without other machining. I am an advocate of machining the fewest possible "special" bits. In all, I think that cutting a couple of grooves in the bronze washer to improve lubrication, or replacing the bronze washer with Garlock DU PTFE/lead thrust washers, might get you most of the advantages of the needle bearing, without the hammering and brinnelling caused by small angular displacements. Garlock also make bushings, and replacing the swivel pin bushes with these might gain a whole lot more than the thrust mods. FRM |
| FR Millmore |
| My fears are based on the number of motorbike steering head bearings I've had to change because of notches in the tracks, and they are much bigger and more lightly loaded, but do suffer from very small angular displacements, as well as water ingress. |
| Martin Layton |
| Martin/FR Thanks for your interesting comments but the Needle bearings seem a cheap enough modification and to me worth trying if there is no machining. It would be easy to revert to standard if the bearings failed. Its a pity there are not others apart from Stan who have tried the bearings to comment. Robert |
| R J Collier |
| If anyone is a member of the MGOC perhaps they would tell you where they got the idea and what results they've seen. They usually don't carry any untested items in their collection. |
| Bill Young |
| Don't assume they're any good, just because MGOC sell them. I replaced the closed circuit breather on my GT with one of those little K&N filters from MGOC once - then lost all of the oil out of the rear seal due to pressurisation. Someone at work had the same problem with a Midget. So I called MGOC and was told that the problem was common. I asked why they sold them then, and the answer was "because people want to buy them". Neil |
| Neil |
| Neil The jury is out as far as im concerned. MGB kingpins with thrust washers were unchanged over 18 years production and used in the MGA and other cars prior to that so at least the design was tried and tested! Its a pity that there are not others who have fitted the needle bearings to comment. Robert |
| R J Collier |
| Robert, I have not undertaken this modification and would advise others against it. Firstly as others have commented there is nothing wrong with the original design, in fact, it is a very good design, very reliable and does an excellent job of taking both the static load (very low) and dynamic load at very low rotational speeds, it is self lubricating and is fail safe (it will not 'jam' the steering if it fails), in fact the mode of failure is just to wear down, not a catastrophic failure, like the cage of a needle roller failing!! The dynamic or 'shock' loads are far greater on the un-sprung kingpins and the way in which the existing thrust washers work is very effective and reliable at catering for the loads whilst maintaining light steering effort. The needle roller mod will not be as effective, you will need to have raceways machined in to the two steel washers, some form of seal, (they WILL need to be sealed from dirt and moisture) and most importantly some pre-load to prevent the shock load from impacting on the balls and raceways. I assume that as these are sold as 'replacement' items no other design changes are made. So without further design changes; a) they won't work as well. b) they won't last very long. c) IMHO not as safe or as effective! If you DO want to try needle rollers, a good bearing factors (Swan Bearings in Preston) will sell you a set for about £2.50 each, much cheaper than the MGOC, and probably a better quality item. Or take a look in RS http://rswww.com - type in 'axial needle roller' in the search field. I would also advise that you add some pre-load to the bearing by shimming, (about 0.002" should be a good starting point). You may also find a shaft seal that will fit the top trunnion too. Best of luck, regards, Mike. |
| MG Mike |
| Mike Thanks for your comments. I will put the needle bearings on hold pending more positive reports! Robert |
| R J Collier |
| Well, I've read a lot of thoughtful comments, boiling down to speculation here, but only 2 hands-on for the needle bearing changeup. Are there others who can tell their needle bearing use stories? Millmore, you are so mean, daddy! |
| vem myers |
| Yo Vic! The comments that Martin, MG Mike, and I have made are a bit more than speculation, being based in sound engineering experience and practice, available in any bearing book - if you haven't got it on your own. But, I suggest that the mod is not difficult and should at least be testable without machining, using the dimensions given. So, have it at and we will expect your reports soon! I am a bit put off by all of this wimpiness by "sporty car" types, thought the point was to give an impression of gnarly he-men who open their beers with their teeth and scratch their balls with a claw hammer. Oh wait, they now demand pull tabs or screw offs don't they? Might be a better idea to spend the effort removing weight from the car (and driver?) and always park for a fast exit. My 108lb wife considered my Aceca-Cobra to be her favorite daily driver, and it had much heavier steering than any B - given the pre-historic MGTC steering box; and, I taught her to drive on the Magnette with the 185-15 Dunlop sticky race tires, followed by Rovers with similar feet. Now, a Rover 2000 can really stretch your arms, especially when the ball joints get old and the springs are saggy, giving a lot of negative camber! Have fun! FRM |
| FR Millmore |
| FR, you got it, I'm just a whimp. ;-) Really, after a couple of bouts with bursitis in my shoulders and having a V6 in the Midget with 205 tires on 7" rims I could use some help with low speed steering effort. My false teeth prevent me from opening my beers that way, and I'd never take a claw hammer to something so valuable. The things I'd do when I was 25 somehow are nice memories but nothing I'd like to repeat now that I'm almost 60. Thanks for you professional opinion though, I do value those. It's been pretty easy to pick out those people on the board that really know what they're talking about, and you are one of them. |
| Bill Young |
| Bill- All my previous comments aside, I do appreciate that sometimes things really could be upgraded for our special needs students, and I like a challenge. It has occurred to me that there are now a lot of pretty nice and compact power racks around. Trouble is, most are behind the wheel centerline, so you need one off a RHD car for the front mounted LHD MGs! I haven't actually studied it, but maybe a good day wasted in a scrapyard would turn up one that is reversible. FRM |
| FR Millmore |
| Bill There would be no advances in technoloy if noone tried anything new in case it failed. We need a hands on test pilot with "the balls" to proove the engineers wrong!......... A 50 something guy with hot rodding experience, bursitis and false teeth in a V6 Midget sounds like the ideal candidate! Robert |
| R J Collier |
| FRM, Several European small cars now have electric power steering, which comprises a servo motor and controller mounted on the steering column. Maybe one of these could be used for power assistance? The problems I can see are 1) finding room for the motor, it sticks out of the side of the column. 2) they break all the time..... |
| Martin Layton |
| Thanks Robert for nominating me to "boldly go where no man has gone before" now that I'm old and feeble. Do I sense a bit of "wait and see if it bites him" in the rest of the group? I'll probably take a close look and make some measurments, the idea of the bearings does sound appealing. |
| Bill Young |
| Martin- GET THEE AWAY FROM ME SATAN! All of this "fly by wire" stuff is frightening in the extreme. They can't make a simple switch you can count on, and you need a flippin' computer to make the stuff work. They are working it into the gas pedal, brakes, suspension geometry, drivetrain, and now the steering?! It's one thing when the gas gauge doesn't work, but a random 0-30 degree error or lost signal fault in a steering sensor? What's it do, slam on the brakes at 100mph because it lost the steering signal? A friend came and got stuck in my driveway, in three inches of snow. I couldn't get the car out because it cut the power whenever IT thought a wheel was slipping "too much". GRRRR FRM |
| FR Millmore |
| Electric PS Looked at this about a year ago, just curious. This is not steer by wire, it's electric motor assistance to the steering shaft- essentially split the shaft and install between the upper and lower section. Faiulre results in an increase in steering effort back to that provided by the straight mechanical setup. What put me off ( this was for a large car project, not an MG) was the cost FRM- There should have been a switch on the dash to deactivate the spin control action that the car 'thought' was taking place. |
| greg fast |
| Greg- Thanks for the explain - much better, and agreed that it is a possible viable aid, effectively the same as the hydraulic ones, and maybe more portable. The Firebird owner did not know of any such switch when I asked him, but he's an artist and has only owned it about 7 years! I just wanted it to go away, so I got my truck out (with some difficulty because he parked right behind the truck) and drug it to the road. FRM |
| FR Millmore |
| A most interesting thread on the use of needle bearings. Seems to me if you want to reduce steering effort on your MGB, it would be much easier, cheaper, and reliable, to install the castor adjusting shims that are available. Reduces the castor to a modern level, as would be used with modern radial tires, which have much more directional stablility compared to the bias ply that the MGB was originally designed for. Every comment on these I have seen has been positive. No machining required, and some can just be slipped in. |
| DLD Densmore |
| Good point about the castor on a B. I was interested in these for my MGA with B spindles and my Midget, neither of which can use the castor reduction method. |
| Bill Young |
| DLD What is the source an dpart number for the shims? Thanks Larry |
| Larry Hallanger |
| OK, then lets consider both the rollers and castor shims. As I recall those shims are a bit pricey, No? And FWIW, I give way more creedence to someone who's used the product, and repeat my request for anybody who's used them. Is there no one, besides Stan, out there in the Wide Wide World of Sports??????Also, FWIW, I have ordered 3 sets of the rollers for inclusion on the stub axle verticle chop done by Dick above. If no one else besides Stan can pony up some personal use experience then I will shortly. Cheerios, Vic |
| vem myers |
| 3 sets??? I do indeed await your report! And a picture of, let's see, a 5 wheeler? FRM |
| FR Millmore |
| Or...an 8-wheeler? 3 sets of two? Dave |
| D O'Neill |
| Mebbe it's one of those 6 wheel F1 cars from the 70s, with all wheels steering. FRM |
| FR Millmore |
| Vic I am not familiar with the castor shims and where they can be bought. Has anyone any info on these? I am also not sure what the stub axle verticle chop is, do you mean machining some height off to accept roller bearings? I look forward to your "hands on" trial! Rob. |
| R J Collier |
| http://www.elephantracing.com/techtopic/rollerbearings.htm |
| Paul Wiley |
| Paul W- Thanks for the excellent link, virtually identical to my first post as applied to this question. I have a slight semantic argument in that I would class the loading as both "false brinneling" and true brinelling or denting from impact. The other things mentioned by Elephant are more related to other issues involving hard bushes in suspension, as I recently argued in posts re "polybushes" on Spridget board. The Elephant solution of bronze (or better Garlock) bushes in poly sleeves is elegant and delightful. The "patent pending" is a little distressing since I had thought of that solution years ago - publish or die! The claim may not be valid anyway since since Rover used rubber mounted bronze bushes in the wretched shift linkage on the 2000; all depends on the wording of the claim. Finally, everyone who does websites should look at the linked Elephant site as a stellar example of good use of modern computer tools for real info transmission. I am writing him a congratulatory note as soon as I post this. FRM |
| FR Millmore |
| FRM, I just took a look at the Elephant site, very interesting. I certainly understand the limited movement on the A arms, but do you think that the kingpins would get enough rotation regularly to prevent this problem? I'm certainly interested in what experience Vic reports. |
| Bill Young |
| I believe the rule of thumb somewhere is to the effect that minimum movement should be at least the angular included distance over three rolling elements and at least a full rotation of each element to prevent false brinelling; that does not happen most of the time in road driving, except when parking or slow speed city turns. As I said, impact damage, which would be true Brinelling, is also an issue. It would all depend on the loadings, number and size of rollers, and material characteristics. It's easiest for someone to just do it as I agreed somewhere way back, but it will take a while; and given Stan's experience, appears that it might work in reasonable use. Hard use on rough roads could kill a bearing that works fine on easy driving on good roads. Mostly tests such as we might do can only give an idea of the change in steering effort over the short term. FRM |
| FR Millmore |
| The kingpin and stub axle with bronze thrust washers design was used in 18 years of MGB production and was carried over from the MGA of the mid 1950s. It was certainly a dated design but was it one that could not be improved on? I wonder why did BMC and BL not consider changing to needle roller bearings given what would have been minimal development costs. Have there been significant technological advances in bearing technology in the past 25 years which only now make needle roller bearings feasable? The Elephant site is very interesting, but given Porches reputation for engineering I wonder if the needle bearings are a worthwhile modification on a Porche especially as they seem very expensive. Robert |
| R J Collier |
| Opps Ive just read the Elephant site again and note that they are bronze bearings and not needle rollers! It looks like thay are back to the old MGA/MGB technology of bronze bearings and grease nipples at $295 a set! Robert |
| R J Collier |
| The RV8 the "last" B design used maintenance free ball joints. |
| Paul |
| I suppose it was because of the relatively light weight of the British cars in comparison to American iron that enabled them to use the bushings. I've been doing some searching and it looks like in the days before ball joints, up to 1958 for GM, that cars and trucks used a form of kingpin steering and from the early 1930s on had a thrust bearing between the steering axle and the upright or beam axle. Their use was phased in around the middle '30s as vehicle weight increased. I never took one of these apart, but on my early Ford V8 axles they appeared to be a ball type bearing rather than a roller. They were about 3/4" to 1" thick. This causes me to wonder about the effects of brinelling in this application if they could use a ball bearing with even less load spreading area than a roller on much heavier vehicles. |
| Bill Young |
| Brinelling (don't we call it 'peening' in the UK?) can also be an issue when bearings are not moved over a period of time or where they tend to settle in the same place. So a needle roller bearing in this application may give problems even if you never drive the vehicle. Neil |
| Neil Lock |
| Neil I agree that needle roller bearings may develop problems if left stood unused, but cars are designeed to be used and the same goes for most moving parts of a car, though perhaps for different reasons ie rusting, perishing etc! How long needle roller bearings will last is only speculation unless someone has actually tried them in this or a similar application. I wonder how many the MGOC have sold and if they have had any problems? Rob |
| R J Collier |
| I've recently bought some, I have a V8 roadster with 195x65x15 tyres and a 12 3/4" steering wheel...castor shims have reduced the low speed steering load somewhat, but I'm hoping that I will notice a further improvement with the needle roller bearings. |
| M Barnfather |
| Bill is correct on the ball thrust bearings, and I never took one apart either. But, ball thrusts commonly have a U shaped race which distributes the load better albeit with some increase in friction, and they often have uncaged balls in low speed applications, which gives nearly as many contact points as the caged needles do. The larger diameter balls are also less prone to the indenting the race, which is the essence of Brinnelling. All such loading involves the deformation of the (flat) race to carry the load. For a roller, the initial line contact area is zero, increasing proportionally to R x Pi x L as the needle deforms the race; for a ball, the initial point contact area is zero, increasing by R(sqd) x pi. The squared R is controlling, and R is considerably larger to start for most ball vs needle races. The U shaped races increase this effect even more. There is another consideration with needles: since the needle is cylindrical and radially oriented, the inner end has to turn at a lower rate than the outer. This gives skidding of the needles, and in fact, if loads are high enough and lubrication is lacking, you cannot turn the thing at all without shearing the needles. So the reduction in steering effort may be much less than you would expect by thinking of them as "rolling element" bearings. In big thrust bearings, there are frequently multiple rows of short needles for this reason. The only real cure is tapered rollers, which works if the taper vs length is such as to equalize the rotation rate at the ends of the rollers. This adds space and also gives high end loading on the rollers, requiring strong cages, and increased friction. FRM |
| FR Millmore |
| MB Where did you get your castor shims and how are they fitted? FR Wow! you obvioulsy have some indepth knowledge of bearings. But are you saying that the needle rollers are ubsuitable for the MGB kingpins? One member has had positive results with the needle rollers over 10,000 miles, but this is inconclusive unless we have others using them to corroberate the results. Rob. |
| R J Collier |
| FRM, At the micro level, which is what you are talking about here, the balls/rollers are effectively shearing/slipping anyway. The effect is the same for axial ball bearings - the outer diameter has to travel further than the inner diameter. Assuming that the size of the indentation is proportional to the stress, itself proportional to the area for a given load, then the ball bearings will 'sink' and thus wear a track for themselves - the width of which relates to the size of the balls and the load. However, the size of the 'track' worn by needle or cylindrical bearings cannot get any bigger so in theory the races will keep 'sinking' until they have worn all of the way through. So one might assume that the specifiers of the bearings will have made sure that the load capacity is appropriate and hence there shouldn't be a problem. Still don't see the point of them personally but I'm not sure it's all doom and gloom. After all, MGOC's suppliers must have tested them to destruction or they're looking for trouble the first time one fails and causes an accident! Neil |
| Neil Lock |
| Rob, They are the Speedline/Costello ones.....a bit over-priced but a doddle to fit,........ axle stands on the front jacking points...slacken the cross-member studs....grease the wedges, and slide 'em in . |
| M Barnfather |
| MB I did a google search but came up with nothing. Do you have a website/contact no for Speedline/costello? Is the cars tracking affected? Rob |
| R J Collier |
| I think it is actually Frontline-Costello in Bath |
| D O'Neill |
| MB You don't have any misalignment with the two steering columns. Regards |
| michel |
| Neil- "At the micro level, which is what you are talking about here, the balls/rollers are effectively shearing/slipping anyway. The effect is the same for axial ball bearings - the outer diameter has to travel further than the inner diameter." Not true, for flat races. The needle is, within its length, at a substantially different operating radius, comparing the inner and outer ends. The balls only have "point" contact. Balls in a groove do have the same problem, but the radii are only as far apart (max) as the width of the track, certainly less than the ball diameter on the deepest grooves; and the loading is mostly in the track center if the thing is not overloaded. But, such tracks are commonly a "gothic arch" which gives two contact paths only a fraction of the ball diameter apart. So, skidding is very low, and since the "arch" is close to the ball radius, impact loads cause full semiball contact very quickly. "that the size of the indentation is proportional to the stress, itself proportional to the area for a given load, then the ball bearings will 'sink' and thus wear a track for themselves - the width of which relates to the size of the balls and the load. However, the size of the 'track' worn by needle or cylindrical bearings cannot get any bigger so in theory the races will keep 'sinking' until they have worn all of the way through. So one might assume that the specifiers of the bearings will have made sure that the load capacity is appropriate and hence there shouldn't be a problem." More or less true, and as close an explanation as my somewhat "cheating" first one, but: assuming it's not grossly overloaded, the contact area for the roller increases only as a slightly wider line of the same length, which is what I was getting at, but the ball contact increases as an ever expanding circle, hence the square function. Further, given the shape of the ball versus the sharp radius of the needle, the deformed area of the race rapidly "nests" for the ball, but the needle wants to hammer into the race. These are momentary increases with impact, not operating deformations. Those are still smaller and beyond discussing here. "Still don't see the point of them personally but I'm not sure it's all doom and gloom." Agreed , and we await the test! "After all, MGOC's suppliers must have tested them to destruction or they're looking for trouble the first time one fails and causes an accident!" Wouldn't count on it. FRM |
| FR Millmore |
| Dave Found it now thanks http://www.mgcars.org.uk/frontline/ Rob |
| R J Collier |
| FRM, My point 1 was that AXIAL ball bearings effectively have the same problem with respect to differing radii as THRUST roller/needle bearings. And they seem to last well enough if there is sufficient lubrication. As for the castor shims - well I worry that that tightening up the nuts, even with some kind of taper washers, is putting shear into the mounting studs which is restricting the amount of preload and challenging the original design intent. Neil |
| Neil Lock |
| Rob, I'm in Blackpool and have a pit in the garage if you want to see what's involved in fitting them. |
| M Barnfather |
| Hi RJ- Well, this thread has devolved again into micro-issues and engineering philosophy, not user experience. I will accept brinnelling effects when I see em: I gotta be from Missouri. The site referenced has ballbearings to argue the dastardly hammering effects, we're talking long needle bearings laid down like in a universal joint. FR as is his wont, fans the philosophy fires generating a storm of "what ifs" and "hither to forestalls". His next post will flame me fer sure as the vile one with the huevos rancheros to attempt a second return to thread topic. Oh well, we now have at least one more hands on testimony after another 30 or so postings on Descarte Engineering: "I wink, therefore I are" The 3 sets is self explanatory sir, no need for further. I was talking to Dick, the gentleman who makes the 1 inch lowered stub axles, asking him about the needle bearing idea. He says he uses a sheet of nylon composite material and cuts out a wafer to insert in the trunnion base. Claims it is very slippery. Perhaps one of you PE's know of this material/product and can give us a friction co-efficient or something else useful for this topic discussion. JR- As is the intent of these threads--to share user knowledge and help eachother with tech issues/problems-as I understand the castor shims they change the angle of the stub-axle, and thereby the tire as it contacts the ground. I imagine a Harley with High-Bars like Fonda's in Easy Rider- would be said to have one hell of a castor angle then! Anyway the scuttlebutt is that todays tires are made to ride on this corrected castor angle. So, I'm told, the castor shims make for better steering. Also, here's a sidebar to jump on guys, the bump steer is a problem to be dealt with. Dick suggests heating up the steering arms and very lightly bending them to match the pitch of the plate. Ok, Millard, bring it on son! Cheerios Vic |
| vem myers |
| Vic The discussion from all sides has been very interesting. If I had wide tyres I would still definitly try the needle rollers and accept that they may have a limited life. Keep us informed of your practical findings. As they say "The proof of the pudding is in the eating" MB Thanks for the offer I may pop over to Blackpool and have a look. Perhaps you could email me? Rob. |
| R J Collier |
| http://www.autozine.org/technical_school/handling/tech_handling_6.htm#Sus-Geo I;ve been using Frontline lit for some time with no issues, but pricey and only really notice at high speed 90mph. B&G kit is cheaper but not as easy to fit. The advisor for An MG is born advises against the needles, which may be based on previous experience with them. |
| Paul Wiley |
| RJ- I'm off with the needles to Dick for stub axle lowering and needle implant. Looking forward to my pudding snack soon. Paul your e-ural article was huge for me. Now I can picture things. Still a bit unclear how a castor shim, increasing castor angle, makes the steering more compliant, easier to rotate, and "wanting" to snap back to straight again. Seems the closer you get to vertical, the easier the steer should be. And how does a mfr make his new tire to match "todays" new castor angles?. Vic |
| vem myers |
| Vic I read Pauls interesting link on car handling but not being a suspension designer, some of the theory including matching tyres to castor angles would need further explanation for me to understand it fully. The MGA derived MGB suspension and kingpins were designed for narrow 560x15 Crossply tyres or 155x14 Radials and 16" steering wheels. I look forward to your results, as I dont think we should just dismiss the needle rollers without trying them especially for those who have updated their cars with 185/195 tyres and smaller steering wheels. Rob |
| R J Collier |
| Yes...I understood that the castor angle issue was to do with cross-ply tyres, and that 'modern' radial tyres ran with increased castor angles than previously. |
| M Barnfather |
| The shims reduce castor angle, the Bs 7 degrees is an odd choice. I think the shims 1/2 it. |
| Stan Best |
| Rob Just looked at the Frontline site and cannot find any reference to the wedges. Can you clarify? Thanks Larry 72 B GT |
| Larry Hallanger |
| Larry Mike Barnfather who lives near me has fitted castor wedges to his V8 B and I hope to take a look at them. Perhaps Mike can clarity? Rob |
| R J Collier |
| http://membres.lycos.fr/mgcontact/fileupload/uploads/wedgekit.jpg |
| mw michel |
| Vic the caster shims "reduce" the caster angle from 7* to about 3*. The effect of caster angle is to lift the front of the car a small amount when the steering is turned from the straight ahead position and this also helps the self centering as it wants to drop down again. The more caster the more you lift the car, the more effort required. 7* is a lot with modern tyres and if you can get by with less the steering must be easier to turn. The only draw back is that you can loose a bit of directional stability at high speed but the modern tyres should more than make up for that. The way to picture it is if the axis of the kingpin is leaning back at the top, as with caster, and the stub is sticking out the side ,when the wheel is turned out it swings back and down, slightly lifting the car. There are many other things that effect steering effort, such as scrub radius etc but caster is the main one that we can play with. Denis |
| DENIS H |
| Yep Michel........that's the chap. It really is an easy mod (provided the cross-member holding bolts are not seized ). |
| M Barnfather |
| I note that a few people say that the MGA uses the same set- up as the MGB. WRONGF. The MGA had threaded swivel pins ans threaded trunnions. They anly had 4 deg castor but were still heavier in the steering with poorer self centering. My BGT has no camber - modded A arms - and 185/60 bridgestone tyres on 5 1'/2 rims. Straight line tracking is not as good but it handles better with good tyre wear. I too have seen many mo'bikes head bearings fail so would not try needle rollers until a lot of people say they are OK. Garth. |
| Garth Bagnall |
| Garth It seems more are against fitting needle rollers than are for fitting them. Thanks for pointing the differences out between the MGA and B. I beleive the basic Kingpin/thrust washer design is similar though. Martin Layton has also said that needle rollers fail in motorbike head applications. I would be interested to know if there a solution to this and if not,why do motorbike manufactures continue to fit them? Rob |
| R J Collier |
| From what I've seen over the years most motor cycle head bearings are ball type due to the relatively small diameter of the assembly. It's been quite a few years since I worked on bikes, but I don't remember ever having to replace the head bearings. I suppose that the dirt or off road bikes would take a lot more abuse in this area than the street bikes I was working on. I believe that I mentioned the MGA, mine has had B kingpins and spindles fitted, so is the same as a B in this area. Also my Midget uses the same type assembly as the B, so bearings might be useful there. |
| Bill Young |
| A lot of motorcyclists 'upgrade' the head bearings to needle rollers. My Honda 750 had needle rollers fitted to it before I bought it. There are some strange 'clunks' from the front-end when travelling slowly over rough ground, so maybe I need to investigate the bearings....and revert to ball races! Dave |
| D O'Neill |
| Well I guess the fair question, perhaps for another thread, is who has tried the castor wedges? Anybody have a "hands on" to report? Vic |
| vem myers |
| Vic- I put the Castor Reduction Kit into my 1972 B and found that it greatly reduced the heavy steering effort that had resulted from my installation of a QuickRack and the sticky P195/60R15 tires. Get the entire kit, not just a set of wedges, because things are more involved than most people would initially think. The heavy steering characteristic is caused by the 7° of positive (+) Castor Angle needed to produce self-centering of the steering action when used with the cross-ply tires available in 1962 when the design was first introduced. Since that era, radial tires have been developed along with improved rubber compounds that possess greatly improved traction. This advance has the effect of increasing the steering load, particularly under tight cornering or when cornering at speed. As modern tires have far more directional stability, less self-centering force is necessary and as such so much Castor Angle is no longer required. Consequently, these tire improvements provide scope for reducing the Castor Angle and thereby obtaining the welcome benefit of lighter steering with the MGB. Looking at the front suspension from the side, the Castor Angle is the angle, measured in degrees, formed between the axis of the kingpin and a perpendicular line to the ground. As the angle is formed longitudinally relative to the vehicle, its more exact definition is “Longitudinal Castor Angle”. In practical terms it is known simply as “Castor Angle”. The Castor Angle given to the kingpin creates two important phenomena for the ride and handling of the vehicle: first, stability in terms of maintaining the straight line of travel of the vehicle and, second, the extent to which the steering self centers after turning, and, third, the tilt of the wheel which occurs during turning. The stability phenomenon is created on the basis of the distance between the point at which the kingpin axis extension falls (in relation to the direction of travel) and the point of contact between the tire and the ground. In the case of positive (+) Caster Angle (where the kingpin extension falls ahead of the point of contact between the tires and the ground), the wheel is pulled, as it is the line of application of the force applied to the axis that passes in front of wheel’s mid-point without taking the direction of travel into account, and each attempt made by the wheel to deviate from straight line travel will be counteracted by the Straightening Couple generated by the force and by the rolling resistance of the wheel. With negative (-) Castor Angle the wheel is pushed as it is the line of application of the force applied to the axis passes behind the mid point of the wheel. Consequently, the best stability condition for straight line travel is obtained with a positive (+) Caster Angle. In this case the phenomenon of “wheel wobble” and the consequent effects on steering are avoided. These different behaviors of the wheels can be verified by driving the same vehicle in forward gear and then in reverse. An improved Castor Angle reduction kit has been produced for both Chrome Bumper and Rubber Bumper MGB and MGBGTV8 models by Brown & Gammons, the mg specialists at Baldock (Brown &Gammons Part # AHH6195 CASTOR). It is designed to accomplish two things - first, to reduce the Castor Angle by 3° from the original 7° to 4° and, second, to maintain the integrity of the mounting of the crossmember to the chassis leg. It is worthwhile understanding how this new kit achieves this goal with well thought out thorough engineering details which ensure that the mounting bolts continue to be positively located in taper seats in the chassis legs and that the rubber mounting pads are not crushed in order to achieve an accurate Castor Angle setting. This is an improvement over another kit currently available, which when fitted results in the taper of the bolt being held away from its seating and the rubber pad being crushed when the assembly is torqued down. In the Original Equipment design the crossmember mounted to the chassis leg in an orthodox manner. The MGB front cross member is fabricated out of pressed and welded steel sheet and is mounted on the underside of the chassis legs (which are box sections extending forwards from the monocoque) with four high tensile steel mounting bolts which are positively located into the chassis leg on tapered seats. On either side that the topmost part is a platform with four holes on which the lever arm shock absorbers are mounted. Just inboard of those platforms are the two large holes through which the crossmember is bolted on either side to the chassis legs by the mounting bolts. The Front crossmember is fabricated out of pressed and welded steel sheet and is mounted on the underside of the chassis legs (which are box sections extending forwards from the monocoque) with four high tensile steel mounting bolts which are positively located on taper seats into the chassis leg. The mounting bolts have screw threads at both their tops and their bottoms and a thicker plain shank in the middle, with a taper at the top. The intention of the design is that the taper locates to a corresponding taper seating in the bottom of the chassis leg. Hence, the mounting bolt is positively located in the center of the hole in the chassis leg when it is bolted up with a torque of 56 Ft-lbs. This leaves the bottom part of the mounting bolt protruding below the chassis leg with a plain section, and beneath that a narrower threaded section forming a shoulder at the end of the plain section. A rubber pad which acts as a packing piece between the chassis leg and the mount on top of the fabricated crossmember is fitted over the plain shank of the bolt. This is held up by a rectangular washer with a smaller diameter hole so that the washer sits on the shoulder of the plain section of the mounting bolt but is held in place by the bottom locking nut. The pressure on the rubber pad between the chassis leg and the crossmember is therefore limited so that crushing is avoided. How does the kit reduce the Castor Angle? The method used to reduce the Castor Angle is to simply rotate the crossmember towards the front of the vehicle by placing a precisely-machined stainless steel packing piece between the front crossmember mounting points and the underside of the chassis leg. Since the steel packing has used some of the length of the plain portion of the mounting bolt, a steel collar is supplied with the kit which has to be fitted. In effect, it extends the plain shank of the mounting bolt back to its original length. Without this collar the rubber mounting pads would be overly compressed, thereby ruining the mounts and the ride quality - and of course the crushing would give rise to variances in the Castor Angle, even between each side of the vehicle. New slightly shallower high tensile steel locking nuts are provided in the kit to fit the reduction in useable thread length of the mounting bolts. Because the angle of the crossmember brackets upon which the steering rack is mounted will have changed slightly (3°) in relation to the chassis legs, the body of the steering rack mast will no longer properly align with the steering universal joint. The steering rack brackets will therefore have to be packed at the front in order to realign the rack with the universal joint of the steering column. Six packing shims are included in the kit for this purpose. Brown & Gammons estimate that installation of the Castor Angle reduction kit requires approximately three hours work. The kit includes comprehensive fitting instructions and detailed diagrams. |
| Steve S. |
| Steve Thanks for you comprehensive explanation of castor angle and its relationship to modern tyres. I think I would consider fitting castor shims and asses any improvement before fitting needle roller bearings. Rob |
| R J Collier |
This thread was discussed between 12/03/2007 and 12/04/2007
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