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MG MGB GT V8 Factory Originals Technical - Better rear suspension
|I've got a tatty but mechanically good condition V8, and I'd like to improve the rear suspension. The front suspension design seems good but the back end can only be desribed as crude. It crashes over potholes and steps out really badly with the power on in corners if it meets any kind of bump. I've got new springs, new telescopic adjustable shocks, new mounting rubbers etc. but the basic problem is the design itself. The unspung mass (back axle + wheels + brakes +springs) is very high and needs a very high spring rate to push it around at a sensible suspension. Plus the fact that the back end of the car doesnít weigh much in comparison to the unsprung mass reduces the ride quality. The obvious solution is reduce the unsprung mass using independent suspension or a De Dion setup. Iíve researched the BB archive here and found a couple of descriptions of independent suspension installations in MGBs. Both seem to have had problems because the height of the hub carrier |
meant that they couldnít get a great deal of suspension travel, so they resorted to stiff springs to reduce the travel and then youíre back to the problem you had in the first place. My next idea was to use a De Dion setup using the original springs (or some of those plastic springs maybe). Advantages; the original suspension geometry would be completely unaltered, the De Dion setup doesnít need a tall hub carrier so thereís no problem with suspension travel and having reduced the unsprung mass, by maybe as much as a third, you could then use softer springs (standard GT springs or even roadster springs) and still end up with a higher suspension frequency thus improving both grip and ride quality. Sounds like a winner to me, what do you guys out there think? The next step is to find a donor car and assess the complexity of the installation. I heard tell the Rover 2000 had a De Dion rear and that car later came with a Rover V8. Does anybody know if the V8 version still
had the De Dion rear? and if so what the axle ratio was? Or is there another suitable donor? Has anybody else tried to do this?
|dont bother with all the expense and useless crap the companies want you to buy!|
keep the origonal shocks and axle and just chage the springs to fibreglass and bushings to urethane and install a v-link this is basicly the same setup used by all the fastest racers and it still provides a better ride on the road. its faster than any of the independant type ssusp out there handles better and alot less trouble. disc brakes are easy to install and very cheap to do and add even more trouble free operation and still at a fraction of the cost and labor of changing the whole desing of the rear susp
|Cory ,what is this particular V Link that u are talking about?|
ive ordered my fibreglass leafs and i also have a pair of Koni's on the back.
Have u considered a panhard rod ? or is this v link a better setup
any info is much appreciated as i have the same sorta problems on my v8
|Steve Berno Australia email@example.com|
|I'm busy researching for a revised rear suspension design myself at the moment-the rear suspension may be crude but you have to understand what pressure the factory was to turn out the original conversion as cheaply as possible.I understand they designed a linkage system which had to be ditched for cost reasons.|
I reckon that on a v8(GT) a multi leaf spring wants to be about 100lb/inch as the friction in the leaves makes the spring less responsive-the std 124lb/inch is very stiff and is really only to control the tramp/torque wind up.
A single taper leaf spring is more responsive as there is no interleaf friction-a greater spring rate can be used(say 140lb/inch) to help control torque wind up.(C'mon Roger when are you going to get those fibreglass springs on the road for a definitive v8 road test!)
I am unconvinced about the benefits of telescopic dampers on a B(and probably getting well known for it by now!)-they are usually mounted at an angle which only makes them about 70% efficient which gets worse as the axle moves up-they are usually set way too stiff and the parallel bushes usually used cause a binding action-I reckon that adjustable lever arms in new condition in conjunction with rose jointed links are the way to go(and I'll let every body know when I get mine on!)
A panhard rod is really useful-it allows the use of bigger tyres with less arch clearance and improves the precision and feel of the car when loaded up on a bend .
The V link that Moss are offering in my opinion will bind up the rear suspension-the B has rear wheel steering caused by the front of the leaf spring being mounted lower at the front-the axle moves forward under compression in roll causing the wheel to turn in and create stabilising roll under steer.The spring also changes it's length under compression due to it's arching action(that's why there are swinging shackles at the rear).Any attempt to restrain it with a rose jointed/metalastik bushed link-even if it has the same centres as the front spring eye to axle centre-must lead to a binding action with an unpredictable change in spring rate.The way to do it is with a link that has some compliance longitudinally-eg voided bush or soft doughnut type mounting.
Another method might be to use a very stiff leaf clamped under the bottom plate and running forward to a resilient/sliding clamp near the front eye to only stiffen the front half of the spring for location purposes and allowing the rear half to work normally.
Yes -the Rover P6 3500 did use a De Dion type of rear end- I've looked at one and I don't think that it would package very well under a B.The idea about using the leaf springs is very attractive but you then have got to create a cradle for a suitable independent differential-and you still have the problem that single wheel bumps will affect the other wheel.
If I lived in the states I would be looking at Corvette rear end and sizing that one up complete with spring.
As I live in the UK I'm looking at the Jaguar rear end esp as later XJ40s with LSDs are now being broken.(parted out?)
|Soon John, soon.|
Work has been inconsiderate in taking up more time that it should which hasn't helped at all.
|Roger Parker Tamworth firstname.lastname@example.org|
|Why not get rid of the leaf springs and lever-arms altogether. I am building a 4-bar system with coil-overs. This is far lighter than leaf springs, adjsutable and none of the friction problems. The 4-bars locate the axle better, you get the control of a panhard rod and traction bars. I believe its the way to go if you want a simple modification.|
|I hear that work has Roger "really running!"|
|Yes Bob it almost has!|
Overall the rear suspension is crude but up until now many of the more advanced, and on paper much better solutions, have lacked enough in practice to make them little or no better than a well sorted standard configuration. Usually this is a simple matter of lack of extensive testing and fine tuning, which is a costly excercise in both financial and time terms. I have little doubt that give appropriate investment in these areas some of these would live up to the on paper promises, and I have no doubt that this will happen sooner or later.
|Roger Parker Tamworth email@example.com|
re your posting about your 4 link system that you are building for your car-are you using top angled arms(Satchell link) or are the links parallel and used in conjunction with a panhard rod or watts linkage? How are you packaging the top arms under the car-are the top links shorter to fit under the rear heel board or are you creating pockets in the heelboard to accomodate equal length links?
You might consider using one top link only to create a three link system-this would allow you to angle the links in side view to create anti-squat while still allowing some roll steer.
In answer to your questions, the top links are angled in and the lower links are parallel. The top links go to brackets on the heel board. All links are adjustable and it should have good anti-squat and anti-tramp characterisics. As I'm sure you understand, this set up gives good longitudinal and lateral location.
|I am having a front and rear suspension fitted by Trevor Taylor Conversions,The front design is absolutly transformed the car feels like a modern system|
check his web site for pics mgcars.org.uk/trevortaylor/
|D.Canning herts uk|
|a four link rears susp my be nice to talk about and look at but it wont make the car any faster or handle any better! all you need is the origonal shocks with fibreglass leaf spring. with a v-link which is two threaded rods one ends bolts through floor where the trans tunnle ends in back and the other end is bolted to the u-bolt on the axle using heim joints. this acts as traction bars, panhard rod, and axle alignment all in one easy setup and weight savings. it also enhances the handling by steering the axle slightly during hard cornering with the body roll. theres a guy who is racing with this setup who holds the track record at road america in elkhart lake wi and he's run full tube chassis b's with coil over front and rear and this simple setup proved faster and much cheaper to do. the fibre glass leafs are one leaf so all binding caused by individual metal leafs are eliminated. the fibre ones work great improving the ride on street cars and saving weight and stability in |
cornering. sometime simple is better!
|cory WI firstname.lastname@example.org|
|These fiberglass rear leaf springs sound interesting. Does anyone know if you can get them in NZ? Can they be got to suit larger and heavier cars?|
|I have some of these fibreglass springs on my car here in the UK, and I have driven another with them. I favour the simpler routes too.|
For sourcing then start at www.mgbmga.com and follow the links around this very informative site.
|Roger Parker Tamworth email@example.com|
|I have been reading with interest, the comments,some solutions seem very expensive, some seem very technical and in the end no one solution seems to work for everyone.|
The following idea is one that I picked up from circuit racers and dragsters over here, I have used it for years it is inexpensive and more importantly it works.All you do is use your standard shocks and springs but to the springs you add a clamp that can be adjusted back and forth along the leafs to give you the stiffness and stability you require. 2 pieces of 2" X 3" 3/8" thick metal drilled with 2 holes and 2 bolts for each spring. Clamped to the spring behind the axle.
I have used this idea on my V8 and B's for years and it works. Did someone say "simple could be better"
|I'm modifying a 79 roadster. The front crossmember has been replaced by a chrome crossmember. The rear has a plastic spring with redrilled front spring mount and a lowering block to bring the whole car down to chrome bumper height. Everyone says to disconnect the rear sway-antiroll bar -- it makes the rear oversteer on the lowered vehicle. However it looks useful as a basis for axle location bothfor anti tramp and panhard rod type location features. I've considered cutting the roll bar in the center and inserting a tube over the roll bar center section to keep the bar in place but eliminate the antiroll effect. Another approach would be to use the connections on the axles for the rear sway bar but run diagonal rods forward to the end of the drive line tunnel for tramp control and panhard type location control.|
Someone else has looked at and tried this I'm sure. Any Input?
|barry petaluma ca firstname.lastname@example.org|
|the rear sway bar is run on alot of the road racers without a problem as long as the rear rear spring are soft and the fronts are stiff. a v-link setup on the rear axle elimiantes the need for traction bars or panhard rods which means less weight and simpler istallation. i run no sway bar on mine in the rear and only a 3/4 in front with mininum body roll (thats on the race track) thanks to the lomered spindles which means i can lower the car 2 - 2.5 inches without the bump steer and scrub that is caused by the susp geometry getting thrown out of wack when lowering. the lowered spindles correct the geometry and make a huge diff in handling. when you want something thats going to work and work for a long time trouble free just remember the simpler the better!|
|So what would you guys recommend for an ex-racing MGA (880 kg with driver) running a near complete lightweight fibreglass body fitted with what appear to be stock rear stock springs and standard shock absorbers and that has a rear end that bounces around like an empty ute (pickup truck). I am really at the stage where I will weld in a 40 kg steel plate into the boot (trunk) floor. Some have suggested removing the second longest leaf each side and others have suggested cutting 2 inches off each end of the second longest spring!! PS my state laws make fibreglass rear springs illegal.|
Are you saying that Corvettes cannot be registered in your state? How would the state know you had changed to fiberglass spings unless you told them?
|George B. Wildomar|
|Yep!! East Coast Australian states (New South Wales and Queensland) have very strict legislation regarding modified vehicles (especially cars made after 1972). No alternate components without prior approval (virtually impossible to get in most cases without putting the car through a full engineering process similar to a new car). Any unauthorised vehicle is considered unregistered and uninsured for legal purposes. Besides do you know what a Corvette costs here!!!!|
I know that we are talking about the rear end of an MGA here but havent you shoehorned a sodding great big Rover V8 into the front end of the car?(that's what I call modified!) I guess that you can pass off the Jag Dunlop rear disc conversion as mga twin cam parts though!
I did tap out my thoughts on rear end location earlier on in this thread-but what would the authorities think of single taper leaf steel springs?
Regards John Bourke
|John, thanks for the suggestion. Believe it or not the Quensland Motor Vehicle Safety Act says you can fit a component from another vehicle of the same make as long as it is a similar configuration (ie: MGB = MGA therfore V8 is OK (but not a Ford or Chevy V8)& Jag Dunlop calliper part nos = MGA Twin Cam Dunlop calliper part nos) and you get prior approval, but try and bring in a wild card (ie: aftermarket fibreglass springs) and they go mental requiring all sorts of tests and engineers reports. Trust me I know..I used to work for the sodding department and was the prosecutions clerk for a while. On a similar note, in Queensland, if I rebuild an existing pre-registered wreck based on a single component (ie: a master cylinder) its classed as a restoration (despite the majority of the car being new aftermarket repoduction bits) but if I make a car using all the aforementioned aftermarket bits and an aftermarket m/cylinder as well then its classed as a r|
eproduction specialty vehicle and has to meet new car safety requirements!!! Anyway, just thought some of you guys might be interested in another example of bureaucratic stupidity. By the way , the V8 conversion is progressing nicely..the problem is hiding all evidence (and cost) of the work from the wife!! What are these steel springs you mention?
I'm currently using the single taper leaf springs from an MG RV8 which will fit a B but need longer rear shackles as the springs are slightly longer.They do have a very high rate though which may not suit the very light rear end of the A.Check out the rig that I made for testing the springs on the V8 conversions site:
www.mgcars.org.uk/v8_conversions if you didn't know that one already!
You should have seen the rather nice silver V8 MGA that was at Silverstone this year-the wings had been slit longitudinally and 2" extra metal had been let in to accomodate the wider wheels (and the exhaust exitng thro' the wheel arches!)
Regards John Bourke
|LEAF SPRING CLAMPS IS NOTHING NEW, MOPAR USED THEN IN THEIR FACTORY SPONSORED RACE CARS BACK IN THE 60S, AND YES THEY WORK.|
CORY: LOWERED SPINDLES SOUND GREAT I USED TO HAVE THEM IN MY MUSTANGS, BUT THEY WERE THE BALL JOINT TYPE SUSPENSION. HOW THE HECK YOU LOWER THE SPINDLES ON A KING PING TYPE SUSPENSION AS THE ONE ON THE MGB?
|The stub axle has upper and lower kingpin bushes if you add bush length to the top bush and subtract it from the lower one the point around which the wheel rotates drops. I know its done this way as I have a pair of 1" lowered stub axle assys!|
|Robert if the wheel goes down, the car goes up. Machining to remove a portion of the king pin at the top and adding a spacer below to make up would appear to produce the effect you are describing. Who markets the modified kingpin assembley?|
|You are right of courese Barry. I got mine from :|
Greenfield WI 53228
Ask for Dick or Tod and tell them I gave you the number.
|Posted 01 November 1999 at 02:12:43 UK time |
Barry, Petaluma Ca, email@example.com
The rear axle rubber stop above the rear axle is about a 1 1/2" lower than the chrome bumper stop. If you lower the rear axle to CB level ( de arched spring, different spring mount, lowering blocks, or some combo of same) you end up with 1 to 2 " less travel than stock and less than a CB car at the CB height. I am stripping parts off a 76 roadster. For my curiosity I cut the bump stop mount and determined that the original frame ready to accept a bumpstop at CB height is still there. Just cut out the crescent that has obvious been added on and remount the stud/bolt that holds the rubber bump stop in place. With the late model with rear sway bar there is a possiblity that the sway bar mounts might hit at the extreme rear axle travel limits. Everyone says you don't need or want the rear sway bar once lowered to CB levels. -- to much oversteer --. The short rubber bounce strap is used with lowering blocks. The axle is up at CB levels. The shocks thought connect to the spring base which is still at the RB level with lowering blocks. I.E. use the RB shock arms. For all my concerns with axle travel I don't hear people complaing about bottoming out with lowered RB rears. Maybe the rear is so light it rarely hits the bump stops. I note the bump stops all appear to be in good condition. Although I also note the bump stop pad on top of the rear axle is usually rust free which indicates contact with the bump stop. Perhaps people don't realize what's happening -- bump stop bottoming. For competition the reduced rear travel might be a benefit.
Perhaps I've found a solution to a problem that doesn't exist.
|This thread is very interesting.|
I have been trying to figure out how to stop the back of my MGC GT from rolling around. I have started using it for sprints, and have fitted uprated torsion bars at the front with spax adjustable shocks and the front is quite stiff, and lowered by around 1.5".
I have 1" lowered standard MGB rear springs, and started off with RV8 lower spring clamps and spax adjustables, but the car was undriveable, much too stiff at the back and very unpredictable over-mid corner bumps. I have now gone back to standard lever arms and the ride and handling are much better.
However I still feel that the thing can be improved upon as in fast corners on sprints the inside front wheel lifts clear of the road by 1/4" (looking at the photos that onlookers have shown me!) and this seems to be because the rear of the car is rolling a lot. I realise the C has a higher centre of gravity etc, but will the A frame mods help here??, or perhaps a complete RV8 rear setup?. What shocks were used on the rear of the RV8??. Could these help Me?.
What are the effects of removing a leaf or two from a pack of rear springs? My Rover P5B has a number of leaves in the rear suspension, but a few are very short. I was thinking about removing one or two from each side to see what the effect would be.
My assumption is that this will make the rear springs softer, is this correct?
|Many comments have been made regarding the deletion of the rear sway bar on a lowered RB. Can the body mount points for the original sway bar be used for fabricated traction bars rather than hanging them from under the spring mounts. Also, if I understand the design of the mentioned V-link, it seems as though a panhard rod would provide much more lateral stabilization. Please explain if I am missing something here.|
As you probably noted I asked the same question. In thinking about it the rear sway bar is mounted to the top of the axle. The link goes straight forward. That would be correct for torque problems in acceleration of braking but not for lateral location. I think I'll crawl under my car and see if the original body and axle mounts could be used with some sort of x configuration. A rod from the left axle mount going to the right side body sway bar bracket and likewise for the other side of the axle.
The V-link should give better lateral stability than a Panhard rod. The geometry of the V-link is such that the arc described is fore and aft, while that of the Panhard rod is side to side. Follow an old T-bird with Panhard rod and watch its rear end shift from side to side as it hits bumps.
|Gday people, a few questions to ask about a better rear suspension.|
One, where can i get these fibreglass leaf springs and do i need to do much to put them on ?
Second , what about this V LINK ? where do I get myself one of those ?
Websites would be of great help
64 B V8
|try British automotive www.mgbmga.com|
|Has anyone seen or experienced first hand the independent rear suspension and modified front designed by Richard Walden in the UK. I read a rave review in the October/November issue of MG World of the car which appeared on the cover page. The limited slip diff is from a Sierra XR4 along with the hubs, discs and calipers. Up front he used bits from a Ford Cortina MKII, IV or V and a 2.8i Capri. Does anyone know if there is an American equivalent of a Ford Cortina or Capri?? Not cheap, but it looks damn spiffy. It also appears that they got it pretty well sorted out by the time the article, which included a test drive by rally driver Tony Pond, was finished. All in all, it seems like a good setup for a V8 conversion.|
I have seen the Walden suspension when it debuted at Duxford maybe two years ago-when you get close to the steup it ain't all that clever in it's execution-I tapped out my thoughts on this BBS maybe a year ago.The front bastardization of Sierra components with bits of metal extending the steering arm looks down right dodgy.I suppose I'm a purist in my modification philosphy-I like to try and use as many MG components-or components that the factory might have had available-otherwise you might as well be driving a Ford or what ever .
Btw I think that the most interesting IRS is the one that Trevor Taylor is marketing-which I believe is developed by NG CARs in conjuntion with Hawk Cars(Lancia Stratos Replicas) .Trevor has some pictures up of this on this site -see his advert at the top the Mg Tech? BBS.It uses a Sierra diff but in a far more straight forward way-I understand that this system is still under development and will debut this spring.(E-mail Trevor if you want more info)
In my opinion ,the biggest problem with both of these systems is the lack of bump clearance for the top wishbones due to the proximity of the chassis rail as it passes over the axle.I think that any IRs fitted has to use the drive shaft as the upper link or the arch has to be turreted to take a strut.
Me-I,m looking Jag rear ends.....
|I agree with John (look back at the first note on this thread) Any rearend setup that uses parallel links, like the Sierra setup, is going to run into problems with limited suspension travel. I like the idea of having the driveshaft as the top link, the only problem is where to put The coil overs. If they go straight up from the hub carrier to the chassis rail it'll interfere with suspension travel, or I'd have to cut the chassis. If they go from the top of the diff casing to the bottom of the hub carrier then you'll lose effect as they'll be nearly horizontal. How about up to the lever arm damper mounting points? Maybe acting via trailing link from the front leaf sping mounting point? I still like the idea of using plastic leaf springs. My original idea was a De Dion setup off a Rover P6 but you then have the problem of there being no space to fit the De Dion tube. |
Has anybody got any info on the track dimensions/final drive ratios of the jag units?
|With regard to someone's comments on non vertical rear telescopic shocks, I didn't like this system so made some simple brackets to move the top mounting point rearwards up the chassis leg,still keeping the main bolt positions through the leg so . These were profile cut from 6mm plate with a bolt welded into it for the top mount and two holes for the "origional" shock bolt holes.This gives longer travel for the shock, I used Bilstein gas shocks , they have been on the car for over 21 years , no problems!!Regards Mike.|
|Two thoughts on rear suspension, which I haven't tried but I will throw out for discussion.|
1) I like Mike's idea of extending the upper tube mounts. One thing which could be done with tube shocks, however, is to stagger them. (One in front of the axle, one behind). Chevy, and possibly other manufacturers, did this on their small trucks to avoid wheel hop on acceleration, particularly on loose surfaces. It performs a lot of the same function as a traction bar. Traction bars essentially control axle tramp. I happened to own two trucks consecutively in the years in which this switch was made, and the improvement in heavy throttle acceleration was amazing. This could be a relatively easy reversible change to try.
2) My nephew, in his misguided way, purchased a very competitive dirt track car this past year to race as a hobby. One modification that almost all these cars carry is a shock installed to prevent axle tramp on acceleration out of the corners. It is installed horizontally from a bracket on top of the differential to a mount low on the panel between the cockpit and trunk. This is so effective that it's use is not allowed at some tracks where the locals don't normally have them installed. This again would be something that could be added easily on a trial basis.
|A couple of weeks ago some of you guys e-mailed me asking for details of my 4-bar, coil-over set up. Unfortunately, I lost those e-mails before replying. You were probably wondering where I got to.|
If you could re-send your e-mails, I shall get back to you.
|Regarding fiberglass rear springs, I have been researching information provided on the British Automotive website. Using his figures, the ride height I desire would be achieved using the CB springs even though I have a RB car (with chrome bumpers). Should I use the higher rate spring (135#) and lowering blocks or just use the lower rate spring (100#)? I would like about a 15" ride height(center of hub to bottom of trim strip).|
|The original roadster spring rate is less than 100 lbs per inch. the GT about 105. The stiffer springs will set you higher and will make a roadster rear pretty bouncy I would think. Lowering blocks of varying dimensions and combinations can take care of height.|
This thread was discussed between 10/09/1999 and 22/11/1999
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.