Welcome to our resource for MG Car Information.
MG Midget and Sprite Technical - Front suspension rebuild
I have just completed a front suspension rebuild - poly bushes in Barry King wishbones and new hubs (along with all the other bits you have to replace, king pins, stub axles etc.). It all went together ok after a couple of attempts to get the wishbone poly bushes in correctly (the poly was pinched between the large washer and the chassis). I have also re tracked the wheels to 2mm toe in with my home made tracking tool (from an idea I found on here).
I have a little problem with it. When accelerating hard and lifting off quickly the car steersright and then left. Just like what happens if the rear axle U bolts are not tight. I have checked the U bolts, they aer fine and the car was not soing this before the strip down, so I am fairly sure it is front suspension but I am lost as to what might be the problem.
I am going to have the tracking check in a garage just to make sure but there is no pulling or tugging on the steering and no feathering on the tyres yet (after about 150 miles) so I am not convinced this is the problem.
I am going to re check everything tonight just to make sure that everything is tight and in the right place (I did think that perhaps the large washers that hold the wishbone bushes in may not all be locating in the chassis correctly causing a wishbone to move.
One last thing, I do have odd springs on the back, something that I am planning to fix but have yet to do so. One has 6 leaves the other 5 and the car is a little higher on the UK passenger (5 leaves) side than the drivers side.
Admitting that to you all I think I have left myself open to all sorts of lecturing on safety etc. (I am a little ashamed already!) but I have yet to find a source of good rear springs and before the rebuild there was not a problem.
Any ideas would be greatly appreciated.
Has anyone any suggestions as to what cold be the problem?
|er, sorry I can only ehco want you're thinking as I don't really know but sounds like thoses rear springs or something up front either too tight or too loose|
|Strange though that there was no problem with the old front suspension. I had adjusted the tracking with my home made stick on the old set up too and it was fine.|
It all moved up and down quite nicely (quite taught) without the springs in and there was only movement in the correct places.
|shows the value of road checking|
if all was OK before and isn't now it points towards the new parts or fitment
but there's always a possibility it may be something related, or not, from new parts and fitment
perhaps the new set up is highlighting the problem when the previous worn set up disguised the problem (like those rear springs, possibly(?))
if it was only drifting one way you could look at tryes, wheels ect. and swap round wheels and check wheel tighteness or wear
the other thing is to check alignment of the rear axle or springs perhaps - don't expect axle to be 100% cental though
others will be able to help a lot more than me but rechecking for errors is always worth while - I once put a wishbone on upside down on a car, not as obvious as you might think when fitting but on checking with other side, after tightening all bolts, it was obvious
Don,t bother with getting a modern garage to check the tracking, most of them have not got a clue about classic cars.
Get a gunson Trakrite, worth its weight in gold.
|That's a bit of a broad statement!|
It all depends where you go, so, it's worth hunting around for a good one, as, not only will they be able to do your tracking, but they will also do loads of other little helpful things like lend you their lift when they aren't busy etc - and have some tyres lying around they will let you have in emergencies!
As for your front suspension - as much as I am looking forward to my wonderful Barry King wishbones going on my car, they have caused nothing but chaos to the other car they are going on - and as for my poor "hand me down" - well, that needs a whole load of work anyway - it's rather surprising it went around corners at all!!!!
Good luck :)
I am beginning to wonder if the issue has always been there but it did not show up before. It dose feel like the back is moving rather than the front. It may time to look a little harder for some rear springs!
|if you go to a tyre place that's used to dealing with high performance vehicles a classic will be a piece of cake to them and not necessarily any more expensive than the national or regional tyre places|
Dave, straw clutching now so don't be offended, did you get instructions on correct fitting order of all parts and did you grease everything both sides - an interuption and you can return to finish forgetting you've missed something
|No offence taken Nigel, I am clutching at straws myself.|
I fitted everything in the correct order and greased everything when it went back on (that needed grease - I left the brake disk un greased!). I am sure I did not forget anything as I would have had some 'Spare' parts left over.
|yes I think we all know from personally experience that mistakes can be made and sometimes it's missing the bl**ding obvious when doing the work|
I was thinking more of parts or even washers in the wrong order perhaps
sometimes only another pair of dispassionate eyes can see what's wrong
tonight more experienced and knowledgeable posters will probably come along with better suggestions
|The left / right steering on acceleration and over-run is so classic of a loose rear axle I would be very surprised if the fault is anything to do with your front-end rebuild. Other than the possibility that having got the front sorted, the rear end fault that was there all along is now much more discernible!|
If the axle bolts are tight, have you checked the rear shackles and the front metalastic bush? And then, 5 leaves and 6 leaves really cannot be good! I would leave the front alone now you have that done and start sorting out the rear to match.
|yet again I was typing and missed Dave's post where he thought it might be rear following from where I put >>perhaps the new set up is highlighting the problem when the previous worn set up disguised the problem (like those rear springs, possibly(?))<<|
I was posting in response to rach's
so I agree with Guy this could be the area to look at but nothing wrong with checking your work anyway
|Guy, I have experienced a loose rear axle before and I must admit it was my first thought and so I checked it. It is very tight. It has nylatron pads, new U bolts and shims and poly shackle bushes. They are all tight. I have not checked the front metalastic bush.|
I have looked at the front tonight and found that on the left wishbone, the big washer for the rear bolt has not pulled up tight to the chassis. In fact the chassis is a little out of shape. I think I need to remove the bolt (with the spring removed) bend the chassis straight and fit it back together properly.
I must admit I don't like the odd springs. I tried to get some from Kim of Magic midget at Midget 50 but he did not have any in stock. I have still not found any good ones.
ther was a thread not long back and I think the concenus was the rear springs are now OK from the main suppliers but there were also suggestions of other places to try
I added this from a previous poster:
Brost Forge Motorspring Service
149 Roman Way
London N7 8XH
and also picked up this info:
decent springs, not cheap (about £250+) from Clive Berry, email@example.com - 01386 882997
I haven't used them, but I think I heard about them on the MGB forum
You might need to C&P
|Dave O'Neill 2|
|another hit from Dave|
actually I find it an incouraging sign when these type of companies can't spend too much time on web sites
and this looks like another interesting company -
'Reliant Robin single leaf rears £15-00 (+vat).
If case you are lucky enough to own a Robin, - if
not buy a spring anyway, an interesting memento !!'
required link - http://www.rossroadsprings.co.uk/
though I'd like to see the 'Crossbow main springs' and 'Theme Park Roller Coaster leaf spring set'
|As noted above, yes usually loose U-bolts - but these ones aren't.|
I have experienced it happen when even though the U-bolts were fully tight, the spring mounting pads were worn and allowing the axle to shuffle and have this effect. Fitting a new set of pads fixed it.
I have also experienced it when using particular types of gravel rally tyre on tarmac, just driving between stages on the public roads at normal speeds. Thought it was U-bolts as usual, checked all that then found the problem went away when I put the ordinary tyres back on.
The particular type of rally tyres had very narrow and deep tread blocks, hence the squirminess, but it does tell me that tyres can cause it too, but it would be a pretty hopeless normal road tyre to have this effect if the pressures were correct.
I did swap the front and back tyres when doing the work. New wheels replaced the back wheels (both were buckled), so the rear tyres went on the new wheels which were then put on the front. The tyres were all the same though and less than a year old. The old fronts did have a little wear on the inside due to the negative camber Frontline top arms. These are now on the back and thinking about it, the fronts still have all the air in them that the tyre fitter put in at Brown and Gammons who sold me the wheels, swapped the tyres over and balanced them.
I think this needs to be checked straight away. They didn't look as 'flat' as normal when I had a look at it last night.
Thanks for your thoughts
I did note you put you had nylatron pads and wondered if they were suitable especially mixed with the other poly bushes
I don't know about nylatron but I thought I read from this BBS that they are more for racing and need more careful installation and maintainence(?)
I've been experiementing with tyre pressures and have found for me +2 psi to Handbook (so now 24 front, 26 rear) with Avo damper set at 2 (or 3 clicks) (very soft) and polyurethane bushes throughout is right for me and smaller B and minor roads
The nylatron pads were not a straight forward fit. I had to shape them to fit between the u bolts. A simple job with the angle grinder and lots of melted plastic! Perhaps not the ideal tool for the job but it was quite easy to do. They are more for racing but as there is a metalastic (rubber) bush at the front of the spring and poly on the shackle, the nylatron pad between the axle and the spring would not make any difference to the ride and would fix the two more solidly. I think it has done exactly what I wanted it to.
|Kim at Magic Midget is looking into having rear springs made - contact him before you order!|
|fair enough Dave, I thought I remembered something about spacing with them which is confusing for me as they seem to get squeezed in a sandwich|
I don't think it'll be the answer but it shows how easy it is to overlook the basics with swapping wheels round like pressures - or in my case once forgetting to torque up one set of wheel nuts
on that, checking all nuts and bolts are tight is never wasted
it'll be interesting to know the final outcome
good luck, Nigel
One of the rear tyres was down to 19 psi, the others were all around 23. They are now 24 front and 26 at the back. I will be looking at the passenger side rear wishbone pin when I get back from my weekend away on Monday. If these two do not cure the problem I think I will look at the rear springs. I know they it be good having different springs on the back and they can only be bad for the handling.
I spoke to Kim at Midget50 about springs. I will call him again next week to see when he may have some.
|Dave, the tyre pressures can only help, try and see what improvement, if only to see, Nigel|
|Latest update for anyone with the slightest interest (I am writing this for myself then!). |
I refitted the inner wishbone bush again yesterday afternoon, this time correctly - the chassis was bent and so the large washer was not locating in the chassis correctly.
Whilst the wheel was off and the car on axle stands, I thought I would take the opportunity to grease the stub axle/king pin. When moving the hub to full lock I felt a small clunk. on further investigation I found that I had up and down play in the king pin/stub axle.
They are newly refurbished and shimmed parts (king pin, stub axle and trunnion) from a reputable(ish) supplier, supplied all set up fitted together and ready to go. On examination, I found that the three shims (about 1.5 mm thick total) to be bent up and burred on the outside edge and a large score on the underside of the large copper/bronze coloured washer on top of the stub axle. There was nothing obvious that could cause this score so I can only assume that the stub axle bush was proud of the stub axle when it was fitted and this has worn away in the few miles the car has done since fitting, thus causing the play.
I have now removed the shims and when the trunnion nut is done up tight there is just a slight drag on the stub axle movement. Undo it a quarter turn and the movement loosens slightly. What's more there is no longer any up and down play.
Could this have caused the pulling to one side on acceleration and the other on lifting the throttle?
I have not had time to test drive it yet (it was late when I finished the work). I will let you know how it goes.
|That's why I wish i had a remear to do my own stub axles. |
I assume you are going to go back to the supplier and get things sorted?
If you do, and they aren't forthcoming, will you let us all know who to avoid in the future?
|Reamer I mean lol.|
Anybody know what a remear is? ha ha.
|A "remear" is when the first mear was not enough.|
I find it not uncommon with new parts that shims and stuff like that need to be double checked. Like buying a new carburetor and confirming that the float is set correctly and that there is no machining swarf anywhere inside. Sure, it should have been done perfectly the first time, but I have more time to inspect it than they did. The number of times that this has happened to me over the years I never put anything on without checking it over first.
The description of the kingpin shims reminds me that if the shims fitted are slightly oversized (OD), they hang up and can give a false "good" reading at first. It seems that the shims used originally were slightly smaller diameter than what is commonly used today.
I did check everything over when I first got them, they both seemed to be set correctly. I didn't strip it down to inspect the shims, big washer and bush, that was my down fall. I am glad that I found the play last night (although I was not impressed at that time!).
I have sorted the problem now and sending everything back to the supplier would be a big inconvenience, would take the car off the road for some time, there would be little evidence of what was wrong so that is not going to happen. Even ringing them up to tell them something was wrong will, unfortunately, be of little use. I will be unlikely to talk to anyone with responsibility for machining these parts or quality assurance and even if they pretended to be interested in my comments they would be unlikely to pass them on to anyone. I would be mistaking them for someone who gave a sh*t.
I know I should be telling someone but sometimes I just lose the will to live.
Dave (first day back at work after a long weekend, so I am miserable) Brown.
Turns out that mear, has an interesting use in spanish. http://en.wiktionary.org/wiki/mear
So indeed, it can be the case that the first mear wasn't enough :)
On inspection of new parts, I agree, I never trust them either for the same reason as you give Norm. But I think you should be able to, unless they tell you specifically that you need to chek them.
I would think, that unless it was a lot of up down play, it wouldn't account for the steering effects under acceleration and decelerarion.
Mine also now have some unadjustable up and down play, and need doing soon (hence my interest in the supplier), but I don't get the steering effects you are getting.
Sounds like you fixed it with the refit of the inner wishbone bush. Trouble is, that having rectified two items, you will never know which was causing the problem (assuming it's now sorted of course).
This thread was discussed between 25/07/2011 and 02/08/2011
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.