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MG MGB Technical - Fitting new rear leaf springs..

I've just fitted some new rear leaf springs to my 72 MGB GT. The problem is the rubber check straps( which are also new )will not reach there fixing mounts. I've checked all the part numbers and there all correct. The straps are about an inch and a half to short. Is this normal or is something wrong? Any ideas? Thanks, Bill.
Bill

Bill. I suspect you tightened up everything with the rear axle hanging on the springs. That way, the system will be sitting to high.

Put a set of jack stands under the rear axle, then, loosen up all of the bolts and see if the body moves downwards. Also make sure the rear spring shackles are slanting backwards, rather than forwards, at the lower end.

Les
Les Bengtson

Bill

Do you have standard rear suspension? if you have fitted telescopic dampers this may have moved the whole set up away from the springs.

Graham
Graham Lavis

Thanks for your thoughts. The suspension is all standard so can't be a problem there. I did tighten everything up off the car then put it on so I hope loosening the bolts off will sort it although i did start to slacken things off when i noticed the problem and nothing moved. Perhaps I need to loosen things a bit more.
bil

Mine were tight too. I was able to get a well placed jack in there and a little force. The car settled in and now there is a good amount of slack. I think you could also drop the car, drive it around the block and let a bump or two help the springs settle in.
Frank Baker

"I suspect you tightened up everything with the rear axle hanging on the springs. That way, the system will be sitting to high."

I really don't think that is possible on the rears, as both front and rear bushes are designed to allow relative movement between eye and hanger/shackle, the spring itself isn't clamped at either end.

The problem is surely the well-known one of the springs being too hard/arched for the application. I've fitted two sets of correct OE springs in the past and had no problem jacking the springs up either to fasten the rear shackles or to connect the rebound strap. On its wheels the springs should be nearly flat, and the shackle nearly vertical, just pointing forward slightly. Like this the straps follow a very curved path from body to axle. However there are countless stories - originally only from the USA but now from the UK as well, that typically available springs cause the rear to stick right up in the air like a submissive monkey, and sometimes the boot has to be loaded in order to get them fastened anyway. If the rear is too high the straps won't have enough slack and will be taking the shock of spring extension over even minor road surface imperfections. This will give a horrible ride, cause them to fail prematurely, then it will be the dampers taking the shock of axle extension, which won't do them any good at all. Whilst they will settle a bit in time (in fact the better the quality of the spring the *less* they will settle) but you simply shouldn't have to do this to get an acceptable ride height. It is simply the springs being manufactured to the wrong spec. It may be that manuifacturers are trying to compensate for today's heavier occupants (Abingdon only allowed for 150lb/11 stone) they have gone way over the top - unless the occupants are heavy enough to flatten the springs!
Paul Hunt 2

Dear Paul. Hope all is well with you and yours.

Back to the subject at hand. I have to disagree on this. I replaced the rear springs on my 68GT a few years back with some springs marked "Made in Great Britain" with no problems noted. Thus, not all of the springs are bad. And, in this case, we do not know. We are trouble shooing, trying to find out what is really the problem.

Earlier this year, I put a 79 mgb roadster back on the road. I have owned it for over seven years now and it has been off the road for quite a number of years. As part of that process, I rebuilt the rear suspension.

I thought the original springs, which showed surface rust, were in good condition. Had them sandblasted and coated them with POR-15. Seems to be holding up well. Replaced all of the suspension bushings, front and rear, with those available from Moss Motors since I had not used them before. All of them are red in color and it seems a slightly tighter ride than the factory standard (as compared to my 79 LE), but not overly so. I would say "it handles well".

I, too, tightened up the suspension while the rear axle was hanging downwards and had the exact problem mentioned. The rebound straps lacked over an inch of being able to be installed. I put jack stands under the rear axle and loosened all of the bolts. Lowered the car onto the rear axle jack stands, making sure the rear spring hangers were rearwards of the centerline between the springs and the body attachments. The bushings associated with the rear shackles have flanges on them and, when tightened, resist easy movement--especially when the axle is hanging and they are forwards of the up and down center line from the body to the springs. IF THE HANGERS ARE IN FRONT OF THE UPPER PORTION OF THE SHACKLE, THE REBOUND STRAPS WILL NOT FIT AND THE SUSPENSION WILL MAKE THE BODY SIT TOO HIGH. THE HANGERS *MUST* SIT TO THE REAR OF THE UPPER HANGER MOUNTS.

If, after these conditions are met, there is still a problem, I will agree that the root cause of the problem is the arch of the springs. But, I had exactly the same problem, due to "operator error" myself and corrected it as I have described.

Loosen everything up, with the nuts barely hanging onto the bolts. Make sure the rear spring hanger bottoms are aft of the uppers. Bounce the body up and down a few times. Re-tighten the various nuts. Check the rebound straps for fit. In my case, the straps went from being 1.5" above the lower attachment points to being 1" below them. System seems to work quite well now.

Les
Les Bengtson

Bill, We've recently discussed this problem on the MGA site where several people, myself included, have bought new springs only to find them to be out of spec. on free camber.
I would recommend you remove your springs and check the camber against the Workshop Manual figure before you start suspecting another cause. While you have the springs out measure the leaf thickness because the working camber is quite sensitive to this thickness.
One person (in the US) had found a spring shop that reduced the camber on his over-arched springs. Mike
m.j. moore

Hi Les - all well here, got an MG ZS 180 added to the fleet now. I didn't say all springs were bad, indeed I said that I'd had two sets with no problems. But after it being a US only problem for some years, there are now more complaints of this too high in the rear occuring in the UK.

I've replaced the springs three times for various reasons and never had a problem attaching the rebound strap, but you do have to jack under the axle while the body is on axle stands, until the springs are compressed but not lifting the body off the axle stands, before you can do so. You certainly won't be able to attach the straps with the axle hanging off the springs, for it is the straps that stop the axle reaching that point.

Rubber bumper cars can have the problem that, as you jack under the spring with the front eye attached in order to compress the spring enough to get the rear hanger attached, the rear eye can wedge up against the chassis rail with the hanger pointing fully forward, and does not angle downwards as the spring is compressed further. This is because the chassis rail hanger holes are *below* the bottom face of the chassis rail, and you may have to lever the rear eye of the spring away from the chassis rail as you compress the spring to start it moving in the correct direction, and to compress it far enough to attach the strap. Once the strap is attached it does not allow the hanger to move forward enough for it to happen again, i.e. simply jacking up under the body until the wheel comes off the ground. On chrome bumper cars this does not happen as the upper holes go through the chassis rails i.e. are above the bottom face of the chassis rail, and the resulting angle of the hanger means that it automatically moves into the correct position as more pressure is applied to the spring. The original poster has a 72 i.e. chrome bumper car.

Unfortunately the MGB Workshop manual does not include free camber measurements, although I have taken posted some measurements at http://www.mgb-stuff.org.uk/wn_suspensionframe.htm and click on 'Spring Specs'. But even if it did they would mean nothing, as would my measurements, if it is the leaves that are too hard rather than being too arched.
Paul Hunt 2

This thread was discussed between 28/07/2007 and 02/08/2007

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