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MG Midget and Sprite Technical - Suspension

New midgets and curious about the suspension
Two parts.. ( 1973 car )

Firstly.
The front is somewhat soft and bouncy. Is this a sign of needing to replace the hydro shocks or can I inspect the fluid lever or something?

Secondly.
The rear seems to be a little lower on the left side.
I would say about an inch.
What is the most likely cause of this?

Thank you
Matthew T

Hi Matthew,

I will take a punt at answering your questions. Hopefully some others will be along to confirm/deny what I am about to say.

The front: Have you tried the old fashioned 'bounce test'? Push down as hard as you can on each front corner then let go. If the shocks are in good order the car should bounce 1 - 2 times before coming back to rest. If it carrys on bouncing up and down longer than that the shocks are probably past their best.

The rear: As you live in Canada I guess your car is LHD. I would suggest your spring on the left has sagged (a common problem I gather). It will happen on the left first as the drivers side is generally more heavily loaded (as there is always a driver, but not always a passenger).

Hope this helps set the ball rolling.

Cheers,
Malcolm
Malcolm Le Chevalier

I would agree with Malcolm about doing the "bounce test" - except I think that 1-2 bounces is too much. Good shocks will allow the car to rebound as you release the pressure on the wing, but it should then come to rest pretty well straight away, without any oscillating up and down at all. If it bounces through 2 cycles the shocks are shot.

Usual first check is to look at the shock body to see if there is any sign of oil leakage, particularly at either end of the spindle. Then it is worth topping them up, this will often cure weak shocks. There is a level filler plug to undo. Use a plastic syringe with a 3" length of windscreen washer plastic pipe pushed on the end and inject oil direct in through the filler plug.

Sagging at one side at the rear is a common fault. Not sure that it is caused by just one "tired" spring though. If it were, then switching the rear springs over would correct the fault, or make the other side sag, which in my case it didn't! It can equally well be caused by the diagonally opposite corner (front right in your case) being too high.
Guy

Thanks......

Which one is the filler for fluid? The larger of the bolts on the top of shock?
What oil to use?
Are the rear shocks similar and need fluid?
Lastly....if I were to try a swap of the rear leaf springs....side for side...Am I looking at a full day job or is this fairly straight forward.

oh...and how does one support the car up. Up until now I've had the jack stands supporting the axle. As this puts load on the springs, I would need to support elswhere.
Thanks
Matthew T

Malcolm,
yes the large nut, I think you have to get the air out and not fully fill to top but check in the Archives as I might have remembered wrong

rear ones are the same but you have to take them off the car to fill

oil is SAE 15 - http://www.classic-oils.net/Product-189/Oils-by-Manufacturer-Brand/Penrite/Penrite-Shocker-Oil-1

as for rear springs again details and photos in threads in Archives

changing springs one side to other might discover the cause of the problem and it might not and it might not be the reason

Nigel Atkins

Maybe my earlier message wasn't clear enough. Swapping the rear springs over on mine made no difference at all ! But if you do decide to try that it can be done easily enough in a couple of hours or you may need half a day if nuts are stubborn. Jack the car under the floor, close to the front spring hangers and using timber load spreaders.

The filler plug on the front shocks is the smaller (7/16"?) One that goes in horizontally, not the large one that Nigel describes. That one covers the valve mechanism.
Guy

good spot Guy, sorry to be clear(ish)

I did mean (I think, the larger) one of the four hex heads you can see from looking down on the installed front dampers (IIRC) the damper plugs can be a bit awkward to get at and a select of socket connectors and bars helps

I'm not sure how people can moan about old cars playing up when they daily put up with these stupid computers playing up for seemingly no reason that can come and go at will - been fighting this computer most of the day

as Guy's also put changing the rear springs over probably wont solve it, I meant that if you look at doing the job you might find the cause without the need to swap the springs over

start with the droopy side compare it visually with other side before starting to remove it as you might discover the cause just by doing this, then start removing the droopy side first as again just by removing it you might discover the cause

the cause could be a combination of things that may or may not include the spring itself

never assume that what is fitted to your car is the original or correct type or component or that it has been fitted correctly always compare and cross reference, if you can with two different sources of information
Nigel Atkins

Very true Nigel! A close visual inspection could just reveal the cause as a broken leaf in the left rear spring!
Guy

or homemade shackle :)

or perhaps the other side or diagonal front is too high :)

Mathew,
on both sides at the rear measure from the centre of the wheel hub to under lip of wheel arch and compare, assuming wheel arches are even of course, don’t expect measurements to be exactly the same

what I’m getting at is when new the cars were not spot on and with possible changes and parts over the years don’t expect too much, if everything is correct side to side, back to front, chassis, suspension, wheels, tyres, ect., then it might not be anything to worry about
Nigel Atkins

Well I did the very technical and proven finger measure. Comfortable four fingers clearance on the right side with room to spare....sqaushed four fingers on the left side.
( yes I'll measure properly later )
Will remove wheels on both sides and inspect/compare.
I'm used to working on MINI suspensions (dry).....none of this fancy leaf spring and hydro damper arm thingies.
Matthew T

it depends how squashed the four fingers were, if not squashed a lot I wouldn't worry too much

you'll probably need to get under the car to do a comparision of rear springs and fittings and other components under there

I'd take lots of photos of each side and then compare them on the computer in warm with a mug of tea, make use of modern tech (when it works)
Nigel Atkins

Up to 1/2 to 3/4" difference is pretty normal. That sound like the difference between 4 squashed fingers and 4 clear fingers. If its as little difference as that I wouldn't worry about it. No one else will notice, and you cannot see when you are sitting in it and driving - which is what you should be doing!

Actually the 4 finger clearance on the right sounds to me to be too much rather than the other side being low!
Guy

Could be shackles not moving free enough to rebound when you, as driver, leave the car. I have the same (Lob sided rear RHD), and many others. As my shackles are removed right now (no boot floor, well almost finished) and they where quite hard to turn, I cleaned and smoothed everything and will grease them liberally before putting back. Maybe then it will be better. OTOH the rear axle isn't centered properly as well, another common thing.
Alex G Matla

This thread was discussed between 18/03/2012 and 19/03/2012

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.