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MG Midget and Sprite Technical - Rear springs

My new midget mark 2 springs have got my newly rebuilt car jacked up so far the leading edge of the rear wheel virtually touches the rear of the sill. It may settle but has anyone had this experience? Roger.
R Gray

Sounds like the rear shackle may be installed incorrectly or in an extreme case the spring put on back to front

Is the rear shackle hanging down?
Robert (Bob) Midget Turbo

Here is a picture of the uprated Springs I recently installed on my car. The spring is only just in the right position. When weight is placed on the rear the end of the spring must move below the mounting bracket. If you get this wrong the end of the spring hits the boot floor. in front of the mounting bracket


Robert (Bob) Midget Turbo

Hey Bob,
Not wishing to hijack, but out of interest, what bushes are you using there?
Neil
Neil (K series)

Seems to me that the distance from the front mount to the axle is pretty consistent and hard to screw up. I would suspect the spring is mounted the wrong way around. Someone want to measure from the centerline of their axle to the center of the front eye and the center of the rear eye?
David "haven't done that one yet..." Lieb
David Lieb

I don't know about that, David... with the springs backwards, wouldn't the tire interfere with the back edge of the arch, and not the front, as Roger describes? As I understand, there's more spring behind the axle line than in front.

-:G:-
Gryf Ketcherside

Hmmm,

Sorry guys I got to go a differant direction...I think he just needs to drive and let the new springs settle out....I remember my new springs where up in the air for the 1st 200 miles now they appear to just sag....

has it been 8 years already...maybe I need to source new springs to go with the new rearaxle assembly

Prop
Prop

Doesn't this happen sometimes if you over tighten the shackle bolts with the car up in the air and no load on the springs? Locking the springs in a jacked up position, I seem to remember something similar to this before.
Graham.
Graham P 1330 Frogeye

Graham's comment has substance. Although I have only pulled up the U bolts until the thread emerges the pads look quite distorted perhaps preventing settlement by pinching things very hard. The springs come with leading eyes fitted so it would be impossible to fit them reversed, and I do think there is a bias front to rear that would show.

The proximity of the tyre to the sill is very close currently, a quarter inch or less. There is some kind of ratio thing that goes on here I think so that the effect is exaggerated as the wheel follows a downward arc dictated by the fixed pivot point of the leading location.

I shall weight the car down and loosen the U bolts with the wheels on the floor. Then apply a bit of bounce and see what I get. Watch this space and thanks for all your input. Sorry the digi camera's broken or I would display.

I'm in Essex by the way Graham.
R Gray

Hi RG, I'm in Chelmsford, why not come to the club meet in Gt Totham sometime. It's on the first Tuesday of the month.
Graham.
Graham P 1330 Frogeye

Although it is true that the length of the spring forward of the axle to the front eye is a fixed dimension, excessive curvature of the spring will bring the axle line forwards. As the springs flatten under load the axle will move back a bit.

Do check that as you lower the car the rear shackle adopts the correct position. i.e. the top end attached to the car must be forward of the lower, spring end. If the spring is very curved when unladen, it can tuck up in front of the floor mounting bracket and prevent the car from settling properly. Sometimes you need to use a pry-bar to lever the shackle over as the car is lowered. In Bob's photo earlier, I am surprised that spring lowered into the right position without a little persuasion!

Further : as the pointy bit of the sill is below the centre line of the wheel, the clearance will increase as you lower the car onto the suspension as the wheel moves upwards into the wheel arch. Tyre profile will also have an effect on that gap.

Guy
Guy Weller

Hi Rich? Rob? Mr Gray

I am sure Graham did not mean that the spring to axle ubolts required slackening these were not the things he meant.
What Graham was refering to was the shackle bolts being tight. Whilst I do not subscribe to that arguement some believe that tightening the shackle whilst there is no load on it can distort the suspension.

Guy I too thought it might not settle correctly which on the first let off the jack the spring did go forward of the mounting :)

I jacked it back up, on the body as before then placed another jack under the axle and let that take the weight as that went up the spring end went under the mounting and all was fine. :)

Neil I have had those bushes in my garage for about 5 years waiting for the opportunity and finally fitted them when I had my springs upgraded. I think they are red polybushes?
Bob Turbo Midget England

I had to use a pry bar also to get the shackles in the correct position - quite a bit of levering / jacking I seem to remember. I leave the shackle nuts loose until in approx road position to avoid excessive twisting of the bushes.

Still think this is a problem encountered with the replacement springs now available. I do not recall having this problem replacing springs in the 70's.

R.
richard boobier

the BMC factory manual also said to put the vehicle weight onto the springs before those attachments are fully tightened up (I guess for this reason).

Oh, and those red poly bushes are currently on sale from Victoria British in the US.


Norm
Norm Kerr

Graham,
I'm sure we will, but I want a car to ride in first. Although I'm in Essex it's Upminster which makes crossing the bridge an easy option. My son lives at Stisted near Braintree so there will be scope for visits to both regions. Thanks for the invitation and input.

Guy, Bob, Richard, Norm.... Thank you for your advice. It has proved reassuring. The car looks pretty dramatically wrong as it is but I can see now where the answer is. I will use all your good advice to full effect. I'm looking forward to finishing the car this year. I bought it in 1967. We used it on our honeymoon. Say no more. I ain't no teenager now!!

Thanks gents... RG...
R Gray

This thread was discussed between 10/02/2010 and 13/02/2010

MG Midget and Sprite Technical index

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