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#1 Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 7:35 am
by jagwit
Helping a friend who bought an S1 in pieces and is re-assembling it now.

The car has so much negative camber at the rear, that the inside walls of the tyres are touching the bump stops. The amount of shimming required to correct it is so much that something is clearly wrong.

I suspect that the lower control arms are too long. I measure them at 313mm (12.32") as per the pic. Is this correct for S1?
Lower control arm length.jpg
Lower control arm length.jpg (57.06 KiB) Viewed 627 times

#2 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 8:07 am
by Robbiee
Hi
That is the correct length
Have you considered whether the drive shafts are too short?
I believe that they come in different lengths
Mine are the early tubular ones so Iā€™m not sure if that would help
Have you got the correct brake discs fitted?

#3 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 8:11 am
by Bob.
Hi Philip
The picture from the ROM shows dimensions for a S3 lower link. Rear track of S3 is 53.75", track of S1 is 50". AFAIK track increase of S3 was done by simply fitting longer bottom links and driveshaft from 420G. Leave you to do the sum to get dimension B for S1.

Image

#4 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 8:20 am
by abowie
Robbiee wrote: ā†‘
Mon Jul 27, 2020 8:07 am

Have you got the correct brake discs fitted?
That's where my money is.

#5 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 8:56 am
by mgcjag
Hi Philip..how are you checking the rear camber...what rear ride hight do you have.....Steve

#6 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 9:19 am
by jagwit
Thank you Gents!!

Excellent input. I am presuming that the owner is reading the manual on how it should be done :roll:

I'll pass this on to the owner who is the one working on the car. At the time it did not occur to me that the drive shafts might be too short or that the brake discs might be too thin.

Bottom line, with a car that came in boxes, one can make NO assumptions. The quality of parts from the usuals are highly dubious. The car has not driven 400km yet and already the bushes are cracking / pulling loose.

#7 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 9:53 am
by christopher storey
You do not mention tyre size. If, as is too often the case, an S1 is fitted with 205/70 rather than the correct 185 R 15 in either H or V rating, it is very common for the tyre to rub on the bump stops . It is simply a function of the tyre being too wide for the aperture

#8 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 10:05 am
by jagwit
christopher storey wrote: ā†‘
Mon Jul 27, 2020 9:53 am
You do not mention tyre size. If, as is too often the case, an S1 is fitted with 205/70 rather than the correct 185 R 15 in either H or V rating, it is very common for the tyre to rub on the bump stops . It is simply a function of the tyre being too wide for the aperture
I can see that being the case. Good to know that!! Will let him know !

(I could have stepped into this trap with another friend's car that has tyres too small!!)

#9 Re: Correct length of IRS lower control arm for S1

Posted: Mon Jul 27, 2020 5:11 pm
by christopher storey
Philip : another hazard of fitting 205/70s is that in some cars you cannot get the rear wheels off without deflating the tyre !