M wheels/tyres and suspension

M wheels/tyres and suspension

Author
Discussion

thornogson

Original Poster:

833 posts

263 months

Thursday 28th July 2005
quotequote all
The M I bought a fortnight ago has got the wolfrace wheels with 195/70 HR 14 tyres.
Initially the car drove ok but a very harsh ride, so I reset the AVO's to No 4 instead of the 10 they were set at.
After a couple of hundred miles the front tyres are now fouling the wheel arches.
According to the handbook the tyres should be 185 so do I need to change them?
Are the tyres the problem or has the suspension settled, and do I need to alter the spring height to bring the body away from the wheel arch.
Any help greatfully received.
G.

davidy

4,459 posts

285 months

Thursday 28th July 2005
quotequote all
The original M tyres were 185's (effectively 82 profile), 195/70's were fitted to the Turbo cars and are what many owners run, I ran these for years without issues.

I would suggest that your front springs may not be up to the job, (as the shock absorber gave a hard ride on a high setting (ie it was acting as the spring) and a soft ride - hitting the arches on a lower setting, suggesting it was functioning as a shock absorber but the spring is too soft.

195/70s should be ok, I'd look at the springs to start with.

davidy

Notanutter

361 posts

236 months

Thursday 28th July 2005
quotequote all
I had a Taimar from new and there was about three fingers of space between the front tyre and the wheel arch, take a look at the 1978/79 sales literature and that's about the same amount.

My 3000S (see my Profile) conversely seems to have a bit too much clearance, although it's been like that for the past 10 years at least, and I've seen some restorations with huge amounts of space (which looks terrible IMHO).

davidy

4,459 posts

285 months

Thursday 28th July 2005
quotequote all
On the finger count, my Taimar was four fingers, but I have small fingers! with 195/70's on 14's.

If its much less than that it does point to saggy springs!

davidy

thornogson

Original Poster:

833 posts

263 months

Thursday 28th July 2005
quotequote all
Just checked and I can only get one finger in, but not two. The springs are supposed to be new. The AVO's are adjustable with a movable collar, so perhaps these want moving upwards?

19560

12,722 posts

259 months

Thursday 28th July 2005
quotequote all
thornogson said:
Are the tyres the problem?

No

thornogson said:
Just checked and I can only get one finger in, but not two.

It does sound like your car is about 15mm too low.

thornogson said:
The springs are supposed to be new. The AVO's are adjustable with a movable collar, so perhaps these want moving upwards?

Sounds like a good first step.
IIRC the clearance form the ground to the chassis immediately behind the front wheel should be 152mm for the 185R14s and 140mm for the 195/70/14s.

thornogson

Original Poster:

833 posts

263 months

Thursday 28th July 2005
quotequote all
thanks for that Johnathan, I will do some measuring.
G.

davidy

4,459 posts

285 months

Friday 29th July 2005
quotequote all
The springs may be new, but they could still be the wrong rate. I'd be surprised if you can get enough adjustment on the spring seat to make up the 'finger' difference (but I'm ready to be proved wrong).

davidy

thornogson

Original Poster:

833 posts

263 months

Friday 29th July 2005
quotequote all
You may be correct, I have just measured the clearance and the chassis is 140 mm from the ground behind the front wheel. Where do I go from here?
G.

davidy

4,459 posts

285 months

Friday 29th July 2005
quotequote all
New springs of a correct rate (or correct unsprung length) I would guess?!?

If the springs are new (ish) or in good condition, the vehicle should be the correct height effectively without a shock absorber when stationery.

I'd talk to Adrian at Exactly TVR and go from there

davidy

>> Edited by davidy on Friday 29th July 09:27

JR

12,722 posts

259 months

Friday 29th July 2005
quotequote all
thornogson said:
I have just measured the clearance and the chassis is 140 mm from the ground behind the front wheel. Where do I go from here?

Double check how the bonnet sits on the car but I guess that davidy is correct and you need stiffer springs and maybe a touch longer as well. PS do you need to update your profile G? J

thornogson

Original Poster:

833 posts

263 months

Friday 29th July 2005
quotequote all
The bonnet sits well on the car and the body has a stay fitted at either side to hold the body stiff so it wont splay inwards.
The shocks and springs were provided by Adrian Venn, so should be right for the car?
G.

davidy

4,459 posts

285 months

Friday 29th July 2005
quotequote all
Ring up Adrian and get the full explanation. Something is not right, wrong springs? 1600M springs? who knows but Adrian will sort it out

davidy

thornogson

Original Poster:

833 posts

263 months

Friday 29th July 2005
quotequote all
Spoke to adrian and he has pointed me in the right direction.
G.

19560

12,722 posts

259 months

Friday 29th July 2005
quotequote all
Which is?

thornogson

Original Poster:

833 posts

263 months

Friday 29th July 2005
quotequote all
Put on ramp, loosen all suspension bolts. Remove shocker and tighten collar up spring by hand only as far as it will go. Do all four corners the same. Refit and tighten everything back up. This gives you a starting point.
If I have got this wrong I am sure Adrian will point it out.

19560

12,722 posts

259 months

Friday 29th July 2005
quotequote all
You'll probably end up with a car a touch higher than 'normal' but hey, this is a TVR. You may wish to read the S forum in which Peter said a very similar thing. www.pistonheads.com/gassing/post.asp?r=2356024&t=196199&h=0&f=11&m=quoteReply&cb=205454
GreenV8S said:
I suggest that before you fit the dampers you estimate the spring seat position to give you your required ride height, and set both sides to the same. If the ride height isn't quite right when fitted then adjust both sides up or down by the same amount to ensure the car stays level. Trying to 'level' the car by eye is a very bad idea and likely to end up with the corner weights miles out.

Have a happy w/e. J

thornogson

Original Poster:

833 posts

263 months

Friday 29th July 2005
quotequote all
thanks for that J.

adrian@

4,314 posts

283 months

Saturday 30th July 2005
quotequote all
The good thing about speaking to me is that I have cornerweighted about 50 M series and like to think that I know where to start from with all my spring rates and send each set out with the spring fitted and marked front and rear and with free advice on how to fit them (I did supply this set some 4 years and 3 owners ago). I too had been reading the thread on the S forum as it evolved, and thought that it was best to keep quiet....`cause I would advise anyone with ride height shocks to get the car cornerweightd to get the very best out of their investment. Take your car to a person that has a lots and lots of expierience cornerweighting with the model car that you have, I guess that might be err....me. I should add that the thread did mention about the fact that raising or lowering the car affects the suspension settings and these will need to be checked and set, I like to think that I am pretty damn good at that too.
(as for hands and fingers as a way to gauge the gap, I did have to giggle....and got a smack for being cheeky by the wife)

supaspark

2,105 posts

239 months

Saturday 30th July 2005
quotequote all
That reminds me I'll get that corner weighting program off to you Monday!
(along with that electric fuel pump wiring diagram you gave me weeks back)
Sorry