• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

tire wear question

Share this page

philman

philman

Jedi Knight
Offline
i noticed a problem on my '76 tr7 fhc. the outside of the front tires wear excessively. If you look from the front end you can see that the top of both tires are pushed out.

I have replaced the subframe bushings, control arm bushings, ball joints, tie rod ends, sway bar bushings. I am using tr8 strut assemblies with uprated springs from TSI, but i chose to keep the stock sway bar so that it wouldn't ride too stiff and am using the original lower control arms.

Am I going to have to change to a bigger sway bar to get proper tire wear, or is something else going on? I didn't notice this until I did all the front end work, so I don't believe the camber was off before.
 
It is obviously an alignment issue. Did you have it aligned after all of the suspension work was done? You may want to take it to an alignment shop to get it checked out.
 
Well, one question that might need to be answered is, are the lower control arms different between TR7's and TR8's. I don't know myself but if the TR7 lower control arm is slightly shorter it might account for your positive camber.

Other than a difference between TR7 and TR8, it could also be a difference between early and late TR7. Since your car is such an early TR7, you might try later TR7 or TR8 control arms. There really isn't camber adjustment per say otherwise. Unless you fab up an adjustable lower control arm or adjustable top mounts.

I can't see the sway bar causing it. It could but I doubt it. Also, fitting a larger sway bar shouldn't make it ride any harder (for straight line ride comfort) unless you drive through a lot of potholes.
 
well, none of the usual vendors seem to list different control arms for the tr8's/tr7's (early/late) other than left and right sides. i even tried using a subframe assembly off an '81 -- which required changing the left motor mount bracket under the oil pan -- in case the sub frame was bowed or the mounting holes for mounting the control arms elongated.
 
Ride height will affect camber....too high and you get negative camber...too low and you get positive camber.

The sway bar will not affect any alignment settings...and won't affect ride quality as it's only really working when cornering.
 
philman said:
well, none of the usual vendors seem to list different control arms for the tr8's/tr7's (early/late) other than left and right sides.
Click to expand...

There you go, I'll bet you know what your next step is. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
TR7 and TR8 suspensions are, for all intensive purposes the same. The spring rates vary slightly and the sway bars are larger for the 8. The subframe spacing is also slightly different. The control arms and strut housing are identicle. I hope you didn't pay extra for TR8 strut housings as they are the same as TR7. The common upgrade is eurethane bushings, stiffer strut cartridges, and stiffer shorter springs. The rear is basically the same deal. I have seen many cars with camber and caster settings outside the factory recommended specs. Poor build quality, worn mounting points, bent suspension pieces, and accident damage are all candidates. A good alignment would be your first step. If the outside edges are worn, it could just be that the tires are toed in. The second most likely candidate would be the ball joints. The third would be the mounting points on the subframe where the lower control arms bolt on. If all else fails, there is always camber plates, and threaded collar spring perches. Way up on the cool scale.
 
Here is another thought. If the wheels are indeed at a positive camber setting, you can try bending the strut housings slightly. The cartridges don't fit snuggly and you can take advantage of the play in there. This is a common way of cheating on showroom stock race cars. You might be able to gain a .5 degree of negative camber. You can also gain a little by slotting the top mounting holes for the strut assembly. There isn't much to gain there before the stock diameter springs contact the inner fender.
 
ok i think i've got something relevant here. I raised the front end on jack stands, loosened the steering shaft u-joint fasteners, dropped the front end back on to the wheels and tightened the fasteners again. now everything looks normal.

could it be that when I took everything apart and put it back together that the steering shaft became too long forcing the steering rack to push the track rod ends out? lack of free play may also explain high speed skittishness.

of course, i need to find two new front tires; it seems nobody makes good 13" tires anymore.... but that's another thread. my local dealer seems to think that i should use sumitomos.
 
Phil, I can't answer the suspension and alignment question, but I'm running Sumitomos on two of my vehicles, and love them.
I run 175 70's on the Midget, and have for two years. They've been great tires, so far.
Incidentally, Sumitomo owns Dunlop.
Jeff
 
that probably explains why dunlop no longer makes the gt qualifier series for 13" sizes.
 
Andrew, that must have happened fairly recently. I was on the Sumitomo site not long ago, and they listed Dunlop as one of their brands.
I can't keep up anymore! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff
 
Andrew, it seems as though we are both right. Sumitomo and Goodyear are joint venture partners, since 1999.
I still like the tires!
Jeff
 
Might still be interesting to find out the difference between the late and early lower control arms. Even if its just to add to the general knowledge base.

Whatever it was causing it, if its gone now great, keep an eye on it.

Was the positive camber the same on both sides? There are only so many things that can effect both sides at the same time equally.
 
both sides appeared to have the same camber (by eyeball) so i started looking for something that would effect both sides somewhat equally.
 
I would have to say that loosening the steering shaft will have nothing to do with your positive camber/toe in problem. The steering rack bolts to the subframe. The tie rods and the steering shaft operate in different planes. It is possible that everything was bolted tightly in place while the car was in the air, and the suspension was in a droop mode.. All final suspension bolts should be tightened when the tires are in contact with the ground. I will always lower the car onto wooden blocks and crawl under the car before final torqueing of suspension bolts. On the race car, that subframe goes in and out of the car often.
 
ok, i can crawl under there and loosen everything and then retighten it. air tools are wonderful. i never thought of the difference between the suspension just hanging there and the suspension supporting the car until i tried the steering shaft bolts. you get a little frustrated and you start forgetting the order you do things.
 
Back
Top