I bought a set of 15" Torq Thrust wheels from Craigslist that have brand new 215/70/15's mounted on them. They look great up front but while adjusting the caster I can only get about negative 1/2* before they want to rub the bottom of the valence while turning during test drives. I need to get into 1* or 2* positive caster for better handling. Question is: Can I shim the front bolt on the upper control arm that much to make these tires work, or would I be better off just getting lower profile tires (less overall diameter). I'm leaning towards switching tires cause I don't know if shims will add any unnecessary stress to the shock towers. Whatcha think?
You can shim the upper control arm unevenly (more shims on the front that rear bolt) Thats a HUGE tire for the front. I've maxed out at a 25.6" tall tire. You are at 26.85". Your wheel offset will also make a difference.
Must be because 1 degree positive caster isn't very much at all. Positive caster is bringing the top ball joint further to the rear than the lower ball joint and should actually help in keeping the tire off the valence - I would think at least
Hmmm, I've been running 205/70/15's on mine for a lot of years with 2 3/4* positive caster and they're 1 1/2" away from the front of the wheel well.
Because they came already mounted on the wheels and thought I would try and run them. I got a good deal on the wheels, the tires happened to come with them. I was already leaning towards getting new tires and now I'm convinced it's the way to go.
I'm not quite sure how you guys are figuring to change castor by any larger amounts with shims on the upper arms mounting bolts.. but you'll never accomplish such changes by doing so without using hellaciously large amounts of them. And then you'll also affect the camber curve in the same process too. Certainly won't hurt it.. but it will change the alignment spec's to be sure. I would do 2 things here if you're serious about improving the front suspension of this car while maintaining the use of stock parts. First and most important would be to do the Shelby(Arning) drop while also incorporating the rearward offset of both arms in the process. 1/8 to 3/16 will make a noticable improvement here and also gain you some of that clearance back in the process. Next easiest thing to do, especially while you've got everything apart, is to make sure your upper a-arms cross shafts are both offset to the rear rather than being centered. Many stock and aftermarket units come that way from the factory for this very reason(which is the only reason why they are marked "left and Right") and to help maintain a better feel for the on-center tracking that increased castor is responsible for. Using both of those tricks will drastically improve the higher speed stabilty of these old cars and give you closer to that newer car "on-center snap back" during low speed menuevars.. ei; coming out of slow corners. These techniques work so well together in combination that I'll never consider using a stock configuration for any car that I plan on keeping for the longer term. The work involved is easily worth the effort in the long run.
Good advice, thanks. I'm finally getting this thing on the road after a drum to disk conversion with a complete front end kit replacement and I'm really not into tearing it back apart again right now. Maybe after I service/adjust the tranny, add posi with a gear change, replace leaf springs/shocks and take care of some minor electrical stuff I'll be ready to go back to the front....
