Wheels, Tires and Alingment. My Post-mortem views.

Deep6

Registered User
Hey all,

I finally got the vibe that I had from my new 17" tires sorted out today.

To sum things up, when I had the tires/rims shipped out to me from Discount tire direct I paid extra to have them "road force" balanced.

Upon bolting them to my car, I still had persistant Vibration at speed. I had a trusted mechanic at a Ford dealership balance the tires again for me and he noted that one of them was bad with 62lbs of road force. The best he could do was 48lbs. According to his Hunter 9700 machine. The other 3 tires had readings above 20 and one above 30lbs. of road force. So he went ahead and re-did the other three and got them down to 18, 16, and 10lbs.

I called Discount tire and they were extremely cool about it. They sent me a new tire along with a new lug set (broke the key and one lug from the set they sent me).

One problem that my dealership friend had was that he didn't want to attempt to align my wheels due to the fact that the rims I purchased didn't have a "Lip" on them. This prevented the alingment heads from getting a good grab around the rim. He was afraid they would pop off and stratch the rim.

So I took my car to a shop that specializes in performance rim/tire combos. This guy seemed pretty knowledgeable about the whole thing and directed me by telling me that his hunter 9700 machine is calibrated on a weekly basis whether it needs it or not. At the dealership this may or may not always occur. So i don't blame my dealership friend for doing his best on a poorly calibrated machine. He also had the proper tire attachments for his alingment heads so he wouldn't scratch rims. He strives to get all of the wheels/tires under 10lbs of Road force for the best ride possible. Well he sized up my front tires and got them both down to 9lbs and 7lbs respectively. But he also noted that the 5.5mm spacers that I was using to keep the tire from rubbing on the bottom of the upper ball joint were probably causing vibrations. He decided to ground down the protrusion under the ball joint by about 1/4". he did that for free. Took him about 2 minutes on each side.

No more rubbing up front without the use of spacers. He also mounted and balanced the new tire over from the bad tire. When he measured the rim runout and road force variation, the best he could do was about 24lbs of road force. He said I wouldn't feel much, but it was more than he'd like. He attributed this to poor rim quality and he noted that my Fittipaldi rims are actually manufactured by the Enkei corporation and most of the rims made in Asia are junk (except for the japanese rims of course... he just had to put his two cents in for SSR rims)

When he did the alingment though, he was able to give me about 0.8º of negative camber up front (as recommended by Ed Nicholson) but in the rear he was reading 1.2º negative camber and Ed strongly recommended only about 0.3º for the rear. According to his information on his Hunter alingment machine, the adjustment for the camber comes from the eccentric nut/bushing on the inside of the upper control arm in the rear. But when my car was up on the lift, my 1995 was equipped with regular, non-eccentric bolts and bushings on the inside of the upper control arm. (My car had previously had a Ford dealership do a "TCCOA Agressive alingment spec" on my car about 2 years ago.)

He also said I was running about 1.2º of Toe-in. On the rear. So i guess I'm asking now... how does one adjust rear Toe and camber on a 1995?

He left things as is with the rear since he couldn't adjust anything or at least thought he couldn't adjust anything. He did claim that if I found out a way to adjust the rear alingment, he would re-do it free of charge.

Last but not least he did give me poopy about running 255-50ZR-17 tires on a 17x7.5" rim. He was like an 8.5" rim is optimal. As a demonstration he got out of the car and walked to the rear bumper and shook the car side to side and there was a couple of inches of play in the car's side to side motion. He noted that he'd seen much worse, but that with this tire/rim combo, I wasn't getting the most "bang for my buck" as far as responsiveness was concerned. He recommended that I run 225mm tires but that is no better than stock IMHO. But he stated that "wider isn't neccessarily better". But I do think that knowing what I know now, I'd probably have gone with the 17x8" rims I was looking at also and the 245mm tire. Think it's too late to send my tires and rims back to discount tire for a refund and start over? I've only put about 300 miles on them... And considering that one of the rims is borderline anyway....
 
The guy was right, putting 10" (255mm) width tire on 7.5" rim is not a good idea.

I'm running 17X9 Cobra R's with 255/45/17 - which to me is optimal, even though it does lower the car another 1/4".
Just a slight bulge with minimal lateral movement, which in turn means minimal transitional transfers in the esses.

Lee
 
Thanks Bruce!

Wow, that really is a great article. Especially for the folks who've got slammed birds! And the modifications are pretty easy. If you're handy and don't mind spending an afternoon under the car, you can get a lowered bird "back to driving normal" in a few hours.

Question though, what did you use to elongate the holes? A dremel? Hand files?

The point of welding the washers on... is to give back the strength you took from elongation? Or just to have it in a new "dead on" position?

I printed up the pictures of the rear Camber adjustment with the "hidden eccentric" and of the lower "H" arm with the Toe eccentrics. I'll show him those pictures and I'm sure he'll give it another shot.
 
I don't have a dremel, so I used a jig saw. I decided on where I wanted the hole to extend to, then took a washer that had the same size ID, and placed the washer so the hole was in the proper place. Shot a spray of whilte paint in the hole to marke what was to be removed. I then made several small cuts as in the sample below. I used a round file to clean up. The washers are used to make a new hole for the bolt that replicates the original. It should be tightened, but NOT welded till you have the proper camber, with the adjuster at the mid point.

cuts.jpg
 
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