Rear alignment - shim kit numbers
 

Hi,

After installation of new tires, my left rear wheel alignment was off, 0.30 degrees, but Toyota who sold the tires and installed them, said, "Fo' getta' 'bout it." So when I had the first tire rotation, although not bad, there was a slight, asymmetry wear, 0.77-0.78.

I bought the Firestone "life-time" warranty and decided to fix the problem with a shim kit. A shim kit consists of a set of metal tabs:

1/128
1/64
1/32
1/16
1/8

The problem is there are no guidelines on how much correction each set of tabs provides. Installing the shims is about as difficult as changing a tire with four bolts on the wheel assembly to loosen and torque-tighten. I have an NHW11, 2001-2003 Prius and after multiple visits, this is what I found:

Toe (horizontal adjustment):
1/32 ~= 0.60 degree (0.30 -> 0.90)
1/64 ~= 0.30 degree (0.30 -> 0.01)

Camber (vertical adjustment):
1/16 ~= 1.7 degree (2.0 -> 0.3)
1/32 ~= 1 degree (2.0 -> 1.0)

http://hiwaay.net/~bzwilson/prius/pri_shim_010.jpg

The Firestone alignment systems, two separate shops, agree that the car is right in spec. However, I'll be doing some high-speed, temperature profile tests to further tweak the numbers.

My goal is to have an even temperature profile across all five treads for all four wheels. This should minimize local stress for longer tire wear and hopefully, the lowest possible drag. I'll then take the car back for one more "baseline" measurement and be done with it.

Bob Wilson

Re: Rear alignment - shim kit numbers
 

What car are the shims for? I thought that no one made shim kits for the Prius.

Wayne

Re: Rear alignment - shim kit numbers
 

It is a generic shim kit, not for any specific vehicle. I've still got a bunch left over. Any interest?

Bob Wilson

Re: Rear alignment - shim kit numbers
 

Maybe the 1/128 and 1/64. My rear is currently;

camber(degrees) -.9 left / -2.1 right

toe(degrees) .17 left / .21 right

I'm trying to get the camber to -1.5 and the toe in the range .05 to .09 (straighter the better).

The alignment at the Toyota dealer today was perfect in the front; -.6 camber, .02 toe. Once I can get the rear done I'll be a gliding fool.

Wayne

Re: Rear alignment - shim kit numbers
 

PM an address and I'll send you four of each including a pair of 1/32. When you get it, put a couple of bucks in an envelope and send to me.

Bob Wilson

Re: Rear alignment - shim kit numbers
 

Bob,

I PM'ed you via PriusChat.com....I'll gladly send you a couple of $$ for the shims you think I need. Trying to correct my right rear on a 2002, which is currently .24 toe (.02 above high-end spec). The camber is good, at -1.4

Thanks,

Randy