Rear Wheel Alignment Solution

[Indy John]

Many thanks to Bob Wilson for his 6/20/08 post. Like at least several of us, I noticed out-of-spec. rear wheel toe and camber on the print-out from a routine wheel alignment of my Gen. II Prius. Bob mentioned EZ Shim #75800, a product of Niwot Corp., Longmont, CO (dba Specialty Products Company), 800 525-6505 or www.spcperformance.com. This clever device is two-sided plastic disc with numerous wedge-shaped segments in varying thicknesses. The intersection of the desired toe and camber corrections on the chart provided corresponds to numbers on each half of the disc. By rotating the disc halves until the desired numbers line up, a custom shim is created that can correct plus or minus 1.5 degrees of camber and plus or minus .75 degrees of toe. And no fear - the chart reads in decimal inches, fractional inches, fractional degrees, and degrees and minutes. All that remains is to snip out two wedges at each bolt hole location (none of the templates on the chart match the Prius) and some of the outer edge to clear the brake lining inspection port. Well … not quite. I found the inner diameter of the shim just a smidge too small to clear the diameter of the hub. Just a little bit of touch-up grinding with a stone in a die grinder did the trick. The best part is the cost – a whopping eight dollars and change at a local distributor (check the website), or double that to order direct from the company. OMG! A few bucks and an hour of my spare time (a second one would be much quicker, of course) compared to trying to beat a new axle assembly out of Toyota (and forget that if you waited more than 12 months after delivery). The four hub bolts are 12mm and come out from behind. They’re just long enough to re-assemble flush with their threaded holes. I made a slot in the brake line bracket with a cut-off wheel. That allowed the brake drum/hub assembly to be positioned out of the way - it would have been more difficult otherwise, and it would be easy to bend or break the metal brake line.

My fingers are crossed that a follow-up alignment check will show the left/right rear wheel numbers to be nearly identical and well within spec. (I’m waiting on the alignment until I can obtain a pair of bolts for the right front to bring that into spec. as well.) I don't think it's my imagination that it seems to track better and be less susceptible to cross winds. (It was already improved from its as-delivered wandering condition by the stiffer replacement brace, Michelin-X tires from Sam’s Club, and front toe correction to .05 degrees on each side.)

[dogfriend]

Originally Posted by Indy John

I don't think it's my imagination that it seems to track better and be less susceptible to cross winds.]

I doubt that it is your imagination either. My car had very strange handling in crosswinds as well when the rear alignment was out. My toe readings were LR .15 deg and RR .40 deg. I used a metal shim supplied by Galaxee and her DH to correct the RR.

I may eventually order the plastic shims so that I can get the camber equal on both sides, but mine is only 0.1 deg different from side to side, so its not a high priority.

[Huntceet]

I've been installing full contact shims of this type for years. One caution, look up the torque for the spindle bolts and use a torque wrench. You can crush the plastic shim if you over torque.

Rod

[Patrick Wong]

45 ft.-lb is the torque spec for the four bolts that hold the wheel hub assembly to the beam axle.