Alignment Shims

I went thru this issue between Firestone and Toyota. F saying they could not bring the car into the T specs without shimming and T saying it the car was in spec. The T dealer printout showed readings out of spec but within tolerance (?). F cut me a deal since I buy all my tires and service there and also sold me the lifetime 4 wheel align. Good investment as I am on my 4th set of tires (always BrStone OEMs).

 

See
EZ Shims - 75200-75400-75800
which says you may also need a 75970 caliper spacing kit.

IIRC, someone has gone through this on a GenIII and posted about it.

Edit: This thread had some experiences with shims
http://priuschat.com/forums/gen-iii...-shim-rear-wheel-alignment-advice-please.html

 

My Gen2 would not track correctly, tramlining, wandering all over the road, poor resistance to cross winds, etc. The problem was not enough toe on one side in the rear, similar to what you have. I ended up increasing the toe to around .20 on each side which solved the problem. I couldn't find anyone willing to do the job so I made my own shims and installed them myself.

But the Gen2 had drum brakes on the rear so installation was very easy. Just take 4 bolts out and slip the shim in and put the bolts back. As you mentioned having disk brakes you will need to shim the caliper.

The difference in handling on my Gen2 was greatly improved so I would say go ahead and do it. Looking at your alignment sheet I think I would just do the right hand side.

EDIT:

I checked my maintenance manual cd for linear solinoid calibration and found this on page 942:

"(a) Perform initialization and calibration of the linear solenoid valve when the brake booster with master cylinder (skid control ECU, brake actuator or pressure sensor), brake pedal stroke sensor or brake pedal is replaced."

Maybe shimming the caliper would not require a linear solenoid valve calibration. I also noticed there are two procedures, one using the Techstream, the other not using it.

 

I shimmed the rear of my UK gen2 Prius to correct excessive camber and found that calliper shims are not required. The calliper moves with the brake back plate staying in alignment with the disc, that is the complete hub backplate calliper assembly are all moved together as one, away from the axle beam assembly by the shims.

 

Well yeah, I have had some experience with this shim business- all of it bad but I don't have enough evidence to blame the shim. My 2010 was showing abnormal rear tire wear by about 5k because the rear alignment was way outside of Toyota's absurdly wide tolerances. The axle should have been replaced but Toyota refused and installed a shim on one side. I came out of the stealership with a readout showing that all was well but the car promptly destroyed both rear tires. Back on the rack the readings were even crazier than before. What happened? I have a good idea but in the interest of brevity I'll just say that the axle and all tires were replaced and I motored out the door with yet another readout claiming all was well. Due to time and health constraints not enough miles have elapsed for me to make any judgement about the success of the latest operation. The post mortem leads to a couple suggestions; instead of breaking the "petals" out of the shim, drill holes with a dremel tool just the size of the bolts to leave more intact bearing area to more evenly distribute the "crush" forces on the shim. (I suggest buzzing holes with a dremel burr or similar rather than drilling because these shims are a brittle mix of metal particles suspended in hard plastic and I suspect drilling would shatter the shim.) As to the caliper-to-rotor alignment conundrum I would suggest feeler-gauging the caliper support to rotor clearance before disassembly and duplicating this dimension with shims when reassembling. Don't bother with the shim manufacturer's shim washers- they are overpriced bits of useless plastic with the wrong dimensions for this car. Based on comments from other users of these humorously named E-Z Shims you will want to be sure to retorque the bolts a time or two (or three) because it seems that the plastic-metal mix "flows" for a while before eventually stabilizing.