I have already installed 7.5mm shims in place of the 4mm factory shims to adjust the camber after I lowered my car, but I need to go a little more - I remember reading that someone had installed 9mm shims on both sides (probably the max you can go without replacing the bolts/studs) to compensate for the H&R lowering springs so hopefully that will work for me as well! BUT, I keep hearing that you can't double up shims (such as using a 4mm and a 5mm instead of just one 9mm shim), but I don't know if that is a fact or just an idea someone had (I haven't seen it definitively documented anywhere).

So, any engineers or Jag techs that can answer the question for me - what is the risk if I had two shims installed instead of just one? Are there any TSB's that speak to the issue? I am not sure where to get a 9mm shim but I can easily get a 5mm shim and add it to my oem ones but obviously I don't want to do anything that could cause a breakage issue - I just can't see what problems it might cause.

Thanks!!!!

 

blindside,
When you consider the mechanical set-up, I would say NO to doubling up Spacers.

The reason is that the transmission of Torque from Differential to Half-shaft is primarily reliant on clamp friction and not the four bolts.
A secondary spacer will introduce another interface that can slip (Same principle and outcome as adding a Washer to a Bolt)..

The risk would be slippage, and high shear forces applied to the bolts.