arenared

Can you measure the amount of thread engagement of your stock wheel bolts into the wheel hubs when mounting the wheels? The stock bolts are M14x1.5 so either the number of turns or mm's will work. (Actually, it's far easier to count the number of turns from when the bolts just start to grab to when they seat.)

The reason I ask, is that I recently figured out I've only got about 8mm of thread engagement, whereas it should be 12-14mm. I'm trying to figure out if it's the wheels or aftermarket 2-piece (aluminum hat) rotors that I have. I suspect it's the wheels since I have the same inboard clearances since before/after the rotors. I think.

Thanks in advance.

Ray S

I have RG5's on my 996. I don't have exact measurement on the thread engagement I am getting but I'm almost positive it is the same as the stock wheels (it feels the same whenever I swap them out for snows).

If your hats are thicker I suspect the difference may be there.

arenared

Thanks, Ray. I thought they were about the same, too, and never gave it a 2nd thought. The wheels are really close to the suspension (only a mm or two clearance). With my (GiroDisc) rotors, the clearance is still about the same. I still have the stock rotors, but I don't know if I want to pull the calipers and rotors off just to measure the hat thickness since, in any case, I need longer bolts.

I found H&R +7mm bolts here: http://www.lpiracing.com/H-R-Wheel-B...-64p152903.htm for a pretty good price. Technically, I could just use the Porsche +5mm bolts, but I want to have a few mm extra to be able to use 3mm spacers. Right now, I am running 295s which are on the narrow side, but there are more choices in R-compounds in 295s and some are really wide. Just 5mm longer will give me 8+5=13mm which is not enough for even a very thin spacer. Of course, it's better than what I have now.

arenared

Hi Ray,

It's not the GiroDisc rotors. I just measured them while I had my wheels off for new tires. I also measured the stock rotors. They are both 6mm thick. I shouldn't have questioned them since Martin at GiroDisc is an **** perfectionist :-)

I doubt 8mm of engagement is "stock". General rule-of-thumb is same amount of thread engagement as bolt diameter. I found a page on H&R (http://hrsprings.com/application_ele...ernotes/3.html) which says for an M14 x 1.5, the min is 12mm.

Anyway, it might be worth checking and reporting back what you find.