jyoteen

I've replaced the pads/swapped them out/changed rotors so many times, but tonight the ONE caliper (passenger side front) that always gives me a tad bit of trouble got cross threaded and as a result the upright? threads are screwed. I got the other three corners fine.

Also, in a brain fart moment, I had the brake system pressurized and popped off the caliper and of course, the caliper piston almost popped out completely. Brake fluid everywhere. Thank goodness I had 5 liters of Motul handy.

I'm guessing the 996 upright is aluminum?

For the life of me, I cannot understand why the bolt is the harder metal if that's the case.

Can this hole be tapped and a larger caliper bolt used? Who has done this, if it can be done.


If not, what am i looking at for cost of replacement? This royally sucks because I just got alignment/corner balance done. Uggh

Of course, now i'm going to miss my track event most likely on sat/sun at Sears Point.

redridge

looks like this might be a good time to mod up to gt3/tt calipers and wheel carriers, they pop up on ebay or post a WTB in the classifieds. I seen the whole setup as low a $1800 a year back. Sounds like someone forgot anti-sieze on that one bolt.

ivangene

snap a photo of the problem spot, there may be a way out of it depending on how agressive the nut behind the wrench tightened the bolt while it was crossed... I deal with these type of things from time to time and there are several ways to fix them...

1. IF only the first couple threads are messed up AND there is enough meat for the bolt to engage on the ones left, you might be able to run a tap thru the hole (from the backside is best if the hole goes thru) and then just be really carefull starting the bolt untill it chatches the remaining "good" threads
2. IF someone wrenched the cross bolt way in and destroyed the threads, you can get a re-coil kit for the hole. It requires a very specific size, straight hole be drilled exactly where the old hole was, then a very straight re-coil tap (bigger than a regular tap) thread the hole making sure to produce clean threads, last insert the coil for "new" threads.. Coils come in several types, lengths and with or w/o locking features... standard is fine and you can ask around but I know for a fact that if done properly the resulting threads are actually stronger than the original ones... obviously you have to get the right kit for the screw as screws come in different sizes, so do the kits, you may need to order it, or it might be a stock item at the local parts store. Take the bolt with you (unless you know the size for sure)

http://www.youtube.com/watch?v=AMbcUa7RAk0
http://www.youtube.com/watch?v=RFYa6sjhh_E




3. The last ditch effort is to replace the part as you already know..

post a picture and maybe this wont be too bad of a job, and remember ALWAYS get screws in several threads BEFORE using any wrenches!!!

I think you can save this - and still make the track day.... but dont do it hastily as you will be really in a bind then!
Ed

jyoteen

Ed,

thanks for the help but I'm pretty sure option 1 is out of the realm of cures. I had the bolt pretty far in. I will investigate again this a.m.

In terms of replacement, the part is aluminum (c4s = same chassis/brakes as the turbo) and something they don't stock. The part is $800 plus $108 for the wheel bearing.

And of course, they'd have to order from Atlanta which takes 5 days. Expediting the part only costs $88 and be here tomorrow a.m. so that's good news.

I'll go try to find a recoil kit.

Thanks again.

ArneeA

Try Helicoil or Timesert

Orient Express

+1 on this. We use these all the time on spacecraft where you can't just get another piece.

Before you do this however try running a tap through it to see if that will clear out the threads.

GMS

Timesert is the way to go, you will need the longer insert (the normal short one isn't long enough)
And replace all four caliper to upright bolts.

redridge

you think these helicoils will do fine under high temp and with 63lbs of torque.... I dont like the idea... Is it the front brakes or the rear.

Maybe the rear you can do it, but I wouldnt do it with the fronts... overall I still dont like the idea

Ubermensch

Timesert as suggested above. I've used them in high heat applications with no problem. I can't speak to high torque applications.

ivangene

ran them on exhaust headers for 3 years and they never came loose or siezed up.. (2 of 6 holes were "fixed") That should be hot enough!!

Ask an engineer.. butu I would not hesitate to push them as hard or harder than stock... IMHO

ArneeA

I also agree on the idea to try and re-tap if there's enough meat.

jyoteen

ok, got a hold of the timesert. I have 2 hours to make this work. Otherwise, i'll have to do OEM. It can't be worse.

jyoteen

took the caliper off and did a thorough cleaning.

Even if the top bolt was catching ok, the receiver threads looked suspect so I just decided to play it safer.

Car at the dealer now.

Ryan C

Glad to hear it, brakes are a serious issue and any problems should really be dealt with the properly. I don't think I would put a heli-coil anywhere near a brake caliper, timesert yes, if it's the right one. But I feel that you've made the best choice. Safety first, you're not the only one out there on the track.

redridge

yes.... the front brakes does 80% of the stopping power... why compromise the design with some band aid fix.... you will have peace of mind this way.... though since you track... I wouldve done the BIG REDS