Rear Caliper Screw F-ed Up
 

I changed my pads today and one of the bolts on the rear caliper mis-threaded. I didn't know what to do so I just tightened as much as i chould but there is like 1/3 cm space bewteen the caliper and the bolt. Any idea's or comments.

The rear caliper mounting hole tends to get chewed up over time....if the caliper's that worn, probably best to just get a new one.

Unfortunately, the rear caliper mounting THREAD is not on the caliper, but on the mounting bracket itself.

As such, purchasing another rear caliper will not solve the problem of a messed up thread.

I tried re-tapping the threads on both the BOLT and hole's thread but it won't hold the minimum torque value.

As such I purchased a NEW bolt (from Mazda Motorsports), and installed a "spark-plug" thread Heli-Coil.

Just go to your local Advance, Autozone, PepBoys, and purchase a Heli-coil 5334 "Sav-A-Thread" for under $30:

http://www.sjdiscounttools.com/hel5334-14.html

Be sure to use some oil and newspapers to catch the fall-out while you're tapping; clean it out VERY well with brake-cleaner, mineral spirits, or acetone.

The instruction say to use an RTV sealant, but due to the higher torque than a spark-plug, I used liquid metal. Also, use the LONGEST insert (you can purchase additional inserts as well).

READ the ENTIRE instructions TWICE before installing and let the liquid-metal cure for 24-hrs MINIMUM (dont' ask me how I know!).

I've been happy with this repair for the last 6-months, and I remove my calipers at least twice every quarter due to track-specific pads & rotors.

:-) neil

The rear caliper and "mounting bracket" are one integrated piece. Yes, you could fill in and re-tap, but I figured if he could do that, we wouldn't have posted the thread. :)

Rynberg,

you are correct, the caliper does have the mounting thread. I was thinking about the bracket that holds the caliper to the hub.

However, my fix is not a "fill-in" and tap, but tapping the stripped-hole to a larger size, in order to install an insert (made by Heli-coil) similar to a Timesert, but not a "Heli-coil" which is more akin to hardened wire.

:-) neil

http://www.thegrillstoreandmore.com/...cs/371722b.jpg

Ah, gotcha. Nice fix. :)

BTW: here are pics of a helicoil vs. a Time-sert:

Note: the "Sav-A-Thread" spark-plug product is produced/made by Helicoil but is NOT a "heli-coil" in the traditional sense since it IS a solid-bushing insert:
http://www.globalspec.com/NpaPics/26...ExhibitPic.JPG

Helicoil:

http://www.helicoil.cz/image/sytem/screwlock.jpg

Time-sert:
http://www.timesert.com/images/index/image003.gif

taken from timesert.com:

TIME-SERT® is a solid bushing insert. This guarantees easy installation and allows for full load use of tapped hole, ensuring protection against stress and vibration.


TIME-SERT® is thin walled due to synchronized internal
external threads. Thin cross sectional area allows for installation in areas of limited space and clearance material.

TIME-SERT® is self-positioning. Having a flange on the top of the insert will insure that the insert will have positive placement and cannot wind down into the newly repaired hole.



TIME-SERT® is self locking. On installation the bottom internal threads of the insert are cold rolled to expand the mating external threads into the base material locking the insert in place.

Ok, also does it make a difference which bolt goes one top and which goes on the bottom. One had a H ( I beleave so ) and another had a T.

I have extra calipers if you need them.

Yes, it does make a difference.

If you look at either the bracket or the caliper (I forget which), the corresponding letter is stamped to match the bolt. You can also just like at your other caliper.

:-) neil