Never use a torque wrench on a brake hose bolt thats being bolted into an aluminum caliper... For years and god knows how many calipers, Ive always crushed the washers by eye using a 3/8" ratchet, and eventually by feel since the threads are so delicate.

I put my nice new PBRs in and one fitting wasnt quite tight enough and leaking ever so slightly after I drove the car. I made the ultimate mistake and actually checked the directions rather then throwing them out with the box like I always do and torqued it to within what was recommended, which Ive forgotten since Im so damn angry. Needless to say, the threads stripped in one of my calipers, ruining it, and now the car is down again... I dont think it was the wrench since its never broken or damaged a bolt.

 

I actually tracked down the instructions that came with my front calipers (the rears came with the faulty instructions) and they came with a very stern warning to not exceed 17 ft-lbs of torque (still too much IMO). I took all the rest of the fittings off to check for damage and from what I felt, it was about 50 lbs of force on my short wrench to get the bolts loose, which is around 18 ft lbs, which was enough to damage the threads on the front caliper. For yucks I checked the Chilton manual and they state to tighten the fitting on the PBRs to 18-30 ft-lbs!!!!! From what I felt it probably only takes around 8-10 ft-lbs to establish crush, maybe a little more. Another very hard learned lesson, as usual.

 

Sounds like Heli-Coil time...

Might not be a bad idea to do both sides.

 

Im probably just going to order a partially loaded caliper or calipers if the other side appears damaged and keep the old repaired ones as spares.

 

Heli-Coils are usually a WHOLE LOT stronger than threads in aluminum....

A better idea might be to run the "repaired" ones, and put your new onees on the shelf.

 

Good point... The larger dia. threads for the helicoil will be stronger so itll be harder to extract the threads. Didnt think of that.


What thread are they? M10 x .75?

 

You WOULD ask that!!!

I don't know for sure, but that sounds about right. It's definitely some kind of a metric fine thread.

Last time I needed some of those screws, I found that VatoZone and Advance both had a bin of those drawers behind the counter, that had them in it. Maybe you could go there at a slow time for them, and pull a caliper, and match a bolt to it, or somehting like that. Or, if your car is down, just take one of your bolts and use the thread gauge.

 

M10 x 1.0 fellas, I just coiled a couple calipers myself.

Ed

 

Thanks... I ordered a replacement caliper in case something unforseen happens (more like when something unforseen happens).

What is the actual listed torque for that bolt, just out of curiosity? Is there a value? Seems like the threads can be both lubricated or not depending on how/when the install is done, which is probably why the front leaked to begin with. All new hardware for them vs. just a replacement for the rears.

 

I noticed on install that one of the bolts in the rear right caliper didnt feel quite right when I was threading it in so I took it out to inspect and sure enough, the threads where previously damaged, so maybe this was a blessing in disguise... who knows.

Ed, how did you go about dealing with the calipers? Do you helicoil with them fully disassembled? Assembled followed by some form of a flush to remove contaminates?

 

Everything I've seen is 12ft-lbs, no more. I repaired mine when they were fully disassembled then I blew them out with compressed air, washed them, and hit them with air again. If it was leaking the issue could have been a faulty or wrong size crush washer, or as mentioned if the threads were buggered up, not letting the banjo bolt do its job.

Ed

 

When you install new (copper) crush washers you should first heat them with a propane tourch till they glow so the copper goes 'dead soft'. When you get new washers they are to hard and require more torque.

 

That explanes why they stripped. I heli-coiled the front one and it seems to be working. As for the rear one with the damaged threads, I just grabbed one of my originals that was still in good shape and just rebuilt that with all the new parts.

Zip,

I didnt remember to aneal them this time around. I did that the last time the old calipers where serviced, and compared to this time, it did seem to make them a little easier to crush. Although on the one that was torqued to what was recommended, the crush washers where totally pancaked, so that was defiantly too much torque. In reality, though, I probably should have used the aluminum washers instead with the aluminum calipers, as they are much softer.