Hey guys,

I've done research online but need some informed advice as things don't seem to be adding up.

Situation

In case it is relevant, the car is a JDM 92' FD, and last year I had the pads and rotors changed at a friends shop. The car has been sitting for a while and I recently noticed that my rear left brake seems to be dragging. Upon more inspection, it seems the pad also not contacting the rotor correctly

Rotor Wear


Upon further inspection, I noticed that the guide pins are not seated properly and likely the cause for the uneven pad contact:

Top Guide Pin


Bottom Guide Pin


The above led me to believe that the top and bottom guide pins were reversed (G and L), but the marking on the caliper and the pins actually MATCHED!

FSM excerpt




The plot thickens:

I went on to inspect the RIGHT side, and although the pins were seated well on the caliper, and there was no brake dragging or abnormal wear, the markings on the pins and the caliper did NOT MATCH!

Questions:

1) Any thoughts on what is going on? I'm thinking threads might be messed up on the left caliper but somehow the right caliper torqued itself down but maybe the threads are also damaged and I don't know it.

2) What do you guys suggest I do at this point?

Thanks guys!

T

 

Take it off and put it back on.... that's definitely odd

 

After a brake job my rear calipers stuck due to corrosion in the cylinder but I don’t think that’s what’s happening here. I agree with cr-rex that is strange. It’s hard to tell from the pic but I think it has to be something more than just those bolts causing that. Might want to call your friend that did the job and see what he says.

 

My pins were reversed on both sides and I did not notice any weird wear, just dragging and the occasional noise, IIRC. I agree with cr-rex. I'd pull those pins on the bad side and just inspect it all. If it looks ok put it back together and see what you get.

 

The fact that the bolts are cockeyed is really weird. Probably need to pull things apart and see what's up. I would also make sure the rotor spins true on the hub.

Dale

 

Beware cross-threading! I've had trouble with the female threads that mate with the guide pins. Watch out for that when assembling.

 

.

 

Hey guys - I took the pics out and put them back in and the problem is still there.

The more I tighten the pins, the more the caliper contacts the rotor at an angle which causes the brakes to drag.

1) Does anyone know if the threads are different on the top and bottom pins? The seem close, but I don't want to risk threading them into the caliper.

2) Is it possible the problem is that the piston was not backed into the caliper when the pads were replaced?

Thanks guys!
T

 

Those bolts are cross threaded, and its quite easy to do. The threads are the same but the bolts are different at the ends(one has a rubber bushing). I purchased a used caliper once that was like this...the way i "fixed" it was i held everything straight while starting the bolts and cranked them down, then the bolts were seated flat.


Also...do NOT over grease the slide ends of the bolts. The grease will pack in and push the caliper away from the bracket, which can cause the brakes to drag. You only need a light layer of grease on the metal.

 

That makes sense, being cross threaded is the only way it would get **** eyed like that.

You may be able to get the caliper to re-thread itself but you may just want to start looking for a good used caliper. It's probably going to have problems long term.

Dale

 

You guys are right, they are cross threaded unfortunately. I'm going to try re-threading them like you mention K-Tune.

That said, the guide pins are still reversed on the other rear side. Should I switching them at this point, or should I just let it be?

Also, just to confirm. I don't have a rubber bushing on either pin, but I believe the RX8s do. Is that correct or do I have the wrong pins?

​​​​​​​

 

Could also be that the caliper needs to be rebuilt. The piston could be 'hanging up' i.e. not sliding smoothly in it's bore and causing the brade pad to not be squeezed onto the rotor properly

 

If you look at the diagram you posted each bolt is labeled as G and L. L is the lower bolt which has a rubber bushing.

Here's a thread that talks about it, you can see another cross threaded bolt in there as well.
https://www.rx7club.com/suspension-w...es-top-727459/

 

lol that's my old thread

 

I had a similar issue where rebuilding helped it however mine was a bit more chaotic in that it constantly lightly dragged and trashed my pads. Rebuilding the rear calipers helped and flushing the system as it was full of random sandy crap. iirc my bolts also mounted flush though... If you struggled trying to rewind the stupid piston backwards(I broke the tool that's supposed to do it) you may need to rebuild it. I ran my old pads until I could properly seat the piston fully back. Check the backside maybe?

If it's only the outside dragging like that maybe it's just the pin getting caught up. I took a green weenie(brillo pad?) to mine to clean off abuncha black crud(old boiled grease?) off the pins and they slided super easy without any fluid pressurizing it and a light sheen of grease.

If it's stripped maybe try using a helio-coil I've never personally used one but they seem legit.....

 

So here is an update guys.

I took everything apart and noticed that there is no rubber bushing on my lower pin as per the pic in gracer's thread. Maybe this is causing the caliber to move around the pin?



Also what I found is that when I screwed the piston back into the caliper (as the FSM says), then reassembled it all, and the rotor is no longer dragging.

I'm not sure if this will hold though, will the piston just work it's way back out eventually?

Thanks guys
T

 

The piston is designed to screw itself closer to the rotor just enough to eliminate excessive piston movement to bring the pads into contact with the rotor. If everything is working as it should, there will be a very light drag on the rotor, but little enough that you should be able to easily turn the rotor by hand. Too much clearance will result in a low brake pedal.