Hey guys, how hard is it to rebuild the 300zx 4 pistor calipers? Also, where can I get parts for them such as pistons, seals, retaining springs, etc.

Is there a write up showing how to rebuild the calipers?

If there is, can you please post it here, I'd really appriciate it. Thanks in advance.

 

PM Dubbya, hes rebuilt a set before.

 

Sure have. I dont think you will be able to get new pistons. The "rebuild kit" comes with inner seals, piston boots, piston boot retaining rings, and bleeder caps. You can buy it direct from Nissan. Basically all you need to do is pop the pistons out of the caliper with compressed air. This becomes a little tricky since its a 4 piston set up. I had to get pretty creative with clamps to get all of them out one at a time. Then its just a matter of inspecting the bores and pistons for any signs of corrosion. I used a metal polish to remove any rust or dirt then just reassembled. DO NOT unbolt the caliper into 2 pieces. Nissan does not provide new seals if you do this, and the chances of ending up with a leak are great. I did this with mine because I didnt know any better. We shall see if they are going to leak or not. Let me know if you need any more info.

 

if you end up unbolting them tfrom each other i found a site that sells the same size o-rings that were there in the first place.

 

Orly? Do tell. I think Matt Blehm would be very interested.

 

Ok thanks, I never messed around with real car brake calipers, only ones the ones that I use on my downhill bike (6 piston calipers).

How exactly did you pop the pistons out? And is it hard putting them back in? At what PSI did you pop them out?

 

Basically you need to force the compressed air into where the brake line goes. Im not sure what PSI, the tank was set for 90, which Im sure is way over kill. They are not hard to put back in at all.

 

Yea but will all pistons pop out at the same time? What happens if one pops out and all the other 3 are still intact? Wouldn't the air just come out of that one piston hole and not bring any pressure to the other 3?

 

Correct. This is where you need to get creative. I basically popped them out one at a time. I used a piece of wood and a clamp to secure 1/2 (2 pistons) of the caliper. Then I forced air into the caliper popping 1 of the 2 remaining pistons out. After that I reinserted the popped piston into the bore. Dont push it all the way back in. Just enough to slow the air flow. Finally I secured the piston I just popped out with a seperate clamp and popped the next one out. I know it sounds confusing.

You will have to rebuild each caliper one side at a time.

 

Oh I get it, yea that sounds pretty simple.

Basically, pop the pistons out, replace the seals, check for corrosion...

I'm going to try to get all the pistons out at once because I want to get the calipers powdercoated it.

Can I just throw them in the powdercoating oven with out the pistons? Will the seal in the middle get damaged? or should I take the whole thing apart.

 

DO NOT take the calipers completely apart.

hell, I don't even bother pulling the seals out of the piston bores when powdercoating. just remove the dust boots and mask off around the edge of the piston.

remember, brake fluid boils at about 450 deg F.. the good stuff boils at 550+..
you cure powdercoat at 350-400F. Thus, the seals inside the calipers are designed for greater temps than you will be using to cure the powdercoat. they will have no problems...

It's a good idea to tear them down and rebuild them anyway though.. if you do that, just pull the calipers out and mask off the piston bores then powdercoat... clean the bores out, lube them with some brake fluid, then reinstall the seals and pistons. veyr easy to do.

just make sure you cured the powdercoat for the proper time amounts, or the brake fluid will damage the finish. also be sure to clean them off with water as soon as you're done rebuilding, to make sure the powder doesn't get damaged.


And no, I don't need the o-rings anymore. I found some Viton o-rings from a leftover project a while back at one of my previous jobs.. just got lucky and they fit perfect.

 

Thanks alot guys, you've been very helpful !

now.. for the final question

do the 300zx calipers come in 26mm or 27mm? or both?

 

26mm and 30mm

 

Hmm, I thought the calipers from a 90 300zx NA are 27mm... so they are 26mm for sure?

 

On the following site they explain and show the differences.
http://importnut.net/300zxbrakeswap.htm

 

i jsut finished rebuilding mine. everything new except the pistons. look for my thread