Front 280ZX Brake Problem

[GoGoGo]

Beyond frustrated at this point so any help would be greatly appreciated. Pulled into Dean Sherman's garage this morning to start working on some long overdue projects. One of the first things we started to take care of was upgrading my front brake pads from some cheap Centric pads to Porterfield RS4 pads along with installing speedbleeders all the way around. Back story is about 8 months ago I rebuilt my rear drums, installed a new 7/8 master and put 280zx front struts and brakes on the car. The 280zx brake setup was used but had fairly new slotted and cross drilled rotors (0.75 inches thick). I remember at that time having to struggle to put the caliper with pads onto the rotor. It was like the thickness of the pads made it very challenging to get the assembly onto the rotor. Dean and I struggled back then and finally got them on and everything worked fine for the past 8 months.

 

This time, we had the exact same problem! PITA to get the caliber assembly with pads (yes we pushed the piston back all the way) onto the rotor. Finally resorted to grinding down part of the bump on the back side of the pad that goes against the piston. That and a soft mallet got them on and once on they turned freely. So we go to bleed the brakes and once that happens the front brakes lock up and the rotors are very hard to turn by hand. Here is what we have tried and the results:

 1. Removed speedbleeders and put stock ones on back on and no change. 

 2. By slightly unbolting the caliper and using the screwdriver to move it around the rotor frees up and stays that way until I push on the brakes and then they bind up again.

 3. Back brakes are fine and not binding. 

 

My main questions are why, in the first place, has it been so hard for us to even get the new pads onto the rotor in the first place?! Every other car you push the piston back, swap the pads in and the caliper easily slides back into place. Wondering if this has to do with the master cylinder? It was cheap through Rock Auto but still.....it was working fine when I pulled in the garage this morning. What are we missing? Anything else to try?

 

Thank so much in advance!

[datzenmike]

Bind up? Maybe too hard to turn by hand but will be easy for the car to roll?

 

 

All I can add is they are non stock parts. Slotted and drilled? The stock ones are not this way. Maybe rotor is thicker than stock? Maybe it is offset to one side?

 

Back in the day I changed my B-210 pads and no way would they go on. I got better ones and found the pad was maybe 1/16" thicker than the proper pad.  Maybe pads are too thick. Maybe the new pads just grip more.

[datsunfreak]

Maybe rotor is thicker than stock? Maybe it is offset to one side?

 

FYI, stock thickness is 0.76"

 

 

The 280zx brake setup was used but had fairly new slotted and cross drilled rotors (0.75 inches thick). 

[Ranman72]

I was thinking maybe the new pads have more grip therefore making it feel bound up by hand but might role more free once driven and broke in 

Not sure why the hard time installing calipers though 

just my 2 cents 

keep us posted 

[datzenmike]

After market parts.

 

Rotor may be offset slightly? If same thickness rotor as stock then what's left? has to be the pad thickness or thicker backing plate the pad is on. Sometimes there are anti squeal shims on the back? Is the piston surface clear of any anti rattle compound? 

[yello620]

My bet is on wrong calipers.

 

With the pistons pushed in all the way and stock thickness rotors, there will be 1/8"+ of clearance between the pads and rotors until you pump the pedal a couple of times to get the pads touching the rotor.

[datzenmike]

Well we have to go with the info supplied, and that is that they are 280zx struts. The evidence.... after market drilled and slotted rotors and pads would suggest it's one of those. After market stuff is always the first thing to suspect.

[GoGoGo]

Thanks for the replies so far! Looks like the rotors are within spec of OEM rotors so we're eliminating that as a potential problem. They were turned right before we installed them as well. The entire front strut and brake assembly came from the same 280zx and was working just fine before the new pads went in. I only had the previous pads for about 1000 miles and they were virtually the same thickness as the new Porterfield when we put them side by side. 

 

After I left last night Dean threw on some worn down pads just to see what would happen and it sounds like after having to pump 4 or 5 times to adjust for the thinner pads the brakes work and don't lock up anymore after releasing the pedal. Clearly don't want to drive around with old pads so I think we're going to try to remove the anti-squeal shims off the back of both pads and see if that gives us enough room to stop them from locking up. 

[datzenmike]

New evidence... anti rattle or squeal shims.

 

I did have some liquid stuff for anti rattle once. Put on, install, and it gels like urethane very gummy. Got all over the piston lip.

[Lockleaf]

One option, though perhaps not the greatest one, is to sand down the pads a little. I've had pads come that were too thick, but otherwise correct. I simply set them on the driveway and put my foot on them and slide them around until they are thinned enough. Again, I realize that this is not perfect, but 90% of a great pad is better than not being able to use them.

[Draker]

Sounds like the pads are too thick out of the box

[fivetenguy]

One option, though perhaps not the greatest one, is to sand down the pads a little. I've had pads come that were too thick, but otherwise correct. I simply set them on the driveway and put my foot on them and slide them around until they are thinned enough. Again, I realize that this is not perfect, but 90% of a great pad is better than not being able to use them.

 

I had to do this in order to get the rear brakes (280zx calipers and rotors) to work on my 510. pads were too thick out of the box.

[deans510]

The result of this brake problem was the removal of the small spring clip that's riveted to the back of the inside brake pad.  The rivet caused the brake pad to skew sideways & bound up the rotor.  Removed the rivet and all is good.

 

As a side note, I acquired an extra pair of new speed bleeders for stock rear brake cylinders which I can't use because I have the complete 280ZX braking system on my 2dr.

 

If any one would like these for the cost of S&H, please LMK at the email below.

 

Dean

deans510gmail.com