New calipers and pads on 240z, now some minor issues

[Guest bastaad525]

Hey all. I just installed a set of rebuilt stock calipers on my '72 with new pads of course. I'm having a couple of funky issues now and wanted to see what you guys thought.

 

#1 - I bled the brakes twice, and was getting NO bubbles at all. I bled both calipers and the master cylinder itself. I went thru a whole bottle of brake fluid, so most if not all of the fluid in there is new now as well. DOT 3 fluid. Yet, the pedal still feels a bit softer/spongier than before I changed everything out. It stiffens up if I pump them. I will try bleeding the rears soon as well, though the Haynes manual says the front and rears are completely seperate... if you only worked on the fronts you only have to bleed the fronts.

 

#2 - I'm getting some squealing. I did use some Permatex brake quieting stuff on the backs of the pads, and do still have the factory anti squeal shims on there. I had NO squeal before replacing them. This isn't that big a deal, just wondering what you guys think might be causing it.

 

#3 - this is the big one. If I suddenly hit the brakes kinda hard, the pedal will jerk to one side, only slightly, but a strong jerk. Now, if I keep the pedal held down, the car brakes evenly, it does not pull to one side at all. Only that initial jerk if I brake suddenly. If I brake just normally it doesn't do it. So it feels like on sudden braking on caliper is engaging ever so slightly before the other one but then they even out. Does this make sense? They are both rebuilt, exact same calipers from the same place. Any idea what might be causing this??

 

#4 - my E-brake is suddenly WAY too loose, even with the handle pulled all the way up the car will still roll down the slight grade I park my car on. It worked fine before replacing the calipers... just wondering why the heck changing front calipers would loosen the E-brake??? Especially after what the haynes said about the circuits being totally seperate (I never knew that....)

[Tim240z]

Did you bleed the rears?

If not start with the right rear and bleed that one, then go the left rear, right front, and left front.

I assume that you meant to say that the car jerks to side, not the pedal?

Sounds like you either still ahve air in the lines, or you maybe have some fluid contamination on one or more of the pads, or wheel bearings or ball joint are going south....

Re-bleed all four corners and check again...

[JMortensen]

I'm not sure on this, so don't go buy parts. Do what Tim suggested first, then consider the following:

1. I think maybe you blew out the master. If the pedal hasn't gone to the floor in 10 years crap builds up inside the master. Then you come along and put some new calipers in the front and push the brakes to the floor and that drags the pistons in the master cylinder over the gunky crap in the master, possibly tearing the seals. Try bleeding again, but you may find that it doesn't get any better.

2. I never use sticky stuff to prevent brake squeal, instead use synthetic brake grease on the back of the pad. Learned that when I worked for Volvo, who are notorious for squeaky brakes (only factory pads and rotors and greasing the pads makes them stop). Pull the pads back out, clean the back off, and put a thin layer of grease where the pistons hit the pad and where the pad rides in the caliper if it really bothers you. Also there is some debate as to whether chamfering the pads works, I think it does.

3. Sounds like a stuck piston in a caliper to me. IME if it pulls left it's the left caliper that is stuck.

4. Dunno. Might relate to #1. I can tell you this. If the rear brakes are way out of adjustment the pedal goes soft, and the ebrake throw gets long. I'd adjust the rear brakes and look for any signs of leaky wheel cylinders while you're in there. If your master took a crap that might explain this because there is a check valve in the rear brakes that keeps the shoes from retracting all the way. If that wasn't working anymore then maybe the shoes are retracting all the way back, and causing a long pedal and ebrake throw.

[2003z]

one other guess here. Did you put the calipers on the correct sides? bleed valve on top? I speak from experience.

[Guest bastaad525]

Thanks for the suggestions guys.

 

I'll try bleeding them again. Again, I didn't bleed the rears as the Haynes manual specifically said I didn't need to if I didn't mess with them at all, but I'll do them this time.

 

Yeah the calipers are definatley on the right sides bleed valves on top.

 

My master cylinder is a recently rebuilt one, I replaced that when I got the 240 shell a few years ago.

 

I'm 99% sure my rear wheel cylinders aren't leaking as I NEVER have to top off the brake fluid.

 

*expletive deleted* I KNEW I should have used the grease and not the sticky stuff!!! Well I don't think that stuff is gonna come off. When I originally swapped the new pads into the old caliper on the drivers side, before I knew I was gonna need to replace the calipers, I put that stuff on there. The next day when I went to swap the caliper, I took the pads out and tried to get that stuff off but it wasnt' coming off. That's not the cause though, as the squeal is definatley coming from the passenger side.

 

I THINK I know why it's squealing. For some reason, only one of the two rebuilt calipers came with new hardware (i.e. the pins that hold the pads in place). When I installed the new hardware I didn't grease it or anything and I'm thinking I should have... maybe that's why it's squealing? Not sure how much trouble I'm gonna go thru to solve this... it's not that bad and comes and goes. Was bugging the crap out of me on the drive to Tim's house thru three hours of traffic though....

 

I really don't want to think that a piston in one of these new calipers is stuck. Oddly, I KNOW for a fact one of the pistons was stuck in my old calipers... thats' why I replaced them but I never had a problem with the wheel jerking to the side like that. Again, the wheel only jerks slightly, then the car brakes in a straight line w/o pulling to the side. And that's only if I hit the brakes HARD.

 

I guess I'll get a good look at the rears when I bleed them, so I'll be able to make a better guess at that point.

[Cody 82 ZXT]

Mike you might pull the front wheels off and see if the calipers are squaring themselves up when you hit the brakes.

 

Have someone apply pressure to the pedal as you watch the caliper. If the calipers move around in funny motion then the pads and rotors are not square. You could replace the rotors or do some driving and they will eventually mate up better than they are now. Not the best solution but, the cheapest and if it's not real bad won't cause to much of a proublem in the long run. You just don't get as many miles out of the pads.