Rear brake question

[VBNSX]

First I'd like to say yes i've done a search and yes i've been to Dan's website..

Background: I've changed my pads numerous times so it's not a how do you change thing..

I usually switch from street to race pads before I leave for every event just to help set the pads in.. well I've noticed that sometimes, the rear piston (I have the tool) as I turn it, doesn't go down at all... like I could be spinning it for decades and it won't move.

Now my procedure is that when I change the fronts, I take the cap off the master cylinder (b/c of the pressure of clamping the pistons down...
When I change the rear's I put the cap back on b/c for some odd reason it won't spin down when it's off. But this time I was spinning it and it just wasn't doing anything.... I eventually got the caliper on (with a rubber mallet) but I know when I get back I won't be able to get the street pad on (due to wear). Oh yeah.. i generally don't take of the ebrake cable too. (I don't imagine that has anything to do with it).

Anyone know what is going on?

All help is appreciated.

x

 

[Jeff A]

Hey X -

Here's a blowup of the rear caliper. It sounds like the adjustment bolt is not properly doing it's job. My guess is that there's goo (that's a technical term!) in that area that is gumming up the works. You probably need to disassemble, clean, and replace any worn rubber parts - particularly the boot and piston seal.

A special tool is need to fully disassemble it, a brake spring compressor. But you may be able to fix it by just pulling the piston out and giving it a good cleaning, without disassembing the internal adjustment mechanism inside the piston. Looking at the diagram on page 19-21 of the manual, there doesn't seem to be any parts in the internal adjustment mechanism that would wear out (no rubber parts). It's probably just that black crud which is really ground up o-ring rubber.

Hope this helps

Jeff

 

[VBNSX]

Thanks Jeff... when I get back I'll just open that up and give it a shot... guess I'll take the piston off and see what's inside...



well here I go to VIR!!



x

 

[Daria]

... I've noticed that sometimes, the rear piston (I have the tool) as I turn it, doesn't go down at all... like I could be spinning it for decades and it won't move.

Hey X,

The last couple of times I changed the rear pads on my car I noticed the same thing occurring – I could be spinning it for decades also. This is what I do now:

I use a small C-clamp and GENTLY put compressive force on the rear piston cap as I turn it in. The key word here is Gently since you don’t want to damage any internal threads. It does not take much force and it works like a charm.

I don’t have the special tool for the rear piston, so I don’t know if you can fit a C-Clamp in there at the same time as using the special tool.

 

[Larry Bastanza]

Before you go to far into it, realize you cannot get to anything in the caliper without the press tool to remove the internal snap ring. You can get the piston out and check the internal threaded rod that will come out with the piston, but that is as far as you can go, without two tools, the press and a pair of right-angle internal snap ring pliers.

I have never had this problem to the extent I could not get the piston to screw back in. I have had it "seem" to not screw in, but I have applied pressure inward while turning and it eventually "caught" and screwed in. As Jeff speculates, IF the internal mechanizm has a problem, let's say striped inside, it could not allow the piston to screw in. I just have not seen that in the past.

In regard to the e-brake cable, I never remove then either, but a siezed one could cause some issues, so I would just make sure the cable moves freely inside it's sheath.

HTH,
LarryB