Wilwood headache - or just another hurdle

[Al_C]

You may recall me making the statement that every time I think I know what I'm doing I get my head handed to me. Well, here's another instance...

The rear brakes are doing their best to teach me all kinds of things about brakes (an admitted weakness...) A week or so ago there was a thread about the e-brake bracket and how it's in the way of the banjo connection. The best solution to that was to rotate the e-brake bracket. I did that. It's a thing of beauty. The problem is that in the process of putting the caliper back together, the piston got extended. Every time you rotate the bracket (duh...) the piston extends as if the e-brake were applied. Consequently, when I went to mount the caliper back on the axle it wouldn't go over the rotor.

OK, next step, get the piston compressed. Piece of cake, right? Not so fast. The simple solution is to use the compression tool, squeeze it back in and move on. Wilwood tech support indicated I shouldn't need the tool, just rotate clockwise and it should compress. It didn't.

The next challenge is that the outside of the caliper (where it says "Wilwood" doesn't have an opening where the tool can go through. So, either I use some sort of spreader within the caliper or take that outside housing off. I chose the latter. Two allen head machine bolts hold it in place. Next, I need to hold the compression tool in place with clamps because the other component of the caliper slides (and comes off when pressure is applied. So far so good - I think. The problem I ran into is that while attempting to rotate and compress, it appears that the piston is actually coming out (i.e. apart).

Now what? So finally, we get to my question. Anybody have this happen before? How do I get this piston compressed? How do I know if I got it back together correctly? I'm moving on to the next step, but these brakes have been driving me crazy for too long. I look forward to your advice!

http://thefactoryfiveforum.com/attachment.php?attachmentid=53140&d=1461425500
http://thefactoryfiveforum.com/attachment.php?attachmentid=53139&d=1461425498

http://thefactoryfiveforum.com/attachment.php?attachmentid=53137&d=1461425495
http://thefactoryfiveforum.com/attachment.php?attachmentid=53136&d=1461425493
This is the compression tool I have
http://thefactoryfiveforum.com/attachment.php?attachmentid=53135&d=1461425491

[DaleG]

Just went through this, though my rear brakes are Ford. I had to rotate clockwise, while pushing to get the piston to recede into the housing. Maybe you have to rotate counterclockwise? Try it. Your tool doesn't look like it has anything on the caliper to hold the push bracket in place, so push by hand while turning.

[Al_C]

Thanks, Dale, it's worth a shot. Wilwood tech support said "clockwise", but who knows. You are correct about not having anything to hold the tool in place. I tried using C clamps to do that.

[BEAR-AvHistory]

They might not match the Wilwood pistons but there is a tool at the auto stores fo the Mustang brakes.

You can get the tool for about $5.00 that fits the indentations in the piston. Got mine at Advance Auto, but its a common piece with the Mustang guys. It mounts to a standard ratchet. Ugly thing, a cube with warts. The warts cover all the possible piston groove locations

[skullandbones]

AL_C,

This can happen with any brake caliper/piston. I have rebuilt so many calipers it looks like I could figure it out but once in a while there will be a stubborn one. It's most likely a slight misalignment of piston on wall of caliper, IMO. I've played with them so finally you can feel some movement and then center and crank. Even though the piston is free in the bore, the tolerances are close.

Good luck,

WEK.

[Al_C]

Thanks for your comments. Persistence pays off. After your comment, WEK, I hit it again, and just kept turning and turning. It aligned itself and retracted. It took a lot more turning than I expected, but it's back where it belongs. Got the caliper reassembled, pads back in and everything fits. Life is good again.

I learned a lot about Wilwoods today: 1. It's easier to adjust the e-brake bracket on the car rather than on a bench. Otherwise you're probably guessing if the cable will interfere with the wheel. 2. You can take the caliper apart pretty easily. In fact, it's easier (in my case) to compress the piston with everything apart. 3. If you push and twist with a compression tool, it will eventually compress. 4. They don't have a torque spec for the outside housing of the caliper (at least the gentleman I spoke with didn't know of one). I put thread locker on the bolts and tightened them to about 50 lbs. The nuts holding the caliper onto the axle are specified at 30, so I think I'm in the realm of reasonable. (They're rear brakes, not front brakes).

[CraigS]

Al, when there is no torque spec available you can find generic charts on the web that go by bolt size. Here is one I found quickly
http://www.repairengineering.com/bolt-torque-chart.html
I would like it if they specified what lube they use. I have seen others where they have columns for regular oil and for moly but didn't find that one in a quick search. I think you have either a 3/8 or 7/16 socket head cap screw coarse thread so that would be the 3/8 UNC row and you are right on for dry TQ. I am not sure if thread locker counts as lube or not.

[Gumball]

Al,

Glad to hear you got it - I reached out to both Ryan and Sten, but neither have Wilwoods. Although, it appears it was a problem that is common to even the Ford calipers. Both of them want to come by and check out your build. Sten's car is getting back on the road with new exhaust soon and I'm pulling mine out of storage today. The three of us will bring our cars over by your house sometime in the coming weeks.

[Al_C]

my driveway and garage are Cobra-friendly! All are welcome!