TheSamba.com :: View topic - Rear Disc Brake caliper/rotor centering question

Wed Feb 08, 2012 9:57 pm

I'm installing EMPI's rear disc brake kit on my 1974 Super Beetle. The alignment of the rotor inside the caliper is such that I need to remove a little material off the caliper mounting locations on the mounting bracket to move the caliper in so that it is better centered. It doesn't rub, but it's too close.

In the picture, I've pointed out where the mounting locations are that I need to reduce. I'm thinking that this needs to be done carefully in order to insure that the caliper doesn't mount in an uneven manner.

I know I'm not the first one to encounter this problem, so I'm looking for advice on how to proceed. I would think a machine shop could take care of this, but I don't want assume that is the case.

Appreciate the help!

David[img][/img]

Thu Feb 09, 2012 12:04 am

If the calipers have a piston on each side, don't worry about it, they'll self center.
If they only have one piston the caliper needs to be able to slide back and forth.
If you still need to remove some material, just go slow.

Thu Feb 09, 2012 1:17 am

Quote: It doesn't rub, but it's too close.

I'm curious to know what part of the brake you feel is too close...and what it's too close to. I have the same kit and same bracket, and everything bolted up just fine. Can you post photos of your concerns?

Without putting that mounting bracket in a jig, and using a mill to remove material, you are likely to cause more harm then good. Those mounts should be machined parallel to the braking surface to ensure even pad wear and no additional noise. Simply taking a grinder to them is not the way to do it.

-Dave

Thu Feb 09, 2012 7:30 am

Quote: If they only have one piston the caliper needs to be able to slide back and forth

X2. They need to 'float' and that will let them be self centering, even as the pads wear.

Thu Feb 09, 2012 7:40 am

That looks pretty tough, I ran into the same problem (not a super). I was able to span my file over both mounting surfaces to ensure it stayed nice and even. But it did fix the problem.

When I mounted mine it was so bad it was bottoming out on the inside of the caliper. Not sure how they can call it a "kit" when it's impossible to mount them without modifications.

You might want to take it to a machine shop.

Thu Feb 09, 2012 8:15 am

Both my front and rear kits came with hardened washers to shim up the caliper on the rotor. The shims will help center the caliper, otherwise you'll eat the shit out the rotor in no time flat. Float or no Float

I hope this answers your question, otherwise I dont completely understand your problem.

I would hold off on the machine shop for now.

Can you mock it up and take another pic?

Thu Feb 09, 2012 8:22 am

Jason, my allignment had to go the other way, washers would have made it worse.

Thu Feb 09, 2012 9:48 am

dpalinsk wrote: I'm installing EMPI's rear disc brake kit on my 1974 Super Beetle. The alignment of the rotor inside the caliper is such that I need to remove a little material off the caliper mounting locations on the mounting bracket to move the caliper in so that it is better centered. It doesn't rub, but it's too close.

In the picture, I've pointed out where the mounting locations are that I need to reduce. I'm thinking that this needs to be done carefully in order to insure that the caliper doesn't mount in an uneven manner.

I know I'm not the first one to encounter this problem, so I'm looking for advice on how to proceed. I would think a machine shop could take care of this, but I don't want assume that is the case.

Appreciate the help!

David[img][/img]
I have the EMPI kit from Topline that included the Stamped metal mount and the Varga Caliper, I had several people tell me to bend the mount to get it to center. NOOOOO!!! Metal has memory and will always return to the original shape. So I took a small angle grinder and carefully removed material from the pedestal on the caliper!! They send shims, but that moves them the wrong direction. It worked really well for me and eventually I will replace with the cast mounts or go directly to the 944 trailing arms and calipers.

Thu Feb 09, 2012 10:17 am

When topline sent me 5x130 rotors I had to buy a spacer for the castle nut to tighen down completely

Thu Feb 09, 2012 1:34 pm

Here is picture highlighting the issue.

The red arrow points to what I am concerned about. Using shims would only make the issue worse as someone else pointed out. The yellow arrow is pointing to the area where I need to reduce the height of the mounting bracket so that the caliper can "move in." The green arrow is pointing to the fix portion of the caliper where the inside of the rotor is very close to.

David

Thu Feb 09, 2012 1:37 pm

That is what I had but worse. Grind the pedestal on the caliper!!!!!!!

Thu Feb 09, 2012 4:23 pm

Exactly the same issue I had. As I mentioned, I removed material from the mounting surface of the caliper until I was happy. I'm happy.

Thu Feb 09, 2012 5:52 pm

Had a similar prob with my 75 irs chassis and empi disc w/ park brakes.
The instructions supplied were wrong,

The circled shim will ruin the sealing ring of the sealed bearing and the spacer is all wrong.

On a recent conversion I did, the parts were poorly made by EMPI.
4 wheel disk brakes with park brakes. 75 type 1 chassis, IRS/ball joints, Chevy-Porsche rotors.

Problem 3...Instructions for IRS wrong, they are written for swing axle and footnotes for IRS are wrong and incomplete. Seal does not ride on the spacer properly. rotor will not center in caliper support.
This is assembled as per inst.

The fix
IRS seal sits farther out in housing than swing

The inner thin spacer and small O-ring are not used,The thin spacer can damage the "seal" of the sealed bearing. By using a seal spacer from a swing axle setup [wider one] it ensures the seal is in full contact with the spacer.

If you still need to move the rotor out farther, put the circled spacer between the "swing" spacer and the rotor.

The supplied washers go between the caliper support and the caliper adapter bracket.

Rear "floating caliper" position.

Hope this helps for anyone having issues.

I documented the problems and my supplier forwarded it to EMPI. EMPI is aware of the problem, but I would not expect them to correct it anytime soon.

Here is problem 1
Rotor will not go on all the way

The fix

Problem 2 Caliper will not mount, hits support bracket before holes line up.

The fix

Thu Feb 09, 2012 10:00 pm

This is exactly the kit I ordered, cast not stamped bracket. I'm going to make sure that it all fits. Thanks for the photos!

Fri Feb 10, 2012 12:31 am

zadieman wrote: Metal has memory and will always return to the original shape.
This is completely WRONG. All the body panels of our cars started as sheet steel. I've never seen a car drop to the ground and flatten itself out.
Once you bend it past the yield point, it stays there.
Don't try to bend cast iron. It will only break.

Fri Feb 10, 2012 12:34 am

zadieman wrote: That is what I had but worse. Grind the pedestal on the caliper!!!!!!!
This is bad advice. The offending part in this case is a poorly designed caliper bracket with the wrong dimension. The best approach is to modify the bad part to be correct. Don't take a correct part and modify it wrong to make it fit. Otherwise, years down the road when you need to replace the caliper, the new one doesn't fit, and everyone scratches their heads all over. Worse is for the poor Golf guy who buys your messed up caliper after it's been rebuilt.

Fri Feb 10, 2012 10:16 am

Bruce wrote: zadieman wrote: That is what I had but worse. Grind the pedestal on the caliper!!!!!!!
This is bad advice. The offending part in this case is a poorly designed caliper bracket with the wrong dimension. The best approach is to modify the bad part to be correct. Don't take a correct part and modify it wrong to make it fit. Otherwise, years down the road when you need to replace the caliper, the new one doesn't fit, and everyone scratches their heads all over. Worse is for the poor Golf guy who buys your messed up caliper after it's been rebuilt.
I understand your issue with my resolve, but this is my car inherited from my brother, I will be the only owner. By the time I need to replace the caliper hopefully there will be better parts. When I bought all the parts to restore the brakes(5 years ago) there weren't many options. The options now still are of mediocre quality. Empi didn't even have the cast mount when I bought these!! But Thanks

Fri Feb 10, 2012 5:41 pm

I'm took the parts into a local machine shop today and he has a milling machine that can easily do the job and not mess up the caliper mounting angle. I've just got to provide him with measurements for both gaps and he'll calculate how much to cut off to get it centered. He's known as Mr. Gadget and loves VW's as well. Sometimes you get lucky and the find right person for the job. Today was my day.

Fri Feb 10, 2012 5:49 pm

Zadiman, like you, no one else will ever own my VW either. My son and I started work on this bug in 1999. He graduated high school in 2000 and then joined the Air Force. He was overseas until he was transferred to a base north of Sacramento in 2007, but whenever he came home on leave, work spent time working on this car. He was barley back in the States a month when he was involved in a car accident after an early morning test flight that claimed his life. Sucks bad, but this VW always reminds me of the good times and I hope yours does too.

Sat Feb 11, 2012 11:35 am

dpalinsk wrote: I'm took the parts into a local machine shop today and he has a milling machine that can easily do the job and not mess up the caliper mounting angle. I've just got to provide him with measurements for both gaps and he'll calculate how much to cut off to get it centered. He's known as Mr. Gadget and loves VW's as well. Sometimes you get lucky and the find right person for the job. Today was my day.

Why don't you use the correct parts {like I posted} and set the rotor out farther? The empi instructions are WRONG.