Rear Caliper Adjuster Disabling

It shouldn't take more than an hour. The hardest parts is compressing the inside snap ring out of the cylinder that holds the jacking bolt in place. You can save time by only removing one and using it to remove the piston nut for both calipers. I don't recommend welding on the caliper unless you are experienced welding cast iron. Its way too easy to crack the housing with the heat of welding and the only way to know for sure is dye penatrant test. Adax's method may sound like genious now, but if you have a failure on track it could be catastrophic.

As a follow up reminder, This year we have had several DNFs due to slide pin failure. Im now convinced that the pin fails after backing out and the driver hitting the gators. Solution red locktight the pin in place and let it cure BEFORE racing. Since doing this the pins have stopped loostening. Before I was tightening after evert session! And yes they were new calipers.

The wheel in my avatar says +1 to this post.

It shouldn't take more than an hour. The hardest parts is compressing the inside snap ring out of the cylinder that holds the jacking bolt in place. You can save time by only removing one and using it to remove the piston nut for both calipers. I don't recommend welding on the caliper unless you are experienced welding cast iron. Its way too easy to crack the housing with the heat of welding and the only way to know for sure is dye penatrant test. Adax's method may sound like genious now, but if you have a failure on track it could be catastrophic.

Welding the caliper is not legal but for someone that knows how to weld (and learned 35 years ago... )it's not that big a deal. The issue I see specifically here on the forum is that most people don't weld. Sort of obvious to me that if you don't know how to weld, then don't weld it. I've taken a break on the build to work on some shop and pit equipment for myself and others. Maybe I'll post something up next week.

BTW, great idea on the red Loctite on the caliper pin...

Interesting. Have you tried using a wrench to tighten them, Glenn?

Seriously, never seen or heard of a pin coming out. Just seems like tightening the pin should be plenty.

I've had one come out and caught another backing out. They do loosten up over time.

Maybe if I drove faster I'd need the brakes...

Which pin are you talking about...the one under the cover (lower one I think) on the rear caliper??

Which pin are you talking about...the one under the cover (lower one I think) on the rear caliper??

The top pin, the one that has an allen head. After 3 DNFS and 10 broken pins at Road America, yes they do come loose! All six cars we took to the runoffls last year experienced broken pins.

I have broken 2 and had numerous loosen up at Road America, including one a couple of weeks ago, as well. I know Wheeler has had this occur a lof in the past as well.

If I recall correctly, the Pombos had a rear caliper pin back out and caused them grief at Road America. Those Road America gators DESTROY cars, Only track I know where I try NOT to use the whole track!!!!

If you remove the jack screw, is there any reason to go through the trouble of removing the adjuster from the piston?

Duncan

If you remove the jack screw, is there any reason to go through the trouble of removing the adjuster from the piston?

Duncan

Think of it the other way around .... if you remove the piston internals, there is no need to remove the jackscrew.

Sorry I can't figure out how to post pictures but the way I remove the adjuster does not require brute force.

1. Get a bolt about 3 inches long that can be threaded into the adjuster. The threads don't have to match.
2. Put a nut on the bolt about 2 inches up.
3. Get washers that the OD is larger than the piston OD and the their ID is larger than the thread sleeve of the adjuster. (Fender washers)
4. Stack 4 or 5 washers under the nut.
5. Thread the bolt into the adjuster (with the washers and nut on the bolt), just get as many threads as you can, center the washers so the threaded sleeve can be pulled into the center.
6. Hold the bolt with a wrench to keep it from turning
7. Turn the nut with another wrench toward the washers as if you were trying to take it off the end of the bolt.
8. As you tun the nut you draw the adjuster out of the piston. Done.

Guys,
I just did this the other night and learned a couple more "tips" in case they help anyone.

1 - if you decide to use the jackscrew to get the adjuster out, per @Adax's instructions (ie: using the jack screw to pull the adjuster out), get the spring clip out with a pick first. Then, apply compressed air to the backside of the adjuster screw and it will pop out. Take precautions on the other side so that it doesn't go flying off. Behind it, you'll see this little rice grain thing (actually about an inch long). Of course, if you have a spare rear caliper sitting around from which you can canibalize the jack screw, even better.

2 - As others have noted, you have to put the jackscrew back because it houses a seal that prevents fluid leaks. I'm pretty sure that we need to reinstall the spring clip too. Reinstallation of the spring clip requires a chicken sacrifice or two. Good thing I work for a chicken company (no really, I do). Let me know if you need a chicken. So, exercise patience and dexterity and you'll get it in there after about 24 minutes of frustration. (As Jason J Ball notes above, make sure you use the same jackscrew on both calipers, as removeing the spring clip from two calipers means double the frustration putting them back in).

3 - getting the dust boot back into the groove in the caliper is a fun challenge. (Make sure that the banjo bolt is removed so that the caliper can vent freely). But there is an easy way (probably a known trick for those who are experienced). Slide the dust boot over the lower portion of the piston (the end that goes into the caliper). Have it hanging over the end like a skirt. At this point, the seal will not be seated at the top groove of the piston. With your fingers, work the "skirt" into the caliper groove. Now, slide the piston back into the caliper. The top portion of the seal will catch into the groove on the piston. Voila!

FWIW, I did this with no vice, sitting on the floor of the garage. I did need to use a crescent wrench to turn the jackscrew down.

The top pin, the one that has an allen head. After 3 DNFS and 10 broken pins at Road America, yes they do come loose! All six cars we took to the runoffls last year experienced broken pins.

I couldn't even imagine what you were talking about till I put the new calipers on last night and then managed to see the allen head by pure luck. I didn't even know that that pin was removable. I always thought it was cast into the caliper bracket. Once it is put in with threadlocker, should there ever be a reason to remove it? (I can't imagine so). Why not epoxy/JB weld it into place?

There are several reasons the pin break.

1- They are old. The clamping force trys to rotate the caliper and bend the pins. eventually the pins just break.

2- The threads are worn. This can occur due to age, especially if the original pin needed heat to come apart. Or just from repeated use, such as on a race car that gets taken apart regularly.

3- pins are not tightened, DUH, this causes the threads to wear. See #2

4- Most rebuilt calipers come with brackets. These brackets are sand blasted prior to being recoated. The sand has a tendancy to stay in the threads. You should run a tap through all rebuild parts that have threaded holes.

5- some rebuilt calipers are powder coated. When the powdercaoting is subjected to heat, it gets soft. Since the pins are installed aganst a powder coated surface, when the powder gets soft, the pins are now loose (see #3 above)

The worst track for this problem seems to be Road America. And I run there a lot, with lots of cars. So, how do you prevent the pins (and the bolts that mount the bracket to the upright) from coming loose.

Use new pins
Inspect the threaded holes and run a tap through them. Dispose of anything with damaged threads.
remove any paint or coating from the surface that the bolt flange will seat against
Use a perminant thread locker (red) on the allen head pin only.
Use a light weight thread locker (blue) on the 10mm hex pin and the bracket to upright bolts.
Check all these bolts regularly. At Road America we remove all rear caliper every night to check the allen wrench bolt.

Note that the left and right caliper brackets are the same. The pins are reversed left to right. 1.6 to 1.8 are different.

Dave

Dave -

If you use blue locker on the 10mm pin, how the heck do you keep from stripping the heads off of them? I've gone through a bunch and keep spares, and I don't lock them.

Had a big pin loosen up on me once. Caught it in post race tear down. Wore the pad at an angle down to the backing plate. Lock them ever since.

Snap-on or Mac 6 point socket

Sorry I can't figure out how to post pictures but the way I remove the adjuster does not require brute force.

1. Get a bolt about 3 inches long that can be threaded into the adjuster. The threads don't have to match.
2. Put a nut on the bolt about 2 inches up.
3. Get washers that the OD is larger than the piston OD and the their ID is larger than the thread sleeve of the adjuster. (Fender washers)
4. Stack 4 or 5 washers under the nut.
5. Thread the bolt into the adjuster (with the washers and nut on the bolt), just get as many threads as you can, center the washers so the threaded sleeve can be pulled into the center.
6. Hold the bolt with a wrench to keep it from turning
7. Turn the nut with another wrench toward the washers as if you were trying to take it off the end of the bolt.
8. As you tun the nut you draw the adjuster out of the piston. Done.

This method took less than 5 minutes! Most of the time spent looking for the correct size washers!

But I did take the spring clip and jack screw out so i could replace the o-ring...but here is my question. Is it necessary to put back the little metal piece of rice between the jack screw and the manual ebrake lever? My concern is if I don't the jack screw can move farther back in its hole and the o-ring will move past the hole for the adjuster and cause a leak??

BTW...i did it without this piece now I'm 2nd guessing myself

This method took less than 5 minutes! Most of the time spent looking for the correct size washers!

But I did take the spring clip and jack screw out so i could replace the o-ring...but here is my question. Is it necessary to put back the little metal piece of rice between the jack screw and the manual ebrake lever? My concern is if I don't the jack screw can move farther back in its hole and the o-ring will move past the hole for the adjuster and cause a leak??

BTW...i did it without this piece now I'm 2nd guessing myself

Doh, Thanks Ron for THINKING, I was blissfully ignorant. Now where did I put those???