Rebuilding Brembro calipers.

[guydoc77]

My bike is an '08 Road Glide. So I took my front fender off (getting it painted), which, of course, involved unbolting the calipers and removing the front wheel. My 12 year old dirt bike riding son came out and squeezed the brake lever..........

As you probably know, service manual states not to apply brakes with calipers unbolted or "disassembly of the caliper will be required". One of the pistons squeezed out and I couldn't push it back in.

So I've disassembled my caliper. Got the pistons out and they look good. Obviously I will thoroughly clean all the parts. Pistons actually look really good and bores look good.

My question is this: Since I'm this far, how do I know if I need to replace the bore seals and the O ring that goes between the two caliper halves? I have researched this a fair amount today and, on another forum, read everything from the calipers are not rebuildable to Drag sells a rebuild kit (PN 1702-0117). At this point, since the bike will be apart for a while, I'm wondering if I should just rebuild both calipers just because I'm there or if I should just slap everything back together and call it good? 

[Jaycee1964]

How many miles on the bike?  Chances are if you clean it up and carefully reassemble you'll be fine.

[guydoc77]

60,000 miles, but...........these are chromed calipers I picked up a few years ago for sale on one of the other forums. Guy was doing an exchange program so not sure how many miles were on them before they were chromed or if new seals were put in as a matter of course at the time of chroming.

[FSG]

to Drag sells a rebuild kit (PN 1702-0117)

Without further information as to it's suitibality for a HD Brembo Caliper I'd be taking it with a large dose of salt as Brembo do not supply a rebuild kit for them, that said QTM do.

Check this post => http://harleytechtalk.com/htt/index.php/topic,35298.msg365115.html#msg365115

or if new seals were put in as a matter of course at the time of chroming.

and you can bet your bottom end they didn't. 

I'd get a new seal kit to have on hand before disassembly just in case.

[guydoc77]

There's more. I have suspected that I've had a malfunction of one or both calipers for the last 5000 miles or so. Occasionally when I've applied the front brakes, the bike pulls to one side. Pads seem to be wearing evenly and very well I might add. I had to really crank on a couple of the pistons to remove them today. I have wondered if maybe I had a piston sticking. Can you tell by looking if the seals are ready for the trash? I've had no leaks of brake fluid as far as that goes. I would think that if a seal was bad, I'd ooze fluid. I certainly have plenty of time to obtain and replace the seals if needed I guess.

[Jaycee1964]

I wouldn't mess around.  Source a new seal kit and rebuild them both.  Hows the finish on the caliper pistons? R they pitted, rusted or otherwise?  How are the bores?  Do it right, they are your brakes.

[ReddHogg]

Brake pull???

[Jaycee1964]

Brake pull???

One front caliper is working harder than the other= brake pull.  Bike can move left or right when brake is applied.

[truck]

Do bikes with one disk pull to the side with the disk?

[guydoc77]

Trust me I've asked myself all these questions already. All I can tell you is that at times, with the front brakes applied, the brake application feels different than before. The only way I can describe it is it's like a delayed braking. With steady lever pull I'll be rolling up to a stop sign and then there is an increase in braking and the bike wants to steer to one side. Only happens when front brakes are applied.

At any rate, I've got the info I need here and I'll rebuild the calipers.

Here's the link to the Drag parts. http://www.dragspecialties.com/products/?productId=51566

[harleyjt]

Brake pull???

One front caliper is working harder than the other= brake pull.  Bike can move left or right when brake is applied.

Really?  What about all those bikes built with just one front caliper? They don't pull.  I've never experienced brake pull on a bike.  Not sure I understand how it could happen with just one front wheel.
jt

[Jaycee1964]

Do bikes with one disk pull to the side with the disk?

Nope,  Because they are not fighting the caliper on other side.

[guydoc77]

FWIW: got the Drag piston/seal kits. Each piston bore has two seals. One is wider than the other. The wider seals in the Drag kit were too narrow to fill the wider grooves in the bores. So I used the old seals since they looked good.

Also, bleeding the Brembos has proved to be a bit of a PITA. Finally got some lever pressure today. Pistons all are pushing out evenly on pads. No visible leaks. Lever still has a bit of excess free travel. I'm going to let it sit a few hours and then bleed again. Don't have a vacuum bleeder so am doing it the old fashioned way. We'll see how the brakes work after bike is back together. If worse comes to worse I'll pick up the QTM seals.

[FSG]

I'm going to let it sit a few hours and then bleed again.

Let it sit with the system under pressure, i.e.  pump the lever a few times then tie the lever back to the handgrip using tape, bungee cord or other. 

[rbabos]

They most certainly do pull. Give it a jab and the jolt will shift the bars in the caliper direction. Only happens for a split second, not extreme but noticable. Cause is caliper torquing one fork tube and with the length of the fxstc forks, they twist easy even with a fork brace.
Ron

[guydoc77]

THANKS Ron.
Do you think I am on track as to the potential cause?
I have the calipers back together and on the bike with wheel installed.
In the process of bleeding them now.
Just about done.
Could a sticking piston cause this?

[rbabos]

THANKS Ron.
Do you think I am on track as to the potential cause?
I have the calipers back together and on the bike with wheel installed.
In the process of bleeding them now.
Just about done.
Could a sticking piston cause this?

Yes or fluid travel not even between them or air in one side.
Ron

[guydoc77]

Thank Ron.
I did consider all the above in the differential diagnosis. And all those issues should have been addressed with the caliper "rebuild".
Bleeding is done now. Can't imagine the lever feeling any better with bike sitting than it does now.
Tried the rubber band on the lever for several hours and bled once more last night.
Proof will be in how it actually brakes when I actually ride the thing.
That will be at least a few weeks as outer fairing is off and on way to Dougz customs.

Also, I have to thank Stroker for his input. I had spoken with him before I started this little project. He told me about someone he knew whose bike didn't feel like it was making power and had a heat problem which was found to be the brakes. Turned out the Brembo caliper(s) were "dragging". The guy disassembled them and cleaned them up and the "dragging" stopped and bike ran good again. Otherwise I probably would have just taken the one side caliper apart and pushed the piston that had popped out back in. These are ebay exchange chromed calipers so I know nothing of their history and I'm glad I took them apart and checked everything.

[Boe Cole]

I've always been one that prefers for a vehicle to stop safely than run.  I do not take chances with brakes and would not consider not rebuilding them if a piston came out.  Rebuild kits are cheaper than hospital, medical and repair bills.  If you can't find a rebuild kit, as long as the boots are pliable and the rings are good, a good cleaning and reassembly is not out of the question.  Bottom line - rebuild.