Pads rubbing after rebuild.

well almost rebuilt, this was a test fit. Pads, rotors, caliper housing, and hoses are still the originals.

Master Cylinder pulled, cleaned, rebuilt with new guts, confirmed that it developed pressure.

Calipers pulled, cleaned, rebuilt with new seals and piston.

When the brake lever is pulled the pistons do engage and the pads clamp down on the rotor. When released the piston does have a slight retraction and releases its iron grip. Problem is that when trying to free spin the front wheel, the pads are rubbing. Its not strong enough to grab the wheel and not let go, but there is friction. As the front wheel spins the sound is constant and not the swoosh swoosh swoosh like a warped rotor.

This was supposed to be an assembly to confirm that the MC and the caliper rebuild process was successful and then remove hoses and old pads to install new.

 

there is a little hole in the bottom of your MC make sure its cleaned out. as i do believe this is a return port of sorts..

 

That had a 16g Ernie Ball stuffed thru it.

 

what kind of shape is your piston in?

 

all rebuilt with NEW parts.....

Its like the pads are dragging a tad.

Is misalignment possible?

Overfilling the system?

 

im afraid your going to have to wait for someone that has put them back together ive only pulled mine apart. lol

 

if it makes any difference... Just got new tires last week. Mounted up without calipers on to go for a short TEST ride and then parked it and started working on the brake system.

Spent this week cleaning the crud out of the calipers, throwing out all of the old pieces (including pistons) and prepping system for reassembly. All new items arrived Thursday and did the following

Friday - MC; Clean MC, rebuild with new items, install on bike, confirm that it is pulling from resevoir and building pressure. QUICK and STRONG.

Saturday - Caliper, Clean all orifices using Dremel Nylon and brass brush. Ran a tap to chase the threads. Cleaned again with brake cleaner and comp air. Lubed and installed seal, boot and piston.

Sunday - Loaded up the old brake pads, hooked up hoses, mounted calipers. checked alignment/ free spin of wheel. Bled system.

The caliper pistons do engage and retract. The sytem feels good for old rubber hoses.

 

Have you ridden it since reassembly with brakes hooked up? I had that problem. Came back from a ride all sorted.

 

wscraig76,

You said the brake lines are the originals, right? Before I replaced my brake lines I did something similiar to what you're describing. I rebuilt the MC and caliper. I ran a piece of old stripped telephone wire through the old brake lines to make sure the brake fluid would go through. Turns out there was something "clogging" one of the lines preventing the fluid from flowing as freely as it should. I bought s.s. lines/washers from Len...problem solved. If it's not a warped rotor, this might be your problem as well. Hope this helps.

Gary

 

Scott, based on this post it doesn't necessarily sound like you have a problem. Believe mine acted similarly upon rebuild, NO BINDING, and more of a dragging sound than real friction? As long as you are confident the calipers and MC were squeaky clean and reassembled properly (all seals lubed with fresh brake fluid?), I would press on. Hope you didn't waste a new set of crush washers on your test. Not that it's relevant to this issue, but... did you rebuild those dirty, silly anti-dive units?

 

Anti dives remain disco for moment and mocked up using the old crush washers. Still waiting on delivery for pads and steel lines. I am thinking that once I get past front brakes, going to swap shoes out back, and then tackle forks and anti-dive at same time. I do understand that this is saying that I intend on bleeding system multiple times (which is acceptable for now.) Was semi concerned about the drag as the wheel will not make a full turn in the free spin test.

 

Howdy wscraig, what you've experienced is perfectly normal, all disc brakes that are new or rebuilt have this drag. You actually want this drag because it means your pad doesn't have far to travel to contact the disc. In other words, it means quicker braking.

 

That's NOT a "normal" amount of drag, not if the wheel won't even spin one full revolution.

Just don't ride it until you get the brakes fully re-done. That amount of drag IS cause for concern.

 

Hey BF, do you even bother to read the posts? Nowhere does craig say the wheel won't spin around once and he states that he's replaced everything but the rotors and pads. Except for a warped disc, from what I read, his brakes are normal. Merry Xmas Fitz!

 

I sure do, Steve; do you?

 

LOL!

 

Staying parked until this demon is sorted out. My life insurance isn't getting a chance to write that check just yet. New pads arrived today and those will go on first. After that, planning on making sure alignment is even and balanced.... An observation that was made after finding a similar post was that it appears that rotors are not sitting dead center in the slots in the calipers that are above the pistons. And that on the front left caliper the rotor is slightly to right of center... And on right caliper it is slightly to right of center too... Guessing about 1/16th to 1/8th inch off. The fact that visibly this distance is similar and that it is out of whack in the same direction on both sides makes me think that I did not propperly reassemble the pinch bolt section on the front axle after the tire change.

 

That was going to be my next reply. Is it axle assembly-related, and the rubbing pads just seems to be connected, because you can hear them?

 

If that is confirmed.. Fitz's "bounce test" will get linked into the thread.

 

Alright BF I see it now, But you it seems you missed the part where he said he had all new parts. But this is all subjective as we don't know how much force Craig used to spin his wheel. I suspect that Craig is experiencing the normal drag of renewed brake pads, and due to his inexperience is worrying needlessly. Craig, there is no provision made by the factory to mechanically retract the brake pads, there is some kind of force that does this when the pressure is released. Maybe it's a vacuum effect caused when the fluid flow is reversed. That is the reason for the tiny port inside the MC.

 

The release of the Brake Pads results when the Brake Lever is released, the Hydraulic Pressure relaxed and the Caliper Piston retreats due to the Volume within the Calipers being reduced when the Fluid retreats with the Master Cylinder Pistons return movement.

The Piston does not move very far.

For the Pads to be released, ... the "Moving Parts" must all be able to move, float and slide effortlessly.

The Caliper needs to Float.
The Caliper Piston need to relax back to its position without pressure.
The Caliper Main Seal's locating channel needs to be free of foreign matter.

Locating Pins holding the Brake Pads need to be Rust Free and smooth enough to allow the Pads to float.

The Tiny Hole inn the Master maintains the Volume of Brake Fluid in the Spave between the MAIN Hydraulic Seal and the Secondary Seal keeping the Fluid in the MC.

A slight amount of Fluid is sent back to the Reservoir when Hydraulic Pressure is Maxed.
As the Pads wear, ... there is LESS resistance to Fluid being Pushed past the MAIN Seal than back through the Replenishment Orifice, ... then, Fluid is added too the Volume below the Main Seal to maintain pressures.

 

I have the same issue and its worse when it spins backwards.. Is there a specific reason for that?

 

Is this talking about Brake Lube.... Like the kind they give you at the parts store when you buy a set of pads?

 

YES. For all of the external, sliding or making contact with each other parts. But buy some of the really good stuff, not the store-brand cheap crap they give you.

On your style of calipers, the "sliding pin" that guides the caliper in its horizontal motion in relation to the "holding block" is very important. I would recommend simply replacing the sliding pins, and be sure you get new pin boots if yours are deteriorated. Len has them.

Daveheller, that is a classic symptom of a balky caliper. It's trying to tell you something ("rebuild meeee......") This applies no matter what style of caliper mounting you have.

***note to all others reading this post*** the brake calipers on the 550s, the 750 SECA and 1100 are very similar and are what is being discussed; the 750 Maxim, 650 Maxim, 650 Seca all have a different type of caliper mounting arrangement.

Back to the original issue; from carefully re-reading your posts, it sounds like the front forks may be slightly out of position. If you've found the "loosen, bounce, tighten in sequence" procedure already I won't go through it again; but it sounds like it might be part of the issue. You can also "tweak" the fork positioning slightly on the axle if need be without causing a bind, as long as it's a minor "tweak." The rotors should be centered in the calipers, but the calipers have to be able to slide freely to center themselves up.

 

Thank you BigFitz.. I rebuilt it this summer but it was a first time rebuild for me and I must have been it to much of a hurry.. Bad move by me!!!..I will order another kit and do it correctly this time... until then it will be parked..Sorry about getting off the point a little everyone..

 

Then it could also be the M/C...

 

Yes Sorry I left that out.. I have a new M/C and brake lines that i am gonna put on with my new bars....I have a lot of work to do this winter...I was worried my rotor was warped and that was causing it...

 

I think that this may be a success story.

A few adjustments have been made and I believe that we are now at the point that some of the other forum members describes as "NORMAL".

1. Caliper/Rotor/Axle Alignment.. I think this was a major player but not the entire issue. It was the first adjustment in the recent set and it was tested and verified independently before moving forwar with the rest. Follow link to a description of it.

http://xjbikes.com/Forums/viewtopic/t=9 ... nment.html

2. After this was completed, started to address the previously unattended issues within the caliper itself. Pad Retaining Pins and all other friction surfaces. While the pins themselves were "cleaned"(soaked in brake cleaner and then rubbed dry) during the caliper rebuild process, they were not "DENTALLY" or "ZESTFULLY" cleaned. In fact they were really dismissed as unimportant. Which resulted in a REDO. After years of build up of road grime, brake dust, old lubricant etc.. the pins became encrusted with a film of sorts that created a tacky surface accross them and prevented the pads from floating across it. To clean these pins..... Brake cleaner failed, Degreaser failed, Dremel ran out of battery so it failed. I actually used a 200 grit sandpaper to get this garbage off and reveal the metal underneath. After which all moving parts were lubricated with Brake Lube, reassembled, bled, and then

BAM got some free spin with a slight pad drag on the rotor. When the lever is squeezed it grabs that rotor real quick and tight, when released we go back to free spin with a slight drag.

 

Good News Everone. Test ride topping out around 45mph no squeeks, no grinds, no nothing but awesome stopieness.

In summary this was an OEM refurb MC rebuild, Caliper rebuild including pistons, and pads (hoses do remain original for now).

Bad News.. While it is nice to actually have a set of front brakes, These brakes suck.

They seem to be more committed to slowing down instead of actually stopping. Of course I understand that brakes do both slow and stop and that stopping is a result of slowing. But maybe I was expecting something that felt more modern. I think my 3000lb car stops faster from a higher rate of speed and it actually feels a WHOLE LOT more positive.

Hopefully, all of you other xjers that have been raving about steel lines are dead on right, and that my dissapointment in this machines ability to stop really well will be cured next weekend.

 

De-glaze the Front Rotors.

You have to pull the Rotors.
Sand the Rotor with a Dual-Action Sander.
First pass: 320 Grit
Second pass: 400 Grit

On the second pass move the sander in a Figure-8 pattern -or- Slanted-ovals from inside-out.

 

Stainless lines should net you some REAL brakes.

 

Craig, a little confused by your comments... awesomes stopieness and brakes suck. I will say that after an initial test ride after finishing the Seca's brakes I did have to adjust the cable somewhat to get "real" front braking action. Have you adjusted the brake cable?

 

Brakes are functioning properly....AND... they even felt more positive on day two. But in general they started with an underwhelming response. Cable adjustment done.

1. Maybe its because I've become accustomed to 4wheel disc with ABS.
2. Maybe its because of R&D spoiling me with newer designs.
3. Maybe a lack of confidence in the ability until further testing was done.
4. Maybe I am hypercritical.

But I did drop another 40 miles on the clock today and at least 20 of it was cruising the city streets and neighborhoods. Stuff where one would use the brakes with frequency. The more I rode and the more I stopped developed into the more frequently I was willing to get into it and become more agressive with grabbing it. If this was to be the end of the brake overhaul I would be satisfied. But I know that there are solutions available that could take it up just another notch.

 

Are they at least better than the brakes on the Elite or Passport?

 

Upgrade to STAINLESS LINES.

Even brand-new, the stock brake was mushy/spongy because of the crappy original lines.

 

No comment.

 

I upgraded my Lines to Stainless-wrapped Brake Lines acquired from XJ4Ever.

The Hydraulic Pressure obtained after a COMPLETE Overhaul was remarkable.

I had to change the Adjustment Screw on my Brake Lever to engage the Master Cylinder Piston later, in order to get my knuckles over the Lever when applying the Front Brakes.

The KIT from CHACAL was a Perfect Fit and came complete with a full set of New Banjo Bolts and Crush Washers.

Three and a half hours including MC Kit, Caliper Seals, installing the new linens and bleeding the system free of air.