[Not Solved] Lazy caliper pistons - cause for concern? | GTAMotorcycle.com

[Not Solved] Lazy caliper pistons - cause for concern?

sburns

Well-known member
Hey gang.

So I have been chasing this strange shimmying/squeaking sound coming from my back tire area. Yes this is different then my tire noise issue.

Anyhow as of now I am not thinking it is the wheel bearings, but not ruled out yet. My attention is now on the rear brake caliper, which I thought the pads might be rubbing against. So I tried some anti-squeak brake paste/silicone for the back of the pads. Didn't do anything.

Just did a through cleaning of the caliper, which has 2 pistons on each side (or pad). On either side 1 of the pistons is a bit lazy and pushes out much later then one next to it. Could this be skewing the pads and causing it to scrap against the rotor at a angle?

Otherwise the brake pressure and function seems the same to me.

Help!
 

Trials

Well-known member
Hey gang.

So I have been chasing this strange shimmying/squeaking sound coming from my back tire area. Yes this is different then my tire noise issue.

Anyhow as of now I am not thinking it is the wheel bearings, but not ruled out yet. My attention is now on the rear brake caliper, which I thought the pads might be rubbing against. So I tried some anti-squeak brake paste/silicone for the back of the pads. Didn't do anything.

Just did a through cleaning of the caliper, which has 2 pistons on each side (or pad). On either side 1 of the pistons is a bit lazy and pushes out much later then one next to it. Could this be skewing the pads and causing it to scrap against the rotor at a angle?

Otherwise the brake pressure and function seems the same to me.

Help!
If your wheel bearings are worn out, what do you suppose that does to the alignment between the brake disc and the calliper ;)
change those bearings! then you can forget about them for a while.
 

sburns

Well-known member
If your wheel bearings are worn out, what do you suppose that does to the alignment between the brake disc and the calliper ;)
change those bearings! then you can forget about them for a while.
Yeah I was thinking to do the bearings anyway. I actually just got the tool delivered today. But this capiler issue kinda reared it's head. So you are saying the bearings might be the source of all of this.
 

sburns

Well-known member
Bearings are cheap, caliper seals are cheap - fix it all and have done with it.
Well apparently HD calipers cannot be rebuilt. Still looking into it. Bearings yes will do.
 
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J_F

gringo diablo
Site Supporter
there's always going to be pistons that move before other ones
if one contacts the pad and then the rotor and the others don't want to move
then yeah, that's indicating a problem

over 100k?

trials' suggestion of looking at bearings is a good one
 

Jayell

Well-known member
Site Supporter

blackcamaro

Well-known member
Your shimmy/squeak....have you checked that the rotor isn’t warped? Harley rotors aren’t great and pretty common to warp on the touring bikes.

The wheel bearings Harley uses also aren’t known to be the best so I would just go ahead and swap them out since you will have everything tore down anyways.
 

sburns

Well-known member
Ok as a test I fully compressed the piston in the caliper and put it back on the bike, and didn't press the brake to build up pressure so the pads are not touching the rotor. Went for a quick ride and only used the front brakea....ya noise is still there.

It's look like @Trials is right on this.

Will tackle the wheel bearings tomorrow.
 

sburns

Well-known member
there's always going to be pistons that move before other ones
if one contacts the pad and then the rotor and the others don't want to move
then yeah, that's indicating a problem

over 100k?

trials' suggestion of looking at bearings is a good one
Close to 110k now....😬
When looking at the pistons they still looked in good condition, no rust, no spots etc.
 

Mad Mike

Well-known member
Check the pins that thread thru the pads, they can get quite grooved, this will interrupt pad travel and can cause strange noises.
 

Trials

Well-known member
Yeah I was thinking to do the bearings anyway. I actually just got the tool delivered today. But this capiler issue kinda reared it's head. So you are saying the bearings might be the source of all of this.
Your brakes and your drive train are constantly trying to tear your wheel bearings to pieces.
Once the wheel bearings develop Any play that results in alignment problems with both the brakes and the drive train :/ the bikes handling goes to **** too. Wheel bearings start to develop play soon after they get water inside them.

My chain rusted over night after the Tweed trial last weekend, it was so muddy the chain was completely encrusted to the point where it was holding the bike back :| no wonder that last lap was so hard!
 

Roadghost

Well-known member
Close to 110k now....😬
When looking at the pistons they still looked in good condition, no rust, no spots etc.

Have to agree with Glee Club. 110km, if the bike was carrying a lot of weight you need to check the play in the bearings. Likely need replacing. Even car bearings don't last more than 150km these days.
 

sburns

Well-known member
Your non rebuild able Harley caliper, is it a 32mm Brembo?
I can't seem to find that info in the service manual or online parts explorer. I'll check user manual later.
 

Trials

Well-known member
I kill wheel bearings in trials bikes and they are very likely the same or very close to the same bearing, the bike with me on it weighs 300 pounds and the distance a trials bike travels is not very much at all. I do beat them against rocks and logs constantly, and I ride it through stupid amounts of mud and water, freezing rain and snow.. They last about 6 years if you are lucky and then they are toast.
You can spot a Harley spec Brembo a mile away.
 

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