Caliper Piston/Pad Real Tight After Tire Change

[BrianK]

Had the dealer change tires yeaterday on my 85 Vmax and everything was going well until we noticed the front wheel brake pads were "real tight" on the front caliper, as if the brake lever was already pulled to about 50%.

Without pulling the calipers off, they tried to push the pistons back a little and bleed the system, but without much improvement.

Even though the Vmax "stock brake system" was working perfectly before the dealer changed the tires, they said that since the system was 22 years old, it most likley needs to have the "caliper piston seals" rebuilt. (of course they don't stock the seal kit!)

They sent me home with these instructions, "ok to ride the bike, but don't use front brakes. Order the front brake caliper - piston seal kit and rebuild as needed."

Actually, I had already ordered the seal kit, master rebuild kits, SS brake & clutch hoses... the other day along with 2k of other parts, but it won't get here for another week.

Couldn't wait another week to go riding and removed both front calipers so I could do a "minor service" to the front calipers, pistons and pads. (remove caliper, pads, pistons, clean all in Dot3. Re-install and bleed system.)

Everything went pretty well with the "minor service" I just did, but the pads are still "real tight" (as if the brake lever has been pulled to about 50%).

1) Are the Vmax brakes supposed to be "this tight initially" after this type of minor service?

2) Will the pads wear off so they front wheel can be turned by hand again?

3) Will the caliper pistons "retract somewhat" after a few miles?

3) Is this a sign of "caliper seal failure"?

Any advice would be appreciated.

BrianK
Houston, Texas

 

[4gasem]

NO that's not usual and shouldn't be driven that way. The wheel should spin freely. Are you sure the wheel was installed correctly?

 

[davidon]

loosen axle and see if you can spin wheel freely or if brakes still bind..you can then see if it's a wheel misalignment or really brakes

 

[BrianK]

When I had the calipers off last night to clean them, I had a chance to see if the "front brake calipers/pistons" or the "front wheel bering/seals" were the cause of my troubles here.

With both calipers removed from the front brake roters, the front wheel & berings ran very smooth".

BrianK
Houston, Texas

 

[Buster Hymen]

First off, how tight are you making the nut on the front axle? Second is it tight on both calipers or just one? Also is your brake fluid level at the right height or is it overfilled? Calipers sometimes stick a bit and don't retract all the way in. When you put new pads on, this will make it tight. Make sure the caliper is all the way back into its cylinder. You should be able to squeeze it in with a pair of Channelock pliers.

 

[BrianK]

First off, how tight are you making the nut on the front axle? Second is it tight on both calipers or just one? Also is your brake fluid level at the right height or is it overfilled? Calipers sometimes stick a bit and don't retract all the way in. When you put new pads on, this will make it tight. Make sure the caliper is all the way back into its cylinder. You should be able to squeeze it in with a pair of Channelock pliers.

The Yamaha dealer did the service yesterday, so I expect the axel nut was tightened to torque spec. They replaced both front & back wheels, and front wheel berings and seals.

When I did the "minor service" last night to attempt to fix the problem (see prior post) and upon removal of the front calipers, one caliper felt like it was a little tighter fit on the brake rotar than the other, but it didn't require any tools to pivot the caliper off the rotar disc.

Front brake fluid level is filled per spec about 10mm down (3/8") from the top edge of the brake well (while cap is off and forks are turned so well is level).

After I did the "minor service" last night and was reinstalling the caliper pistons, I was able lube with Dot3 and press the pistons all the way down into the caliper housing. Re-installing the pistons was a real bitch since I wasn't able to install new seals last night and I do not have a "brake caliper piston clamp".

Re-mounting the front caliper/pad assemblies over the "brake rotars" was a breeze since I was able to fully compress the pistons prior to re-mounting.

After the "minor service last night" and even though I drained out all of the Dot3 from the front brake system, I was able to re-bleed the brake system just fine and as expected from prior experience in about 30 minutes.

Regarding the "retraction" of brake piston/pads after brake lever has been released, what part of the system is responsable for this process? I don't see that happening right now.

BrianK
Houston, Texas

 

[4gasem]

The Yamaha dealer did the service yesterday, so I expect the axel nut was tightened to torque spec.

Regarding the "retraction" of brake piston/pads after brake lever has been released, what part of the system is responsable for this process? I don't see that happening right now.

BrianK
Houston, Texas

The wheels need not be tightened to specs. I would say 65-75% of spec is more than fine. I torque my after market wheels to 50% of spec.

The rotors are what push the pads/pistons back in as they spin as they aren't perfectly true.

Good luck

 

[BrianK]

The wheels need not be tightened to specs. I would say 65-75% of spec is more than fine. I torque my after market wheels to 50% of spec.

The rotors are what push the pads/pistons back in as they spin as they aren't perfectly true.

Good luck

Hummmm, Only the rotors spinning push the pads back in? No Kidding! I thought that would wear out the pads way to fast.

I would have thought the master cylinder would have some minor role in pulling the caliper piston back slightly, even just to eaise the direct force on the piston.

Thanks,
BrianK
Houston, Texas

 

[4gasem]

Hummmm, Only the rotors spinning push the pads back in? No Kidding! I thought that would wear out the pads way to fast.

I would have thought the master cylinder would have some minor role in pulling the caliper piston back slightly, even just to eaise the direct force on the piston.

Thanks,
BrianK
Houston, Texas

Nope... When it's raining you want the pads just barely hitting the rotors to keep them dry too.