Front Wheel Brake Dragging

[Reginald]

While I was replacing my front fork springs I noticed the front wheel was not spinning easily.

The front wheel was dragging a bit from the brakes before I started, it sounded like the rear brake. The front wheel wouldn't make a complete revolution on it's own after pulling it by hand; it used to spin almost twice. So while the front was off I cleaned up the brakes with brake cleaner. When I got it all together, I still got the drag and same weak spin I got before. It's the left front pads that are dragging, the right pads spun correctly (put them on one at a time find the problem). I don't believe the disk is warped because the drag is constant when I turn spin the wheel.

Any ideas on what to do about that brake drag (something simple). I've never worked on a linked system before and am intimidated by the thought of taking the calipers apart and bleeding the system. May have to take this thing to the shop.

 

[flyfisher]

Left side could be SMC related.......I'd check that.................good luck..................ff

 

[Don B]

I can't say for sure, but don't think a problem with the SMC would cause the front brakes to drag. The front brakes' hydraulic system is completely separate from the rear brake and SMC. The easiest thing to check first would probably be to make sure the caliper will slide in and out easily (no binding). Pushing the caliper inward the first time will take a bit of effort since you'll be forcing the pistons Into their bores, but it should move in and out easily then until the brake lever is applied. The beginning of the chapter on the brake system in the service manual has some troubleshooting tips that may guide you the right direction. Another thing to consider is whether the proper sequence was followed when the front wheel was installed.

 

[CruSTy]

+1 Not likely the SMC.

I can't say for sure, but don't think a problem with the SMC would cause the front brakes to drag. The front brakes' hydraulic system is completely separate from the rear brake and SMC. The easiest thing to check first would probably be to make sure the caliper will slide in and out easily (no binding). Pushing the caliper inward the first time will take a bit of effort since you'll be forcing the pistons Into their bores, but it should move in and out easily then until the brake lever is applied. The beginning of the chapter on the brake system in the service manual has some troubleshooting tips that may guide you the right direction. Another thing to consider is whether the proper sequence was followed when the front wheel was installed.

Other things to check sticking are the rear brake foot lever or rear master cylinder sticking. Though this would likely cause both front caliper center pistons to apply along with the rear brake causing rear drag also. Sitcking front piston or caliper slide are the highest percentage cause to try first.

 

[Reginald]

consider is whether the proper sequence was followed when the front wheel was installed.

I followed the manual for the front wheel installation.

The pads were dragging before I started the fork spring upgrade project. I had to add more preload to the front forks (had 46 mm of sag) so I dismantled the front end again. Now after reassembling a 2nd time I'm getting one revolution and a quarter. By hand with a plastic wedge, I had pressed in the left caliper pads. The left brake pads are still dragging a tad to much in my opinion. As a result, I'm thinking the pistons are sticking a bit.

Do you think if I took it to the shop and had them replace and bleed the brake fluid this would clear up? Or is this going to cost me a bundle for a rebuild?

I had the brake fluid replaced at 22,000 miles and only have 31,000 on the bike now. I wouldn't think a caliper rebuild would be necessary at this low mileage.

 

[Firstpeke]

Fluid is not what causes the dragging, it's the pistons not retracting properly or the caliper not sliding when brake applied / released.... the caliper needs a strip, clean and possible seal replacement, then refill and bleed the fluid..... I would guess if your pistons were pushed back on the left caliper for a pad replacement without being cleaned, then dirt would get behind the seals.... then the pistons start sticking.....

 

[Igofar]

PM sent....stop using spray can brake cleaner....it will swell the seals and o rings and make things worse.

 

[Tom Mac 04a]

+1 on DONT use brake cleaner... it can swell up the seals.

A good cleaner is just plain old brake fluid and a toothbrush or plastic scrubby. I save some of the leftover fluid ( btw, I won't use it after a month of opening ) from a bleed.

Remove one side, Put a piece of wood between the pads and get the pistons out... with a little brake fluid, scrub off the crud that builds up. Wipe all down with rags and reinstall.

BTW< Don't forget to lube the pins properly... and watch out for painted items.

This will solve many problems and is easier than pulling fully apart for new seals... Of course you still may have to , but its an easier quick fix most of the time.

 

[Reginald]

Can you tell if both brake pads are dragging ? If it is related to the piston not returning, then that will almost certainly be the case. But there is a slight possibility (especially if you have new/thick pads) that the front axle is not inserted properly.

Are they OEM pads ?

With the pistons eased back and the pads no longer in contact with the brake disc, can you slide the caliper side to side - so that inside and outside pads touch the disc in turn ? If not, then the sliders need cleaning and regreasing (rubber silicon grease). But this can be difficult on the left caliper and you may need help. ..

I'm pretty sure it's the pistons not returning. It was dragging before I started my spring upgrade, I was getting 3/4 revolution. Also, after I installed the front wheel, I removed the left caliper and spin the wheel; no drag from the right caliper. I put the caliper back on and removed the right caliper; I got dragging from the left caliper. If the wheel/axel wasn't right then the right caliper should have acted up, but it didn't. Additionally, I pressed the pistons in with a wedge of plastic and the wheel spun better (1 and 1/4 revolution), but not good enough, ... I want almost 2 revolutions. Hopefully, my push didn't wreck the seals.

I'm using OEM pads.

I'm going to follow your recommendation on cleaning, but if it continues I'll ride it to the shop. I'm a mediocre mechanic and this linked system is way over my head. I've worked on single disk systems I've owned in the past so I understand the basics from cleaning, bleeding, to pad replacement but don't feel like I can bleed this ST system.

I'm not sure the local shop cleaned the brakes when they put on new pads. I noticed things when I was upgrading my suspension like rust on my rear axel that make me suspect it! Huh, don't they clean and grease axels when replacing tires? Also, when I took my left cowl off the electrical bundle that fits into it was jammed into hoses next to the engine; it was filthy!!! They are taking short cuts and I'm not liking it. But I'm wondering can they bleed this thing correctly?

 

[SteveST1300]

Bleeding the system is not hard just a bit of time and following the correct sequence.

 

[Don B]

If you really feel more comfortable taking the bike to the dealer to have the brakes flushed and bled, remove the right middle cowl first. That way the service tech won't have any excuse to "forget" bleeding the PCV. You could either hope that they know about tilting the LF caliper to bleed the SMC, or give a subtle reminder if you're comfortable doing so.

 

[Reginald]

Not necessarily. The axle nut pulls the axle over to the right fork, and pulls the shoulder at the left end of the axle against the inner race of the left hand bearing. Providing you have the spacers on the correct sides, this puts the fork, the caliper and the brake disc on the right hand side all in the correct position in relation to each other. However, the left hand fork (and consequently the caliper) are free to move in relation to the axle and the disc (just a little). This is why it is important to check that the end of the axle is flush with the hole in the fork leg.

Not sure this is flush. See pictures - the left side is taken with the 032 feeler gauge. The left side axel protrudes less than that gauge. The right side pic is to show I have collar on correctly.

If that's not flush do I use more torque until it's flush? Everything is in place correctly.

Could my torque wrench be out of tolerance? It's a 30 year old high-end, dial-in craftsman.

Thanks for your assistance.

 

[gmtech94]

I have always loosend the pinch bolts after service and bounced the bike up and down a few times to help align the fork tubes seems to work as they can adjust to being paralell easier ,the first pic shows the tube to be off slightly which will cause brake drag .

 

[Reginald]

I have always loosend the pinch bolts after service and bounced the bike up and down a few times to help align the fork tubes seems to work

Ok, let me understand the difference here. The manual says:
1) Tighten the axel
2) Tighten the right pinch bolts
3) Bounce bike with brake applied several time (I did it three times)
4) Tighten the left pinch bolts
What I understand you're saying is
1) Tighten the axel
2) Bounce bike
3) Tighten all the pinch bolts

 

[gmtech94]

Yes I usually loosen the pinch bolts up to set the fork tubes . Then retorque all the bolts and give a check ,is it a possibility that the wheel bearing are going out of the front wheels also causing a drag ,check with both calipers removed and all fasteners torqued up should be smooth and rotate a few turns .

 

[Reginald]

is it a possibility that the wheel bearing are going out of the front wheels also causing a drag

It's the left caliper pads dragging. I checked the bearings and spun it without any brakes, it spun so many times I didn't bother to count. I checked each caliper independently and found the left caliper to be dragging. The wheel spun 2 1/2 times with the right caliper. It's spinning 1 1/4 times right now with the left caliper, so it can't be to bad a problem.

you may have to physically pull (or push) the fork across a little to make the axle face flush, before tightening the pinch bolts

I've followed ya'll's instructions and it appears the axle straightened out a tad, a micro measurement for which I have no tools to measure. The beveled part of the axle is flush with the machined face of the fork; all the circumference is equally flush. The surface of the axle is actually inside the fork leg outer surface when I put a flat gauge across the fork leg surface. The axle is torqued to 58 lbf-ft.

I just checked the 0.7mm caliper clearance to the disk and its good. So it looks like the front tire is correct.

Tomorrow, I'm going to clean up the breaks and see if that works. I'll follow Joe's article to do it. I'll also pull the collar to the needle bearing, clean, and then repack the bearing with EP moly-grease (the left caliper's pivot).

If none of this works,.. it goes to the shop,... eight miles shouldn't hurt it.

Thanks for the help.