Front Calipers

[DMPLATT]

These things are going to flipping kill me.

I have the calipers that have 2 guide pins that go into the caliper mount. They have the rubber boot as well. I've greased, cleaned, re-greased and did all I can think of.

I finally realized that I just can't tighten the bolts holding the calipers on to the guide pins. If I tighten them all the way, then the wheel locks up. If I snug them, the wheel locks up.
If I snug, then back them off a half a turn - all is well. No lock up, no drag and no brake squeel.
Well, I ended up losing a bolt. Now, after having to take the wheel off for repairing a leak, I thought I would investigate.

I CAN'T find what the deal is. I tried moving the axle one way or another, no difference.

I also don't have warped rotors. It's the same all the way around and on both rotors.

Any help here would be appreciated.

[sv650]

The threaded portion of the caliper that accepts the bolt is not round. If it is turned the wrong way, it forces the caliper out of place. Might this be the problem? Check that there is no gap between the caliper and the carrier.

SV

[DMPLATT]

The threaded portion of the caliper that accepts the bolt is not round. If it is turned the wrong way, it forces the caliper out of place. Might this be the problem? Check that there is no gap between the caliper and the carrier.

SV

Thanks.

I've heard about the pin not being round before, or having flats on the guide pin that fit a certain way. However, unless I have a serious wear condition, all 4 are round. They do have a flat, but I figured that was to avoid a vapor or air lock condition. They (all 4) rotate freely in the caliper bracket?

The gap I'm looking for, not sure what you mean. There is a gap between the caliper and the guide pins. This is because if I tighten them up, the brakes bind. So, I'm assuming I may have an alignment issue? What if I used some washers as spacers and try to tighten them up then? I can't see any problems this would cause?


Thanks again.

[Bolder Biker]

Dave,

I am not clear from your post what exactly your front brake problem is. However, I have encountered, and solved, a binding brake problem on my 1983 GS750ESD.

Early in my ownership of the bike, I found that the steel fork brace (under the plastic mudguard) was out of tolerance. When the brace's mounting bolts were tightened into the fork legs (with the front wheel removed), the legs were pulled too close together. The final result of this was that one (or both) of the caliper housings would rub against a brake rotor when the front wheel was remounted. My solution to this problem is to leave the brace's mounting bolts loose until after I have the front wheel and brake assembly properly mounted and the axle pinch bolts tightened. Getting at the fork brace's mounting bolts with the wheel in the way is a PIA but this tightening sequence cures the problem that I encountered.

BB

[DMPLATT]

Thanks BB. That may be part of the problem.

I'll try to be a bit more clear.

You must have the same calipers that I do.
You have the bracket that bolts solid to the forks. You then have the 2 (I call them guide pins) that slide into the bracket (with the little rubber boots). These are what "Float" when the calipers are on. They have a thread hole in the center. THis is where the caliper bolts bolt into. There for, you have the calipers bolted to these 2 "Guide Pins" and this allows the caliper to float back and forth.

My Problem is that when I tighten the caliper bolts to these "Guide Pins" my brakes bind up completely. So, what I have been having to do is to leave the caliper bolts loose. Enough so that the caliper Appears solidly on, but not tight. I just noticed last night that I lost 1 bolt. 8O

So, I'm thinking of trying to put a couple of washers between the caliper and the guid pins to see if I can get them to tighten.

Hope this clears it up for ya. Sorry for my Nomenclature. Don't know the proper Lingo.

What you have described could make perfect sense. Obviously I have something out of adjustment or a spacing is off. I'll check into that.
Is there anyway you could measure your spacing on that fork brace? That may give me an idea.

Thanks

[Bolder Biker]

Dave,

You may have the problem that I did. The caliper does "float" but only within a limited range. When my bike's fork brace pulled the fork bottoms too close together, the caliper housing rubbed against the rotor and the caliper didn't have sufficient range of movement to float away from the rotor.

I just looked at my bike and saw that I really can't accurately measure the proper separation of the fork bottoms because the brake rotors, etc. get in the way. If you have the same problem that I had you should be able to see it by getting close to the ground and looking up into the "slot" where the rotor passes through the caliper. When you turn the wheel, you will be able to hear and see any rubbing of the rotor on the caliper housing (as opposed to the normal floating contact of the pad on the rotor). You will need good natural light (or a flashlight) to see clearly. I first became aware of the problem on my bike when I took a short test ride down the street after re-installing the front wheel: I could hear the rotor rubbing continuously even though I didn't have the brakes applied.

The cure for my bike's problem was to reassemble the front wheel and brake assemblies with proper alignment, tighten the axle clamps and axle bolt, before finally tightening up the fork brace under the front mudguard. This last bit is a little swine as you have to reach up between the tire and the mudguard with a crescent wrench to tighten the 4 brace mounting bolts......not immensely difficult but a tedious process.

BB

[DMPLATT]

Thanks BB.

THat is precisely what I was looking for. I knew something had to be out of alignment/adjustment. For BOTH to be off, that makes perfect sense.

Thanks. I'll check her out tonight.

8)

[Bolder Biker]

Dave,

Please let us know what your check turns up. Good luck.

Simon

[Griffin]

I had the same problem on my GS700 last year after removing the front wheel to mount a new tire, then reinstalling it.

I loosened the front brace and the forks immediately sprang apart a further 1/8" or so. I then loosened every nut and bolt on the forks, the front axle, and the calipers, then retightend them again, this time saving the front fender/fork brace fasteners for last.

Problem solved.