How much travel at your front brake lever?

[tconroy]

Measured at end of the ball on the end of the lever, my 1983 GS850G brakes engage firmly at 16mm (5/8 inch). Very hard braking might take them to 21mm or 22mm. Stainless brake lines rock. \\/

The brake on the 1990 VX800 also engages firmly at 16mm, and has a slightly harder feel since there's only one (stainless) line and one, more modern dual piston caliper. Hard braking takes it to about 21mm.

Even though the GS weighs about 100 pounds more than the VX, the GS850's dual calipers give more braking power and feel than the VX800's measly single caliper. Neither bike can touch the brakes on a more modern sportbike, but with the stainless lines, the GS brakes are pretty dang good.

I remeasured more acuratly and have 3/4. When spinnig my front wheel off the ground I get a slight scraping sound,is that the way it should be or do I have a problem.It will spin about 5 times before slowing down and stopping.

[bwringer]

I remeasured more acuratly and have 3/4. When spinnig my front wheel off the ground I get a slight scraping sound,is that the way it should be or do I have a problem.It will spin about 5 times before slowing down and stopping.

The slight sounds (kinda like ringing the rotor as the holes go past the pads) and the number of turns sound pretty normal. It doesn't sound like you're dragging.


One thing I haven't seen mentioned yet is the condition of the pads. They tend to wear in a slightly angled way because of the inevitable slight amount of play between the calipers and the pins.

If you put worn brake pads back in a different position than how they came out, or if the pads or mounting pins are severely worn, you can end up with more brake lever travel and some dragging. The calipers have to squeeze further to take up the slack, and the high spot might remain in contact with the rotor.

[KEITH KRAUSE]

Thanks for the replies everyone. Here's the latest for those interested.
I went to a Suzuki/Yamaha dealer today and took my ruler with me. All the bikes I checked were brand new and I'd assume the brakes were in top condition.
When squeezing moderately on the lever, I measured the travel at the end of the lever ball between 1 1/2 and 1 3/4". That's from all the way out/released to what I call a moderate amount of pull at the lever. This was on about 7 bikes and different models. The only bike that had less was an R6 and that measured at 1 1/4". This made me feel a little better but it really conflicts with what you guys are measuring.
I asked the lead mechanic and another mechanic right next to him what they thought of my problem. Their first thought was I didn't bleed correctly. The next thought was I may have damaged the rubber cup in the master cylinder when I used the contact cleaner to flush out remaining silicone. They said the rubber cup may be contributing to overall poor feel but the seemingly excessive travel wouldn't be caused by a damaged cup. So that lead us back to bleeding.
To my surprise, they said to take home their bleed pump and I could be 100% sure that any excessive travel wouldn't be because of a poor bleed.
Well, I hooked it up and it wouldn't draw fluid from the left caliper unless I pumped the lever. A few small bubbles did appear. I re-filled the reservoir 5 times before I called it good. It worked well on the right caliper. One medium sized bubble appeared and I again re-filled the reservoir about 5 times after seeing that one bubble. I now noticed the reason the left caliper didn't allow the pump to draw without lever pumping was because the "speedbleeder" (a one way valve/ball and spring) bleeder I use, must have a weak/cocked valve inside. It has a very small/slow leak. I guess the malfunctioning valve is giving too much resistance and the pump can't work as designed at that caliper. I still would think the bleed was successful though. Agreed?? I of course have ordered new bleeders but I'm hesitant to believe the very small leaking bleeder is to blame for the travel issue. I'm talking one drop after about 50-60 pumps at the lever, no noticable leak if not pumped.
After all this, I re-meaured the travel and it may have improved just a little bit. But still very close to 1 3/4. Not much more than the new bikes on the lot but way more than you guys are reporting.
I'm not sure what to do at this point. The brake does work but it just doesn't feel right with the amount of travel it has.
I'll put in the replacement speedbleeder as soon as I get it and I'll ask the dealer if they think another bleed with their pump (if they'll loan it to me again) would be needed. When I removed the leaking bleeder to look at it, fluid came gushing out under pressure. I can't believe air could get in under that condition but I'll ask if I need to re-bleed after replacing the bleeder. One of you replied that leaking from the caliper bleeder with no pressure applied suggests the piston/cup assembly in the master cylinder is bad?? I'll have to look into that as my next try at fixing this but I don't have that much faith in it.
Beyond that, all I can think of is the possibility that silicone residue may be the problem. The two mechanics doubted that possibility because of how I explained my cleaning attempt. Very little could remain but I suppose it's still possible. Not sure what I can do about it though.
Thanks very much for the replies and I'll read those articles you guys included.
Thanks for reading this. You know I always try to give detailed info even if it is a long read.

[bwringer]

When I removed the leaking bleeder to look at it, fluid came gushing out under pressure.

Residual pressure pretty much tells you right there that you have a problem with the return circuit in the master cylinder. In other words, you probably have silicone sludge clogging things up.

Also, you can't use a vacuum bleeder with speed bleeders. You have to use regular bleed screws. You should be able to get ones with the same thread at any auto parts shop. Wrap the threads with some teflon pipe tape (the thin white kind) to keep air from seeping in while you're vacuum bleeding.

A MityVac pump is only about $30 and is a mighty handy thing to have for many other uses, so you might consider buying one instead of borrowing the dealer's.

The easiest way of telling if a brake problem is trapped air is whether you can pump the brake a few times to get a firmer feel or less travel. If you can, it's most likely simply trapped air. On a properly functioning system, the lever feel and travel don't change when you pump them. If you can't pump it up, then it's probably not trapped air.

I think you'll find a surprising amount of ugly gooey mung when you pull apart that master cylinder. I agree that deterioration in the seals is probably not the problem -- it could be in the future if the Suzuki seals aren't compatible with the silicone fluid or with the cleaners you have used to try to flush the system.

If you do find that the seals are damaged, one thought I had is that maybe the aftermarket rebuild kits might be made with a different material than the OEM, and possibly more or less tolerant of the silicone fluid. Dunno.

[KEITH KRAUSE]

And to answer at least reply, the pads are in very good condition and they only go in at one position.
The piston/cup set is only a couple years old too. If it has a problem, it would only be the possibility the cleaner compromised the rubber cup and how it slides smoothly. There's absolutely no leak at the bore from a damaged rubber cup.

[bwringer]

A few more thoughts...

What sort of bike do you have? I'm trying to picture which braking system it is. IIRC, most or all of the 80-85 GS bikes used the same brake system, so we would have directly comparable results. With stainless lines, you should get no more than 16-21mm of lever travel. Period.

You can't really compare lever travel with modern 4 and 6 piston calipers and different master cylinders. Apples to oranges. The amount of force you'd apply to stop a GS moderately would be enough to lock the wheel and send you into the weeds on a modern sportbike. They need more level travel to give you the needed degree of feel fine control, so the master cylinders are sized differently.

On a GS, the single-piston calipers and relatively large master cylinder diameters mean that you have to give the lever a manly squeeze to get good stopping, and that it's not going to move very far between "whoa" and "OH %$#@!!!!".

[bwringer]

And to answer at least reply, the pads are in very good condition and they only go in at one position.
The piston/cup set is only a couple years old too. If it has a problem, it would only be the possibility the cleaner compromised the rubber cup and how it slides smoothly. There's absolutely no leak at the bore from a damaged rubber cup.

You're not getting any leaking and the lever doesn't sink under constant pressure (at least not that you've mentioned), so I agree that the seals aren't the problem.

[KEITH KRAUSE]

OK. To answer a few more.
The old seals were swelled and the pistons were both sticking out noticably when I took off the calipers. New genuine Suzuki seals fixed that. The pistons move correctly.
The lever travel doesn't decrease if I pump it. The lever doesn't get any harder.
I did see air bubbles escaping out of the smaller return hole (under the reservoir bottom). After some time, but not before the bleed was completed, the air bubbles completely disappeared from the hole. I did clean and blow this return hole out, without seeing any blockage, about a year ago. I don't completely doubt that a very small amount of silicone could still remain and I'll deal with that if I can't get a fix another way.
I agree it seems like a return problem, but with the return hole clear and the pistons now retracting correctly, I can't see how it's happening.
The silicone residue remains a possibility and I admit I don't fully understand how only a film of silicone, if that much remains, could cause a travel problem. There's no way a glob or large amount of silicone remains.

[KEITH KRAUSE]

Sorry if my replies are a little behind your replies. I take a long time to think what I'm typing.
My bike is a '79 GS1000E. Single piston calipers. Dual rotors. SS lines.
I agree it's hard to compare different models and it's also difficult to explain just how much travel I'm getting and what kind of lever force is being used. I'm just trying to get some idea to compare. I think something's wrong but what's confusing things is how you guys have even less travel than me BEFORE I replaced the seals. I had 1" and I KNOW for a fact that it was too little, based on what the bike had awhile back when there was no problem. As the dragging/sticking got worse, the lever travel decreased to 1". Before the problem, I can't say how much the travel was because I never would think to measue lever travel. But the lever travel was noticably more than 1" and my brakes worked perfectly.

[KEITH KRAUSE]

Bruce, old buddy. If you have no brake problems, could you give a measurement please?
Also, anyone, the levers I've used for many years are the "dog-legged" levers. They make it easier to reach the lever. They certainly aren't the problem but because they are closer to the grip, they are making my "excessive" travel problem more noticable. Stock levers would help somewhat in that the lever wouldn't come as close to the grip. The travel wouldn't seem as excessive then.
I wonder what the difference is from the stock levers and the dog legged style? If anyone can show a pic of the stockers next to the typical dog legged style or just measure how much "further out" the stockers would be, I'd really appreciate it. If I can't fix my problem, stock levers would help minimize the problem.

[renobruce]

Bruce, old buddy. If you have no brake problems, could you give a measurement please?
Also, anyone, the levers I've used for many years are the "dog-legged" levers. They make it easier to reach the lever. They certainly aren't the problem but because they are closer to the grip, they are making my "excessive" travel problem more noticable. Stock levers would help somewhat in that the lever wouldn't come as close to the grip. The travel wouldn't seem as excessive then.
I wonder what the difference is from the stock levers and the dog legged style? If anyone can show a pic of the stockers next to the typical dog legged style or just measure how much "further out" the stockers would be, I'd really appreciate it. If I can't fix my problem, stock levers would help minimize the problem.

Hey, Keith,
I just finished installing my SS lines, but have not yet bled the lines. I will get that done later today and post my results for you. I had no brake problems prior to putting the new lines and new pads on.

[renobruce]

I'm getting 1 3/4" travel from the end of the handle, which feels about the same as I was getting before the SS lines. But boy, what a difference the braking performance is!

[renobruce]

Oh, and the very end of my brake handle is exactly 4 inches from the start of the grip (inside to inside).

[Rocketman]

Thankfully, the one problem I haven't had (yet!!!) with my '82 GS850L is braking, However, I just measured 3/4" end ball travel to moderate braking, 1" to full pulled in brake handle. That's with broken in pads and SS lines. Hope that helps.

[KEITH KRAUSE]

Thanks for the replies.
Bruce, all the way out, my dog legged lever is only about 3 1/4" from the grip, so when I pull in my lever it now comes to about 1 1/2" of my grip...just doesn't feel right. I'm assuming your lever that is 4" out is stock??? A lever that is 4" out would certainly help this situation, though it's not the levers fault. When I pull in the lever now with two fingers, the lever starts to touch my fingers remaining on the grip, especially with my glove on.
Anyway, I believe I've figured out the problem and I'll post it in a bit for those interested.