How much travel at your front brake lever?

[KEITH KRAUSE]

Help me out guys.
I need you to go get a ruler and measure how much travel you have at the lever.
I'm not allowing for that small 1/8" of slack before the lever actually touches/pushes the piston/cup assembly. And I'm not allowing for a hard squeeze either. Just the amount necessary to stop the bike and compress the forks a little after you push it forward a little with your feet.
So the distance from where contact actually starts until a moderate pull at the lever.
Please be accurate. I'm trying to figure out if I have a problem and need some bikes to compare mine to. Thanks a lot!

 

[tconroy]

Help me out guys.
I need you to go get a ruler and measure how much travel you have at the lever.
I'm not allowing for that small 1/8" of slack before the lever actually touches/pushes the piston/cup assembly. And I'm not allowing for a hard squeeze either. Just the amount necessary to stop the bike and compress the forks a little after you push it forward a little with your feet.
So the distance from where contact actually starts until a moderate pull at the lever.
Please be accurate. I'm trying to figure out if I have a problem and need some bikes to compare mine to. Thanks a lot!

I have right at 1/2" or a hair over. It's hard to hold the ruler and brake with the bike going forward all at the same time.Plus there is no spongyness at all.With the front wheel proped up off the ground it will stop the wheel solid at 3/16ths of travel. I hope that helps you because you have helped me so much its the least I could do!!!!

 

[Clone]

4-5mm, I would say next to none. When I grab the brake it is pretty instantaneous. I cannot pull it all the way to the grip and i even have big foamy grips.

 

[KEITH KRAUSE]

Thanks for the reply. Hard to believe you only have 1/2" travel to reach moderate braking. My travel WAS right at 1" and that was with the pistons sticking too far out because of swelled seals. I found 1" travel was great for feel but I knew it was related to a malfunctioning brake system.
My pads were starting to drag on the rotors and it was because I ran silicone Dot 5 fluid and it swelled the seals. With the pistons not retracting correctly after releasing the lever, it took only that 1" before solid braking took place. I would think 1/2" would suggest you have a brake problem similar or worse than what I had before my seal replacement.
Anyway, to let you all know what's going on now, after replacing the seals with genuine Suzuki and changing the fluid to the "new" 5.1, I now have 1 3/4" of travel before noticable braking takes place. So I've gone from too little to what feels like too much travel. I'm about as sure as I can be that the brakes have been bled correctly. I bled them the same way I always have. The pads and fluid amounts are good too. I run SS lines.
You can imagine, especially after riding the bike awhile with the original problem/lack of travel, the 1 3/4" present travel feels wrong. It doesn't feel spongy, just too much travel to get to solid braking.
So I'm asking anyone out there with a known good front braking system, please measure the travel as I said above and let me know what you've got.
If I do have a travel problem, you would typical blame air in the system but I bled them through an entire 3 reservoirs full AFTER the last bubbles were seen. I can't believe there's air still in there.

 

[KEITH KRAUSE]

And in case I'm not being clear about what point to measure at...
I'm not talking about the pinch point of the lever, I'm talking about at the end of the lever, where the ball/tip is. What distance does your lever travel before moderate braking force is being applied. Thanks!

 

[bwringer]

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.

 

[Boondocks]

My lever travel is about the same as Brian's.

I'm sure that you know now that DOT 5 silicone based brake fluid was not a good choice, and is not recommended for use in our bikes. Spongy brakes due to compressibility are only one of the concerns. Since your problems haven't cleared up after switching to DOT 5.1 (Super DOT 4), I would think that the prior use of DOT 5 is responsible. The silicone based DOT 5 is notoriously difficult to remove.

An expert's advice at DOT 3-4 Verses DOT 5. Which brake fluid should I use? states that once DOT 5 is used it is so tenacious that you will never get it out of your system, and recommends not trying to change back to a non-silicone brake fluid.

 

[SqDancerLynn1]

Try the rubber band trick . Wrap a lg rubber band / cable tie around the lever & handle to lightly apply the brakes. Leave it over night. I usually use a piece of vacuum hose into a sm bottle with some brake fluid in it. submerge the hose, open bleader screw & slowly blead brakes- watch fluid for bubbles

 

[denydog]

My lever moves one inch before firming up. One and a half inches with a hard pull.

I have the SS braklines, but the cylinder also has to actuate the antidive plumbing and the hydraulic brake light switch, which requires extra lever movement.

 

[Captk]

Mine travels from 16 - 20 mm and thats from the point where you can feel the brakes actuate to the point wher it's impossible to push the bike.

I have the Anti- Dive gear on mine and changed the fluid about 6 weeks ago as part of routine maintenance.

I've got one of those little brake bleeding kits, which is just a clear line with a one-way valve attached.

The way I was taught to bleed them is like this....

1) Bleed F/Left AD till new fluid shows
2) bleed F/Left Brake - new fluid, no bubbles
3) Bleed F/Right AD till new fluid shows
4) Bleed F/Right Brake - new fluid, no bubbles

In other words you're working from the furtherst point away from the master cylinder to the closest point.

Hope this helps.

 

[KEITH KRAUSE]

OK. Thanks for those replies. I've got 1 3/4" to solid braking.
I have to think it's the silicone. I suppose it could be air, I mean, you can't actually see inside the parts, but I've never had a problem bleeding air out before.
I had the parts completely taken apart, trying to remove any silicone residue. I did read that article and will re-read it. The only parts that could still have any residue would be the brake lines. For the lines, the only thing I could think of to do was to flush some contact cleaner through them that leaves no residue itself. I followed that with fresh fluid. Per that article, it said some solvents could leave a residue as bad as the silicone. That's why I decided on the contact cleaner. I had to try something that seemed "clean".
How exactly does any very small amount of silicone left inside cause excessive travel??? I don't get it.
If that's the case, I guess I'd have to go back to silicone and possibly live with replacing my seals sooner than normal. All because there's some tiny amount of silicone still sticking to my lines?
Odd thing is, I used silicone since 1980. I had absolutely no problems and had the original caliper piston seals in there until 1999. Then, as part of my restoration, I replaced the seals with genuine Suzuki seals about 6 years ago. Awhile back, the pistons started sticking and it appears it was due to the silicone swelling the seals. The pistons couldn't retract. I saw no evidence of corrosion or wear in the bores or any problems with either piston, so I have to believe the seals were the problem. Now I have this excessive travel. The other strange thing that's not jiving with you guys is that as the dragging/sticking got worse, the lever travel lessened. At 1" I had to fix it. I know I had more than that before the problem. Now you guys say you have even less than me. I'm totally confused here.
I'll re-read that atricle. Any other help on what you would do or have heard of is appreciated.

 

[waterman]

Keith, have you inspected your master cylinder for blockage? If I understand correctly, you have noticed that the brake lever requires less travel to activate and the brakes are sticking or seem that the brake pads are not retracting. I question whether it is the brake caliber piston seal swelling or it is a blocked return hole in your master cylinder. I struggled with non retracting, locking pads until I cleared the small brake fluid orifice in the master cylinder. The symptoms were similar, very little brake level travel and locking brakes. After the fix it seemed as if the brakes were weak since I was used to the short lever travel.

Before I had fixed the problem I would bleed a little fluid out of calipers before each ride. My lever travel would increase and the brakes didn't seem so sensitive. Check to see if after you apply brakes and let off if you still have pressure in calipers by opening bleeder screws. If fluid spuirts out, I would suspect master cylinder needs attention.

I have had good luck bleeding brakes by loosening the master cylinder banjo nut connection. It seems that the air will collect at this higher elevation. To do it just squeeze lever while cracking bolt until fluid comes out. Yes it does make a mess. Good luck.

 

[Boondocks]

OK. Thanks for those replies. I've got 1 3/4" to solid braking.
I have to think it's the silicone. I suppose it could be air, I mean, you can't actually see inside the parts, but I've never had a problem bleeding air out before.
I had the parts completely taken apart, trying to remove any silicone residue. I did read that article and will re-read it. The only parts that could still have any residue would be the brake lines. For the lines, the only thing I could think of to do was to flush some contact cleaner through them that leaves no residue itself. I followed that with fresh fluid. Per that article, it said some solvents could leave a residue as bad as the silicone. That's why I decided on the contact cleaner. I had to try something that seemed "clean".
How exactly does any very small amount of silicone left inside cause excessive travel??? I don't get it.
If that's the case, I guess I'd have to go back to silicone and possibly live with replacing my seals sooner than normal. All because there's some tiny amount of silicone still sticking to my lines?
Odd thing is, I used silicone since 1980. I had absolutely no problems and had the original caliper piston seals in there until 1999. Then, as part of my restoration, I replaced the seals with genuine Suzuki seals about 6 years ago. Awhile back, the pistons started sticking and it appears it was due to the silicone swelling the seals. The pistons couldn't retract. I saw no evidence of corrosion or wear in the bores or any problems with either piston, so I have to believe the seals were the problem. Now I have this excessive travel. The other strange thing that's not jiving with you guys is that as the dragging/sticking got worse, the lever travel lessened. At 1" I had to fix it. I know I had more than that before the problem. Now you guys say you have even less than me. I'm totally confused here.
I'll re-read that atricle. Any other help on what you would do or have heard of is appreciated.

If you don't have stainless steel brake lines, your lever travel will be greater due to the expansion of the OEM rubber lines. If brake components are dragging/sticking, they are not returning to the fully relaxed position, in effect being partially "on" all the time. Thus it would seem that less lever travel would be required when brake components are starting from an "almost on" position. The sticking parts are typically caused by fluid contamination or air pressure in the lines.

DOT 5 sometimes gets blamed for seal damage, but it is usually caused by contamination of the brake fluid. The article at DOT 5 Silicone Brake Fluid Warning has some interesting contributions about contamination. Contact cleaner that I have used is mostly alcohol. According to the link, flushing with alcohol can cause problems. Flushing should be done only with DOT 3 or DOT 4.

The article at Understanding Brake Fluid is one of the best.

There are also interesting articles at DOT 3 vs. DOT 5 Brake Fluid and
Brake Fluid Does Wear Out

 

[flyingace]

If you're still collecting samples, I have box stock lines and hardware with 1 inch of lever travel before braking begins.

 

[Metal Jim]

Brake bleeding.

Brake bleeding.

Keep in mind also that aftermarket handlebars car create new high points in the system that could be difficult to purge air from. If your master cylinder outlet is angled up, count on air in the pocket. You can always pull your master cylinder off the bar (leave hydraulics connected) and straighten out the line as best you can for optimum gravity bleed or in worst case, wet build from the caliper up. Keep on tapping, one bubble is enough to affect feel. There is no "give" in hydraulic fluid (for our purposes), so feel is an issue of containment. Given stainless lines, something else is getting out of the way.

 

[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.