Squishy front brake lever- not air.

[Wayne]

I have a 1980 GS1100 and a 1981 GSX1100. Basically the same bike.

The latter has original unrestored calipers and master cylinder with only a fluid change.The brake lever is firm and solid with powerful stopping.

On the other bike, the lever was squashy when I got it. I completely rebuilt calipers and master cylinder with Suzuki kits. I have done a good dozen Suzuki brake rebuilds and think I know what I'm doing. But the brake lever is still squashy and the brakes abyssmal. They have new EBC Ferrodo platinum pads that have done about 300 miles. The lever needs to be full hand pulled in until it almost touches the grip before you'll get adequate stopping.

Both bikes have original brake hoses and the squishy brake bike is very low mile and in all but showroom condition. The other one is a "used" but tidy bike.

The squish is not air. I spent a lot of time bleeding and you can pump as much as you like, it doesn't get firmer (like it does with air in the lines).

Was there a change to master cylinder diameter ? (they had some variation, for example, among KZ1300s).

Is everybody else's 1980 GS1100e lever squishy or firm ?

I find it hard to believe that it could be due to swelling hoses (?) but any comments appreciated.

 

[Guest]

Hoses swell internally and you sometimes can't even see it happening. They might move a little.

SS lines would fix that.

One way to test that is to pump allot and then tie the lever down hard over night. It should set the line in a stretched position and the lever should feel stiffer after you pump it up again and get all the slack out of the system. That won't last but it will tell you if its the lines.

I've had to vacuum pump one set at least 10 times in a row just to get a good handle feel even with ss lines on a single caliper once.

I'd say try vacuum pumping it instead of normal bleeding.

 

[Wayne]

You're dead right on the vacuum pump. I couldn't bleed it and had to use a vac pump to get rid of all the bubbles. But that was weeks ago.

I'll try your suggestion of pumping and leaving overnight. It's 6 pm here so perfect time to go to the shed right now and try it.

 

[Nessism]

Suzuki recommends changing the brake lines every two years, so you are 30 years over due. I'd change them out ASAP and go from there.

Most likely the caliper piston isn't moving out close enough to the disc. Tying the lever back often helps this. Making sure the caliper sliding pins are not worn and are properly greased with high temp caliper grease is also important.

 

[koolaid_kid]

My GS brakes were squishy no matter what I tried, cleaning, bleeding, new pads, etc.
Then I installed stainless steel brake lines. Instant firmness. Just my personal experience.

 

[Spiff]

Change your brake lines if you haven't done it.
If there where differences in piston diameter you wouldn't even be able to bleed them.
I've tried as I got the wrong diameter master cylinder piston with an overhaul kit I bought...

 

[Baatfam]

Most likely the caliper piston isn't moving out close enough to the disc.

Or...if you just rebuilt the caliper with new seals, they might be pulling the piston back a little.
One tip I got that worked on mine, (yes, I have stainless lines), was to unbolt the calipers, pull them off the rotor and carefully pull the brake lever until the pads are closed some.
Now push them back apart just enough to fit back over the rotor.

Worked for me and a few others on here.

 

[1980GS1000E]

Bad hoses.

 

[Agemax]

what brake fluid are you using?

 

[Guest]

Or...if you just rebuilt the caliper with new seals, they might be pulling the piston back a little.
One tip I got that worked on mine, (yes, I have stainless lines), was to unbolt the calipers, pull them off the rotor and carefully pull the brake lever until the pads are closed some.
Now push them back apart just enough to fit back over the rotor.

Worked for me and a few others on here.

By tying the brake lever and leaving it, I found that it had the same effect. Before that I could watch the pads retract after letting the lever go. After it settled overnight the pads stayed in place and I got a few more pumps before it got hard and stayed hard.

I used Apex for my lines. Got then off of ebay from Raymond chan. I like em. Good price too. What ever size, shape, color, fittings you want.

 

[Baatfam]

By tying the brake lever and leaving it, I found that it had the same effect. Before that I could watch the pads retract after letting the lever go. After it settled overnight the pads stayed in place and I got a few more pumps before it got hard and stayed hard.

Man, I tried that a dozen times with no luck. The only thing that worked for me was to remove the calipers and do like I did...

Go figure...

 

[1_v8_merc]

Sounds like brake lines, been there, done that with a couple of my bikes.

It's worth a note....some bikes have perfect stopping power after 30 years, with factory lines. And other bikes aren't that lucky. It could depend on how the bike was used, stored or maintained over the years. Either way, stainless steel lines will only Increase your braking power.

 

[Wayne]

Mechanix - I've just tested the lever after pumping it several times and then cable tying it to the grip in a closed position overnight. On releasing it this morning and then squeezing it's hard and firm.

That apparently tells me that the lines are at fault. Brilliant idea, thanks. I was showing a mate who's been in the industry 40 years, ex racer and owned several dealerships and he'd never heard of that trick. He was impressed that it worked so well to point to a weakness.

I'm into restoration to original so I'll have to source something from Suzuki or that bloke who makes them up mentioned below.

I will also pull the caliper off and try the other suggestion about squeezing the pads in just a little just out of interest and in the meantime. Thanks.

Thanks for all the advice. The calipers were rebuilt with new pistons/rubbers/seals and new grease and new pads. And I have other 30 year old bikes that ran fine with original lines so as some of you have said, it can work sometimes and other times it just doesn't (but I do get 'round to changing them anyway).

But obviously this one needs the lines changed now. I just couldn't believe that so much lever movement was in the lines.

FInally, for interest, after a full rebuild I change all my bikes to Silicon Dot 5. So I wasn't thinking it was the fluid as it works fine in my other Suzi's.

I'll get new hoses and go from there. Thanks.

 

[Guest]

Or...if you just rebuilt the caliper with new seals, they might be pulling the piston back a little.
One tip I got that worked on mine, (yes, I have stainless lines), was to unbolt the calipers, pull them off the rotor and carefully pull the brake lever until the pads are closed some.
Now push them back apart just enough to fit back over the rotor.

Worked for me and a few others on here.

I've done this "adjustment" on several bikes to cure the "soft" lever syndrome... all had SS lines too.

 

[Nessism]

DOT 5 fluid is know to contribute to a more spongy level feel compared to DOT 4. You should also change the brake lines if you ever make the swap. The stock lines are full of sludgy scale which will contaminate the fluid. Some people make the swap without changing the lines, but it's not recommended.

 

[Dogma]

I didn't see any mention of cracking the banjo bolt at the master to bleed it there, too. Quite often this is a high spot in the system and will trap a bubble. I suspect that tying the lever back over night is addressing the same problem.

 

[ramos]

I'm sure it' been put up before but since were on a a brake topic can anyone post up a link for some decent ss lines for my 81' 1100e? thanks, Ray...........

 

[Guest]

I'm sure it' been put up before but since were on a a brake topic can anyone post up a link for some decent ss lines for my 81' 1100e? thanks, Ray...........

Apex.

What ever you want, he will make it. Just look on eBay for SS brake lines and all kinds of listings will pop up.
Guys name is Raymond, made me quite a few lines.

Just measure yours for length and type of fittings and there's different colors.

He might have a diagram already made for your machine.
If not he'll ask for your measurements and use that for the next person.

Here's a link for all Suzuki's he has.

22$ a line and 13 shipping.

 

[Guest]

I didn't see any mention of cracking the banjo bolt at the master to bleed it there, too. Quite often this is a high spot in the system and will trap a bubble. I suspect that tying the lever back over night is addressing the same problem.

I don't think its an issue at all. Just from experience with vacuum pumping I noticed that when there is an air bubble in the lines It moves with the fluid and doesn't want to go back up.

I've sucked fluid out of the caliper and filled the reservoir and then stopped suction with lots of air in the line from the bleeder and the bubble didn't move. Well it might have very slowly.

I believe the air bubble near the reservoir would move with the fluid instead of staying where it is.

Then again I attribute it all to having a high amount of suction and constant feeding of fluid.

Tying the lever back wouldn't do anything to an air bubble it would just be there again after you let the lever go.

One thing that does help with bleeding is Teflon tape on the threads of the bleeder screw. That way there is no air being sucked into the pump and you see only fluid moving when all the air is out.


What do you think?

 

[Wayne]

More interesting points, thanks. While the bike definitely needs new lines as per the overnight test, I also tried the "remove-the-caliper" advice.

I was surpised how far back the pistons were. I squeezed them in until they could just fit over the disc and it made a significant improvement. Bike was at least safe to ride today.

As for the teflon, I use it on the bleed nipples as well and note that on my one modern bike, the official service book recommends it.

Dot 5 may be a bit spongier (I haven't got the fine hand to really feel) but I have it on 5 vintage bikes and all is good. But I guess that it all added up: Pistons pulling back too far plus dodgy hoses.

There could be a bubble at the top union but like Mechanix, I find they seem to move with the fluid. Also I do my bleeding over days and use a rubber mallet to gently tap bits to encourage bubbles to move up. Nothing wrong with cracking the union just to check though.

Thanks for all the help. Great tips.