What to do when front brakes are bad?

[Anonymous]

I have a recently bought 1979 gs750e. The only big problem with it at the moment is that the front brakes are a bit lousy. They work, but there's no power in them. The discs and pads are in good condition.

My first try was to bleed the system. No problems, it turned out to be almost air-free from the beginning. I have then cleaned the parts with petrol (well, gas if you want...). The discs were quite dirty, and perhaps a bit oily. Still there's no good 'bite'.

My next move might be to change into steel braided lines, but I'd like to ask you guys if there is something else to think of first? After all it's a bit expensive if it's not the problem. So:

How do I know if I have to get new lines?
Can the master cylinder be broken if there aren't any leaks?
Is there something else to look for? How do I test it?

regards
/ Henrik

 

[daveo]

Well the manual says to replace the lines every 2 yrs. although I've never known anyone to, so, the lines probably could stand to be replaced.But if the brake handle isn't hitting the handlebar the lines or master cylinder probably are not the problem. Rather I would suspect the pads, the stock ones are marginal at best, I've been quite happy with, and noticed a huge improvement when I installed EBC brand disc pads.

 

[Anonymous]

The lever does hit the bar. It gets harder after a few tries, but it's not enough. Is this a sign of bad lines?

I forgot to write that it seems as if the handle might not swing back enough. The brake light is sometimes still lit for what I feel is a little too long.

/ H

 

[daveo]

yeah the lines need to be replaced, they're probably 23 yrs. old anyhow, I'd do the pads too though, those EBCs really put a bind on

 

[earlfor]

Re: What to do when front brakes are bad?

I too have a79 GS750E and had the same complaint about the brakes. They were absurd. Everything seemed fine and the pads were hardly worn. I think they had hardened and possibly glazed due to age though. I replaced my front and rear pads with
the EBC pads and the difference is like night and day. If you order pads for both wheels, make sure the parts person realizes the front and rear take different pads.

Earl

I have a recently bought 1979 gs750e. The only big problem with it at the moment is that the front brakes are a bit lousy. They work, but there's no power in them. The discs and pads are in good condition.

My first try was to bleed the system. No problems, it turned out to be almost air-free from the beginning. I have then cleaned the parts with petrol (well, gas if you want...). The discs were quite dirty, and perhaps a bit oily. Still there's no good 'bite'.

My next move might be to change into steel braided lines, but I'd like to ask you guys if there is something else to think of first? After all it's a bit expensive if it's not the problem. So:

How do I know if I have to get new lines?
Can the master cylinder be broken if there aren't any leaks?
Is there something else to look for? How do I test it?

regards
/ Henrik

 

[Anonymous]

It seems there is some air in the brake circuit. I'd suggest you replace the brake lines with steel braided ones (makes a 20 years difference). I did it with my Suzi 850 and the break performance is much better then it used to be. Those teflon hoses are not really much more expensive then the rubber ones; it worth the time and the money.
And yes, check your brake pads too.

Jojo

 

[Dink]

I took EBC pads out of my 1150 because I was unhappy with it's braking performance, I replaced them with Vesrah pads which gave a huge increase in performance. I must admit I thought the pads that were in it were stock Suzuki ones and it was only when I removed them that I discovered they were EBC,I have actually left EBC pads in my rear brake because I felt it was a bit strong and they deaden it nicely.
Dink

 

[Anonymous]

You may aswell change your pads because of the very small expense. However, if your brake lever is pulling back and touching the bar then you have air in your system. Remove the master cylinder cover, pump the lever a few times, pull it back as far as it will go then tie it back and leave it over night. Any air in the system will bleed upwards. Next day, untie the lever and slowly let it spring back. Is there any improvement ? You might have to do this over two or three nights. Also, new braided hoses will be an additional improvement, I have them, but you might not have to do this if they bleed OK.

 

[Dink]

I am going to disagree with the mad hatter on this one. You have already stated that you have bled the lines. I do believe that replacing the lones is your first step, however you mention that your discs are "greasy" this is most certainly not good, clean your discs with a brake cleaner and lightly scuff them up with emery paper and you should do this to your pads too in case they have been contaminated.But replace your brake lines as they are most likely original and well overdue for replacement,go to braided steel or kevlar for the extra power and feel they will provide.
Dink

 

[Anonymous]

Hmm, I didn't think of bleeding the lines 'upwards'. My technique was to pump fluid downwards via a transparent hose into an oilfilled jar until I didn't see any more bubbles coming out.

I'll try the other way as well before I change the lines. The pads should be quite new so I don't think they are the problem.

Oh, and I must tell you about my troubles getting the right caliper off: One of the bolts came out smoothly. A bit tough, but still no problem. The lower one however was stuck like :twisted: . Even though I had a HQ wrench of the right size, I still managed to make the bolts head completely round. So, next step was to take the Dremel multitool, grind a groove and use an impact screwdriver (those you hit with a hammer so they turn a little). No result whatsoever. At last I had to take a wrench of the right size, and weld it to the bolt. I was worried I might twist the bolts head off, but I was lucky this time. That finally did it!


/ Henkoman

 

[Anonymous]

Henkoman

If you washed the pads in gas you'll have to toss them. NEVER use petrochemicals and especialy gas on any brake component. Wash your discs with a high detergent cleaner (409 here in the US) then after they are dry, spray with brake cleaner, especially one with 1,1,1, trichloroethylene if you can get it. Pull the calipers and spray them inside also.

Scuff the discs with a scotchbrite. Put in new EBC pads if you washed the old ones in gas.

Take the top off the master cylinder and SLOWLY squeeze the lever. If there are small bubbles, you probably need a master cylinder rebuild.
It's really easy, but assemble ONLY with fresh BRAKE FLUID.

You probably need new brake lines. Feel the line as you squeeze the lever. If you can feel it move, new lines are in order. I'd just replace them anyway, when I did mine I couldn't believe the difference.

Again, NEVER use anything but a brake cleaner or brake fluid on your brake components.

 

[Anonymous]

Take the top off the master cylinder and SLOWLY squeeze the lever. If there are small bubbles, you probably need a master cylinder rebuild.

Nope, no bubbles. I guess the master cylinder is ok then, thanks for the tip. I'm now trying to bleed the system in the way I got suggested in this forum. If that doesn't work, I'll replace the lines.

The primary problem is that the lever hits the handlebar. As long as it does, I can't tell if the pads are good enough. When that problem is solved, I'll consider changing the pads.

/ Henrik

If you washed the pads in gas you'll have to toss them.

I didn't put my pads overnight in gas, I just used it on a cloth to remove oil from the discs before I used detergent. Oil and gas are different purities of the same stuff, so I don't believe it get's worse if they were already oily from the beginning.

 

[silverhorse47]

oil on brake pads

oil on brake pads

The problem with oil on brake pads as I understand it is that it looks like it is gone...the surface appears clean after swishing it off with whatever solvent...but when the pad heats up due to friction against the rotor the oil wicks out to the surface of the pad and lubricates the rotor. There just isn't any way of getting oil out of a brake pad once it is contaminated. To be safe, get new ones.

 

[Anonymous]

spray with brake cleaner, especially one with 1,1,1, trichloroethylene if you can get it.

Being an Enviro Chemist, let me just say that while this is not technically illegal... if you don't catch your overspary and drip but just let the TCE hit the ground that's very bad :twisted: .

TCE is a neurotoxin, carcenogenic, and I know of a town in northern OH that can't drink their water anymore because of it. 8O

Please be careful with any petroleum distillates. Just my two cents.

 

[earlfor]

WOW! Thats what I call a FROZEN bolt. I'm glad welding it was sucessful as I cant imagine what the next more extreme measure would have been.

Earl

[quote="Henrik Palm"
Oh, and I must tell you about my troubles getting the right caliper off: One of the bolts came out smoothly. A bit tough, but still no problem. The lower one however was stuck like :twisted: . Even though I had a HQ wrench of the right size, I still managed to make the bolts head completely round. So, next step was to take the Dremel multitool, grind a groove and use an impact screwdriver (those you hit with a hammer so they turn a little). No result whatsoever. At last I had to take a wrench of the right size, and weld it to the bolt. I was worried I might twist the bolts head off, but I was lucky this time. That finally did it!


/ Henkoman[/quote]