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Oops! brake mistake

  • Thread starter Thread starter midnightcafe
  • Start date Start date
M

midnightcafe

Guest
So I took the 79 750L out for its maiden voyage today, 1/2nd gears were fine. Third gear arrives and the bike labors, slowing down. I pulled the clutch in and the bike was slowing to a stop. A street later and I pull over and look down. The rear brake caliper was smoking!:-k

The rear brake pedal was seized but I thought it wasn't engaged since I could move the bike around (with some effort). I had to GREASE the disc after it cooled down and it rode home about two minutes, with some heat on the caliper. I torched the pedal and it freed but I still have to play with it.

Think the brake is salvageable/anyone had this happen to them before?
 
If you didn't melt the seals in the caliper or warp the rotor you should be good.
 
My 850 had that problem when I bought it; rear master had seized. Time for a full system tear down and clean out. Lube the brake lever pivot as well.
 
Nessism said:
Time for a full system tear down and clean out. Lube the brake lever pivot as well.
Click to expand...

second that

also, new brake pads even if your still look good - they have a glazed surface now, not good
 
I have had locked brakes on 2 of my old bikes when I bought them. It turned out to be the tiny little resevour return hole in the master cylinder (front on one bike, rear on other) rust gets in the little pin hole and wont allow fluid to return. Bleed off a tiny bit of fluid and you will know right away because the pistons will release and free up the wheel. It realy could be a number of things though. Better safe then sorry, listen to these guys and clean and rebuild.

Jim
 
The foot control pedals are prone to seizing at the pivot point. It's just a steel bell-crank turning in a reamed-to-size steel hole in the frame. Clean it all up, and re assemble w/ good water resistant grease.
 
The back master was gummed up with the piston seized in the bore and the lever was stuck on my GS when I got it. It had been sitting for 7 years. The first thing I did was pull clean and rebuild, masters and front and back calipers.

Brakes are critical for safe operation....duh:eek: so you can't scrimp on them. As suggested, get them clean and working properly and make sure you do replace pads as they will be glazed. Have a good look at the pistons and caliper bores as on three bikes now I have found the pistons to be pitted and requiring replacement.

Be safe
Cheers Spyug
 
:confused:I'm sorta confused now. Just pulled the rear caliper and saw the seals were good. I'll need new brake pads as they are glazed. HOWEVER the pistons show corrosion. Do I need new pistons? that would mean i need new seals and o-rings, where can I get a kit that features all this?
 
Suzuki dealer, BikeBandit, flatoutmotorcycles....

I believe they call it a piston set....new piston, seal and dust cover.

Z1 has caliper rebuild kits for some bikes also...but I don't think it comes with a piston. (It didn't for the fronts on my 1100)
 
spyug said:
The back master was gummed up with the piston seized in the bore and the lever was stuck on my GS when I got it. It had been sitting for 7 years. The first thing I did was pull clean and rebuild, masters and front and back calipers.

Brakes are critical for safe operation....duh:eek: so you can't scrimp on them. As suggested, get them clean and working properly and make sure you do replace pads as they will be glazed. Have a good look at the pistons and caliper bores as on three bikes now I have found the pistons to be pitted and requiring replacement.

Be safe
Cheers Spyug
Click to expand...


The brake lines develop a scale on the insides so it's a good idea to replace these as well. Service manual calls for replacing the rubber brake lines every year...so if the stock lines are still on the bike, you are about 25 years overdue!:-k
 
midnightcafe said:
:confused:I'm sorta confused now. Just pulled the rear caliper and saw the seals were good. I'll need new brake pads as they are glazed. HOWEVER the pistons show corrosion. Do I need new pistons? that would mean i need new seals and o-rings, where can I get a kit that features all this?
Click to expand...

what matters is if there is any corrosion on the OUTSIDE of the pistons
if the corrosion is minor it can be polished out
 
2782949858_d94e4286fa.jpg


So this is what the rear caliper looks like. awful! full on corrosion in and on the edge of the piston.

I'm having trouble remove the pistons from the caliper, anyone have any tips? i don't know if they are salvageable.
 
Nessim is of course correct about the lines and I forgot to mention that. I switch out to stainless steel, pricey but unbeatable for feel and positive fade free stops.

To get the pistons out I use two methods. I have a spare master cylinder and short line which I hook up and pump away. They usually come out after a little time. If not method two is to get a grease fitting of the right thread/size and use a grease gun to pump the caliper full of grease. This always works. Once you have the piston out clean all of the grease out and any gunge or rust you may find. An important thing when cleaning only use clean brake fluid as other chemical residues can cause problems when the system is back together and the fluid is topped up.

Some guys just use compressed air but i have never been able to get that to work. If you try compressed air be careful as the piston can come out flying. Cover the caliper with a shop towel.

If the piston has any rust or pitting in the area that sits in the bore you must replace it. Any pitting or cracking on the surface of the piston can cause rust to form and if left long enough the piston could seize. Not good if you zooming along at 90 mph and 500 yards from a red light.

Think safe and do a good job.

Good luck with it.

Cheers,
spyug
 
Just reconnect the caliper to your master cylinder and pump it out that way.
 
you re right those pistons dont look to good
but wait til you have them out of the calipers and see if they are rusted or pitted in their contact area
outside surfaces can be cleaned and a little brake caliper grease aplied so no new rust is formed
the best though would be to replace the pistons and the rubber seals
 
psyguy said:
you re right those pistons dont look to good
but wait til you have them out of the calipers and see if they are rusted or pitted in their contact area
outside surfaces can be cleaned and a little brake caliper grease aplied so no new rust is formed
the best though would be to replace the pistons and the rubber seals
Click to expand...
Ditto. What we see there doesn't matter. It's the inner piston and caliper that matters.
If you even have a cheapo elecrtric air pump use it on the flat side and pop that piston out. Block the connection to the line and do the same with the other side.
 
I put the rear caliper back together and pumped some brake fluid into it. The piston outisde the bike came out, while I had to take the other side to the vice and pull hard. Both pistons have corrosion below the seal level, so they're junk.

2787059759_def58b065b.jpg


2787913526_ab5a8bc4d3.jpg

they may look clean underneath...
2787060335_8307c9e9e5.jpg

but this is the gunk that seized them in the first place.

I could get stainless steel custom fabricated pieces at $32 a piece, but I don't think I'll be needing that kind of material.

QUESTION: would a 'piston set' as seen below (number 1) include just the two pistons?

2787977244_73c9514bf8_b.jpg
 
So I just called three dealerships and one FINALLY picked up. The guy was nice, greater boston motorsports, thank you. He explained to mee that EVERYTHING the number 1 line covers is included in the piston set. That means, shims, brake pads, pistons, seal boot covers, seals, and the o-ring! This is about $33 out of flatout motorcycles. decent deal!
 
Including the brake pads? I hope that parts guy is right but for that price, it doesn’t sound right.

Not sure if you ordered already but you might want to take a scotchbrite to the pistons and see what they look like after a little cleanup. The corrosion won’t hurt anything as long as it’s above the sweep area of the piston seal – dust boot sweep area doesn’t matter other than you don’t want to damage the dust seal.
 
While you have the calliper apart and sorting that end please check the master cylinder and pivot point on the pedal/frame aslo.

Its worth doing the whole job.

Suzuki mad
 
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