Suzuki GSX-R Motorcycle Forums Gixxer.com banner

1 - 8 of 8 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Alright guys I'm in desperate need of help. Not sure what else to trouble shoot. The issue is the front brakes drag a lot. One very hard turn on the front wheel and I only get 3/4 of a turn out of it.

Full story: so I wrecked my bike. I replaced the front wheel having the new one checked to be straight before powder coat. I'm almost positive the forks are straight but I swapped them out for good ones I was already planning on putting on for the different color. I replaced the pads with new ones and as always I extended the pistons beyond the grim/buildup giving them a good cleaning (some were sticking a little). I put the bike all back together and I could get maybe 1.5 turns at best from the wheel but I noticed both rotors had a spot that rubbed hard (I checked them individually) and the rest seamed okay. No pulsating from the front brake lever but looking at my original wheel it appears the outside rim is straight but the wheel is taco'd at the hub or spokes so that would explain why the rotors were bent.

So I replaced the rotors and now it rubs harder but consistently across the full rotors. I pulled the calipers to check for sticky pistons but I can push each one in by hand with a bit of muscle. Wheel spins forever with the calipers off. I just rode 50 miles at high speeds not using the brakes once and the left rotor was too hot to hold but not touch and right rotor was warm on a 45F morning. Even in the twisties the drag is enough to feel entering the low speed corners. I had to replace my brake resvoir but the brakes still drag with the cap off... just trying anything I can think of here.

I also have this mystery crap getting splattered on my front wheel. It could be brake pad material because the wheel is getting a heavy dusting but I wouldn't expect it to splatter and at first it was a very excessive amount, getting less and less with every ride. It is jet black and marks rags pretty good... doesn't feel wet. Brake fluid, bearing grease, and fork fluid are all fresh/not black.

Any help is greatly appreciated!
 

·
Registered
Joined
·
105 Posts
They didn’t powder coat the area where the rotor and bolts sit on the wheel did they? Possible the thickness of the coating is pushing the rotor against the pad 🤔
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
They didn’t powder coat the area where the rotor and bolts sit on the wheel did they? Possible the thickness of the coating is pushing the rotor against the pad 🤔
Good catch. They actually did after I told them not too and they replied "we know better". I removed the powder so the rotors are mounting to the original machined surface so it shouldn't be any issue.
 

·
Registered
Joined
·
96 Posts
Sounds like a master cylinder, or brake hose problem to me.

If you squeeze the lever really hard, then release it, then open a bleed nipple on a caliper, does a bit of fluid seep out (or worse, shoot out)? If so, check again on the other side. If they both do it, it's likely to be the master cylinder or the single brake line from the master cylinder (common to both calipers), if only one does it, check the brake line (if any) dedicated to that caliper.

You don't say what year your bike is, but have you checked if it needs the Suzuki recall work done to replace the original master cylinder?
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5
Sounds like a master cylinder, or brake hose problem to me.

If you squeeze the lever really hard, then release it, then open a bleed nipple on a caliper, does a bit of fluid seep out (or worse, shoot out)? If so, check again on the other side. If they both do it, it's likely to be the master cylinder or the single brake line from the master cylinder (common to both calipers), if only one does it, check the brake line (if any) dedicated to that caliper.

You don't say what year your bike is, but have you checked if it needs the Suzuki recall work done to replace the original master cylinder?
Not a drop. :confused: I thought you might be onto something.

It is a 2012 750 with the updated master cylinder. The rebuilt the master about 6,000 miles ago also.
 

·
Registered
Joined
·
96 Posts
That's me out then... Apart from to say that if there's pressure on the disc's from the pads, but no hydraulic pressure, it would point to a mechanical restriction in the calipers, possibly heat related?
 

·
Registered
Joined
·
708 Posts
I'd say, pull apart that left caliper
As it is, you are running the risk of losing brakes when riding, stop trying to analyze from the outside before things go wrong, you already exhausted all observable causes
If that doesn't expose/fix the issue, there may as well be some clogging in the brakehose/right caliper

Oh and one thing: Now it may be a stretch (on which side did you go down?), you say your forks are straight, but are the caliper anchors?
You say you wrecked it, which in my vocabulary is the superlative of "crashed", which may bring along a host of unseen issues
 

·
I know things... A lot of things.
Joined
·
3,152 Posts
Perhaps you could try pulling the pads back and spinning the wheel. It should spin freely. Now slowly pump the lever until you see the pads come up to the discs and you feel a beginning of resistance on the lever. Do not apply enough force to press the pads against the discs. It will probably now spin less freely. Now give the lever a good pull. If then the wheel stops spinning freely, that would probably mean that the pads don't retract as the lever is released.

(Perhaps you could also try putting a sheet of paper between each pad and the disc. I haven't tried it, but I suppose it should be possible to pull the paper out after releasing the lever. If you can't after that final pull, but could before, it would further corroborate the "no retraction" hypothesis. It would also allow you to pinpoint the sticking caliper(s).)

As for how to fix the problem. There are several possible reasons, but if I understand correctly that the brakes were fine before the crash, but are sticking after it, it seems likely that the problem must be due to the crash. Given also what you report about jetting grime, I wonder if one or more calipers got bent somehow. If so they may now be leaking on application of the brakes and sucking in air, instead of retracting, due to the vacuum generated in the lines as you release the lever. This may be happening on a single caliper piston or more. It might be possible (it is on my K5 750) to visually inspect the motion of the pistons as you apply and release the lever, by shining a light between the caliper and rotor.
 
1 - 8 of 8 Posts
Top