yamaha thunderace needs better breaks help!

[alanTDM]

Product Fitment
yamaha yzf750r 1994 rear brake caliper
yamaha yzf750r 1996 rear brake caliper
yamaha yzf750r 1997 rear brake caliper
yamaha yzf750r 1998 rear brake caliper-oem
yamaha yzf750sp 1996 1996 rear brake caliper
yamaha yzf1000r thunderace 1996 rear brake caliper
yamaha yzf1000r thunderace 1997 rear brake caliper
yamaha yzf1000r thunderace 2000 rear brake caliper
yamaha yzf1000r thunderace 2001 rear brake caliper

[Jon_W]

You need to change the warped disc. That won't help.

As to the front brakes, get them and the master re-built. Not worth skimping £££ on somthing so vital. As Scotty says you'll do no better than the blue spot calipers on there.

[danwiltshire]

Thanks all for the info looks like ill be listening and rebuilding them going to cost a bomb to do but if it makes a big difference then has to be done

[danwiltshire]

One more question sorry if im asking to much. Do i have to replace the pistons or can i just do the seals and clean the pistons up with break cleaner?

[Scotty]

It all depends on the condition of the pistons. Are the brakes binding at all? Check that first, if they aren't then you don't need to strip them down, certainly not at the moment. If they are binding then the pistons and seals will need cleaning up. If there are lumps of salt corrosion on the pistons (it's the normal problem with binding brakes) the dust seals may become dislodged when removing the pistons, they're relatively fragile. The main fluid seals probably don't need replacing, they can be carefully removed using a non-sharp tool (so they don't get cut or nicked) and cleaned up. Whilst the calliper is stripped it's a good idea to clean up the seal grooves in the bores - on a ZX-9R I bought ten years ago the brakes were binding really badly, there was some corrosion on the pistons and they cleaned up ok, but most of the problem was a build up of oxidation due to road salt BEHIND the main seals that pressed them excessively hard against the pistons and prevented them returning after the lever was released, causing major binding issues. A good clean of the seal grooves with a special tool that I made and they were fine. Get some special red grease to lubricate the pistons and seals on re-assembly too.
Sorted 8-)

[Scotty]

If you need to strip your callipers, HERE is a really useful guide that may help.

[danwiltshire]

Spot on have now ordered all the parts i need. The brakes are not binding as far as im aware i can see a dust seal trapped outside of two of the pistons does this mean that could be the cause?

[Scotty]

Hmmm, I don't know that a dust seal would have any significant effect really, is there any evidence of uneven pad wear that might indicate that the piston in question is not moving freely? It wouldn't hurt to sort it but if it isn't causing the problem I'd save it as a Winter job.

Which parts have you ordered? :-?

[danwiltshire]

Pad wear seems to be equal all over. Ordered all new seals for now untill i get paid then was thinking of getting new pads and master rebuilt?

[Scotty]

Have you ordered dust seals or the main seals? :-? If nothing is binding, their replacement isn't really a priority (like I said earlier, save it for a Winter job). New pads are probably a good idea, I really like SBS road compound, can't remember the prefix, maybe HS followed by the individual fitment number. If you asked on here "Which pads should I get?" you'll get a dozen different replies and none of them necessarily wrong, it's down to personal preference.

If the master cylinder works smoothly and isn't leaking it's questionable whether it needs a rebuild. Does the lever feel spongy when pulled? You already have braided lines on the front but who knows how old the fluid in them is, so a thorough bleed won't hurt them.