Members My rear brake on the 748 is no existent. In fact it might as well not be there it's that much use. Even on a slight incline it won't hold the bike & stop it rolling backwards. I've had the brake line & the pads checked & the garage says they're fine. Any solutions to this annoying problem gratefully received. Thanks
That sounds like unacceptable service from "the garage" - or perhaps they dispute what you say about not being able to hold the bike on a slope? Unless the brake is doing something weird like working in one direction only (highly unlikely!), then it should be obvious if it is as poor as you say (by trying to push the bike along), and the rolling-road MoT test gadget would prove that. Of "things to check". I'd say the brake hose is least likely to be relevant (unless it is leaking fluid, or the brake feels completely spongy) and simply "checking the pads" is not good enough, because a caliper could have seized pistons in which case the pads might look OK, but they would not be getting pressed hard against the disk - easy to check by taking the caliper off and confirming whether the pistons move in and out freely - 15 minute job. The master cylinder could be a fault area, but if it were, then I'm pretty sure you would have obvious sponginess.
If you had seriously sticking caliper pistons you would know about it by now as they nearly always start binding more and more accompanied by smoke and a brake pedal that moves freely to full travel with no resistance. so unless you have got hydraulic issues with air in the system or the pistons are so corroded that they aren't even moving at all (highly unlikely) it's almost certainly the age old problem of disc and pads overheating and glazing. Is the disc dark in colour even with a hint of blue about it? It sounds drastic but if it is you could get some temporary relief by deglazing it and fitting some good quality new brake pads of the right compound with a view to replacing the disc in the future.
They're all crap. Mine will work OK if I bleed it properly (need the caliper off to do this) but after a couple of months it's crap again. Not sure why? as both the master cylinder and caliper are the same as on a Monster (and other models) and my M900 brake is OK but I think the heat in the master cylinder doesn't help - cylinder mounted to a bracket directly on the crankcase and that also holds the exhaust. I always bleed it before an MOT and then hold my breath when it's on the roller...
The brake are known to be notoriously ineffectual, it is has been said that they are really only there to satisfy construction and use, MOT etc. I have had this problem myself and there are several issues. If the disc or pads are glazed then cleaning might help. After that check for free piston movement in both caliper and master cylinder. Check that your rear brake pedal is adjusted properly, don't attempt to over adjust it as you will find it will bind when hot. This happened to me and my caliper caught fire on a track day. It destroyed the pads completely and melted all the seals in the caliper and did a few other nasty things as well. Sometimes the brake lever does not return correctly as early models had a weak return spring arrangement for the brake lever, these items are now deleted but to improve things buy the return spring, brake pedal return pin and the tiny clip as fitted to a 998 or probably other later models as well and fit them. This gives you a better return on the brake lever so when you press it you get the full effort and travel behind the brake pedal. When I did this "conversion" it made quite a bit of difference, but I was using Corse style rearsets and not stock ones. If you check the caliper pistons then clean them all up thoroughly and use red rubber grease to refit them and check they are totally free and not dragging. Underslung calipers often get a lot of corrosion in them and if they are sticking then removing the O rings in the caliper very carefully and cleaning out the grooves where they sit will improve operation. Corrosion often gets behind the grooves and causes the pistons to pinch up. I have just done the above to a Suzuki item and it was so corroded I could barely get one piston out, it took 175 psi to actually pop the piston out in the end, and when it did it was like a bomb going off!!! and potentially that is a way of damaging a finger or two, so if you have seizing pistons be careful. You will need air to pop them out of the caliper though unless they are very free. I hope this helps, come back if you need more information.
Apart from the obvious problems like partial seizing after standing, master cylinder seals or too little play in pushrod, I never had a problem with any of my 748/996s once I got used to the glazing problem which is usually all it is. The disc is slightly too small for the job and just argues with the engine braking hence the overheating. If it was only ever used in neutral it would be good as gold : )
Rear brake is best used as a foot rest as it's crap!! Something to do with the heat build up do to lines close routing to the exhaust. You don't really need the back brake anyways....
