New brake discs?

Hi all,

Recently rebuilt the calipers all round and added braided hoses and EBC HH sintered pads

The reason for the rebuild was that the fronts had seized and warped the disc causing it to shudder when braking.

I had the discs skimmed and were told that these are now flat. However, I went for a spin today and they are still shuddering

Would anything else cause this shuddering, or do I need to get new discs?

If so, any recommendations for discs?

Thanks,

Gareth

Assuming the company who skimmed your discs did a good job try this:-

Get the front of the bike off the floor so you can spin the front wheel. Use a piece of wire taped or cable tied to each fork leg ant level with the disk surface as a reference pointer. Try to get as small a gap as possible. Now spin the wheel and observe the gap between the wire and the disk. There should bo little in the way of perceptible difference in the gap throughout the whole disc area. If you can see a 'wobble, the discs could well be warped. Also remember that these discs are semi floating, that is they are designed to have a minimal amount of lateral movement on the mounting bobbins.

With sliding calipers, they can absorb quite a bit of warp in the disc before you get much in the way of brake shudder. If, as you say, these have been recently rebuilt, there should be no problem here. Are the pads new too?

If discs and calipers are OK, check the following:

1 Disc bolts.
2 Caliper bolts
3 Tyre pressure and tread condition
4 Wheel bearings
5 Steering head bearings

Hope this helps and I'm not 'teaching Granny to suck eggs!'

Rich

Thanks Rich,

Yes they are new pads as well.

Won't be able to raise the front to look until later in the week, but will give it a whirl.

As for the others, I torqued the disc bolts and caliper bolts as per Haynes. Tyres a still fairly new and are at the right pressure.

I felt the wheel bearings when the wheel was off and they 'felt' smooth - how do I tell for certain?

I'll check the head bearings when the wheel is up - it's not notchy at all when the wheel is down.

No worries about the granny sucking. It's confusing the hell out of me (if the discs aren't warped I mean).

Cheers,

Gareth

Hi Gareth.

Should have the info on checking wheel bearings in your Haynes.

If it's none of the previous, it only really leaves the forks!

Good hunting....

Rich,

Will check the book.

Can you expand a bit on the forks? Sounds expensive

Gareth

Hi Gareth,

I doubt very much if it is a problem with your forks; as I said, this is a process of elimination.

If you think of the forks simply in terms of a rod sliding in and out of a tube, the areas wich take the greatest stresses (especially under braking) are found at the bottom of the rod and the opening of the tube. These are prone to wear and, when worn, can cause a wobbly front end! Usually, this will be associated with leaky fork oil seals and unless on your machine it is a manufacturing fault or you have covered huge mileages, I don't think this is the root cause of your troubles.

Also, it is reasonable to assume that:-

1 If the machine was fault free BEFORE the calipers seized and damaged your discs

2 Your calipers are rebuilt and fitted correctly

3 The pads are new and without manufacturing fault

the fault will almost certainly lie with the discs!

Try the method I described previously to ascertain wether there is any throw in the discs. I had a similar problem and when I inspected my old discs, there was 0.5 mm of throw at the greatest. This was enough to cause hideous shudder under hard braking! I changed them for a set of Stealth Viper waveys and 'Hey Presto', shudder gone and more feel than the original discs.

Not sure now of the contact but think it was the 'Disc Doctor'. Have a look on-line . Alternatively, post on here in the wanted section a plea for some discs!

Regards

Rich

My 2000 SV has 25K miles and had to service the calipers for a second time. Not only do the pistons get stuck and corroded around the dust seal, the pins where the calipers float get stuck!. I had to prise apart the bracket from the caliper and then push out the rubber condom from inside the big hole. There was a shedload of corrosion there pushing on the rubber and binding against the pins! A chopstick is a good tool to remove and replace the rubber condom.

After removing the corrosion, I used loads of red rubber grease around the condom and pushed it back in. The caliper now slides up and down the pins like a ... (use your imagination).

I did have some judder at very low speeds but now seems to be going away after the caliper overhaul and new pads.

richwill68, I have the same discs as you? good aren't they. Where did you get yours from?

Have you noticed how they wear slightly different on the inside edge of the swept area? Think this is due to the drillings not going that far, but just wondered if yours were the same.

Danno.

Originally Posted by Dan_SV

richwill68, I have the same discs as you? good aren't they. Where did you get yours from?

Have you noticed how they wear slightly different on the inside edge of the swept area? Think this is due to the drillings not going that far, but just wondered if yours were the same.

Danno.

Hey Dan,

Yeah, the Vipers were great; completely transformed the brakes. Have standard pads and discs on the SV, with braided lines. I don't see the need for more in the braking department as I can lock the front at will, so anymore would be a bit like overkill for me.

When these discs wear out it'll be Vipers for me again.

Later

Rich

I have the Viper Waveys, with Carbone Lorraine Pads. Just need some braided lines now to get them exactly where I want them.

Danno.