Sprint 04 discs

Has anyone else had problems with front discs warping? I have had mine replaced twice under warranty at 20000km & 35000km (12500m & 21875m). I may be pessimistic but I think it may be happening again.

[DaveM]

Nope,
coming up on 20,000kms and no problems so far. A lot of brisk two up riding in the local hills, plenty of braking involved no rotor problems on mine.

Davem

[SprintST]

I've warped rotors at about 30k miles on both my 99 and 02 STs. But it takes 35k miles to finish off the OEM pads. I never understood that one.

[triumph_955_st]

My 04 is in the shop right now. It's getting the valves adjusted and a few other things done. One of which is a warped disk.

[ElTigre1]

I, too, have warped discs on my'02 Sprint St. I bought the bike with 10,000 miles on it and the first signs showed up at about 12,000 miles. I've never had the problem with motorcycles before but have had some card discs get warped. Funny, you can buy double-walled discs for cars for half the price of bike discs.

[ST-ern]

Yeah, mine too.

Started pulsing at the lever at about 18000 km. By 24000 I took her into the dealer. They measured run-out, wheel rim and checked for bearing probs - all -ve. They reckon there might be vertical run-out and have approved replacements. They're on the boat from the UK.

Meantime, I don't brake going into bends cos I can't feel what the fr*gging front end is up to for all the vibration.

[RexxyPup]

Hi, I had mine replaced after 12k miles from New. The main mechanic took the time to explain why it happens, so I thought I'd take the time to pass it on... Sorry if I'm teaching you to suck eggs here!

It's all to do with grease and those silver cymbal like assemblies that hold the brake disc to the mounting spider.

The brake rotor and the spider aren't directly linked to each other. You should be able to take hold of the rotor and wiggle it slightly in the same plane as the wheel. Mine will move fore and aft (or up and down :wink: ) by about 1mm.

Inside the cymbal things, the rotor and spider form a pair of forks that touch each other at the tips, leaving a round hole between the two prongs (I hope you can visualise this)

You can think of the Cymbal as a sort of loose rivet with a slightly smaller diameter pin than the hole it is in. This allows the disk to float, self centering between the pads under braking and allowing for the expansion due to braking heat as well.

From the factory, those cymbals are filled with grease which over time gets flung out. Not a lot you can do about this, nor have I found a way to get grease back in. When the grease has gone, the cymbals can collect dust (road and brake) and clog up, preventing the disc from floating freely.

So if the disk is now effectively rigidly attached to the spider and you do some heavy braking, the disk will expand due to the heat, but is constrained in one plane, so expansion has to go somewhere and it warps the rotor.

The only solution the Mechanic could give me was to regularly spray in the cymbals with brake solvent and wiggle the discs until each rotor arm can be seen to be moving separately to the spider arm. Because there is no longer any grease in there, it has to be fairly regular.

If any of you guys can (or have) figure (d) a way to get high temp grease back into those cymbals (are you sick of that word yet :-D ) please let me know.

In the mean time, happy cleaning!

Rexx

[ This message was edited by: RexxyPup on 2006-02-10 05:23 ]

[stevesrs]

A tip I had from a mechanic was to periodically check the round things that connect the rotor to the disc carrier for rotational movement. If they don't move, he forces (gently) a hex key that will just fit in the hole and twists it back and forth using a SMALL quantity of WD40 as lubricant, this helps remove any road/brake crud

By the way the discs on my RS are still fine at 22,000 miles

[triumph_955_st]

My dealer just called and told me my bike was done. The rotor was replaced under warranty. Now if Mother Nature would kindy call and tell me winter is done, all will be well. In fact I even went by a station with gas selling for 1.99 a gal. :chug:

edit: I flipped through the paper and saw and ad, "Take this ad to the Racepark and get 2 tickets for a special screening of The Worlds Fastest Indian". I just got back home with my tickets. After I filled up with 1.99 gas.

[ This message was edited by: triumph_955_st on 2006-02-10 16:01 ]

[ST-ern]

Thanks Rexxypup. That's worth investigating.

Mine still are 'grabby' with the lateral run-out within tolerance though.

Your theory could still explain vertical run-out, esp as the rotors wear and the 'tracks' are moving up and down against the pads.