Warped front disc - advice needed..

[steventhechef]

I have just come back from the local motorbike mechanic - not Triumph - and he confirms what I thought, that I have a warped front disc on my 03 Sprint RS.

I got a second opinion from another motorbike mechanic just to confirm the worse case scenario.

I have already pulled the calipers off, exercised the the pistons and sprayed them with Motul disc brake cleaner and then reassembled them with no noticeable difference.

Bugger there goes the cheap option!

The symptoms are pulsing brake lever
1) at low speed - feels like in, out, in, out, without the associated pleasure!
2) at high speed - jump on the brakes / head shake (back and forth) unless I brake steadily and then it is OK with just the pulsing.

It is more annoying as opposed to down right dangerous.. I have lived with it for a few weeks now and it just bugs me not being right.

One guy tells me that I should replace the (slightly) warped one and the other guys says that I should "always" do both and likens the discs to brake pads. You must always do both!!

It is "only" $250 AUD (Metalgear) for each one - $600 for both - fitted but I am not the sort to spend money just because someones says I need to!!

Any advice from my learned colleagues???? Help is what I need..

[DaveM]

Hi mate,
I don't know........... but I have to visit the dealer to pick up some small expensive item which I shall not discuss here incase I start another upsetting thread.

I'll ask the mechanics there tomorrow and tell you what they say, I'll call you on your bat phone. The guys all know me well. (uno tyres and stuff)

I had them all rumudging through their tool boxes today in the vain hope they might have had one of those small expensive items I could snavell for free!

I hope you can get a cheap fix for your pulse. Have you tried a disprin?

DaveM

[steventhechef]

Hi Dave and thanks for the reply.

Disprin!! I have Leonie on Mogadon as she hates me spending money on the bike!!

[Simmo]

Hello all,
A friend who has an Aprillia Falco had this happen just as you describe. He had the Chain Gang man provide replacement rotors for both discs with a slight wave pattern. The metal is slightly different but the brakes work much better, with better and more predictable initial grab and then a stronger feel. Not sure of actual braking distances but the mate says it feels heaps better. The Chain Gang man seems to know his stuff and it is probably worth talking to him.
I caused the discs on my 01 Sprint to warp which was caused by some really strong and prolonged braking and with sticky calipers. One disc warped such that was a consistant run out from the inner circle to the outer circle of about 2mm. Didn't pulse but the braking effort was severly impacted. Interestingly I traded it shortly later and explained this to the dealer, being an honest person, and as the discs were not measurably worn in thickness he was satisfied to issue a road worthy certificate. The discs were stuffed though.
Let us know what you do.
Cheers, Simmo

[oldndumb]

FWIW, the shop manual has a warning which says that discs must always be renewed in pairs even if one of a pair is servicable.

If the good disc is approaching the wear limit, I would replace both. Otherwise, you could opt for one and then do a series of careful test rides and brake tests. Probably wouldn't hurt to get a second evaluation and have an experienced rider evaluate the braking performance also.

What is a "Mogadon"?

[Grae_ST]

OnD

Mogadon is a powerful hypnotic drug, possessing strong sedative, anticonvulsant, and muscle relaxant....

As for the disks, I would personally change the pair, I won't take any chances with brakes. EBC have contour/wave rotors for the Sprint's.

Cheers, G

[oldndumb]

Originally Posted by Grae_ST

OnD

Mogadon is a powerful hypnotic drug, possessing strong sedative, anticonvulsant, and muscle relaxant....

As for the disks, I would personally change the pair, I won't take any chances with brakes. EBC have contour/wave rotors for the Sprint's.

Cheers, G

I would probably change both also and opt for the EBCs.

Where was this Mogadon stuff when I needed it? I could have used it with my first two wives.

[gavinb]

Steve,
I was just talking to someone this week re warped disks, he reckoned that he could wark a disc quite quickly if he wanted to ( he does race bikes) by lots of very short sharp and hard breaking, effecively you are heating up part of the disc or at very best having varying temps arround the disc.
Conversely he also claims to be able to take the warp out, over a period of time, be using good braking tecniques.
It may be a load of c*** but I would give it a go, no harm done.
Basically for the next few months try not to have short bursts, hold the breaking longer and try to get some heat into the whole of the disc this way as the disc heats and cools evenly localised stress points are taken out.
If you try it please let me know if it works.
Cheers Gavinb.

[pushr0d]

Steve, assuming you've a pile of miles on the rotors, I'd suggest you change them both.

With all the things to worry about while at speed, you sure don't want "iffy" brakes in the mix.

AFA a warped rotor staightening itself, I'd think it'd be like trying to smooth out a sheet of Aluminum foil after you creased it.

The way I see it, you've three options: New OEM (yuk!), eBay used (dicey), or aftermarket. I'd go with a set of waves and new pads. Make sure you get the ones for the Southern Hemisphere!

[oldndumb]

Originally Posted by pushr0d

The way I see it, you've three options: New OEM (yuk!), eBay used (dicey), or aftermarket. I'd go with a set of waves and new pads. Make sure you get the ones for the Southern Hemisphere!

I think the International Universal Spoliative Act requires vendors to only ship coriolis compliant parts to each hemisphere. But, it is always best to be safe and specify which hemisphere you are in when ordering.