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final drive question


jojo

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my back wheel has developped a very small amount of side to side play. It's barely perceptible but it's there.

I'm heading to France for 3 weeks on saturday with the intention of putting 4k on the bike. How quickly the final drive play can start affecting the handling? Is there any risk of loosing the FD altogehter?

it's a '04 RT with 36k on the clock.

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Is there any risk of loosing the FD altogehter?

 

It depends on where the play is coming from. If it's the final drive pivot pin bearings, you will be fine. If the play is developing because the big crown bearing is starting to fail, you are at risk of having a complete failure on the road.

 

How to tell:

Using two people you need to wiggle the wheel in the way that you feel the play while touching with your fingers to find where the play occurs. If it's between the wheel and the final drive, then you have a serious problem (crown bearing). If it's between the final drive and the swingarm, then it's not so serious (pivot bearings).

 

Another clue: If you spin your rear wheel and it feels rough, like a bad bearing, you have a bad crown bearing. You need to ignore the rubbing of the brakes and feel for a low frequency rumbling. It might help to push the brake pads away from the brake disk to do this.

 

What to do:

Crown bearing - I would have it replaced before the trip. Best to see a dealer unless you are mechanically talented. There are critical adjustments that should be checked (in my opinion) that require quality measuring tools most of us do not own.

 

Pivot bearings - Sometimes the play in these can be adjusted out. I did so on my '02 but it came back again and that time not only was the bearing bad but the pin too. I think it best to just bite the bullet and replace these bearings, skipping the adjust it out attempt. The good news is this could wait until you get back from your trip.

 

Stan

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Well thanks Stan. That's rather reassuring. There is no noise at all when I spin the wheel (apart from the brake pads drag) and I'm pretty sure that the play is at the rubber boot between the FD and the swing arm. But i'll take a closer look later on to be sure.

When you say that a crown bearing failure is serious, does it mean I can be stranded somewhere or that the all FD can break off the bike...which could be very messy if riding at high speed frown.gif

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Well thanks Stan. That's rather reassuring. There is no noise at all when I spin the wheel (apart from the brake pads drag) and I'm pretty sure that the play is at the rubber boot between the FD and the swing arm. But i'll take a closer look later on to be sure.

When you say that a crown bearing failure is serious, does it mean I can be stranded somewhere or that the all FD can break off the bike...which could be very messy if riding at high speed frown.gif

 

If your crown bearing fails, you will be stranded. Your final drive will not break off, but you still could have a pretty serious issue if it desides to lock up your rear wheel. Most of the failures I've read about (mine included) were a NON-violent failure. The rear wheel develops a rythmic thumping/roaring while riding, and there is a little wobble/play in the rear wheel. Usually, they tend to start leaking gear oil from the main seal at this point. Worst case scenario is that the cage of the bearing gets shredded and it wedges the peices in the gears in the final drive causing the rear wheel to lock up. I've read about it, but have never seen or personaly talked to anyone that had it lock up, so take that for what it is worth.

 

Like Stan said, your best bet is to figure out exactly where the play is coming from. You could also drain your final drive fluid and see what it looks like. If the crown bearing is failing, the oil will be murky looking and have metal shavings in it. Mine looked like liquid metallic silver paint when I drained it. It also had a few chunks of the carrier mixed in.

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Thanks Keith. I checked the FD oil level last weekend and the oil looks like new (I changed the FD and gearbox oil back in May). That confirms that the play seems to be coming from the pivot bearing. i can live with that as long as it doesn't affect the handling.i'll change them bearings when i come back from my trip

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Jojo:

Checking the oil level is not the same thing as draining the oil and checking it for metal particles.

 

Also, I take issue that you could not lose your rear wheel if you lose your carrier bearing.

 

Check it out carefully. I am hoping it is a pivot bearing, but..... you do want to be sure.

Tipover Bob

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Why delay the repair? If it's the pivot bearing you can change them in about an hour, that's including the disassembly and reassembly. Only delay I had was ordering the parts.

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well...since I couldn't do the job myself before heading off on my trip this Saturday, I got the dealer to change the bearings for me. As I suspected it was the pivot bearings. It cost me a rip-off €224 ($300) (€60 in parts and 2 hours labour) but at least it buys me some peace of mind.

I read somewhere on this board that the bearings should be re-torqued after 500 miles. The mechanic said there was no need for this. Should I believe him???confused.gifconfused.gifconfused.gif

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read somewhere on this board that the bearings should be re-torqued after 500 miles. The mechanic said there was no need for this.
I've never done it. Just rechecked for play a few hundred miles after replacement. Given all the reheat and such needed to release the pivot pin of the loctite, clean it to be able to reapply and correctly re-torque it, etc., you'd basically be back to an initial installation point. So what's accomplished? But then thats just MHO.
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IIRC, the retorque is if you replace the needle bearings with Tom Cutter's bronze bushings. The bushings need retorqued to compensate for the initial wear-in. The stock needle bearings don't have a retorque requirement.

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