XS750 Final Drive Swap

[DGXSER]

Hmmmm

Scott,

I consider this educational and I take your concern as a safety concern for me and other members only. Not as busting my chops or anything else I own.

It appears I was thinking ( a dangerous past time I know) about an entirely different matter than the one you were driving at. I was thinking we were discussing ensureing and trying to measure proper gear engagement area between the ring and pinion gears. This I think we agree is not in danger if you do not remove the pinion.

I completely agree that tightening that bolt should be done to the specs provided. Which the spec says to tighten the nut on the Type II at up to 108 ft-lbs. But then says bearing preload of about 4 inch pounds. I will share that I could not for the life of me find a wrench in town that could measure 4 inch pounds with any accuracy at all, and I looked, really looked. After all, this is basically taking a 4 lb weight and sitting it one inch from the edge of a counter or the like on a board and holding the board down at the edge with your fingers / hand. That is how much force it should take to rotate the FD on the wheel when the force is applied at the area the nut is located. As I understand that, that is the bearing preload.

In short I think we agree what should be done. And my anal retentive nature kept me restless in bed for a week after I installed that FD having put locktite on that nut, but not really torqued to spec. But to this day I do not think I have seen a tool that could measure accurately the force we are talking about, at least not in any stores.

[3Phase]

... to this day I do not think I have seen a tool that could measure accurately the force we are talking about, at least not in any stores.

Calibrated wrist/elbow: not available in stores! In-lb beam wrenches are available but they're not cheap in that range with anything resembling precision.

If the bearing preload gets too tight too fast it means the crush washer is ruined.
Don't try to play fast and loose with Locktite, just get a new crush washer; still available from Yamaha. Do it right so it won't break or lock up when you downshift a couple of gears to ride the twisties or romp on it to pass in front of a truck holding up a long line of cars.

[gareth]

Starting over...

Just bought a decent looking xs850 final drive on eBay, includes the original shaft.
I just can't cope with this kind of doubt on a motorcycle that I regularly push over the ton for a quick thrill. I had a transmission lock up on a Honda Sabre V65 a couple of years ago, travelling at just 30mph, and I never trusted that bike again, even after I swapped in a new engine.

So it's back to Plan A. An XS850 drive, to guarantee a Type II component. I will block the oiling holes with pellets of rubber sealed in with RTV and then pour a thick epoxy seal around and over them;

I am done worrying about preload, bearing clearances, wrist wrenches and crush washers.

I would like to thank Scott and DXSER and anyone else who contributed to this thread. If you Doubting Thomas's had just said "Way to go..!" and left it at that, and NOT pointed out some of the pitfalls, I might just be riding around blissfully ignorant on my scoot. I enjoy wrenching on this bike, but when safety and confidence meet my limited skills, I am always going to err on the safe side..

Thanks, Gentlemen.

[DGXSER]

I understand completely Gareth. So, your plan is not to touch the nut in contention here.

[gareth]

I understand completely Gareth. So, your plan is not to touch the nut in contention here.

I'm done messing with that box-grinder. I already have the drive shaft set up with the 16mm spacer, a bit of experience now fitting it, and I expect Final Drive Swap Part Deux to be a more serene experience.

[3Phase]

... I will block the oiling holes with pellets of rubber sealed in with RTV and then pour a thick epoxy seal around and over them;

I am done worrying about preload, bearing clearances, wrist wrenches and crush washers.

You're welcome, Gareth, and that's almost exactly what I plan to do if I have to replace the final drive again!

October 2010 will be two years for my bike with the 750 mod and I had to change the crush washer, then reset the bearing preload. I've been watching the drive like a proverbial hawk to make sure the oil is clean and free of metal after a fast run or a long trip and I try not to 'shock' it when doing normal shenanigans, either. It gets old quick and it wears on you while you wonder.