750 Final Drive enigma

[MAXIMAN]

I have found a bit of a mystery regarding the 750 final drive. As you know the 750 drive and the 1100 drive are damn near identical with just a few very minor (seemingly minor) differences.

One of those differences is the "bearing spacers" (essential shims) at the base of the pinion nut. These are used on the 750 drive but not the 1100 drive.

Secondly - As you know in 1980 Yamaha replaced the XS750 with the XS850. When they did this the new 850 employed a drive with no bearing spacer shims like on the Eleven.

If you read the supplementray drive manual you'll see the reference to these shims. To adjust the bearing pre-load the manual indicates you add or remove these shims.

I suppose regarding the Eleven the only way to adjust the pre-load is via pinion nut torque since it employees no shims.

Any comments?

Secondly - by searching the Yamaha parts diagrams I found only the 750 drive employees these shims. According to the parts diagrams the 850 does not.

[MAXIMAN]

No ideas as to why they did this?

In any case I think an 850 drive would be superior because you don't have to shim the pinion nut fo bearing pre-load. Just tighten it up I suppose.

Here's a link to a PDF file for the manual I posted at omnidrive.com if you'd like to have it for reference.

XS1100 XS750 XS850 Drive supplement manual

This manual references final and middle drives for the shaft drive XS models.

[skids]

Shims?

I do have a question regarding the "shims." When I did mine, I used a xs750. When I pulled off the big nut, there was a thick washer (shim?) under the nut, which I replaced with a regular washer to seal the rtv and old lube holes. The pinion assemble did nit come apart other than that. Is there a problem with replacing the OEM thick washer with a regular thickness washer??? I just rode the bike on a 600 mile trip without any mishap...

[MAXIMAN]

Did you check the preload as per the manual? As long as the pinion nut is torqued and the bearing pre-load is right it shouldn't matter.

[skids]

Preload per the manual????
This was not in the tech tips that I followed. I torqued the nut good-n-tite as best I could while trying to hold the radial gear from turning.

[MAXIMAN]

That's because I did not have a drive manual at the time. Actually I did not even know a drive manual existed until recently.

Anyway it's posted above.

[Rubin]

So Maximan, just to clear up the fog in my brain, I would be better off with the XS850 final drive and drive shaft? And this "should" bolt right up to the current XJ11 middle gear?

[xschop]

shaft

No, you will need to use the xs11 shaft with a spacer reguardless of 750/850 Final drive. The xs850 shaft is too short!

[Rubin]

Thanks for the reply chop, found a couple on flea-bay and I think it is time to get one.

[Rubin]

Maximan, we went back and forth about spare spacers, do you have any left lying around?

[xschop]

5K

BTW...WILL HIT 5000 MILES IN A WEEK OR SO AND WILL PULL OUT THE SHAFT AND POST PICS OF THE SPLINES AND SPACER FOR AN UPDATE....CHOP

[MAXIMAN]

rubin-No there all gone. But the copper collar will work fine.


Hey CHOP! Drain your FD oil and look at it and let us know what it looks like. Curious to see how that 750 drive is holding up.

[johnrobey]

Does anyone know it the early venture drive is the same as the xs?

[ExcessiveBiker]

I am coming up on 4000 miles on the 750 drive, with only a better operating 1100 to show for it. Gas mileage stays around 37 and a pleasant ride at 70 mph.
As far as adjusting the gear lash in the finals, there are only two ways to do it and torque is not one of them. You must shim the pinion in or out OR shim the ring gear closer or farther from the pinion assy. Torqueing only has an effect on nut preload to the pinion shaft which just clamps it tighter to it's carrier bearing, and has no effect on lash adjustment.
There has to be shims somewhere.

Put in a 750 final today, it is just what this bike needed.
easy ridln'
ExcessiveBiker

[MAXIMAN]

Originally posted by johnrobey
Does anyone know it the early venture drive is the same as the xs?

I dunno if it will fit an XS...I doubt it... but it's a straight swap for a V-Max. A lot of V-Maxers stick a Venture drive on their V-max for more top end speed.

Exassive biker -

There are no shims on the 850 drive...not on the pinion assembly.

There are shims on the 750 drive....called bearing spacers in the manual and parts catalog.

Both drives have a crush washer (formally dubbed expansion spacer).

I've disassembled two 750 drives and three 850 drives now and have confirmed this. If you have information that proves the 850 drive employees pinion bearing shims then please divulge. They certainly are not in the parts catalog.

ALL DRIVES...I reiterate...ALL DRIVES have pinion shims like you are speaking of...which allow for the adjustment of gear lash. These gear shims are between the gear coupling and final drive housing.

I am not talking about these gear shims. I am refering to bearing shims...called bearing spacers in the manual and parts catalogs...at the base of the pinion retainer nut. These shims certainly have some "bearing" (pun intended) on the pre-load of the pinion bearing of the 750 drive. They are not present on the 850 drive.