Install XS850 Final Drive on a '79 XS1100SF or '80 XS11SG?

[tn11]

Hello all. Wondered if anyone has installed an XS850 final drive on a '79 XS11SF or '80 XS11SG? I have one of each, but need to sell one. Anyway, I've heard that the XS850 has a taller gear, which I believe I would prefer. Is this just a bolt-on job or is it a big hassle? I see lots of '80 XS850 final drives on ebay. Would one of those fit my '79 1100SF and/or '80 1100SG model? Thanks.

[bikerphil]

Yes the 750/850 finals will fit with a little modification....

http://www.xs11.com/forum/showthread.php?t=11703

[Cobia]

I have an 850 final drive on my G and as Phil said, it goes in with no issues. He should know, he installed it.
Re: Taller gear? I couldn't tell you for sure, but it feels like it does.

[DGXSER]

Yep, the XS850 has taller gears than the XS11. IIRC, it is 3.3:1 on the XS11 and 3.9:1 on the XS750/XS850 FD. I know it will drop almost 1000 RPM off your tach at highway speeds.

I have installed three of them so far, it is a very simple swap.

[Schming]

Yep, the XS850 has taller gears than the XS11. IIRC, it is 3.3:1 on the XS11 and 3.9:1 on the XS750/XS850 FD. I know it will drop almost 1000 RPM off your tach at highway speeds.

I have installed three of them so far, it is a very simple swap.

Correct ratio on the XS11 FD but the XS 750 & 850 are 2.9:1

[DGXSER]

Of course Taller gear = lower ratio. If only my fingers would type what my brain tells them to.

[Schming]

Of course Taller gear = lower ratio. If only my fingers would type what my brain tells them to.

Just trying to keep ya honest and I expect the same in return.

[trbig]

Nope.. That FD won't work at all. Send it to me and I'll take care of it for you..

[DAVINCI]

Tod, let the guy get some use out of it before you blow it up

Yes, Swamp Thing has the 850 FD, works fine.

[tn11]

Thanks for the info. I read the "how to" link Phil posted. These instructions were for modifying/installing an XS750 final drive on an XS11. Are the XS750 and XS850 final drives the same? Would the same instructions apply if I install an XS850 final drive on my XS11SF? Thanks again.

[Schming]

Thanks for the info. I read the "how to" link Phil posted. These instructions were for modifying/installing an XS750 final drive on an XS11. Are the XS750 and XS850 final drives the same? Would the same instructions apply if I install an XS850 final drive on my XS11SF? Thanks again.

On post #2 of the swap thread TC stresses the torque on the pinion bearing:

" One thing I've picked up on that everyone should be aware of. I did not realize this when I wrote up the procedure.

The torque on the pinion retainer nut IS CRITICAL. As is the preload.

I suggest following the manual. After installing the larger washer to seal the spooge holes on the drive coupling be sure and torque the pinion nut to the specified torque...54-61 ft-pounds for a type one, 75-105 ft-lbs or there about for a type two. Then double check the bearing preload with the appropriate inch-pound torque wrench.

On a type one it is about 10 inch pounds.

On a type two (read 850) it is 3.4 to 4.3 inch-lbs.

If the bearing preload is not within the specified range damage could result as I found out on mine."

I believe this is the only difference, but read the whole thread and reread it while your doing the swap, step by step and you'll be ok.

[DGXSER]

Schming, I assume yours was a Type I FD.

First, yes, the 850 FD and the 750 FD are about 100% the same thing. There are some subtle changes, in which the 850 is a better unit, but for purposes of installation, they are the same.

As to the torque on the pinion nut, ignore everything said about the torque required. First time I did this mod, I tried to get to those torque numbers and never made it, however, the FD would no longer spin at the torque I did apply. From great advice I got on this site, I followed the procedure outlined below.

So, for the XS750 type II and or the XS850 FD (essentially a type II also), install the washer with the appropriate amount of RTV and such. Then tighten the nut until the FD starts to resist turning. In other words, tighten for the 3.4-4.3 inch pounds of resistance to turning. Which ain't much.

On the type I FD, the bearing spacing is set by the torque. On the type II they used a crush sleeve, so once the torque is applied, the sleeve is crushed and keeps the load on the bearing. This is why you do not need to torque it so high again.

[motoman]

Of course Taller gear = lower ratio. If only my fingers would type what my brain tells them to.

Taller gear= higher ratio.

[Schming]

Schming, I assume yours was a Type I FD.

First, yes, the 850 FD and the 750 FD are about 100% the same thing. There are some subtle changes, in which the 850 is a better unit, but for purposes of installation, they are the same.

As to the torque on the pinion nut, ignore everything said about the torque required. First time I did this mod, I tried to get to those torque numbers and never made it, however, the FD would no longer spin at the torque I did apply. From great advice I got on this site, I followed the procedure outlined below.

So, for the XS750 type II and or the XS850 FD (essentially a type II also), install the washer with the appropriate amount of RTV and such. Then tighten the nut until the FD starts to resist turning. In other words, tighten for the 3.4-4.3 inch pounds of resistance to turning. Which ain't much.

On the type I FD, the bearing spacing is set by the torque. On the type II they used a crush sleeve, so once the torque is applied, the sleeve is crushed and keeps the load on the bearing. This is why you do not need to torque it so high again.

Correct me if I'm wrong, but aren't the type I FD's the 750's and type II the 850's, and all the FD's have the crush washer ?

[crazy steve]

Correct me if I'm wrong, but aren't the type I FD's the 750's and type II the 850's, and all the FD's have the crush washer ?

The type 1 uses a specific-length spacer to set preload, only the type 2 uses a crush spacer. Don is correct, you need to look at the bearing preload and actually try for the lower end of the scale unless you install a new seal. A used seal will offer less resistance.