Type 1 and Type 2 differentials

[XSPastor]

It looks like the expansion spacer (crush washer) is available from this site:

http://www.yamahaaccy.com

12 SPACER, EXPANSION (1J7-46129-YO) $10.91

At least, I think that's the part you're talking about. Good luck.

[3Phase]

Thank you, Pastor, Randy, Ray, and T.C.!

I ordered a new crush washer and it should be here Tuesday. The front pinion seal was in stock locally so I'll be able to replace it after adjusting the preload. The pinion bearings may still be available but if it goes to that level it'll be cheaper, easier, and a lot less time-consuming to buy another used differential and be done with it.


Regards,

Scott (can't just bolt on a new differential like everyone else, go for a ride and be done with it; noooo, that'd be to easy....)

[0011mixam]

Re-use your original crush sleeve

I re-built an XS850 final drive before installing it on my XJ. It is what you refer to as "Type 2" with the crush sleeve instead of shims on the pinion shaft. All I did was find a steel bar that was slightly smaller diameter than the ID of the crush sleeve. I clamped the steel bar in a vise and then slid the crush sleeve over the bar and lightly tapped on the raised ridge with a small ball-peen hammer while rotating the sleeve. It doesn't take much to "widen" the crush sleeve a few thousandths of an inch (measure it before and after with a vernier caliper). I then re-installed the crush sleeve on the pinion shaft and carefully torqued the nut in small increments, while checking the preload rotating torque by hand in between. I stopped torquing the nut when I started to feel a slight bit of drag on the pinion shaft. By then, there was plenty of torque on the nut to hold it in place.

So far the final drive seems to be working fine after 1500 miles.

[3Phase]

I re-built an XS850 final drive before installing it on my XJ. It is what you refer to as "Type 2" with the crush sleeve instead of shims on the pinion shaft. All I did was find a steel bar that was slightly smaller diameter than the ID of the crush sleeve. I clamped the steel bar in a vise and then slid the crush sleeve over the bar and lightly tapped on the raised ridge with a small ball-peen hammer while rotating the sleeve. It doesn't take much to "widen" the crush sleeve a few thousandths of an inch (measure it before and after with a vernier caliper). I then re-installed the crush sleeve on the pinion shaft and carefully torqued the nut in small increments, while checking the preload rotating torque by hand in between. I stopped torquing the nut when I started to feel a slight bit of drag on the pinion shaft. By then, there was plenty of torque on the nut to hold it in place.

So far the final drive seems to be working fine after 1500 miles.

I didn't make up the names, honest! Type 1 and Type 2 (Type I and Type II) are what Yamaha call their differential gear sets, both middle drives and final drives.

I was going to rework the crush washer if I couldn't find a new one but, fortunately, I found a new one. A single turn of 0.015" wire (garbage bag tie) just above the crush washer was just about right; it's not too far off.

I can't prove it but I suspect that the crush washer continues to collapse over time and under load and causes the pinion bearings tighten up and increase the bearing preload. Reshaping a used washer may or may not not work for very long. What I'll probably end up doing is setting the bearing preload with the new crush washer, then measuring the crushed washer and replacing it with the appropriate number of hardened steel arbor shims.

Hopefully I'll be able to get 1500 miles, too!



Regards,

Scott

[0011mixam]

3Phase:

Sorry for implying that you made up the "Type 2" name. I should have remembered that from my copy of the shaft drive service manual.

I'm pretty confident that there's no harm in re-shaping the crush sleeve. All metals can undergo "elastic deformation" (like a spring) up to a certain point, from which they will spring back to their original shape when the load is released. If you go beyond this point, the metal goes through "plastic deformation" which will not spring back. For example, let's say that the crush sleeve can elatically deform 0.002 inch if compressed by the nut on the final drive. If you torque the nut to compress the sleeve a total of 0.003 inch, 0.002 inches of this will be elastic deformation, and the remaining 0.001 inch will be plastic deformation. When you relaxe the load, the sleeve will still spring back 0.002 to account for the elastic deformation, which will result in a thickness 0.001 inch less than before you started (ie, the amount of the plastic deformation). Please note that this is only an example, and I don't know exactly how much you can compress the sleeve before plastic deformation occurs.

By "cold working" the original crush sleeve, I plastically deformed it to make it thicker. When installed in the final drive and the nut is torqued up, the sleeve elastically deforms up to the elastic strain limit of the steel, after which it plastically deforms a bit. You'll still have the load on the nut due to the elastic deformation within the sleeve. Further, unless the nut is over-tightened, there is no reason for further deformation of the sleeve, so it will not collapse over time. Like you said, someone over-torqued the nut on your Type 2 drive, which resulted in too much bearing preload. Keep in mind, the tooth contact pattern is set by shims, and the crush sleeve only serves to control bearing preload. Many automotive differentials use this same type of crush sleeve with the pinion bearings, without any problems of it loosening up over time.

Since you have sourced a new crush sleeve, this is all a moot point anyway. Good luck with setting your pinion bearing preload and here's to many many enjoyable miles on your XS.

Perry

[3Phase]

Thank you for your help. Perry! You made me think about this even further and then do some empirical testing and measuring!

I just went out and measured with and without the 0.015" wire tie on the bad crush washer and this is what I found:

The crush washer width sets the installed length of the entire pinion assembly at the recommended torque and bearing preload.

After setting the bearing preload and installed length, shims are installed between the pinion assembly and the final drive housing to set the final installed depth and ring gear contact. The new 750 final drive has, for example, two 0.015" shims for a total of 0.030" that determine the final installed depth and contact with the ring gear.

Preload first; shim second.


Regards,

Scott

[3Phase]

New Crush Washer Today

The old washer was 0.275" thick.

The new washer was 0.310" thick out of the bag.

After torquing to the correct preload the lash and pinion/ring gear contact is okay and the new washer is 0.295" thick.

No pinion housing shims had to be added or removed.

So far, so good!



Regards,

Scott