Failed XS750 Final Drive (Images and video link)

[3Phase]

Stick A Fork In It

It's done.

The gear teeth are no good. The large right side ring gear carrier bearing is notchy and noisy and so are the pinion shaft bearings.

On the bright side it looks like the Type II (b) XS850 final drive is better than the Type II (a) XS750 final drive.

You're welcome; here the pictures! :-


The Type II (b) XS850 pinion gear looks like it might be a little heavier than the XS750 Type II (a) and there are splines on the input shaft like the Type II (b) XS1100 final drive.






These XS850 pinion gear teeth are worn and smeared. This is not a good part, it's a paperweight.






These XS850 ring gear teeth are worn and smeared. This is not a good drive, it's a doorstop.

[natemoen]

Now how do we tell the 750 and 850 drives apart?

[BrianMo]

drive shaft spacer

Hi.

Great read.
I am looking to make the swap on my 1100SH.
Just a quick question.
Maybe I missed it, but how did the 3/4" copper spacer on the drive shaft hold up during all this? Or did you do something else?

Thanks
Brian

[CaptonZap]

Now how do we tell the 750 and 850 drives apart?

The 850 FD I just picked up has 1J7YO cast into the unmachined face of the FD that is covered by the plastic shield that is bolted to the rear wheel.
The 11 FD has a different number, and the 750 FD I have has no casting number at all.
I don't know if this is indicative of all FD's, but it is what I have. Maybe Three Phase can look at his and let us know what number he has on his FD. CZ

p.s. For those that don't know, the type two drives have a flat head machine screw in the steel plate that holds the pinion assembly into the aluminum housing. (Where the four bolts are that bolt the FD to the swing arm) Which means that the drive has to be off the swing arm to be able to tell.

[3Phase]

Now how do we tell the 750 and 850 drives apart?

That's a good question, Nate.

I really know what to call the two different Type II final drives except Type II (a) and Type II (b). Maybe Type II (Y0) and Type II (Y2) to match the casting numbers would work better.

I don't have any pictures of a XS750 Type I drive but the original Tech Tip does.

The second picture in the first post in this thread has the 750 Type II (a) next to an 1100 drive but I'll reattach it here so you don' have to go back one whole page to see it.

I don't have a clue if there is a 750 Type II (c) with a Y1 casting number on the side cover or if Yamaha silently rolled the 750 and 850 Type II (b) final drives together under a shared 1J7Y0 Y2 part and casting number.

The XS1100 and XJ1100 final drives both share the same 2H700 part and housing casting number but I'd have to remove the rear wheel from my bike to see the side cover casting number on the XJ drive. I'll have to check that later. Much later.



XS750 Type II (a) final drive casting numbers.

Housing: 1J7Y0
Side cover: 1J7-Y0 (stamped by hand)







XS850 Type II (b) final drive casting numbers.

Housing: 1J7Y0
Side Cover: 1J7Y0 and Y2 (cast)







XS1100 Type II final drive casting numbers.

Housing: 2H700
Side Cover: 2H700 and Y1 (cast but not in picture)







XS750 Type II (a) and XS1100 final drives side-by-side.

750 on the left, 1100 on the right. The 750 final drive ring gear is not as sturdy as the XS1100 ring gear and it does not have an axle tube support brace.

[3Phase]

Maybe I missed it, but how did the 3/4" copper spacer on the drive shaft hold up during all this? Or did you do something else?

Brian, I did something else that worked really well and I have a cunning plan for the next one.

For what it's worth I'm still using same the yoke and u-joint that were on the bike a little over 50,000 miles ago.

[BrianMo]

Ok - thanks - good luck with phase 2

[3Phase]

-- Maybe -- on the road again with an XS850 final drive

I took apart the final drive the rest of the way today and the pinion bearings turned out to be okay after I cleaned them; not great but okay. I removed the bad side carrier bearing and replaced it with a good bearing from another final drive. It took a fair amount of time to set up correctly and to seal the two holes in the input coupler so I can use the XS1100 drive shaft. I almost forgot about the holes and it wouldn't have been pretty.

That was a lot of tedious and messy work. Have I ever mentioned how much I detest working with sharp machined surfaces, old moly grease and old gear oil? No? Okay, "I detest working with sharp machined surfaces, old moly grease and old gear oil!"

Columbo's XJ final drive has been removed and the swingarm bearings needed to be cleaned and greased again so that's done. Everything is ready to go back together tomorrow after I finish aligning the swingarm.

Hopefully the result of all of this will last long enough for me to be able to find another XS850 final drive that's in better shape but I'm about to break off the shift lever trying to find 6th gear on the freeway with the XJ final drive!

There are already more than enough sites on the 'net that show how to change bearings and set up gears and it's really not something that should be attempted by someone not familiar with how its done anyway so I only took pictures of the plugs for the input coupler... that I just discovered are still down in the garage on my phone so I'll post those tomorrow.

[latexeses]

Scott,
You got it bad!

[3Phase]

So far, so good!

Scott,
You got it bad!

Nah, I just don't want to waste $30!

I just got back from a test ride with a slow warmup of the 'new' drive on surface streets followed by some freeway miles, then some spirited fun boot-scraping through the canyons on the way back home. The drive works just fine and it didn't overheat. It might be psychosomatic because I spent so much time with its oily little metal innards in my hands but it feels more solid when I ride than the XS750 final drive I used to have on Columbo.

In my opinion: using an XS750 final drive is like dropping the rear end from an I6 1/2 ton truck under a 1 ton V8 truck. The XS850 final drive looks and feels to me more like a 3/4 ton rear end from a V8 truck under a 1 ton V8 truck.


Moving right along! Here are the pictures of the plugs for the input coupler:


Make a couple of aluminum plugs out of some nails.






Trim one side of the nail head to fit next to the washer in XS850 input coupler.






Mix some JB Weld to seal the nails in the oil holes in the XS850 input coupler.






Cover the nails in JB Weld and put them in the oil holes of XS850 input coupler.

Seat the nails with a flat face round punch or a screwdriver.

While the JB Weld is curing put the final drive out of the way somewhere with the input coupler facing down so that no JB Weld can ooze into the pinion bearings.

[cywelchjr]

It's done.

The gear teeth are no good. The large right side ring gear carrier bearing is notchy and noisy and so are the pinion shaft bearings.

On the bright side it looks like the Type II (b) XS850 final drive is better than the Type II (a) XS750 final drive.

You're welcome; here the pictures! :-


The Type II (b) XS850 pinion gear looks like it might be a little heavier than the XS750 Type II (a) and there are splines on the input shaft like the Type II (b) XS1100 final drive.

So it looks like my swag likely was right, that the 850 got a beefed up version of the 750's type II drive, and then the 1100 got a beefed up version of that with a different input shaft and gear ratio. So the hunt begins, and the price for 850FD's just went through the roof!

The real question, did 750's built after the advent of the 850 get the 750FD or the 850FD? I'm guessing that they got the 850FD, it just makes better economic sense.

[DGXSER]

Cy, the XS1100 as we all know, including you, originated in 1978, at the same time Yammie only made an XS750. In 1980 they upgraded the XS750 to an XS850, they did not make both the XS750 and the XS850 at the same time.

So the XS1100 FD had to come long before the XS850 FD.

[BA80]

Yeah Cy you maroon, you should know that. What's wrong with you.

[cywelchjr]

Yeah Cy you maroon, you should know that. What's wrong with you.

I've been hanging around with you guys too long, that's what's wrong with me. Next my bike will start acting like Nates and I'll have to rebuild the engine and paint it yellow .

[cywelchjr]

Cy, the XS1100 as we all know, including you, originated in 1978, at the same time Yammie only made an XS750. In 1980 they upgraded the XS750 to an XS850, they did not make both the XS750 and the XS850 at the same time.

So the XS1100 FD had to come long before the XS850 FD.

You know, your right, I'm not sure what I was thinking, other than I never really paid much attention to the 750's and 850's. I know you can see 750 FD's that look like they have the support collar, so I wonder if they are actually early 850 FD's or something in-between, so are there only two type II's or three?

So the change to the type II might go along with the 1100 FD, then again maybe not. It's hard to know for sure this far after the fact.