Final Drive Transplant _ Kudos 2 XSChop!
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XS750 Final Drive Conversion
"Mod of the Year, 2006!"
by Cody(Maximan) and XSChop, posted 11-12-06
First let me say this is absolutely the most straight forward mod I’ve ever done to my Eleven. And the results are spectacular. I am so utterly please with this modification I would recommend it highly to any Eleven owner that is not pre-occupied with ¼ mile times. If you want a top end – gas sipping XS11 this mod is the BOMB SCHNIZZLE. You won’t regret it. Besides it is so easy to do (other than a few hours of time) you could easily revert to the OEM drive if you want lower gears.
Secondly I must pay “kudos” to Chop (xschop). I nominate Chop for coming up with the coolest mod for 2006. I’m not sure what inspired him to experiment…and I am not sure I care to know. IT WORKS! The rev reductions are not only real but are very significant. At the end of this procedure I will post my real world results. In short they are outstanding.
Last edited by crazy steve; 06-20-2012 at 06:12 PM.
Chop used it becasue it was readily available. However...I would seriously consider a steel or bronze spacer. I have not checked mine (copper) since the install but I will in a few days to see if there is any noticable wear. In any case i am going to replace the copper with a bronze spacer.
I was in an oilfield supply store the other day and stumbled upon a perfect spacer. It is a rocker arm bushing for a 346 Fairbanks Morse engine. It is made of bronze instead of copper and actually fits a little better than the copper tubing and the wall thickness is about 1/2 mm thicker. Being made of bronze it should be more durable.
The copper will work but I think this bushing would be a better long term solution. You should be able to get one at any oilfield supply. It is readily available through Arrow Specialty Products. Arrow Specialty can be found on the net. They have offices in NY and OH and other places but most Oilfield supply store would be able to get this common part for you. The Arrow part number is 1009 for a 346 Fairbanks Morse.
You'll have to cut it to length. But you'd have to cut the copper collar to length too.
Arrow Specialty Products handles these parts. The Arrow part number is 1009 in their catalog.
2301 E Independence
Tulsa, OK 74110
Phone: (918) 583-5711
But you can probably call these guys and ask for parts:
Then tell them you need a rocker arm bushing for a 346.
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.
After the 3000 miles trip to west Texas I pulled the drive for inspection. There were some small metal shaving on the magnetic drain plug and the pinon assembly was very loose. MY BAD!!!
I chucked that drive and installed another. This time around I torqued everything back to spec and the bearing preload was fine.
HOWEVER... should you button everything up to spec and the beaing preload is not close to the specified torque in the manual...you should replace the expansion spacer (a crush washer) that is between the pinion gear and the retainer nut. These are only $10 and will assure you the right tolerances are maintained.
So far I know of no one that has had this problem and simply re-torquing everything back to spec should work fine without having to replace the expansion spacer. At least it worked for me on the second drive.
When I first did the '750 mod I bought all the recommended parts but I didn't trust the spacer idea so I cut the barrel off the yoke from a bad u-joint and extended the splines the full length of the driveshaft again.
At the time I wanted it to be stronger than just the spacer but I also wanted to be able to undo the mod. I used the driveshaft to hold the parts together and aligned while I drilled and pinned both pieces with a couple of broken 1/8" drill bits, then covered them with JB Weld. The JB Weld crackled off like I thought it would but you can still see one of the holes in the yoke and it still has the pin in it.
When I decided it was time to make it permanent I brought the driveshaft along to the welder's shop so the parts would stay lined up through the heating and cooling.
However it turns out it uses up two XS11 yokes so don't mess up.
Cut The Yoke
Dress And True The Spacer
Check The Splines
Extended Yoke vs Spacer
XS1100 U-Joint Yoke Extended
1982 XJ1100J: SS Brakes, '850 FD
1980 XS1100G: "Columbo" SS Brakes, ACCT, 2nd Gear Mill mod
1979 XS1100SF: W.I.P.