I was getting ready to swap a 3.90 r200 rear end into my late '72 240z (Also installing a "ZXb" 5-speed 0.745 5th gear) and ran into a snag. While I got the 280z side flange shafts that work with the 240 half shafts, I did not realize that my r200 had the wrong pinion drive flange. My r200 has the rectangular flange with the 2" pilot and 2.94" bolt circle. The one I need is the 2.2" pilot with the 2.75" bolt circle.

Question is, if I can find the correct companion flange, how hard is it to change? I ask this because I am concerned about the thrust washers behind this flange and want to know if there is any special requirement to make sure the pinion depth is not disturbed other than just putting back the thrust washers in the same order they came out.

I hope this makes sense. I know differential assembly is tricky and I just want to make sure I don't make a mistake.

Also, Anyone know where I can find the correct companion flange?

When I swapped out my companion flange I did not have any issues with the thrust washers. I never removed them when swapping the flange.

You will have to worry about torquing the pinion flange down too much. If torqued down too much it will eventually destroy the pinion bearing.

Here are a couple of links from Hybridz on the topic. Make sure you read the whole thread in both, there is some misinformation in the beginning posts. [Edit - no offense to JMortensen (one of the posters in the other threads). Apparently there had been some funky information floating around in general at the time (over 7 years ago).]

http://forums.hybridz.org/index.php/topic/19920-r200-seals/

http://forums.hybridz.org/index.php/topic/17356-370-lsd/page__p__126272__hl__%2Bpinion+%2Bflange+%2Bcrush__fromsearch__1#entry126272

Edited November 7, 201014 yr by Zed Head

No offense taken. I thought at the time that the R200 had a crush sleeve, and that idea was reinforced by Kim Blough. Steve Golik corrected me. I tried to correct Kim Blough, he apparently "knows" that he is right and finally asked me to stop bugging him about it. Now I've been into a couple of these diffs and seen the solid spacer for myself and read the FSM. It's a solid spacer. Solid spacers are not really torque sensitive. No amount of torque is going to crush the solid pinion spacers and change the length of the spacer. You need to get enough torque for it not to loosen up, and not so much as to destroy the threads. That's basically it. That's why the FSM has a WIDE torque spec of 137-217 ft/lbs. I have a good quality Ingersoll Rand 231 impact, so I set that puppy on 5, let the compressor fill up and blast away at it 3 or 4 times and call it done.

FSM with pinion torque on p39:

http://www.xenonz31.com/files/Z31%20R200%20Differential%20Service%20Manual%20%28includes%20Limited%20Slip%29.pdf

Edited November 7, 201014 yr by jmortensen