Santa brought me a new (well, mostly new) differential for my 240Z. I was running a 3.90 open diff and now have gone to a 4.10 with LSD. Basically took an R200 4.10 open unit (used of course, but in very good condition) and installed new bearing/seal and a limited slip unit. Spent new years day installing the beast! After the install was completed, I took the car for a drive. Oh yes! With the late model 280ZX tranny, 4.10 gearing, and 24" rear tire diameter....the car seems to be geared just right. So at 3000 rpm, I'm going approximately 75 mph (calculated). Anyway, I am pleased with the upgrade and will not miss having the inside rear tire cut loose, when coming out of twisty corners aggressively. Also, I now have an R200 3.90 (open) differential for sale. Its is excellent condition, nice gloss black paint with a polished out cover. I have been running SWEPCO 201 gear lube in the diff.

So what do you guys and gals think of the upgrade?

Very similar to what I want , do you think you lost alot of top end?

I found a 300zx turbo lsd in the wrecking yard over the weekend. It is a 3.70 but woud like to make it a 3.90 or perhaps a 4.11. Would I just need to swap out the ring and pinion? It looks brand new inside and for only paying $20, I will just keep the 3.70 if it is too big of a deal.

Thanks

seerex, Actually I think I may have gained top end with the 4.10 gears because now I may be able to pull up to or close to redline in 5th gear. With the 3.90 gears I don't think I would have been able to even get near redline with the horse power I have....approximately 160 HP. I don't think I've ever had my Z much over 100 mph anyway. It's a street car and my interest lies in attacking twisty roads, not top end speeds. Anyway, I'm happy with the results!

Zeus, You are correct! You can change out the 3.70 gear for either a 3.90 or 4.10 gear however, you will need to install new bearings and seals plus have the new (or used) ring and pinion set-up for proper backlash. Depending upon which transmission you are running and of coarse your tire size, the 3.70 gear may be just fine. Tell us what you have!

240zx,

I currently have 195/60/14 falken azenis rubbers. Eventually, when the car is back together, she will wear 215/50/16. I have a 77 5 speed and plan on keeping it because of the lower gears. Last time I drove the car was with the 3.36 and a very tired :dead:(nothing done to it in 30 years) l24. Apon restoration, I will have a fresh l28.

I really am going for the low end power as this car will be a weekend only driver and autocrosser...

thanks for the quick reply

Zeus, You have the early model 5 speed. On this tranny, 1st and 2nd gear are lower than on the late model 5 speeds. 3rd and 4th gear are the same for both trannies. 5th gear on your 5 speed is slightly lower than the late model units. The early tranny is refered to as the wide ratio unit and the late model is the close ratio unit. So, the 3.70 gears should work well for you. As you know, the lower the gearing, the quicker the car will move out. I, on the other hand, have the late model tranny which was matched from the factory with 3.90 gears in the differential (came out of a 1981-83 280ZX). It was fine but I just wanted a little extra acceleration, so the 4.10 gear worked out perfectly for me. Let us know how it all works out.

thanks for the reply 240zx.

i will definantly wait until after the car is back together before swapping out parts in the diff. I am sure i will be happy no matter what....i will be driving my Z after all