4:11 vs 3:90 diff which one better on street n freeway?

[Z train]

If any one is interested,i'm taking a 3.71 rear out of a 79 810 that i'm parting.

[240ZMan]

I run a late 280zx 5 speed with 4.11 and love it. When I ran NA with a medium cam it was great because it didn't take long to get into the power band, and the cam pulled well to 7k so there was still a usefull rev range. With 225/50-16 tires (almost identical to the stock diameter) it's turning 3100 rpm at 75 mph. Given how loud the rest of the car is (it's a 73 so not much sound insulation) the revs really don't matter. And on the track it's great. 2nd is good to about 65, third to 95, and fourth to 125.

Now that I've gone turbo it does seem a little short and if I was to do it again, I'd go for a 3.9 if I could find one. But the benefit of it is that the car can easily be left in third from below 25 mph up to 95.

Given how hard it is to find these diffs, I'd suggest you go with whichever one you find first that is in good condition and hold out for a 81-83 5 speed.

[Galaxybj]

In my 5/71 Z I installed the early 5 speed and 4.44 lsd from Datsun Comp. I used the same gearing in the transmission as the 2000 roadster. I really enjoyed it on the open road, twisty roads, and in town. I look forward to getting her back on the road to once again enjoy it. Of course, due to a tranny change while it was out of my possession, (it had a 79 280Z tranny put in) I am looking for the 81 to 83 tranny.

[fiveleaf]

The stickies that Pop's Z mentioned are here:

http://forums.hybridz.org/forumdisplay.php?f=62

I got (In my opinion) the best info out of this one. About a month ago, I printed it in color, made my notes, and put it in the z closet.

http://forums.hybridz.org/showthread.php?t=114798

For what it's worth, I would also wait on buying.

Tom.

Edited January 22, 2010 by fiveleaf

[texasz]

I'm planning on running a '77 5-speed (early?) and an R180 3.9. The engine will be a 3.1L stroker with about 10:1 compression. The car will be for autox and some street driving (just for fun on nice days not a daily driver).

Opinions?

[jmortensen]

If you've already got those parts, run them. You'll see how big the hole in the gearing is from 2-3 and when you hit 3rd how much it bogs down. Then you can switch to the later ZX 5 speed and report back about how much better it is.

Thanks fiveleaf. Glad people are still getting good use out of that thread. Took me a while to compile all the info.