knight_white99

iTrader: (5)

Question for you experts...

I want to run a 3.9 gear for track events, and I want to save my stock rear end for the top gear, high speed, open road events. I want to be able to just swap out the entire pumpkin instead of having to change the gears every time (a far easier job).

I am looking to save some dough, so I was looking into buying a used (i.e., salvaged) rear end. I know that the Base model cars don't have limited slip, so I am looking for a non-Base model rear end.

There is a salvage dealer in NoCal who wants to sell me the rear end from an automatic. He says that since I want to swap out the gear any way, it doesn't matter if its from a MT or auto. Is this true? He says that the only rear end that his info says is "locked" is the automatic. The used automatic rear end is cheaper than the used MT rear ends - why would this be?

Is there any difference between the automatic rear ends and the MT limited slip rear ends?

Thanks.

GaryM05

I believe that the 5AT rear end is a 3.3 FD, whereas the 6MT is a 3.5.

knight_white99

iTrader: (5)

Yes, I know that. That's not important, since I will be changing out the stock gear (in either case) with the 3.9 ring and pinion.

What about the REST of the pumpkin/diff? Are they interchangeable?

GaryM05

Sorry...I guess I mis-read what you were looking for, and when I saw you ask 'is there any difference between the rear ends', figured I'd mention that as a difference.

I don't know of any other difference besides that, but you could always try visiting your trusty neighborhood Nissan parts department and ask about any part number differences between the various components in the 2 pumpkins.

Good luck with your project.

C Ray Z

iTrader: (2)

BJ is always very helpful. They build the rear ends so they wouold know for sure. Phone 513-735-2300

Good luck

Kolia

iTrader: (2)

It all sounds like a good idea.

May I ask what kind of event would require the swap back to the 3.5 unit? Will you be doing speed challenges?

I barely make it to fifth gear with the OEM final drive down the back straight at MidOhio, going ~120mph. I doubt I’d need a seventh gear with a shorter ratio.

Is it really worth it to swap both drives?

knight_white99

iTrader: (5)

I run in events that require high top speeds, like the Silver State Classic in Nevada, where speeds can often exceed 150mph. When you have straights that are as long as 14 miles, it's easy to reach 150mph and beyond. The 3.9 gear would not be good for these events.