[sinister76ta]

I have a 77 Esprit I got from AZ a few summers ago. Last fall I stripped down a running but super rusted 77 4 speed T/A. I want to take the full 4 speed set up including the 400 and put it in the Esprit. How complicated would it be to take the gears out of the open rear end in the Esprit and put the posi gears from the T/A' s rear in it. The housing from the Esprit is super clean and the posi's housing is rusty and pitted, that's why I want to change out the insides. Thanks in advance, Chris

[steve25]

Yes, you can swap everything over, but the gears will have to be set up with new shims as every rear is machined to a tolerance and are not dead on the same.
If you do not have the tools to set the pinon depth and the back lash and the ring gear than take it to a shop that does, you are going to want to install new bearings anyway ( you need a press to do this work)even if the current ones are ok it pays to do it now and not have to take it all apart in 15k miles and have it set back up again.

[ta man]

I'd also check what the current pattern and backlash is and try to duplicate it in the new rearend.

[JJKJ]

It depends on what your goal is as well. If you want to use the gears and posi, follow the advice above. If you're just looking to swap the posi in, that would be easier. As long as you don't pull your pinion gear, you wouldn't have to reset the pinion depth which is the biggest pain when setting up a gear set. Setting the pinion depth is the most difficult because you have to press the pinion bearing on and off each time you adjust the shims to set the correct depth.

If you just swap in the posi unit, then you can get away with moving your ring gear from your old open unit to the new unit. You'll have to check your backlash and shim accordingly but that's the easier part of assembling a gear set. The shims for setting backlash aren't under a pressed bearing so they're easy to swap. Prior to disassembly of your open unit, I'd use a dial indicator to check backlash (play in the ring gear). When you reassemble, use your shims to get the backlash to the previous reading.

[Z Code 400]

I am sure I will catch flak for this, but in most cases, the difference between housings will be minimal.

I had a complete disc brake 10 bolt posi with 2.76:1 gears from a 1979 Trans Am. I installed a set of 3.23:1 gears from a 1994 Impala and I just dropped them in, using the pinion shim from the 2.76:1 gearset, the 2.76:1 posi and side shims.

When I checked the pattern and backlash, everything was perfect. We used to do this ALL the time on dirt track cars and we never had to change the shims more than just a few thousandths. Always check everything twice.

Here is a link to a post regarding questions about pinion shims and setting up used gears: http://forums.maxperformanceinc.com/...highlight=gear

I'm doing a 4 speed swap in a 1975 Formula, so that thread might be helpful to you: http://forums.maxperformanceinc.com/...d.php?t=591598

Best of luck...Robert

[67 Lamnas]

As long as each rear has it's original GM gears, and the pinion depth settings are still legible (usually white or yellow ink "43" or "45", e.g.) it's really easy and no measuring is required for the pinion depth if changing housings......setting backlash is another story, though, but the process is fairly easy also