littlejep

I just completed my auto to manual swap and have read some things that say iI should swap the differentials aswell.

Is there that big a a difference between the auto and the manual differentials? Will I notice any differences, or is it not worth the time? what would you do?

btw both cars were 88' SE's

thanks,
chris

Scott 89t2

the auto rear ends were 3.9:1 and the manual are 4.1

the car will accel a bit faster with the 4.1

Evil Aviator

Auto 3.909 vs. Manual 4.10 gearing

In English, that means the 3.909 will have slightly better gas mileage, and the 4.10 will have slightly better acceleration. Since the choice is yours, it would be best to try out a friend's car to see if you like the 4.10 enough to spend your time and money on one. I guess another choice you have is between a regular 4.10 and a limited slip 4.10.

Icemark

I feel there is a noticeable difference between the 3.9 and the 4.1 rear end gearing, (the 4.1 is about a 20% increase over the 3.9), and if you spend a lot of time at stop lights or that 0-60 is more important than anything else you should change to a 4.1.

But remember that the speedo will need to be recaliberated as well.

Scott 89t2

he might be using the one in the 5 spd now though so it would be correct after puting the 4.1 in

littlejep

looks like I will be swapping the auto diff with the 4.1 from my wrecked 88'...

anyone done this before? how much time should I set asided? a day weekend???

Evil Aviator

I'm not sure how long it would take to swap out the pumpkins, but it's not going to be fun. If you can use the whole rear sub-assembly from your wrecked 88, you can swap it in an hour.

littlejep

yeah the rear was untouched. this sounds like the way I should do it. What is included in the whole rear sub-assembly? how do you take it off all intact??

thanks
chris

Evil Aviator

See the structural picture in the service manual. Basically, you just remove the wheels, disconnect the sublink, shock absorbers, propeller shaft, the two bolts that hold the subframe to the car, and the two differential mounting bolts. I can't remember if there is any particular order, but you just drop the whole subframe assembly off the back of the car.

You could maybe just drop the differential after removing the propeller shaft and halfshafts, but I'm not sure because I don't know anybody who has tried this.

Icemark

actually easier to swap just the diff rather than the subframe and diff, if the subframe is in decent condition.

Unbolt the propeller shaft, and axles, sublink, left side of the subframe.

Pull the subframe down a little to access the front two bolts for the front diff mount.

once those two are out, then you can unbolt the diff and diff carrier assembly (also only two bolts holding the whole thing in after the front diff mount is undone)

Drop/pull down the passengers side of the diff carrier, then you can wiggle the front diff mounting bolts out of position. once they are free of the subframe, pull the whole diff and diff carrier out between the exhaust pipes.

Reinstallation is exactly opposite. Tighten all the 14mm nuts to 45ft/lbs and all the 17 mm and larger nuts to 75 ft/lbs.

Evil Aviator

How easy is that if you don't have a hydraulic lift and an impact wrench?