5-speed case differences

[Nate]

Do all 5-speed cases have the same internal dimensions? What are the differences in the pinion bearing housings? Is it possible to machine an old case to accept a new housing? Since '91+ had different forks, is it possible without too much fuss to put all of the innards of an '91 box in an '89 box or an '87 box if the pinion bearing housing could be dealt with?

[DeLorean]

I do not know the answer to your question, however rather than doing machine work, it's probably a heck of a lot easier to simply go down to your local U-pull it, and $75 later and about 2 hours worth of work, you have yourself a 89-93 C-900 5 speed trans. before you pull it, "go fishing" in the side cover with a magnetic pick up tool to make sure the thing is not blown. if it comes out clean, very good chance it will work fine as-is, especially if the car was wrecked or looks to have had a headgasket failure.

[Luke]

I think you could use the later bearing and carrier in an earlier box, but you would need to use the later ring and pinion shaft setup for sure. Also in mid 86 they added internal centering and changed the casting of the box to accomdate that as well. Like Jeff said best bet is just to start with decent core from a similar year. The 89+ boxes are really better in every aspect.

[Nate]

What is "internal centering." I have only rebuilt an '85 box.

[DeLorean]

it is basically a spring set on the internal shift shaft with a fixing point inside the trans that "centers" the shifter. If your trans does not have internal centering, you will need a shifter that has a centering mechanism internal to it. 1985 and earlier cars all have this. You can use a trans with internal centering on a car with external centering, but not the other way around, or you will have no centering. This means that if you were shifting from 2nd to 3rd gear for example, as you shifted out of 2nd you would have to center up the shifter yourself (or make a good guess at it) and pop it into 3rd... you can get pretty used to doing this yourself :lol: but anyone else who's not would have quite the time driving your car.

[Rob]

dunno if this helps but my dad rebuilt a 1980 900 5spd trans with 1987 gears. they fit in with no problem. 1987 is of coarse before they moved to the larger pinion bearing in 1989.

[Raul]

Do all 5-speed cases have the same internal dimensions?

Yes they do, exept the bigger hole for bigger bearing in '89+, in '91 they went with different cutouts inside the case for different fork system. Other than that they all have same dimensions.

What are the differences in the pinion bearing housings?

Bigger space for bigger bearing in '89 onwards.

Is it possible to machine an old case to accept a new housing?

Yes it is but I doubt you that you got precision CNC machine to do just that.

Since '91+ had different forks, is it possible without too much fuss to put all of the innards of an '91 box in an '89 box or an '87 box if the pinion bearing housing could be dealt with?

no, you can't put forks from +'91 onto -'90