Replaced transmission, having small issues

[rochab77]

Okay I have a 95 525i, and I replaced my transmission with one from a 93 325i vanos. With my stock computer it doesn't shift properly from 2nd to 3rd. It acts like it comes out of gear then pops into 3rd and so on. When I put the transmission computer from the e36 325 donor car it shifts fine except the traction control light stays on and if I select third or second it goes to the lowest gear possible, even in manual mode. When I floor it it upshifts at about 5700 rpm even with the detent depressed. I know this is how it shifts unless you select 3rd which would normaly put it into sport mode and let it shift at about 6,500. Could my shifter be incompatible with the e36 transmission or e36 computer? I am thinking about going to get my original transmission rebuilt or convert to a manual in the near future. Also the car won't kick down unless I depress the gas pedal to the floor and push the detent. With my stock computer the downshifts are more immediate and the transmission responds quicker without having to depress the detent. Both are the GM transmissions. Did I get the wrong transmission? I had to swap out the tailshaft also to make it work, but other than that they both look the same. I want to be able to use sport and manual mode without it going down to first every time I select 3 or 2, and without losing my traction control. Do I need to go back with my original tcu or stick with the e36 tcu since it shifts without slipping?I'm a bit confused here and don't want to have to go back and chang ethe trans again it I don't have to. Thanks all.

Brian

[m735is]

I'll start by saying that I no experience with either of the models you're talking about.

When I put a 92 tranny into my 88 (both 735's), I had to swap tranny computers to match the tranny. BUT, I had to make sure the tranny computer also matched the options on my chassis. And I needed the tranny switch to match.

So my advise is to look up on realoem and compare tranny computers for each model and see what it says for options. Then, if there is a difference, get the computer that matches the tranny and your options on the car. Check out valve body numbers too.

There could be some internal differences of the trannies which you would have to ask an expert, like the manufacturer, or a specialist (Kirt Koeller for ZF trannies-possibly others). With his help I found out about a small but important change that made me find the correct computer for my application.

[rochab77]

I thought of the valve body being different too. I will have to compare tranny part numbers and if they are different, find out what those differences are and correct them. Thanks for the reply