Transmission swap

[Herbmiester 936]

I am looking to swap the GM 6L45 in my 130i for a ZF6HP. Some of you may wonder whey swap an auto for an auto, but bear with me I do have what I think are solid reasons. Firstly and probably the big one for me, is the GM6L45 is an average box. It's not that smooth, especially when being pushed. It clunks up and down and does have a habit of chopping down when its not needed or holding on when it should drop down. I find it a bit of a guessing game. It does work ok when you use the paddle shifters. My 6l45 has had a service ad works as it should.

In comparison the ZF box's I have had are noticeably smoother. The y have a much more refined converter lock/unlock and shifts are smoother. It also seems to be a lot smarter about when it shifts up and down. Finally it can be made very sharp with an XHP flash tune. Having had 6HP boxes in a few cars now and have always been impressed. 

The question of why not manual convert is a simple one, at best its a 5k job and could easily be 7k plus. One the other hand the ZF swap is a 1 to 1.5k job. Also my wife drives the car in Wellington traffic and is not interested in having a manual. I can get my manual fix driving the E34. 

Getting the right ZF box is the key and there are a few small parts needed. I am pretty sure I can do it myself (using a lift), and again if the right box is used, no reprogmaing of the TCU or DME is required. I am still gathering information but  this article from XHP covers it. I am in the market for a ZF 6HP19/21.

https://www.xautomotive.com/blogs/news/from-gm-to-zf-6hp

 

[Eagle 1680]

Biggest issue for me would be the used auto box gamble. You'd probably do a service, mechatronic seals etc and probably a few drain and fills so that's another $700-800 on top. Then you kinda have to hope the rest is ok because they do have quite a few potential faults that can occur.

Getting one from a damaged working car or something the you can at least test drive, check adaption values and fluid condition would be good, or even having it inspected\rebuilt.

[Herbmiester 936]

Yes getting the right box is the key. My research, including a good chat with the local transmission guy, painted a decent picture on ZF6 reliability. He really doesn't like the 6L45. 

[Kiwi_BMW 89]

Why don't you fit a 8hp45, it would bolt up to the N52 and Cantcu controller.

While the 6hp works quite well it isn't as smooth as the 8hp

[Herbmiester 936]

An 8HP is an awesome trans and I have driven, and owned a few cars that have it. However, it's quite a bit more expensive to buy, and there is no simple "how to" guide to fit it. I dont know if I will need new driveshaft, what trans mounts will work and the fact the Cantcu controller is $2k. The 6HP is a simple bolt-up and the DME talks to the TCU with no programming needed.

[Olaf 3345]

yep, the ZF6HP is an excellent box, and given it appears to be a relatively simple swap, indeed why wouldn't ya?   The ZF8HP is astonishing at its smoothness and intelligence; I can't vouch for more or lesser longevity or reliability of 6HP vs 8HP.   I agree with what you're saying John, there's a big difference between swapping in a trans that the car is engineered for, and customising an entirely different trans swap.

I'm in the same camp - I certainly love the manual driving experience, a conversion would not get a look in with anything my wife drove even infrequently.  I drove manual in Mexico City for ~2.5 years, if I was doing that again it'd be auto all the way.  Modern autos are bloody brilliant.
 

 

[Vass 871]

2 hours ago, Olaf said:

I drove manual in Mexico City for ~2.5 years, if I was doing that again it'd be auto all the way.

 

[Olaf 3345]

it's okay mate, heel-and-toe double de-clutch downshifts with blips when I'm pedalling a manual 😁