Transmission Swap - '02 2.7 Tip into a '97 2.5 Tip

[TNT79Bronco]

'97 Transmission failed. Have a line on a pretty good priced '02 Tip.
What do I need to do to put the '02 Tip into the '97?

Any advice on doing it? What is a 75k mile '02 Tip worth?

[TNT79Bronco]

Anybody? Bump? Gotta have some transmission experts out there somewhere...

[TNT79Bronco]

Hello????? Hello?????? Anybody out there??????? Nobody has any knowledge of transmission swap information?

[Gilles]

Originally Posted by TNT79Bronco

Hello????? Hello?????? Anybody out there??????? Nobody has any knowledge of transmission swap information?

TNT,

Yesterday I was browsing through the DIY section and on the oldest posts it was an interesting discussion about transmission swappings.

The post I saw was for mechanical gearboxes, but I remember that there was some talking about automatic boxes as well.

Good luck!

[Gilles]

Originally Posted by TNT79Bronco

Hello????? Hello?????? Anybody out there??????? Nobody has any knowledge of transmission swap information?

TNT,

Yesterday I was browsing through the DIY section and on the oldest posts it was an interesting discussion about transmission swappings.

The post I saw was for mechanical gearboxes, but I remember that there was some talking about automatic transmissions as well.

Good luck!

[78F350]

I am certainly not an expert, but:
https://infopart.org/zf-1060030050-part Says yes.
I have read that the early 1997 transmission control modules may not be fully compatible in the later cars, so I'd recommend picking up the TCM as well if it is available with the transmission.
This is fun to browse through if you like parts catalogs:
https://www.zf.com/global/media/zf_media/document/int_print_catalogs_documents/usa_4/5hp19flporsche.pdf

I have a ZF5HP19FL in a VW Passat Parts car that I will probably put in a Boxster eventually just to satisfy my curiosity. It looks like I'll just have to swap a few peripheral items over.

[lkchris]

I suspect with the newer trans you'll get a rear axle ratio more compatible with a larger, more powerful engine. That is, it may turn the older car into a dog.

[Smallblock454]

Think that won't work without reprogramming the TCU, because gear ratio and thereby torque values ware completely different. And because the programming is not nit documented in any way nor there is a official software to develop it, i would say the electronic part will be a very very difficult project. Better go for a manual, or a AT transmission from you MY.

Regards
Markus

[itsnotanova]

I know of two people who have successfully swapped a 2.5 tip into a 2.7 box, but not the other way around. They noticed no difference and I want to say it was all plug and play.

[78F350]

I'm not a mechanic and my limited knowledge of this stuff comes from reading through tech manuals that I really may not understand.

The basic gear ratio of all ZF5HP19FL (986 Tiptronic) transmissions is the same. From ZF:

The difference is in the final drive which comes from the bevel gear set that is installed. Here's a view the ZF parts manual pgs 4 & 20 and a posting of info that came "directly from ZF". I highlighted a bit to help clarify what is related to what:


Still may be a bit confusing if you don't drink as much coffee as I do, but the point is that on the 2.5L 1997 transmission has a final drive ratio of 4.2 whereas the 2.7L 986s have a 4.16 ratio. Different, but significant? I don't know. What is more disturbing to me is that I see the version of the transmission in my Passat has a 3.3 ratio.
...and finally to invalidate my other data is the info from the '03 Boxster Owner's Manual which show different ratios for the final drive. It also has the base listed as an S though so maybe the writer had a bit too much Hefeweizen on his lunch break.

I'm guessing they are both right and I am misreading how the numbers are represented. Ok... that's my post for the day, time for a nap.

[Smallblock454]

Hi,

i dont't think the gear ratio is the main problem. 4.2 vs. 4.16 is not that significant. The main problem is the TCU software, because the shift process is managed by the electronic.

2.5 engine: 204 HP at 6.000 rpm / 245 Nm at 4.500 rpm
2.7 engine: 220 HP at 6.400 rpm / 260 Nm at 4.750 rpm
2.7 engine: 228 HP at 6.300 rpm / 260 Nm at 4.700 rpm

The question is if the 2.5 TCU is accepting the 2.7 AT gearbox. If yes, there won't be a bigger problem by gear ratio. But if not, than the 2.7 TCU won't fit to the 2.5 ECU, because rpms will be too high.

So for me this is not a mechanical topic, it's an electronic one.

Regards, Markus

[78F350]

In the case that the original 1997 transmission control unit doesn't work, the module from the 2002 will work. Simply remove and unplug the old unit, install the new '02 unit in it's place. The 986 USA Katalog shows that the modules previous to 2000 are not forward compatible, but the 2002 can be used in all earlier models.
From Illustration 901-03 from the "Main Group 9: Electrical Equipment" section:

I expect that the 1997 TCU will be functional, but not optimal.

Disclaimer: Markus usually knows what he is talking about, and I'm just reading from the manual.