Topic: Transmission Opinions

[stan98tj]

This summer I plan on swapping out the 2.5l with a 1.9l VW TDI. I'll be headed out to sea soon and I wanna start getting stuff ready so I can get this going soon as I get home. I spoke with HPA Motorsports about the swap and got a ton of info from them, BUT I do have a few lingering questions. I currently run a 3spd auto and I'd like to keep the jeep as an auto (feels easier to wheel with an auto) but I want to make sure the 3spd auto can handle the new power boost. Basically this engine will be making 255 ft lbs torque at 2300 RPM, will this basically eat up my transmission and spit it out all over the road, or will my 3 spd handle it??

ALSO, gearing is an issue as well. I just regeared to 4.56 and at around 60mph i sit at about 2900 RPM, 65 has me around 3k or 3100. HPA's test vehicle is a YJ on 33s, 5spd with 4.10 gears and they are right around 2200RPM at about 65. The HPA tech advised me 2300-2900 is where I would want to be for optimal performance. Do you guys think my current 4.56 gears will work or will I perhaps need to go down to 4.10?

[sharpxmen]

your auto will be fine
as far as gearing since it's a diesel you want lower rpm, but the 1.9tdi works just fine between 3 and 4k so i don't see an issue with the numbers you posted.
a bigger challenge would be to get it to shift at the right rpm and where the t/c locks (if needed, it might just work right off the bat, i have no idea)

[aw12345]

Well you can always try bigger tires to get the rpm where you want it or find an overdrive automatic that will mate with the VW engine., AW4 with manual shift setup should work or if there is an adapter a 700r4

[stan98tj]

your auto will be fine
as far as gearing since it's a diesel you want lower rpm, but the 1.9tdi works just fine between 3 and 4k so i don't see an issue with the numbers you posted.
a bigger challenge would be to get it to shift at the right rpm and where the t/c locks (if needed, it might just work right off the bat, i have no idea)

the tech i was talking to from HPA felt that 3k would be a bit on the high side, said i should be 2300-2900 range for optimal power/mpg. that's what had me concerned.

[stan98tj]

Well you can always try bigger tires to get the rpm where you want it or find an overdrive automatic that will mate with the VW engine., AW4 with manual shift setup should work or if there is an adapter a 700r4

would the 2.4l auto work? I think that may be a 4 spd. the tech i spoke with told me i can easily tune the motor to get upwards of 300 ft lbs of torque, im just unsure if my 3spd will hold up. Did the 6cyl come with 4spd autos? I looked up the 700r4 and it seems to be a GM transmission, HPA only made adapters for Jeep's line of transmissions, so I don't think ill be able to run one.

[sharpxmen]

the tech i was talking to from HPA felt that 3k would be a bit on the high side, said i should be 2300-2900 range for optimal power/mpg. that's what had me concerned.

i drove 2 vehicles with this engine (an '05 VW Golf and a '06 Seat something, both were new with a few thousand miles on them at the time), it spins up to (and even over) over 4k no problem, wear and tear better at lower rpm but like Art said if you really feel like it's too high swap for bigger tires next time around. I think the rpm would be the last of your concerns (i'm sure you'll find takers to swap axles to 4.10 for your 4.56 most likely for free labour included).

[stan98tj]

i drove 2 vehicles with this engine (an '05 VW Golf and a '06 Seat something, both were new with a few thousand miles on them at the time), it spins up to (and even over) over 4k no problem, wear and tear better at lower rpm but like Art said if you really feel like it's too high swap for bigger tires next time around. I think the rpm would be the last of your concerns (i'm sure you'll find takers to swap axles to 4.10 for your 4.56 most likely for free labour included).

I have an 8.8, I don't see myself trading axles with anyone lol. I didnt want to go up to 35s yet (or ever?) as I don't really want to dump more $$ into the d30 to get it ready to run that size.
By the way, in your experience, have you found the 1.9 to be pretty robust and reliable?

[sharpxmen]

I have an 8.8, I don't see myself trading axles with anyone lol. I didnt want to go up to 35s yet (or ever?) as I don't really want to dump more $$ into the d30 to get it ready to run that size.
By the way, in your experience, have you found the 1.9 to be pretty robust and reliable?

they were both rentals, drove them about 6k miles each time, no issues - the gas mileage was absolutely awesome (mind the size of the vehicles), the Golf was slightly better as it was a little bit smaller but i did drive them both pedal to the floor across Germany  and it was still very good (the VW went close to 120mph, the Seat a little lower due to larger frontal area). as far as reliability can't tell long term but they are pretty solid and last long miles but then again take it with a grain of salt as the Jeep is twice as big most likely. The motor is a far reminder of a diesel, very quiet for what it is, nothing like a 4BT.

[stan98tj]

ok, given that you guys feel that the 3spd can handle the torque, if I do feel however that the RPM are too high and dont want to re-regear or go up to 35s, do you see any issue with swapping out the 3spd for a Jeep 4spd auto from a cherokee or 6cyl tj or even the one in the 2.4l? Just wanna cover all options with this.

[aw12345]

The issue with electronic transmissions is that either they have a tcm that is integrated into the engine computer, or a stand alone tcm that communicates on a data line with the engine ecm. You stick a none Chrysler engine in and the you start having language problems even if you get the tcm and the ecm of the Volkswagen engine to talk to one and other. Hence my remark that a AW4 with a manual shift setup could work or the choice of a 700r4 where all you have to do is make the torque converter clutch work. That explain your question?

[stan98tj]

The issue with electronic transmissions is that either they have a tcm that is integrated into the engine computer, or a stand alone tcm that communicates on a data line with the engine ecm. You stick a none Chrysler engine in and the you start having language problems even if you get the tcm and the ecm of the Volkswagen engine to talk to one and other. Hence my remark that a AW4 with a manual shift setup could work or the choice of a 700r4 where all you have to do is make the torque converter clutch work. That explain your question?

Ok, last question. Where does the AW4 come out of and does it already come with manual shift or do I need to mod it?

[neale_rs]

I'm no expert on TJ automatic transmissions but I think you need to be careful with the bellhousing bolt patterns.  Aren't the ones for the 2.5 different from the 4.0 and 2.4? 

[Jeffy]

I'm no expert on TJ automatic transmissions but I think you need to be careful with the bellhousing bolt patterns.  Aren't the ones for the 2.5 different from the 4.0 and 2.4? 

The 2.4L share the 4.0L bolt pattern which is similar to the GM 90* bolt pattern.  The 2.5L uses a pattern similar to the GM 60* bolt pattern.

Any automatic is going to need a manual shift valve body if you want to manually shift it.  Might as well go with a reverse pattern while you're at it as well.

[sharpxmen]

aren't any standalone transmission control 'puters out there? i'm not an auto transmission enthusiast so i have no idea how common they are or not

[Jeffy]

aren't any standalone transmission control 'puters out there? i'm not an auto transmission enthusiast so i have no idea how common they are or not

IIRC, there is one for the 700R4 or was it the 4L60e?  Honestly though I think Stan's overthinking it.