Which tranny?

[stevenmd]

No, I'm not talking about a comparison between Griff and Sasquatch.

The automatic transmission out of a RRC, DI, or DII:
Which one is "tougher" and why?
Which one is more reliable and why?
Which one has the best gear ratio to mate up to a diesel engine and why?

Thanks!

[Disco Mike]

Steven, since you have no tranny ECU, that rules out the D2. I am not sure if Rover had a special build for the D1 and the RR, when installed with a diesel like they did with the D2's in the UK.
I wouldn't worry much about gearing that can be changed alot thru tire size, which t/case you use or diffs.
I am going to say the D1 will be your best bet.
Hope all is well, have a good Xmas.

[Disco2Guy]

Can't comment about the D1 or RRC, but the '03 and '04 D2 trannies are stronger since they are mated with the 4.6 engine, instead of the 4.0 for the earlier D2's.

edit: Ok, nevermind. DiscoMike know's what's up.

[stevenmd]

Steven, since you have no tranny ECU, that rules out the D2. I am not sure if Rover had a special build for the D1 and the RR, when installed with a diesel like they did with the D2's in the UK.
I wouldn't worry much about gearing that can be changed alot thru tire size, which t/case you use or diffs.
I am going to say the D1 will be your best bet.
Hope all is well, have a good Xmas.

Gonna mate up to an LT230 and have the SIII axles (Salisbury).

[Roveron]

Yes, there was a different tranny in the rest of the world for the diesels in Disco 1's. I know those 2 guys here that have diesels in RRC's with manual trans, so comparing to an auto, its a little different. Obviously, the rpm range is the biggest factor as most diesels don't really get over 2000 rpm's. Putting a manual behind it in my opinion would be the best and easiest, because then you can feel when to shift. The NAS auto trans shifts a little high to be mated to a diesel and make reasonable power.

As far as changing tires through the diff, sure, but remember, the diesel torque is different, the whole reason to change gears in a gasser is to bring the rpm's so the engine can ACTUALLY work, instead of bogging down. I doubt a diesel will bog down, unless you are running like 2.5 gears or something crazy. And again, gear changes bring the rpm's up, not good for a diesel.

I know of one guy here on the right coast that imports diesel auto trannys. Just to give you an idea, a 200TDI with 80k and the auto diesel to go with it is about $4700.

I have researched this a lot as we are probably going to do this with the upcoming tax money in Feb. I think. Over a course of a year, you would buy the engine back in fuel savings. But I am leaning towards a manual instead.

Let me know if you have any more questions.

Here is Duncan's website. I have talked to him a bunch of times and he has been very helpful. I also know of a certain individual on this board that has 2 200tdi's on the way and is selling them. (ahem) cough cough.
http://landroverimport.com/index.html

[Roveron]

Can't comment about the D1 or RRC, but the '03 and '04 D2 trannies are stronger since they are mated with the 4.6 engine, instead of the 4.0 for the earlier D2's.

edit: Ok, nevermind. DiscoMike know's what's up.

Interestingly enough, the same auto trans 4HP22 is used in the 4.0 and Td5. The 4.6 has the "tougher" 4HP24.

[stevenmd]

Rick - I want to do an auto tranny, not a manual. So you're saying the regular auto tranny wouldn't shift correctly for the rpm's of a diesel? So I would need to source an auto tranny set up specifically for a diesel engine?

[stevenmd]

Interestingly enough, the same auto trans 4HP22 is used in the 4.0 and Td5. The 4.6 has the "tougher" 4HP24.

According to Duncan's website, the ZF 4HP22 tranny wouldn't shift correctly with the diesel engine - revving the engine too high before shifting I believe?

[Roveron]

I don't know the trans that they use in the uk. When I talked to Duncan, he recommended getting a diesel box to be able to use the full range of the engine. Picture a horsepower curve if you will. The diesel compared to a gasser is WAY lower in the rpm range, so your shift points aren't effectively using the right power curve.

The regular NAS auto box will work, but to maximize the diesel engine and be efficient, I would try and source a diesel auto box. Most of the conversions I have seen do not include the ZF auto box, so there really isn't much info out there as far as longevity of the engine and trans when mated.

From my understanding of the manual, the diesel version of the auto box, specifically the Td5 with the 4HP22 that you are referring to, uses a different torque converter. So in theory, you could use your box, swap out whatever housing and converter is related to the diesel in the uk, and go that route. What Duncan is saying, here in the states, our boxes don't have that option, as diesels weren't available here.

I don't know what Keith used in his diesel conversion. He is the only one I know that might have an auto box. Not sure.

I know a performance tranny shop will be able to take your torque converter and lower the engagement rpm. We used to do it all the time, (except raise it) for race engines. Its pretty simple. And at the same time, have them weld the fins so they don't break. You could also change the clutch packs inside and vary the engagements that way, but we are WAY off at that point. Probably easier to mod your torque converter and a calculated gear selection to make it all work.

[stevenmd]

I don't know the trans that they use in the uk. When I talked to Duncan, he recommended getting a diesel box to be able to use the full range of the engine. Picture a horsepower curve if you will. The diesel compared to a gasser is WAY lower in the rpm range, so your shift points aren't effectively using the right power curve.

The regular NAS auto box will work, but to maximize the diesel engine and be efficient, I would try and source a diesel auto box. Most of the conversions I have seen do not include the ZF auto box, so there really isn't much info out there as far as longevity of the engine and trans when mated.

From my understanding of the manual, the diesel version of the auto box, specifically the Td5 with the 4HP22 that you are referring to, uses a different torque converter. So in theory, you could use your box, swap out whatever housing and converter is related to the diesel in the uk, and go that route. What Duncan is saying, here in the states, our boxes don't have that option, as diesels weren't available here.

I don't know what Keith used in his diesel conversion. He is the only one I know that might have an auto box. Not sure.

I know a performance tranny shop will be able to take your torque converter and lower the engagement rpm. We used to do it all the time, (except raise it) for race engines. Its pretty simple. And at the same time, have them weld the fins so they don't break. You could also change the clutch packs inside and vary the engagements that way, but we are WAY off at that point. Probably easier to mod your torque converter and a calculated gear selection to make it all work.

Um, yeah, this is getting all too technical for me, Mr. Hawking...

I am thinking of a diesel powerplant for my 109 so I will have to purchase whatever tranny I need anyway. Perhaps it would be easier for me to source the right auto tranny than to try and convert an existing (although readily available) NAS auto tranny.