Thinking about a drivetrain swap

Donor vehicle: 89 XJ Limited (4.0, Asin 4 speed auto, NP242, 3.55 axles)

Recipient vehicle: 88 XJ Chief (4.0, BA 10/5, NP-231, 3.07 axles w/ CAD)

I'm pulling the 4.0, Asin 4 speed auto and NP-242 T-case from the 8 9 and
dropping them into the 88. I'll also be pulling the cruise control system,
brake pedal, steering column and the engine / trans computers from the 89

The 88 has several rods knocking and I'm going to rebuild it and then later
swap the 88 engine for the 89 which has a couple weak lifters but runs well.
The 88 also has fewer rusted spots.

Has anyone ever seen, or better, driven a 4 speed automatic XJ with the 3.07
axles?

My concern is shift points and fuel economy. I do not do anything slightly
resembling serious offroading so I don't need steep axle ratios. Off roading
to me is a firetrail back to a fishing hole.

Thanks in advance.

--
Budd

Every vote counts ... unless it wasn't cast.

So, after a week, I'm thinking if I'd asked about lifting the XJ 20 feet,
adding fifteen more gears while installing 5 ton Army truck axles with 15
foot tall tires plus also swapping the 4.0 for a diesl locomotive engine I'd
got 10,000 replies.

Oh, I forgot the rattle-can over Herculiner paint job.

This newsgroup is as useless as the online XJ forums.

I'm outta here

--
Budd

Every vote counts ... unless it wasn't cast.

Budd Cochran wrote:

> Donor vehicle: 89 XJ Limited (4.0, Asin 4 speed auto, NP242, 3.55 axles)
>
> Recipient vehicle: 88 XJ Chief (4.0, BA 10/5, NP-231, 3.07 axles w/ CAD)
>
> I'm pulling the 4.0, Asin 4 speed auto and NP-242 T-case from the 8 9 and
> dropping them into the 88. I'll also be pulling the cruise control system,
> brake pedal, steering column and the engine / trans computers from the 89
>
> The 88 has several rods knocking and I'm going to rebuild it and then
> later swap the 88 engine for the 89 which has a couple weak lifters but
> runs well. The 88 also has fewer rusted spots.
>
> Has anyone ever seen, or better, driven a 4 speed automatic XJ with the
> 3.07 axles?
>
> My concern is shift points and fuel economy. I do not do anything slightly
> resembling serious offroading so I don't need steep axle ratios. Off
> roading to me is a firetrail back to a fishing hole.

Bud, my MJ came with the 3.07 axles and a BA10/5 pos. tranny. I swapped in
an AX15 tranny and I've put just over 100k on it. Lots of that was on the
highway between Colorado and South Texas one summer and I can only say that
above 4-5000' that 5th gear was useless unles I was downhill with a
tailwind. At the same time my son had a 90 XJ with the slush box and 3.55
which was pretty snappy and drove well on the road a 5-8000' where the MJ
was pretty anemic without down shifting so I would expect the auto with the
3.07 to be seeking a lot on the road. Off road, either should be OK as long
as you aren't into rock climbing. On the highway, you may get a different
result if you swap in the MOPAR 4.0 for the Renix version - there is a
significant difference in torque/power.

--
Will Honea

"Will Honea" > wrote in message
...
> Budd Cochran wrote:
>
>> Donor vehicle: 89 XJ Limited (4.0, Asin 4 speed auto, NP242, 3.55 axles)
>>
>> Recipient vehicle: 88 XJ Chief (4.0, BA 10/5, NP-231, 3.07 axles w/ CAD)
>>
>> I'm pulling the 4.0, Asin 4 speed auto and NP-242 T-case from the 8 9
>> and
>> dropping them into the 88. I'll also be pulling the cruise control
>> system,
>> brake pedal, steering column and the engine / trans computers from the 89
>>
>> The 88 has several rods knocking and I'm going to rebuild it and then
>> later swap the 88 engine for the 89 which has a couple weak lifters but
>> runs well. The 88 also has fewer rusted spots.
>>
>> Has anyone ever seen, or better, driven a 4 speed automatic XJ with the
>> 3.07 axles?
>>
>> My concern is shift points and fuel economy. I do not do anything
>> slightly
>> resembling serious offroading so I don't need steep axle ratios. Off
>> roading to me is a firetrail back to a fishing hole.
>
> Bud, my MJ came with the 3.07 axles and a BA10/5 pos. tranny. I swapped
> in
> an AX15 tranny and I've put just over 100k on it. Lots of that was on the
> highway between Colorado and South Texas one summer and I can only say
> that
> above 4-5000' that 5th gear was useless unles I was downhill with a
> tailwind. At the same time my son had a 90 XJ with the slush box and 3.55
> which was pretty snappy and drove well on the road a 5-8000' where the MJ
> was pretty anemic without down shifting so I would expect the auto with
> the
> 3.07 to be seeking a lot on the road. Off road, either should be OK as
> long
> as you aren't into rock climbing. On the highway, you may get a different
> result if you swap in the MOPAR 4.0 for the Renix version - there is a
> significant difference in torque/power.
>
> --
> Will Honea
>
I figured under 50-55 mph I'd just shift to 3rd and not D and then OD
wouldn't engage if it begain hunting too much.

Over 50-55 I'd shift to D.

The current speed it goes to OD, depending on driving style at the time, is
between 35 and 40.
Below that it engages the converter lock up but not OD.

My older brother has a Mopar 4.0 in his 99 XJ and I don't see that much
advantage to it.

I'd rather have the torque band of the old carbureted 258 (peak TQ @ 1800
rpm, iirc), but I'd need to also figure out how to either control the auto
with a standalone computer or swap in a TorqCommand 3 speed auto out of an
older Jeep / AMC 4x4 vehicle, say, an Eagle.

I think I could tweak it to about 25 + mpg compared to a highway best of 20
with the Renix F.I.

If I could do that, I'd be as "happy as a tornado in a trailer park."


--
Budd

Every vote counts ... unless it wasn't cast.

Budd Cochran wrote:

> I figured under 50-55 mph I'd just shift to 3rd and not D and then OD
> wouldn't engage if it begain hunting too much.
>
> Over 50-55 I'd shift to D.
>
> The current speed it goes to OD, depending on driving style at the time,
> is between 35 and 40.
> Below that it engages the converter lock up but not OD.
>
> My older brother has a Mopar 4.0 in his 99 XJ and I don't see that much
> advantage to it.
>
> I'd rather have the torque band of the old carbureted 258 (peak TQ @ 1800
> rpm, iirc), but I'd need to also figure out how to either control the auto
> with a standalone computer or swap in a TorqCommand 3 speed auto out of an
> older Jeep / AMC 4x4 vehicle, say, an Eagle.
>
> I think I could tweak it to about 25 + mpg compared to a highway best of
> 20 with the Renix F.I.
>
> If I could do that, I'd be as "happy as a tornado in a trailer park."

The pre-chrysler 4.0 peaks out way too high for me as well. It actually
does pretty well at sea level - 5th gear is usable once I get South of
Amarillo on the way to the Rio Grande Valley. One good point is that low
range is really pretty good on the fire trails and dirt roads as the top
reasonable speed is under 30 mph. I would like a lower creep at times, tho.

All that said, ANYTHING is better than that POS BA10/5 so go for it. Look
up the torque/hp curves for the MOPAR mpi, tho. There are significant
differences between the Renix and the MOPAR setups. A lot is due to the
better head and manifold design. I have been tempted to swap in the later
engine but this one just keeps going and going and ....

--
Will Honea

Every vote counts ... unless it wasn't cast.
"Will Honea" > wrote in message
...
> Budd Cochran wrote:
>
>> I figured under 50-55 mph I'd just shift to 3rd and not D and then OD
>> wouldn't engage if it begain hunting too much.
>>
>> Over 50-55 I'd shift to D.
>>
>> The current speed it goes to OD, depending on driving style at the time,
>> is between 35 and 40.
>> Below that it engages the converter lock up but not OD.
>>
>> My older brother has a Mopar 4.0 in his 99 XJ and I don't see that much
>> advantage to it.
>>
>> I'd rather have the torque band of the old carbureted 258 (peak TQ @ 1800
>> rpm, iirc), but I'd need to also figure out how to either control the
>> auto
>> with a standalone computer or swap in a TorqCommand 3 speed auto out of
>> an
>> older Jeep / AMC 4x4 vehicle, say, an Eagle.
>>
>> I think I could tweak it to about 25 + mpg compared to a highway best of
>> 20 with the Renix F.I.
>>
>> If I could do that, I'd be as "happy as a tornado in a trailer park."
>
> The pre-chrysler 4.0 peaks out way too high for me as well. It actually
> does pretty well at sea level - 5th gear is usable once I get South of
> Amarillo on the way to the Rio Grande Valley. One good point is that low
> range is really pretty good on the fire trails and dirt roads as the top
> reasonable speed is under 30 mph. I would like a lower creep at times,
> tho.
>
> All that said, ANYTHING is better than that POS BA10/5 so go for it. Look
> up the torque/hp curves for the MOPAR mpi, tho. There are significant
> differences between the Renix and the MOPAR setups. A lot is due to the
> better head and manifold design. I have been tempted to swap in the later
> engine but this one just keeps going and going and ....
>
> --
> Will Honea
>

LOL!!! the 88 has 385K on it and the 89 325K. Still, I had a 65 225 Slant
Six in a 64 Valiant with a carb and 425K miles ... there was a tough engine!

The 10/5 doesn't like cold weather (below 40F.) ... shifts stiffly and acts
like it's never had synchros and that's with the recommended multi-grade
lube. I even considered ATF for winter use . . .

Neither the Renix or Mopar 4.0's has the torque band I like: Build usable
torque just above idle quickly, peak at 1200-1800 and hold it to 5000 ...
that was the old 258 ... and the Slant Six.

I even considered a 4.2 crank in the 4.0 with a cam change to the carbed 258
cam as a possiblilty but I'd need to order 8 to 8.5:1 pistons so I wouldn't
need 91 octane fuel.

I've even considered a 225 /6 with a 904 if I could get it to fit the 242
T-case.

BTW, I'm at 5400 feet in Canon City CO almost due south of Colorado Springs.


--
Budd

Budd Cochran wrote:

> Neither the Renix or Mopar 4.0's has the torque band I like: Build usable
> torque just above idle quickly, peak at 1200-1800 and hold it to 5000 ...
> that was the old 258 ... and the Slant Six.
>
> I even considered a 4.2 crank in the 4.0 with a cam change to the carbed
> 258 cam as a possiblilty but I'd need to order 8 to 8.5:1 pistons so I
> wouldn't need 91 octane fuel.

We have similar tastes, it seems. I think a good diesel would suit me just
fine - one like the tractor I use over at the church.

I'm in your neighborhood fairly often - if I can get the time between
doctor's appointments anymore. Between the wife and myself, we seem to
spend an inordinate amount of that free time in retirement sitting in
waiting rooms. There are definite drawbacks to growing older....

--
Will Honea

Every vote counts ... unless it wasn't cast.
"Will Honea" > wrote in message
...
> Budd Cochran wrote:
>
>> Neither the Renix or Mopar 4.0's has the torque band I like: Build usable
>> torque just above idle quickly, peak at 1200-1800 and hold it to 5000 ...
>> that was the old 258 ... and the Slant Six.
>>
>> I even considered a 4.2 crank in the 4.0 with a cam change to the carbed
>> 258 cam as a possiblilty but I'd need to order 8 to 8.5:1 pistons so I
>> wouldn't need 91 octane fuel.
>
> We have similar tastes, it seems. I think a good diesel would suit me
> just
> fine - one like the tractor I use over at the church.
>
> I'm in your neighborhood fairly often - if I can get the time between
> doctor's appointments anymore. Between the wife and myself, we seem to
> spend an inordinate amount of that free time in retirement sitting in
> waiting rooms. There are definite drawbacks to growing older....
>
> --
> Will Honea
>

Will, are we twins that were separated at birth (02/20/47)?

I've looked into a diesel conversion also with either the Jeep offered XJ
diesel (Perkins, I think) or a something like a small Cummins 4 cylinder or
even a Kubota engine.

I don't need triple digit top speeds and I only drag around a 1000 lb
capacity trailer I use for reyclables or a fishing boat.

I hear ya on the doctor visits ... I have T-2 diabetes and a heart condition
and the better half has sleep apnea and chronic asthma. I had more miles
going to doctors on my Jeep than I did going fishing.

If yer in the neighborhood, drop by and I'll put a fresh pot of coffee on.


--
Budd

Budd Cochran wrote:

> Will, are we twins that were separated at birth (02/20/47)?
>
> I've looked into a diesel conversion also with either the Jeep offered XJ
> diesel (Perkins, I think) or a something like a small Cummins 4 cylinder
> or even a Kubota engine.

Forget the Jeep part - real POS. I tried it in an XJ and was less than
impressed.

> I don't need triple digit top speeds and I only drag around a 1000 lb
> capacity trailer I use for reyclables or a fishing boat.
>

If you have the 3.53 diffs, it's hard to beat the 4.0. The 3.07 I have is
too tall and the D30 is actually too wimpy for the rest of the drive train
in the MJ. I'd love to swap in a pair axles from either an XJ or the export
version of the MJ to get the 3.53 ratio and a D44 in the rear end. Hauling
a full load in the pickup is dicey as it is now.

> I hear ya on the doctor visits ... I have T-2 diabetes and a heart
> condition and the better half has sleep apnea and chronic asthma. I had
> more miles going to doctors on my Jeep than I did going fishing.
>

More things we have in common. VA says the diabetic condition is due to
agent orange exposure in 'Nam where I flew a lot of fire suppression
missions for the Ranch Hand outfit while they were spraying the crap.

> If yer in the neighborhood, drop by and I'll put a fresh pot of coffee on.
>

I'll do that. Drop me a phone number via email.

--
Will Honea

"Will Honea" > wrote in message
...
> Budd Cochran wrote:
>
>> Will, are we twins that were separated at birth (02/20/47)?
>>
>> I've looked into a diesel conversion also with either the Jeep offered XJ
>> diesel (Perkins, I think) or a something like a small Cummins 4 cylinder
>> or even a Kubota engine.
>
> Forget the Jeep part - real POS. I tried it in an XJ and was less than
> impressed.

The two heaviest things I haul are the little trailer and a receiver mount
carrier for the better half's mobility scooter so I don't need a lot of
power or torque.
>
>> I don't need triple digit top speeds and I only drag around a 1000 lb
>> capacity trailer I use for reyclables or a fishing boat.
>>
>
> If you have the 3.53 diffs, it's hard to beat the 4.0. The 3.07 I have is
> too tall and the D30 is actually too wimpy for the rest of the drive train
> in the MJ. I'd love to swap in a pair axles from either an XJ or the
> export
> version of the MJ to get the 3.53 ratio and a D44 in the rear end.
> Hauling
> a full load in the pickup is dicey as it is now.

D-35 high pinion front, D-30 open rear on both XJ's. True, both are light
duty units compared to the bigger Danas or even the 9.25 Mopar, but they're
all I need.
>
>> I hear ya on the doctor visits ... I have T-2 diabetes and a heart
>> condition and the better half has sleep apnea and chronic asthma. I had
>> more miles going to doctors on my Jeep than I did going fishing.
>>
>
> More things we have in common. VA says the diabetic condition is due to
> agent orange exposure in 'Nam where I flew a lot of fire suppression
> missions for the Ranch Hand outfit while they were spraying the crap.

Sorry to hear about your exposure Agent Orange. I was Nat. Guard Combat
Engineer during 'Nam but never saw action. I do want to thank you for your
service for our country and it's citizens.
>
>> If yer in the neighborhood, drop by and I'll put a fresh pot of coffee
>> on.
>>
>
> I'll do that. Drop me a phone number via email.
>
> --
> Will Honea
>

Ya got it coming to ya, Will!