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post #1 of (permalink) Old 10-13-1999, 06:38 PM
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Warn overdrive questions.

Hello, I am new to the board. I receintly rebuilt a '42 GPW from the frame up. I installed a 225 V6, SM420, Dana 18 T/C, and 427's in a 44 rear/ 30 front axles. I also added Sagnaw power steering. I am curious about the warn/saturn overdrive that mates to the Dana 18. Someone has one in a local classified and I am planning on checking it out. Does anyone have experience in this unit? What should I look for and what is a resonable price?

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post #2 of (permalink) Old 10-13-1999, 06:46 PM
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Re: Warn overdrive questions.

I had one in my old 70 CJ5 with 225 V6, SM420, and 4.88:1 gears. There are a couple of different versions of the Dana18 transfer case.
There is a small hole and a big hloe version. I believe they also had different spline counts on the shafts. You have to match the overdrive
to the version of Dana18 you have. I had no problems with mine and it sure made the Jeep much more liveable on the highway. If you can
get one it's a great addition to your Jeep.

Gary

Gary
post #3 of (permalink) Old 10-13-1999, 11:31 PM
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Re: Warn overdrive questions.

There are three models of Warn/Saturn overdrive:

1. There is the version for the early 26-tooth Model 18 transfer cases. These were used in early post WWII jeeps, were all small hole
cases and had either 3/4" or 1 1/8" intermediate shafts.

2. There is the version for the later 29-tooth Model 18 transfer case when connected to a T-90, T-86 or T-98 transmission with a 6-spline output
output shaft. This could have been a big-hole or a small hole transfer case dependent upon which transmission was bolted up. They
all had 1 1/4" intermediate shafts.

3. There is the version for the later 29-tooth Model 18 transfer case when connected to a T-14 transmission with a 10-spline output shaft.
These were all big-hole cases with 1 1/4" intermediate shafts.

If you used the original Model 18 transfer case from the GPW in your buildup, it has a 27-tooth input gear and there is no overdrive
available for it. It also has a 3/4" intermediate shaft. I suspect your SM-420 has a 6-spline output shaft.

Reasonable price varies by location and condition, $400-$600 seems pretty typical. (they're ~$1200 new)

Jim Kyser
[email protected]
1946 Willys CJ-2A

Jim Kyser
[email protected]
1946 Willys CJ-2A
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post #4 of (permalink) Old 10-13-1999, 11:32 PM
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Re: Warn overdrive questions.

There are three models of Warn/Saturn overdrive:

1. There is the version for the early 26-tooth Model 18 transfer cases. These were used in early post WWII jeeps, were all small hole
cases and had either 3/4" or 1 1/8" intermediate shafts.

2. There is the version for the later 29-tooth Model 18 transfer case when connected to a T-90, T-86 or T-98 transmission with a 6-spline output
output shaft. This could have been a big-hole or a small hole transfer case dependent upon which transmission was bolted up. They
all had 1 1/4" intermediate shafts.

3. There is the version for the later 29-tooth Model 18 transfer case when connected to a T-14 transmission with a 10-spline output shaft.
These were all big-hole cases with 1 1/4" intermediate shafts.

If you used the original Model 18 transfer case from the GPW in your buildup, it has a 27-tooth input gear and there is no overdrive
available for it. It also has a 3/4" intermediate shaft. I suspect your SM-420 has a 6-spline output shaft.

Reasonable price varies by location and condition, $400-$600 seems pretty typical. (they're ~$1200 new)


Jim Kyser
[email protected]
1946 Willys CJ-2A
post #5 of (permalink) Old 10-14-1999, 09:11 AM
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Re: Warn overdrive questions.

Jim, thanks for the info, the T/C is out of a '53 jeep and originally mated to a T90. I have an Advanced Adapter to the SM420 but could not remember the tooth or spline count, I guess I should pull the PTO cover to be sure.

post #6 of (permalink) Old 10-14-1999, 10:04 PM
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Re: Warn overdrive questions.

Yeah, pulling the PTO cover and counting the teeth on the input gear is the easiest way to be sure. You can also confirm the
spline count on the SM-420 at the same time. That way you'll get the part you want and not be looking for someone to swap
with because you got the wrong one.



Jim Kyser
[email protected]
1946 Willys CJ-2A
post #7 of (permalink) Old 10-17-1999, 01:31 AM
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Re: Warn overdrive questions.

Be sure to check the condition of the planet set in the overdrive also,they burn up easily if the t-case was run with low oil levels. The parts are available from Advanced Adapters but they can be expensive. They also have a very good booklet on these units that I recommend you read before you buy one. there is only one way these units come apart but the booklet explains it well. I ran one in my '61 CJ-5 with a 283 and a T-98 with 4.27 gears and 31-10.50 tires, it really made a difference in highway rpm and it allowed gear splitting off-road. There is nothing like 16 forward speeds, 4 reverse speeds, and 3 neutrals! Good luck.

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