WARN Overdrive - M38A1

Bob_C · Post by **Bob_C** » Sat Apr 30, 2005 9:00 pm

Now before you all raise $&%, I know the M38A1 never had an overdrive unless a civy put it on. But, mine has one -- and I have no intension of taking it off. It's in great shape and it'll save me a few pennies at the gas pump.

I took mine off this afternoon to finish cleaning the transmission /xfer case. I'm just about ready to paint it all -- but I would like to have a manual for the WARN overdrive, so I can find out the torque specs and everything. If anyone has an idea where I can find one of these, or at least the torch specs for the bolts, please let me know.

Thanks!

BobW · Post by **BobW** » Mon May 02, 2005 4:33 am

The Warn installation manual can be found here..
http://www.public.asu.edu/~grover/willys/warn.html

Bob_C · Post by **Bob_C** » Wed May 04, 2005 8:42 pm

Thanks Bob!

petesilfven · Post by **petesilfven** » Fri May 06, 2005 8:07 am

Go to Advance Adapters www.advanceadapters.com and get their installation manual. They are currently making the Warn overdrive, and their manual is the best. It has exploded parts illustrations.

jonesal · Post by **jonesal** » Wed Aug 18, 2010 8:47 am

I'm just about to buy a Warn overdrive for my M38A1. Is it possible for you to post pics of your install? I'm nervous about parking brake clearance and shift linkage clearance. Seeing pics would help greatly. I realize I have to hack one hole for the shifter to come up into the cab.

Thank you.

Allen
'55 M38A1

Post by **wesk** » Wed Aug 18, 2010 10:59 am

Allen,
A very simple work around for the A1's vertical rod brake linkage is to switch to a guide tube and pull cable (5/32" stranded steel cable) to route the linkage away from the OD.

The Advance adapter OD is a Saturn which is the warn OD with a few improvements but it is completely interchangeable with the Warn. The rights to the Warn OD production were obtained in 91 by Advance Adapters and is their current Saturn line.

http://advanceadapters.com/category/32/ ... fters.html

Their freebie conversion manual PDF download is:
https://secure.advanceadapters.com/imag ... manual.pdf

26 & 29 tooth Saturn Manual:
http://www.atlas-tc.com/pdf/Misc/saturn.pdf

chuck · Post by **chuck** » Wed Aug 18, 2010 2:06 pm

There is tons of info on these units.Check out The Book Of Moses Ludell, Hermtheoverdriveguy.com and the CJ3B page. I put one in my M38 with all the levers and you should see the look on peoples faces at car shows trying to figure what they all go to
Chuck

Cacti_Ken · Post by **Cacti_Ken** » Wed Aug 18, 2010 9:15 pm

My OD experience.
I like my OD also. You may recall back in the spring time I installed it. I was asking questions I believe on this forum about it. There seem to be a shifting problem. I wasn't experienced enough with an OD to know any better. When I shifted practically everytime into OD it would grind slightly upon engaging. I drove it like that off and on short trips for about 250 miles until one day it would not stay engaged.

I removed it and from the transfer case. unbolted the rear end housing of it and saw brass chips. I closed it back up and call Herm with an explanation of what have seen in it. He tells be to send it back for inspection.

I boxed it up and sent it back. I wait a couple of weeks and call Herm back for a diagnoses. He already has it boxed up to send back to me.
He said it was the first time he had seen this sort of component ware out.
I believe it was called a brass syncronizer.

Anyway he ships it back at no charge and no charge for repairing it. I thought that was very nice of him.

I receive and install it again. Still wondering what made it go out before, cause I didn't want to go thru it all over again without knowing the cause.

It seemed to go into gear when I shifted it without the engine running.

I jacked the wheels off the floor and started the engine. Shift transmission into gear, then shift the OD into gear. And It did the same thing as it had done before. slightly grind.

So I shut it down to study and trouble shoot. After a few hours, I saw that the shift linkage bar was hitting the Transmission housing. It was preventing the shift plunger from engaging the OD fully. It felt like it was engaging fully but evidently it wasn't. It only liked about maybe a 1/8" to 3/16" more travel if that much.

Only way to remedy the problem was take the linkage bar and reshape the off set in it. So I took the torch and got the bar cheery hot to flatten it out and then bent it again to a new offset measurement.
I reinstall it. It cleared the transfercase ok now. It's really a close fit. to get it to not contact any surrounding metal.

I did the engine run and shift the OD to engage. walla, smooth as butter now and no noise.
The one time rebending worked out.

I have a couple hundred miles on it now and it shifts smooth everytime.

I sent Herm an email about my findings. He appreciated the note and said he would inspect the other ones he had.

I really like it's performance. Of coarse you lose a lot of power with the L134 but I believe it will be less wear on the engine running lower RPMs. And you still obtain some more speed. Just takes a little longer to get the speed.

Maybe this writeup will help someone else if they encounter the same thing.

Post by **wesk** » Wed Aug 18, 2010 9:36 pm

Ken,

Did you get some before and after photos and measurements of the shifter? I'd like to put together a little piece for the web sites download section.

Cacti_Ken · Post by **Cacti_Ken** » Thu Aug 19, 2010 8:39 am

As usual, no I didn't take before photos. I only have one which I believe is after I got it to fit. And it is in place. I'll send it to you.

jonesal · Post by **jonesal** » Thu Aug 19, 2010 11:30 am

Ken,

That's exactly the expereince I was wanting to hear. Thanks. Any comments on how you cleared the parking brake rod? I think Wes has a good work around, but I was hoping to keep some sort of rod in place. I've thought about a different rod setup I could use, but am curious about actual installs.

I also have collected most of the bits to install a pto winch, but I think the overdrive is higher priority for this year. Winch is next years project - and then the fun begins trying to make that work with the overdrive. I think the exhaust will need to be redone...

Thanks,
Allen
'55 M38A1

Cacti_Ken · Post by **Cacti_Ken** » Fri Aug 20, 2010 6:12 pm

Jonesal, I guess I should clerify that my vehicle is a M38. There was no issue with the parking brake.

I am not familiar with the transmission and transfercase in the M38A1.
I am curious as to how an overdrive and PTO both can be incorporated on it.

I drove the M38 to my American Legion post yesterday. The highway is 4 lane all the way to the city. The weather was dry. I could have got off about three fourths of the way there and took some back roads the rest of the way, but I was feeling relative comfortable in the moderate heavy traffic and stayed on the main hiway till the exit in town. I was doing at least 50 most of the time. A city cop passed without a glance at me.

While I was there it rained heavily. By the time that I got ready to head back it had slowed conciderable to a sprinkle so I took the back roads as far as I could home. Then got off the 4 lane onto the servce roads as much as I could too. Had to still use the wipers though. All in all it was close to a 50 mile trip.

I have gamma goat lenses on the rear and have installed the electonic turn signal as used in the more later vehicles. When I see 18 wheelers aproaching from the rear I put the turn signal in emergency hazard mode.

Post by **wesk** » Fri Aug 20, 2010 11:57 pm

There's a piggy back setup for the PTO.

You should drive my old Fiat spider with a semi on your tail! I had a woman in a Suburban run me right up on the sidewalk in Milwaukee one day.