How does the Warn Overdrive work?

Ok yes I'm a mechanic so I know the basics of what an overdrive is used for etc. But how does the Warn overdrive work? I've never seen anything like it,,,,,do you shift on the fly from direct drive to overdrive??? Then shift back out of it to direct drive when you slow down??? While I was underneath my Jeep I realized I have the Warn Overdrive but it's missing the linkage, so I'm getting that from Herm. I read some earlier posts about the overdrive but nothing seemed to give me a clear understanding on how it works. Your thoughts would be greatly appreciated, Thanks again guys,
Mike (littlepurplecj)

 

use the clutch to shift in and out of OD. like another gear.
make sense? i.e. if you are in 2nd gear and want to go to 2nd +od depress the clutch shift to leave trans 2nd alone and shift only the OD lever. once you're in OD shift normally. or you can depress the clutch shift to 3rd and also shift out of OD while the clutch pedal is still depressed to be in regular 3rd.

i.e . just treat it as if it were another gear but one that adds on after the transmission gear. a two speed shift?

does that help or even answer it.

 

i will sometimes split shift depending on load and speed. 1st to od to no od (direct) and 2nd to od to no od and 3rd and so on like a 1/2 gear ( well 3/4 actually).

you must depress the clutch each time from no od to od and back out again.

 

So you can use the overdrive in any gear? so its kind of like running a six speed transmission instead of just three? So if I'm pulling a load probably not a good idea to use the OD, but if I'm just cruising down the road it'd be worthwhile to use? Sounds kind of like a pain in the butt, is it worth it?

 

as I have learned it. The warn OD is a planetary gear setup. beyond that I don't know, never took one apart.

 

depending on what gearing you have, you can just leave it in od around town or not use it until you get on the highway. it's all about options

i have semi-low gearing so i just leave it od around town and it's like i have my old t14 and 3.73s.

definately worth hooking it up.

chris

 

nope
I'd take it off if I were you
send it to me







yes, it is worth every penny
once you get to using one, you'll never go without one !

 

Man I don't think you need that OD with 38.5" mudders! You need an underdrive! What kind of gears are you running?

BUBBA

 

i like it a lot. i usually end up in 2nd and od around the neighborhood with my 31" tires and 4.88 diffs.

on the highway i figure 3rd direct at 3000 rpm is about 56mph and 70mph with od (give or take)

crawl speed in low range 1st direct at idle of 750 is about 1.9mph and in od about 2.4mph

it's also nice when using low range4wd off road and wanting to speed up for a while without shifting into high range4wd esp. when you know your gonna have to shift back to lowrange off and on.

 

Ok this is sorta on this topic. I've not seen it but read about having the warn on it if you put in an automatic? I've had several overdrives and know you use the clutch when you move it in and out. Could you split the gears with it with an auto or would it just more or less be another hi/lo range added?

 

Per the AA saturn manual, "On automatic applications, the transmission should be shifted into neutral". Thats all they say. I'm assuming gears can be split, but you go into neutral, then back into whatever gear. I have the entire manual in electronic form. I can email it to anyone interested. It's a good reference to have. I used it when rebuilding my Warn OD. A few parts are different between the warn and saturn, but it is very similar.

 

Yes, you can use it in any gear, even reverse! I usually just use it as my top gear on the street. That is the easiest way to use it. I do split gears with it off road though. Doesn't matter what it is you're trying to, you can find the perfect gear for it. For me anyway, I can't imagine not having it. If you decide you don't like it, you'll easily be able to find a buyer.

 

Right now I just have the stock 3:73's w/ powerlocker front and rear but I have an open carrier and 5.38's for the front,,,,just looking for 5.38's for the rear. I might downsize from the 38's to 35's. But I like the way the 38's look on it,,,,IMO.

 

Hey guys,

I was talking to an engineer I work with today and he told me that you can't use the overdrive while the Jeep is in 4x4 or it'll detonate it??? Is this true??? Bought the overdrive linkage from herm today. Can't wait to get it in and see how this new toy works,

 

Mr Engineer is WRONG
the Warn overdrive can be used in all gears, all transfer case positions
use it with no fear in 4wd
some folks have opinions about use in low range
be smart when using it, that's all

 

It is a planetary system.

It has been a long time since I had one of these apart.

there are three small internal gears (planets, so to speak) that revolve around the output shaft of the transmission. These, in turn spin a 'barrel' gear that has a splined inside. Outside of the 'barrel' gear there is a 26 or 29 tooth gear that turns the input of the trans case.

When in overdrive, these 'planets' effectively change the gear ratio to the transfer case because they rotate on their own axis and spin around the input shaft at the same time. Sorta like the Earth's spin on its own axis and rotation around the sun at the same time. Hence, planets.

When shifting out of overdrive the lever locks the rotation of the 'planets' causing a 1 for 1 rotation of the transmission output shaft and the barrel gear.

It is actually pretty clever -- although Warn did not invent the planetary system. I believe model A's or T's used the same thing, mot as an overdrive, but as the transmission.

Oh, there are special bearings in these things (torrington). They are always bad in any used Warn overdrive. After looking at one I was surprised that they even worked, they are so thin.

From looking at the guts of the unit, I would leave it in overdrive or straight through and not shift it when moving. I don't think that shifting into or out of od while moving would necessarily damage the unit, but I do think that it would cause increased wear and tear on the internals.

kamel

 

Why do you say that? The sychros are the same ones used on the T-90. The biggest reason they die is from lack of lubrication. (That's how I killed mine) My uncle installed one in his '67 CJ-5 in 1969. He drove it over 250,000 miles until he finally retired it in 1994. Never had a problem with the OD.

 

The syncros in the OD look VERY similar to those found in the T90. When rebuilding my entrie drivetrain, I asked Herm if they were the same, and he said they are slightly different. But to my naked eye, they looked identical. After talking to Herm though, I made sure not to use T90 syncros in my OD.

 

Reserecting an old thread. Can this overdrive be used behind an automatic transmission (C4) with a Dana 18. If so, can you just leave it in OD. I have 5.38 diff gears which I may change as well.