Warn overdrive opinions please!

Hi everyone,...sorry for the life story, but I'd appreciate your input!

I am facing a little bit of a dilemma. We use our '46 2A for street and highway driving, and we do quite a bit of moderate trailriding with it. So far, it is obvious that the jeep needs lower gears for the trail, so I am keeping the 5.38s in the axles, and I rebuilt the t-90 with gears from a t-90c so the first gear is now 3.39 instead of 2.9. Not a big change, but it helps.

I do want to swap in a t-98 or an sm420 with the granny gear, just so that I don't beat the heck out of the jeep by going to fast in the rocks, like we have been, but at this point in time I am not ready to give up the t-90 and I plan to do a 4 speed swap at a much later date when I have more time to do it right.

However...I was debating whether or not to just install some of the aftermarket low gears sets available for the Spicer 18 transfer case. The transfer case low gear ratio of 4.86 offered by O'Brians that I want to use does not work with a warn overdrive, but I have a Warn OD waiting on the shelf to install. So, if I gave up the overdrive and went with these 4.86 low gears in the t-case, I may not even consider a 4 speed swap because it would give me the crawl speed I want for the trail. If I keep the overdrive, I am relagated to transfer gear ratio options of 3.15 or 3.6, and I would probably want to put a 4 speed in it if I went with either of these ratios.

So, I started thinking about how valuable it would be to have the overdrive for the highway driving and 40 mile round trips to work that I do. The jeep has a healthy L-head in it and I imagine that I normally travel to work between 45 and 50 mph, so my questions are...

How useful does everyone find there overdrives to be when traveling on the highways and do you use them a lot? The guy that I bought my overdrive from said he pulled it off because he never used it.

The RPM savings on the highway will save gas and engine wear and tear, but is the money that these overdrives are worth justify keeping them?

And finally, how reliable are they, do they wear out fast, or have a history of being problematic?

I would appreciate peoples opinions, as it will help me decide which direction to take my Willys!

Thanks, Daniel

 

I cant imagine that I'll be alone on this one, but I would say keep it. If you go with a 4 speed with a good low gear, like a T-98, or SM420 I would think that will be all the 'low' most people will need. FOr what it will cost you to do that 4.86 conversion, or even a 3.15 gearset in your D18, I would go for a good truck 4 speed, and keep the OD. With my T-98 for example, I ahve a gearing range from 6.32 to 1, to .75. Thats a spread of almost 7.07 to 1. If you need more than that, than maybe swap out gearsets in the T/C. I can tell you from my experience, that with my gears, I rarely need low range.
Reliability....well I have only had mine a couple years now, but from everything I've read if you keep it oiled, it will last like anything else. I wouldn't trade mine for anything. Besides my T-98 its the best mod I've done.

 

Thanks, I agree with the fact that the 4 speed swaps are about the best swaps that can be made, I am really considering it in the 2A because I am spoiled by our other crawling jeep with a t-18, dana 300 and 7.17s in the dana 60s. However, I just cringe at the thought of cutting up the vintage 2A too much, I have heard that the body needs a lot of modifications to make the t98s fit, keep the opinions coming...we'll see if the masses can help persuade me in a particular direction.

Thanks for the post!

 

4speed+OD. If you did the gears in the T-case then you could only have fun with that in low range. The OD you can play with at all times

 

True, I should do that, but the 2A is in pieces at the moment for a quick winter redo, but I also have the darn t-98 sitting on the shelf and it is taunting me as well! So much to think about!

 

My vote is 4 speed and OD. I have an SM465 behind a Chevy V8 with the original Model 18 tcase and 4.89's in the axles. I NEED my OD to be able to efficiently drive this thing anywhere. It'll crawl at half walking pace, but still cruise at 70 mph.

 

i've only got the t14 3speed in my 69. but even with the v6 and the 4.88's and 31" tires i really notice the difference in rpm and noise when i engage the OD. the .75 reduction really helps for those "inbetween" situations for gearing on and off road. definitely worth it for highway.

i will eventuall look towards an sm420 i have a line on for about $75.

in essence i really like the od. wish i had one when i owned my 47 2a many years ago.

 

SM-420 and a Warn is a tough combo to beat. Don't worry about the Warn durability. They're pretty tough when in good shape, especially behind an L-head.

I pulled mine out of a junkard Scout, installed it, then drove 3 trouble-free years with it behind a 270hp/270lb-ft engine. Everything from dune running, to hardcore rock trails, to 75mph on the highway. I pulled the Spicer 18 a few months ago and it's now sitting on the shelf waiting for my next Jeep that runs a Spicer 18.

For what it's worth, T-case gears aren't the way to go in my book.

 

I think you should go directly to your shelf and ship the O/D to me and I will extensivly test the usefullness of it and report back to you in say 2 to 3 years with a full report.R) R)

 

Send it to me, I'll test it for ya!

I was out on Saturday just cruising around town and I am still amazed at how well it does at top speed (about 50 with 33" tires).

Leave the 3 speed and add the OD. Mine is capable over almost any obstacle as-is. gud-enuff! 8)

 

Besides the fact that I have seen some poor quality tera gears and that o'brians gears are practically mortgage material, what are some of your issues with them Christian? You tend to have an inside scoop on things, and I'd like to hear your thoughts.


Secondly and speaking to everyone now...
Why doesn't anyone make a sm420 adapter to the spicer 18 that is as thin as the 1" t-98 to d18/d20 adapter? Or do they? The sm420 is such a nice transmission but it's main advantage of it's compactness is ruined by the aftermarket's lack of adapters that are less than 4" long for it! Someone just needs to make an adapter with a replacement mainshaft for the spicer 18 and 20s and get away from the little "spud shaft" cop out...

Daniel

 

:iagree:

 

The SM 465 has a 1" kit through Novak

 

It seems clear so far that the majority of people favor the 4 speed swap with the OD, so I think that is the direction I may go.

Does anyone know how much body modifications have to be done to the flatties to get the 4 speeds into them? The transmission tunnel cover needs to be remade for sure, but what about the stock underseat gas tank? The jeep also has a twin stick pto, pto winch, factory governor and all that jazz. So adding the 4 speed affects more than just the drivelines and body. I guess I am trying to have my cake and eat it too, by trying to keep it as stockish as possible and still be able to wheel it.

One of the main problems here is that a lot of our trails are rocks so going slow is a prerequisite to not breaking things, and leaving just the three speed without gearing down somewhere else will not do for the trails we run.

 

That is interesting, but I would rather have a t-98 than a sm465 due to factory parts being available for the t-98s to make them fit easily and these are nearly the same length, however, the SM420 is about 1.5" shorter than both of these transmissions, and that could be a huge advantage in a short jeep.

 

Thats true but once you add the adapters on the 420 is around 15.5" and the 465 is around 13" per novak's site. Granted the 420 does have a .5 lower ratio but it will be longer once you add the adapter on. The t98 was offered from the factory but finding one with the factory adapters is not easy since they are few and far between. I would go the t98 route if you have one on the shelf.