1961 Willys Pickup Warn overdrive conversion to Saturn/Warn overdrive~

troyskibert

Gear Grinder
Aug 12, 2013
19
Paradise, California
First Name
TeeRoy
Willys Model
Pickup
Willys Year:
1962
I would like to replace my existing warn overdrive. It is a Warn with an electric silenoid and a cable that ingages the unit. It was on my truck when I bought it 6 years ago. I want to go with new Saturn/Warn shift on the fly overdrive married to my Dana 18 T-case. From what I can see in the Dana 18 Parts diagrams, that this transfer case has a brake drum married to it for parking brake as it is labeled on diagram. I have not split the old Warn over drive off the Dana 18, so I can't see what parts had to be taken off the transfer case to marry these two, and if I will have to buy these parts to make this conversion work. I can see in pic's I found on Internet, that the new Warn/Saturn OD is not mounted/married to transfer case at the output shaft like the old Warn OD. The new Saturn OD mounts to the left of the outputshaft, opposite of the inputshaft, and has a cover over it at this time. I"m a newbee with the Dana 18, but I have found a lot of awesome info of how to rebuild them, etc. I wrote Warn/Saurn an email and am waiting to hear back from them shortly. I will also send this email to Herm, the OD dude, he probably knows. I couldn't find anything on this forum, besides people commenting on how nice the shift on the fly Saturn OD is compared to stopping and engaging the OD.
 

wcnilsen

Bigger Hammer
Jul 14, 2013
88
Camas, Washington
First Name
Chip
Willys Model
Wagon
Willys Year:
1959
Teeroy, you can run both if you want, as you probably already know you can't run the electric one in 4 wheel drive like you can with the Warn/Saturn/Husky full time. However, in 2 wheel drive you can run both. I'd love to run both with 5.38 gears. Good luck.
 

muleskinner

Bigger Hammer
Oct 6, 2009
37
High Desert Caiifornia
First Name
mike
Willys Model
Wagon
Willys Year:
1955
The Overdrive that you are talking about has a much higher final drive ratio than the Warn that bolts to the PTO outlet.The Warn or Saturn has a 25 % reduction where as the Borg Warner is what you have has a 33% reduction. True the fully syncro shift is nice with the Warn even in reverse. The electric can only be used in 2 wheel drive and not ever in reverse. I like the previous post run both if you can. I have never talked to any body that has both overdrives in use.
 

troyskibert

Gear Grinder
Aug 12, 2013
19
Paradise, California
First Name
TeeRoy
Willys Model
Pickup
Willys Year:
1962
Wow, I didn't even think of running both as an option. That would be amazing if possible, and if anyone knows of anyone who has done this, please reply to this thread. I am going to email Herm again and ask him what he thinks about running both OD's. The dentist I am doing this engine swap for wants to commute with this old truck and get 35+ MPG. I told him that I will try and see what I can do. With the highway gears I have in the donor 1986 GM 10 bolt axles with power steering and disk brakes, that are going into Willys, 3.07's I believe, and two overdrives, the Doc can go 70-75 MPH and get 35+ MPG like he wants to do with this 1961 Willys pushed by this Cummins 4BT turbo diesel that I am swapping into this truck.

Using both OD's would make this Willys a 12 speed with 3 low/granny gears since I am running a mid-range 4 speed tranny with granny gear married to the Dana 18 via a Novak divorced t-case adapter kit.

Thanks for the input, all the more, the marrier! I would have never thought of running both OD's, but will see if the Doc would consider letting me do this if it is possible. I will tell you all what Herm, the OD guy, has to say about all this~
 
Last edited:

diggerG

Well Oiled
Oct 2, 2011
4,536
Wrentham Ma.
First Name
Greg
Willys Model
Wagon
Willys Year:
1963
Sounds to me, that with the Cummins 4B pushing maybe 125 - 140 hp. then the 3.07 gearing should do the trick for max mileage. If you ran a warn od you may be lowering your effective axle ratio to about 2.3:1, and with the BW od, maybe about 1.5:1 or thereabouts. Not enough gear to get that truck going. I"d try just the axle swap first. I know of a Chevy 3/4 ton 4 spd 4wd pickup with a 4 cyl Isuzu in it with the factory 4.11 gears and that motors along great on highways. It makes about 25 mpgs with stock tires. This truck wouldn't do well going lower than your 3.07's. And even with the 4.11's it is slow getting going. I think the Isuzu would be comparable to the Cummins hp wise. OK, the Isuzu has a turbo on it, maybe more rpm's than your Cummins. Do your math first. diggerG
 

schimms15

Sharpest Tool
Apr 6, 2012
251
Milwaukee
First Name
Luke
Willys Model
Pickup
Willys Year:
1951
digger no OD he should have no problem getting going and once he is up there and has momentum then kick in both ODs and he should be good to go.
 

diggerG

Well Oiled
Oct 2, 2011
4,536
Wrentham Ma.
First Name
Greg
Willys Model
Wagon
Willys Year:
1963
Schimm, with all due respect, I don't believe it for a second. Maybe, with a warn od only it wouldn't quite reach the point of losing engine efficiency, (without any hills or traffic lights) but beyond that not a chance. A second overdrive? forget it. I know what my Chevy with the Isuzu does with 4.11's, and 3.07's would be about it for that running gear. Just because you lower the rpm's of an engine moving a vehicle, that doesn't always follow that it's being more efficient. Let's see what TeeRoy does and let us know. it's somebody else's $$$$. diggerG
 

schimms15

Sharpest Tool
Apr 6, 2012
251
Milwaukee
First Name
Luke
Willys Model
Pickup
Willys Year:
1951
ok i see what you are saying. i guess it depends on what kind of mods are made to the cummins, ive seen a 6 cummins 24 valve pushing a lot of horse power but he modded it a lot. we will just have to see how it goes and what the out come is.
 

diggerG

Well Oiled
Oct 2, 2011
4,536
Wrentham Ma.
First Name
Greg
Willys Model
Wagon
Willys Year:
1963
The beauty of TeeRoy's idea is that the 4B and 6 cyl Cummins have the same bellhousing bolt pattern, so everything that bolts to a 6 will bolt to a 4. 5 spd with od anyone? I would think about that first. Maybe he doesn't know about that yet. He will now! diggerG
 

willysmn

Gear Grinder
Sep 11, 2013
11
New Mexico
First Name
Pruit
Willys Model
Wagon
Willys Year:
1953
diggerG is correct about the resulting gear ratio with 2 overdrives and the 3.07 axle; it would be way too high, unless you have mucho power and are going to Bonneville. The OD he has now is a Borg Warner, not Warn.
A 5 or 6 speed New Venture trans would probably work with the 3.07 rear end.
IF he had the Willys 4.88 or 5.13, both ODs might be OK, but the resulting final drive with just the Warn/Saturn OD and a 3.07 is 3.07 X .75= 2.3:1, add the BW OD and its 2.31 X .67=1.54, WAY too much gear. The 2.3 would work with a diesel maybe, they don't turn much RPM and develop torque at low like 1200 or 1500 rpm. But a nice close ratio 6 speed would be nice and it would keep the 4 banger Cummins at peak torque. But those 4 banger cummins (4BT) are real noisey in UPS trucks.
 

diggerG

Well Oiled
Oct 2, 2011
4,536
Wrentham Ma.
First Name
Greg
Willys Model
Wagon
Willys Year:
1963
You should hear'em in a chipper when the muffler blows apart. The crew needs ear protection for their ear protection. diggerG
 
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