New To The Forum With Some Questions

Recently I got the chance to buy a 1956 Willys CJ-6. Its got the 134 4cyl, T90 3 Speed, Dana 18 twin stick with a Dana 25 and Dana 44 front and rear. No rust runs great. Got a couple of questions. I have never owned an old Jeep closest thing I own is a 1966 IH Scout 800 with Dana 44 front and rear closed knuckle front. What is the top speed of a 134 4 cylinder ? Also what gear ratio was most common in these Jeeps ? I know my grandfather's 1961 Scout 80 had 4.27s but I heard some of these jeeps got up to 5.83s. The reason I ask is I want to make this a vehicle I can go pick up feed bags for the farm, go on hunting trips and such. The longest drive is 55 miles to my hunting spot on my uncle's farm. The max posted speed limit on this trip is 55mph but you have to 60~65mph for about 37 miles of it because of truckers trying to run you over going 80mph. I dont want to run the dog out of it and blow its top. The owner said his father rebuilt the engine back in 2017. This all being said if say this jeep had 4.27 gears could it sustain 65mph for say 50~60 miles and not blow its top ? I took it up to 65mph when I test drove but the only local road that allows such a speed limit is a interstate so I tested it out on a 3 mile stretch of local highway that is posted 45mph and isnt too busy and the Jeep seemed to do alright. But like I said 3 miles doesnt equate to 50~60. I heard that there are Warn Overdrive units but I am not the most mechanically inclined and only about 3 shops in my area would take the job when I asked for an estimate and they told me 3 months which is some b.s. If I have to do a warn unit are they hard to do by yourself ? Also if need be could what gear ratios can I change out to ? Something like 3.55 or 3.73 ? Just asking as I want to know if this is all feasible and even worth the time. My scout is nice and all but its a USMC Vietnam War 1966 Scout 800 that already is hard to get parts for and the way people drive these days I am afraid someone will hit it and destroy it which is something that keeps me from driving it often besides local car shows or down the street to the local feed store. Thanks for all who reply.

 

Stock gear ratio is 5.38's. Top speed is probably 45-50, you may get it to go a little fsater if you've got a really good running engine , but you'd be spinning a lot of RPM's on a long stroke engine.

 

With five decades of f-head jeeps like yours, I too consider 45mph a reasonable cruise speed, with 50mph as emergency maximum.

You may have been able to hit 65, but it won't be for long before you blow the bottom end doing that.

These jeeps were meant for trails and local roads, where they excel. But a 55 mile commute is a LONG way in such a jeep.

 

Have you considered flat towing it? I have a full floater kit on my Dana 44 rear axle so I have hubs on all 4 corners. I can just unlock all 4 hubs, hook it up, and take off. It pulls easily behind my V6 Toyota Tacoma. You'll get the best of both worlds. Freeway speeds tend to be pretty unpleasant after a few minutes.

Edit: I also have 5.38's and a 4.3 Vortec. No overdrive.

 

My 67 CJ5 has the F-134, and taller gearing than a 56.

I have had it up to 60 MPH for short bursts, but I would not want to drive it that fast very far. I too consider 45 MPH top speed, and only go faster than that when I need to, which is very seldom the way I use my Jeeps.

An Overdrive would help for long distance driving, and the longer wheel base of your CJ6 would make it more comfortable to drive at higher speeds, but I would still not want to go too fast in it. The OD units are pricey, but are not difficult to install if you follow instructions.

 

If you are convinced the drivetrain is mechanically sound, I see no issues for your intended driving use.
If the Jeep has 5.38s, so much the better. Consider an overdrive.
The important issue for you, being new to Jeeps, is seat/driving time behind the wheel.
Acquire some hours of driving and see if you're comfortable driving distances with it.

My Jeep had an F4 in it when purchased, and I drove the snot out of it (high school) , making several driving trips to Colorado and back.
Also pulled the Jeep trailer behind it as well.
Yes, it had 5.38s and an overdrive.
The F4 is a tough engine and mine saw 4000rpm on the road and in the dunes.
I disagree with those who say the F4 is only good for local roads and 45 mph.

 

The F4 has plenty of power for going over 45 MPH, it is the short wheel base and high center of gravity that sets the limit for me.

If one is going to drive at 60 MPH or over, the steering system, and brakes better be spot on perfect.

 

56 should have 5.38s but 4.27 was an option.
I drove my f-134 5k miles on the interstate (16mpg best) before the blowby killed it. It just doesn't have a lot of horses. The overdrive is a simple install but it has to be done right or it can fail. The 5.38s and overdrive give an effective 4.10 ratio.
I now have a 4.3 chevy and overdrive but still prefer to flat tow (ecoboost Expedition @15mpg). The 6 will be better tempered on the highway but it's simply not enjoyable with original brakes and steering.

 

I don't think so. 5.38's were the sole offering until the T90C arrived in 62. At that point 4.27's were standard with the 5.38's still an option. An overdrive will help functionality but is only a little help with top speed because you flat run out of power. Very useful between 2nd and 3rd in a lot of situations. I don't think there is a problem piloting one of these at 55 IF the steering, brakes, and suspension are in good condition and properly adjusted. Obviously a different engine but stock Ross box and 9" brakes in my 3B at more than twice that speed once upon a time loooong ago. But only once-----

 

Welcome from Michigan, I have an F 134 in my 64 Jeep with 66 373:1 axels from a V 6. I have stock size tires on it, I can go 60 mph but don't. My top speed is 55 mph, but I don't like to go that fast. I bought a Tow Dolly for my Jeep, I disconnect my rear drive shaft and hang it on a ratchet strap thru the frame. Duct tape the caps on so not to lose one. The only thing turning is the rear axel. I pull my Jeep at 65 mph with my truck and stay behind a big truck to be safe. Good Luck.

 

I guess I should give some more info on this Jeep of mine. So like I said its a 1956 CJ6. Previous owner rebuilt the entire drivetrain. F134, T90, Dana 18, the front Dana 27 and the rear Dana 44 as well as two new driveshafts for front and rear. A new radiator, clutch and carb were installed. The original heater was rebuilt and a new heater core installed. The Jeep was converted to 12v and the vacuum wipers motors were replaced with electric motors. The brakes were all replaced including new drums, shoes, hardware, wheel cylinders, brake lines, master cylinder and porportioning valves for front and rear. New tie rods were also installed and steering box was rebuilt and repacked. This was all done in 2017 so its got 6 years and only 2,897 miles on the rebuild as the previous owner only drove to his hunting spots and local car shows with it. The only original non re built items are the fuel tank, all the gauges, the body, bumpers and paint also the windshield is original. I will try and get some pictures up here. This Jeep is mechnically new I guess lol. Was just wondering everything I could do to get this thing up to par.

 

On a Second note I talked to a local Jeep group who has a meet twice a week and an older fella there has a 1950 willys truck. He told me that the Dana 25 in his truck has 3.73 gears that he had installed by a local garage but that a Dana 27 cant take anymore than a 3.92. Since my jeep has a Dana 25 could I get in a 3.73 gear set in the front ? I know the Dana 44 can take a 3.73 without a doubt. His 1950 willys truck has the F134 and T90 same as mine but he bought an OD unit through Novak I believe is what he said and had a shop put it on for him. He said with the overdrive you can double every gear is that true or is that just a fart in the wind ? He was kinda saying it was like splitting gears. I know my 1964 Mack and 1957 IH can do that with the twin stick but in a Jeep ? Seems kinda odd lol. Anyway I was just wondering if the modifications made on a Willys truck with the same components can be replicated on my Jeep. Most of the year this jeep will only drive 6-8 miles a day cause I work 6 minutes from my farm at a local county government. The only time it would drive farther is the 4-8 hunting trips I make that are 110 mi round trips. I dont really want to put non original parts like a Chevy Engine or a chrysler transmission. I see that enough in the IH Scouts. My 1966 Scout has the 196 4 cyl, Dana 44 front and rear with T90 and Dana 20 and it can run 70 easy no issues 75 it gets a little high at 3400 rpm. However my Scout is one of 17 USMC Scouts that were in Vietnam that still runs and drives and is legally registered in the US so I hide that thing under lock and key and drive it sparsely. Not that I dont like this new Jeep but I really like my Scout lol.

 

There is no way on earth a f-134 will pull 3.73s with a .75:1 overdrive. That would be equivalent to 2.7975 gears in the axle without an overdrive. 1909rpm at 65mph on 28" tires.
4.27 plus overdrive is 3.2 or 2495rpm @65mph with 28"tires
4.88 plus overdrive is 3.66 or 2855rpm @65
5.38 plus overdrive is 4.035 or 3247rpm @65
Or 2754 rpm at 65mph with 32s

At 55mph you have over 100lbs of force on just the windshield and you have 114ftlbs available at the crank. add the rest of the frontal area and the driveline efficiency equivalent to our government, There is mathematically no way on earth a f-134 is pulling 3.73s in overdrive at 65mph. You need more torque or lower gears and higher rpm.

5.38, or 4.88 with an overdrive will give you 6 usable gears. I'ld go 4.88 with overdrive with 28" tires and put the windshield down.
No idea if 4.88s were made for the d25 but the 4.27 was in the military jeeps before 5.38s were available in the CJs.

 

That was the standard gearing for WWII MB/GPWs with D25s.

An F-134 isn't going to like that, but the Buick 350 in my '71 loves it even with 32" tires.

 

As to overdrive "doubling" every gear, "yes" in the sense of having twice as many gears - but "no" if you mean the rpm. An overdrive might shift the rpm range down by 25% or so, but as has been pointed out, that also reduces the power by the same. No free lunches in physics.

FWIW, easier to answer questions here clearly if they come just one or two at a time.

 

I'll second that. With 3.73's, you will be struggling on the flat with a tailwind. Another option is the D25 4.09/4.10 gear sets. Those were used with the OHC 230 engine in the wagons and pickups so are not too difficult to find. That ratio is close to the same as you get running 5.38's and a 25% overdrive.

 

Not a fan of the F head myself. I tried that for a while. Another thought. Is it hilly country or basically flat?
Personally I like the v6 with OD and 5.38's. And I do live in very hilly country.

 

I spent most of my "coming of age" driving my father's 57 FC 150. Both 134's have my respect but neither fit well in the present world. You will not keep up with any modern traffic short of forced induction on one, period. They are what you expect from a mid 1920's basic design. There are a lot of different gearing options one could use, but none of those alter the top end speed by a meaningful measure. An overdrive and the stock 5.38's probably remains the best option and is for sure cheaper than regearing both axles. If nothing else, you can reduce the rpms in a lot of situations. These 134 powered Jeeps can do a surprising amount of off roading but just don't have any high expectations for the on-roading driving. The 225 V6 was a night and day improvement.