M-37 Gearing

[MolderBrown]

Can anyone give me a gear ratio for a 1952 m-37 , whereby I can pick up 5-7 mph ? I'm not trying to create a hotrod , but with todays drivers , a fellow could get seriously run over if his max speed is only 55mph .

 

[rosco]

Even if you have a faster ratio, the stock 230 flathead hardly has the power to run it, and will fade even worse, on a hill. It was built for off-road, with some Highway capabilities. Where as the new 4x4's are built for Highway, and just some Off-roading. Alter it, and you just find the next weak spot in a row. Like just try to stop it fast from 55 MPH.

 

[Bill W]

They make 4:89 gearing for the the 37's ($$$) and that will give you the 5-7 mph your looking for but make sure you reread what rosco stated.

 

[MolderBrown]

Thanks guys .

Dan

 

[MolderBrown]

Can either of you suggest an engine that will fit the m-37bwithout major engineering ?

 

[tbone1004]

go to http://www.g741.org/PHPBB/ tons of thread about repowers. 4 cylinder diesels are common, the sixes won't fit without surgery, but most any smaller block v8 will fit and the smaller inline 6's will fit without major engineering. We have the advantage of a divorced transfer case so you can use 2wd trannies which saves cost as well as having to do major drive shaft modifications. Gives you a lot more flexibility on where to put the engine since you only have to get the short shaft adjusted and balanced instead of the long ones. I keep hemming and hawing on what to put in mine, but it's down to a 4.0l jeep, or isuzu 4bd1t due to local availability to me, but for now my 230 is running well so it stays until I get the body fixed up to where I want it.

Also budget $1k ish for brake work to get it to actually stop when you tell it to.

 

[jimmystikx]

I'm going with a CUCV pullout motor and full powertrain swap. Though from my reading, the 6.2L would be fine for just an engine/ tranny swap. I'm doing full driveline to get disc all around, allow me to run tubless, and it'll be cheaper and less hassle that going through and rebuilding the differentials, replacing bearings and seals and converting the hubs to disc on the current axles.

 

[Heath_h49008]

I keep toying around with the idea of an M37 or M715 with axles out of the common M1008, smallblock gasoline engine and an overdrive tranny.

Not that I need another project I don't have time for, but it would seem to be the easiest solution to the shortcomings of the types.

 

[jimmystikx]

I would think that gearsets for the Dana's on the M715 would actually be available.

 

[JimC2]

I put a big block Chevy in my 37 about 45 years ago, and kept the stock 5.83 gearing and 9.00x16 directional tires. It was an easy swap. It'll go faster than you want to go, but don't stop so hot from speed.

 

[MolderBrown]

One of the guys suggested that I replace the 900/16 tires with 1100/16's and that I would pick up a few mph without gutting the 230 engine . Anyone have a source for 1100/16 tires with military tread ?

 

[vtdeucedriver]

He is right about the tire size, you will see some dodges with a NATO looking tread. These were from the french I think. Much bigger, possibly a 11.00 but definatly a 16" as they fit the stock rim.
Again, be careful on your speeds. If you run at 55, that 230 likes to throw the #6 rod. I had seen a scrap yard that got a salvage contract from a local base here back in the day...............lot of vented blocks.

 

[whatadeuce]

I did have a 1952 M37 that came with 4:89 gears. Ran it frequently in the suburban areas. AS for the bog down uphill, I found I couild manage with gear selection, but I accepted that I was driving a relatively slow vehicle. Do you really weant to make all those cahnges for modern performance? Im afraid you are defining what we call a hotrod.

 

[JimC2]

Nothing slow about a V8 powered 37 with stock drivetrain. It'll go faster than you want to drive it

 

[Bill W]

He is right about the tire size, you will see some dodges with a NATO looking tread. These were from the french I think. Much bigger, possibly a 11.00 but definatly a 16" as they fit the stock rim.
Again, be careful on your speeds. If you run at 55, that 230 likes to throw the #6 rod. I had seen a scrap yard that got a salvage contract from a local base here back in the day...............lot of vented blocks.

You mean like this ( #6 out of my V-41 parts truck )

 

[BrutusM37]

I got my first M37 a few weeks ago and had been dealing with the same dilemma until I discovered this thread about putting a different carb on the 230 . . .http://www.steelsoldiers.com/showthread.php?56047-18-mpg-m37-quot-plus-quot-more-power!!!&highlight=

I'm hoping regearing and swapping the carb will leave me enough power to turn my 11.00-16s in 4th gear going up mild hills at 55 mph and get at least 15 mpg on the flat. For now I'm going to keep it at 50 mph or lower to preserve my engine.

I was going to regear to 4.89s and repower with a Cummins 4BT but then discovered I would have to either put an OD box in with the original trans or do a trans swap (Ford ZF-5 was what I was planning on). The project was already approaching $5000+ in the planning stage just to get a few more mph and mpg verse running the Holley/Weber carb mentioned in the linked thread. Not worth it in my mind. I'm going to try the carb swap first and see what happens.

Here is a handy equation to calculate your engine RPMs based on tire size, axle gearing, trans gear, and vehicle speed:

vehicle speed (ft/min) / advance (ft/rev) X Axle ratio X Trans gear = Engine RPM

Speed: Vehicle speed in feet per minute
Desired speed in mph / 60 X 5280 = Desired speed in ft/min
55 mph = 4840 ft/min
60 mph = 5280 ft/min
65 mph = 5720 ft/min

Advance: this is the distance the vehicle moves forward per revolution of the tire
9.00-16 tire is about 35" diam (Circumference= pi x Diam (ft) = 9.1583 ft/rev (don't forget to convert your tire diameter to feet)
11.00-16 tire is about 39" diam = 10.205 ft/rev

Axle ratio:
5.83 or 4.89

Trans gear:
1st - 7.02
2nd - 3.57
3rd - 1.70
4th - 1.00

Example 1: 55mph, 9.00-16 tires, 5.83 axles, 4th gear
4840 / 9.1583 X 5.83 X 1.00 = 3081 RPM

Example 2: 55mph, 11.00-16 tires, 4.89 axles, 4th gear
4840 / 10.205 X 4.89 X 1.00 = 2319 RPM

 

[whatadeuce]

Hello BrutusM37, thank you for these calculations.

 

[jimmystikx]

Brutus, that's interesting about that 2bbl carb, good info and sounds way easier to tune than the stock ones.

 

[U1100L]

Got an Offenhauser intake that would take 2 Ball & Ball carbs or same bolt pattern. However, the little 230 runs so good the way it is. Did do the 4.89's 15 yrs ago and disc brakes, power steering, well I say assist... Took the fear lauching it down the sidewalk away.