Slow Down an M37

[Day Radebaugh]

I live on a farm, and use a Roxor to manage pastures and spray weeds. Roxor is a great vehicle, and is just about exactly a WWII Jeep. Problem for me is that it goes too fast, even in 4WD low. I want to be able to crawl down the fence lines and lean out with my sprayer and murder the weeds and trees.

Thinking about replacing it with an M37, which are common out here in Kansas. I'd like to find a way to slow down an M37, which I assume would involve replacing the transfer case. As I read the M37 Wiki, M37 low range gives you about 2:1 reduction. I'd like to achieve nearer 4:1.

Can this be done with reasonable effort?

Thanks

 

[Bill Nutting]

You can run at idle in first gear, low range and it will go about as fast as you walk. I used mine In parades and just let it crawl. I rarely had to adjust my speed. If the parade stoped, I Just pushed in the clutch. When the parade resumed, I just let out the clutch. I never had give it any gas above idle. I don’t think you will have to modify anything.

 

[Day Radebaugh]

You can run at idle in first gear, low range and it will go about as fast as you walk. I used mine In parades and just let it crawl. I rarely had to adjust my speed. If the parade stoped, I Just pushed in the clutch. When the parade resumed, I just let out the clutch. I never had give it any gas above idle. I don’t think you will have to modify anything.

Here's data on Roxor (a comparison of it to the WWII Jeep):

The Roxor has much taller 3.73 differentials, but nearly makes up for that with a 3.778:1 first gear ratio. Those two, combined with the same 2.46:1 low-range gear as the Willys yields a crawl ratio of about 35, just below that of the Willys.

Here's what I know of the M37: Front axle stock 5.83 gears, 38.2in tires (36.672 loaded rolling diameter).

Roxor/M37:
diffs: 3.73/5.83
1st gear: 3.778/6.68
low range: 2.46/1.96
tires: 16/16
crawl ratio: 35/70

You are pretty much right

Thanks

 

[John Mc]

Do you have an idea of how slow you want to go (in MPH)?

in 4WD low range first gear, my 91 year old mother can easily out-walk my M37, unless I’m flooring it.

 

[Day Radebaugh]

Do you have an idea of how slow you want to go (in MPH)?

in 4WD low range first gear, my 91 year old mother can easily out-walk my M37, unless I’m flooring it.

I do not. The way I spray in the Roxor is that I creep down the fence line in 4WD LOW, and lean out of the cab with my sprayer and hose down the weeds and trees. The Roxor goes too fast too really soak them, so I'm on and off the clutch frequently. To slow it down by half--as I calculated above--would surely help.

The other vehicle I'm considering for this application is a Unimog, but they're so darned hard to find and expensive that I've about given up on them.

The pastures on the farm are pretty rough, with cattle trails, stream beds, and plenty of rock. I think the clearance of the M37 would be even more suitable for this than the Roxor.

 

[Bulldogger]

Do you have an idea of how slow you want to go (in MPH)?

in 4WD low range first gear, my 91 year old mother can easily out-walk my M37, unless I’m flooring it.

+1 on that. It's an M37 in low gear that wins the slow race nearly every year at the Graves Mountain Rally. In low range first gear they barely crawl, but they also don't stall. I'd say it's perfect for what you need.
BDGR

 

[Day Radebaugh]

+1 on that. It's an M37 in low gear that wins the slow race nearly every year at the Graves Mountain Rally. In low range first gear they barely crawl, but they also don't stall. I'd say it's perfect for what you need.
BDGR

Thanks very much, I do appreciate your opinion. I was going to go down the BIG BUX Unimog route. Do you have recommendations for where to find a decent M37? I've got projects coming out my ears on a farm, and don't need a fixxer-upper.

 

[MarkM]

Can you put smaller tires on the Roxor? That may be the easiest way to slow her speed down.

Mark

 

[Day Radebaugh]

Can you put smaller tires on the Roxor? That may be the easiest way to slow her speed down.

Mark

Cannot. Need the clearance in the pastures.

 

[41cl8m5]

Just remember if you have the original motor it is a flat head and idling a flat head can build up carbon deposits on the head and spark plugs faster than normal. Maintenance for this condition could be more frequent although it is not to hard to do. Good news is the TM section has a manual on it

 

[Day Radebaugh]

Just remember if you have the original motor it is a flat head and idling a flat head can build up carbon deposits on the head and spark plugs faster than normal. Maintenance for this condition could be more frequent although it is not to hard to do. Good news is the TM section has a manual on it

Understand. There's back roads around here where I could blow out the carbon.

 

[87cr250r]

The rock crawlers mate up a NP205 and 203 transfer case for their low ratios. Kind of a long setup, though.

 

[Canadianz]

Ha! Making an m37 slower, that’s funny.

In all seriousness, you might have an issue being higher up than the Jeep and having a door in the way, depending on what the range of your sprayer is…. But I don’t think you will find it to be too fast in low range.

 

[Day Radebaugh]

Ha! Making an m37 slower, that’s funny.

In all seriousness, you might have an issue being higher up than the Jeep and having a door in the way, depending on what the range of your sprayer is…. But I don’t think you will find it to be too fast in low range.

No worries; I'll take the door off. Roxor has no door, and I fold down the windshield except in the very worst conditions.

 

[nattieleather]

Why not look for a doubler for the Roxor? I think the aftermarket biz is making it. Bolts on to t-case and superlow gearing. Let Google be your guide.

 

[Day Radebaugh]

No worries; I'll take the door off. Roxor has no door, and I fold down the windshield except in the very worst conditions.

Thanks. Did not find an external crawler box, but did run across this: https://www.thecj2apage.com/forums/...gears-in-dana-spicer-model-18_topic44041.html
This looks like a big deal, big enough that--for me at least--it would make better sense to sell the Roxor and get an M37.

 

[eaw46]

If the Roxor works for you then get an M38. The two have similar configuration. it is about the same price as a new Roxor but seems to go up in value every yr instead of down. The crawl speed is lower and it can be licenced for the street where the Roxor is not in some areas. The M37 is more like a truck so if that's of use to you then it might be a better answer.

 

[Day Radebaugh]

If the Roxor works for you then get an M38. The two have similar configuration. it is about the same price as a new Roxor but seems to go up in value every yr instead of down. The crawl speed is lower and it can be licenced for the street where the Roxor is not in some areas. The M37 is more like a truck so if that's of use to you then it might be a better answer.

See my calculation of the crawl ratio above. It was derived from the following source:https://liftkits4less.com/blog/heres-how-the-mahindra-roxor-compares-to-a-1948-willys-jeep

which claims the Roxor has about the same crawl ratio as the M38.

Not true?

Thanks

 

[Montanaiceweasel]

With my '55 in low range, granny, you could walk faster. If you want to get really jiggy with it, since the timing is TDC, pop the clutch in reverse while traveling forward and use that reverse gear.

 

[eaw46]

My M38 has a lower crawl speed than my M38A1 I would say it's about 3.5 mph as its just lower than a good walking speed. If you ever get to AZ or up into Canada drop by and let's go for a ride. My 404 Mog has a crawl speed of about 2mph.