Hey half track guys

[Blythewoodjoe]

Quick question. Are the two axles in my M15A1 half track geared the same. In other words does the transfer case turn the rear axle for the tracks once for every turn for the front, wheeled axle. I have no drive train and was thinking about putting in something to make the front axle turn. I have lots of deuce transfer cases and modern engines.

Thanks,
Joe

 

[NDT]

Nope not the same ratio. Are you having trouble finding a 160AX engine and transmission/transfer?

 

[vj]

halftrack

joe, you might be going the wrong way on this, i guess you got the tracks and boogies,, i would try to find the correct set up, i know you want to use what you got, , but if you got the bed and a lot of the h.t. , i would try to go the right way. post a picture of it, i can tell you more. i got 4 halftrack, and i work on them, wendell

 

[Blythewoodjoe]

Well here's the story. I may never have the money to put a running stock engine and drive train in this half track. I plan to put an engine and trans in it and either hook it directly to the real axle or install a transfer case and possibly connect the front axle. If the axles are completely different gearing I will not even think about the transfer case.

I plan to BOLT everything into the half track in hopes that one day I can find or build a running stock engine and all the stuff needed to put it back to original. In the mean time I don't plan to let it sit in the yard rusting. I want to have it move on it's own power and I have several drive trains available at no cost to install. I know some folks find this offensive but it takes money to play with these things right and until my house is paid for I can't justify spending thousands of dollars on a stock engine. But I do want to see the old rust bucket move around the yard. I have tons of scrap trucks, a welder and rods.

So anyway, I assume most all wheel drive trucks have the same gears in the front and rear, but does a half track? And if not does anyone know what the ratio between the front and rear out puts on the transfer are.

Thanks,
Joe

 

[rivired]

That would be a hard find..i never though about a T case with diff ratio outputs!..

Great to see u wanna get it movin tho and not rustin

Good Luck!

 

[m.walker]

I would hazard to guess that maybe the t-case has the same outputs just the ratios are different because of a tire on the front and the wheel driving the tracks are different sizes . Put marks on the yokes to the drives , roll it one full turn of the front tire , count the revolutions of each yoke , if they're the same run any combo you like . Just put something in small enough that you don't have to cut out anything . I'd put in something small with an auto just to putt around in . In this day and age money is scarce for alot of us ! Let us know how it turns out .

 

[halftrack]

You would be wasting your time and money. Just save and get the right setup from the get go or you will never be satisfied with the project.

 

[lacoda56]

The diameter of the drive sproket is quite a bit smaller than the dia. of the front tire, so I would think the t-case ratio would be too far off for any other than stock replacement. If you're not planning any serious mud runs or hill climbs, I don't think track drive only would be a problem. I know the purists will be on a rant, but it's yours and you should be able to do what you want. Way better than on a scrap ship to china!
By the way, the t-case and trans are a single unit. If yours works out, I have a junk M3 out back that I might try something similar with. Too many projects, not enough time!

 

[spudwacker]

Just an observation from a farm boy and an off roader. Being that the drive sprocket is a different diameter than the front tire (as lacoda56 has stated) the diffs would have to have a different ratio to get the front tire and the drive sprocket to turn at the same road speed. The drive sprocket doesn't care if it is on a 20ft long track or a 100ft long track, all it cares about it how many revolutions the outside edge of the drive sprocket has to move for every revolution of the drive shaft.

Our AG tractors that have mechanical 4wd have one ratio for the front diff and another for the rear diff, the little tire in the front has to make more revolutions per distance traveled than the big tire in back; but the transfercase has the same ratio (otherwise expensive parts go boom) and that is why you have different ratios on the 2 diffs. So if you change tire size on the front of the halftrack, you have to figure out what the new ratio will be to maintian the same road speed of the drive sprocket/front tire.
I hope this helps.

 

[ida34]

I don't know half tracks but I would doubt the transfer case would be the mechanism to compensate for the different diameters of the drive sprocket and front tire. I think it much more likely that the both outputs of the transfer case both move at the same speed when the case is locked into all wheel drive. It would have been much easier to have different ratios in the front and rear diffs to make up the difference. If this is the case then you would be able to use a none original transfer case.

 

[dfanders]

M2A1 with modern engine & tranny

We have a M2A1 that was "modified" in some times past. It currently has a 70's era jeep wagoneer V-8 engine and tranny. It does drive both front and back axles. It does have a secondary electric cooling fan.

The good:
Plenty of power
Modern parts

The bad:
No hand brake ( this was on the rear drive shaft that got changed with the the new tranny)
Will take significant work to get it back to orginal.

I will be getting into the exact make and model of engine, tranny, transfer case today. I can look into this.

We call this our "hollywood" halftrack. It was bought becasue we only intend to use it for tactical WW2 re-enactments. It is not ment as a show piece for a public demo. I woud say , it you can get the orginal parts, go that route. Since our set-up came to use this way, we work with what we got...

PM me and i can give you part numbers as needed.

Good luck !

 

[Ol-Paint]

Per "Standard Catalog of US Military Vehicles 1940-1965" by Thomas Berndt, "The drive sprocket was much smaller than the front wheels, and consequently the front and rear axles had different gear ratios to compensate for this." Unfortunately, the book does not give the axle ratios, but only says the "Overall Ratio" was 6.8:1 for White halftracks, and 7.17:1 for International.

Douglas

 

[lacoda56]

No wonder I didn't think of it before, it was too obvious! I knew there was a different ratio because of the different diameter of the drive sprocket vs. the front tire but for some reason I've always thought the t-case took care of it. Duh....

 

[dfanders]

Engine & tranny

Our "Modified" M2A1 has the following:

Engine -AMC 360 with 2 BBL autolite carb
Tranny - T18-1B
Transfer case - Dana 20T

All of the above came from a late 70's jeep wagoneer.

Front drive shaft appears stock. Rear drive shaft was cut and welded at the u-joint to make it the correct length. We lost our hand brake in the process.

Will we return to an orginal engine and tranny - YES , someday. Our plan is to work on the armour and exterior first. Since we don't show this, we just need a running engine now. The halftrack does not have orginal armour , pulpit mount ,etc..so alot has to be done there.

Cheers,

 

[AndrewH]

If you are just using axles from around the farm, and you happen to have a truck which had FULL time 4WD, like a waggoneer with quadra track or one of the older full time chevy 1 tons, I think those t-cases had a differential in them, thats why they offered the hi loc and the lo loc position on the t case shifter. If you could get the ratios close enough maby one of those cases would let you make it drive both the tracks and front axle. Any experts?

 

[spudwacker]

Guys, the front tires are like twice the size of the drive sprockets for the tracks. That is why the ring and pinion has a different ratio than the Ring and Pinion for the drive sprockets. If they had the same gear ratio the tracks would get drug by the front end. Any Transfer case that I am aware of made for any major auto mfgr will deliver the same rpm to the front and rear drive shaft (that is why you can take a T18 and stik in X or an NP205/07/08 etc and do the same.

The transfer case that came with the half track puts the same rpm to the front as it does the rear, the diffs are where the gear reduction/ratio change occurs.

Our 4wd farm tractors transfer cases do this as well and we have little tires up front, and big ones out back. It is the differential that has the different ratios that allows the tires to have the same ground speed.
Guys that do sand drags with 4wd that have big tires on the back and little ones up front, have one ratio for the front diff and another for the rear.

 

[AndrewH]

I understand the ring and pinion in the axles are different front to rear in the original setup. But this fella would like to use parts he has, Does anyone know what the original front axle ratio is and what the original rear drive ratio is? If he can come up with something close he might be able to make it work. Like he said this is not a museum piece. It needs to move itself. If anyone can find the rear drive ratio, maby he has a close one and can at least make it track driven. -Andrew

 

[WarCloud]

It is. The diff ratios are different, the T case has the same output drive ratio front and rear. We're talking 1930's mechanical engineering. There was no way to build the trans case to do this without it being essentially TWO trans cases in one, but using two different diffs is easy. That's how it got done.
Just a personal opinion..I love US halftracks, have always wanted one, but the prices got insane about 8 yrs back when everyone got stupid on refinance money and the price of everything went ballistic.. So I never got a shot at buying one. But if I had, it would never be rigged up or modified to use anything not original. These are just too rare and expensive anymore to butcher. With restored h-tracks going for $50,000, it's worth doing right.
And the old warriors deserve respect. Just my .02

 

[waayfast]

I suppose in a perfect world, waiting to get the money to "do" it all correctly certainly would be the best way, but the world (an this present-day economy) sure as heck aint perfect.I think that the attempt to repower with whats available to the owner is actually a VERY good idea.I would suggest that if Joe works on this, that at least it is getting some TLC,rather than just sitting out back,rusting-moldering away until that "perfect time" some where in the distant future when he has the money for the right goodies.That's not to say just grab the torch,some old rusty pipe,angle iron and the welder and butcher it permanently---just make sure it can be put "back" someday when you DO get the correct stuff or at least if sold to someone else with more resources(money) they could realistically restore it "properly".My fear is the longer is sits the worse it gets and "oh,well I was always gonna fix up the old girl but the wife wanted it outa here so we sold it fer scrap-------"
OH,and since we have our halftrack people on here I have this question:is the drive axle (for the track) diff. and axles interchangeable with any other trucks? The axles and drop-in are GONE in the frame I hope to get!Pretty sure it is aWhite--pretty sure it aint a IH

 

[Monkeypirate]

gear ratio's

Hello all,
Im new to the MV restorations group. been working on cars for a long time, thought i would try my hand at some thing Next level so i picked up a M2 white half track. will be starting on it in the next year. I have two other cars to finish first though. I didnt see a reply on the gear ratios for the axels so i thought id mention them. The front axel has a ratio of 6.8:1 and the rear axel has a ratio of 4.44:1. this information is from TM9-1710-1942. I havent seen any information to indicate they ever changed the ratios later on.hope this helps you with your problem. Although i like an original vehicle, there is some thing to be said about a modified one too. Look at all the street rods/Hot rods around our country. Lots of those vehicles are very rare them selves. But a modle T with a blown Hemi just cant be beat!