m37 differentials

[jeck2323]

I'm buying an m37 for use in a local crawler club. What is the best way to add posi-trac/locking differentials? The motor is blown and I have a 6bt 12 valve out of a 93 dodge. How hard would this conversion be? I'm excited about the m37 and am glad I found this site. thanks for any help you guys can give! John

[W_A_Watson_II]

You might consider an axle upgrade with the 6BT. My M with the stock 230 had already broke a rear axle, and after I went with a mildly built 318 I twisted a rear and granaded a front joint.

As for the lockers, I'm running ARB's front and rear, and would only do the ARB in the front. There is a I believe Detroit that will work as well.

[jeck2323]

Thanks for the input. After reading some older treads I see that an axle upgrade is probably a good idea. What did your 318 conversion require? I'd rather not change the whole drive to start out. thanks again, John

[Gordon Maney]

The 6BT is an extremely heavy engine for an M37.

[W_A_Watson_II]

John,

For my 318 conversion with a hydraulic clutch, it basically required custom mounts & intermediate shaft, a modified radiator and hanging pedals. A lot of info on my site: http://m37.wawii.com/

[jeck2323]

I'm realizing the 6bt will be too much for the m37. What's the downside to fixing the original engine?

[MasterYota]

I'm realizing the 6bt will be too much for the m37. What's the downside to fixing the original engine?

If HP and torque, with the limited RPM range will work for you, then nothing. If your looking for passing power, economy, and the ability to keep up with others, then considering a swap might be a better idea.

The 4bt is a popular (albeit: expensive) swap. And the usual candidates of small block engines have all be done as well with varying degrees of cost. Small block chevy would probalby be cheapest, while a dodge engine would "keep it in the family".

My first M37 had a swapped in 305 with an SM465 4spd. I needed to build two engine mounts, and one tranny crossmember, and then fabbed up some clutch linkage and exhaust. That was it. Cost me less than 800 bucks (for the drivetrain - add about 300 bucks to rewire the truck) and I enjoyed the heck out of that truck. The engine was great on the highway, and I didn't break a single component while out wheeling. It was a good setup. I imagine that any small block would yield similar results.

I doubt that "for money spent" you could equal the same gains with the flathead with the same budget. Now I didn't build a new V8, it was used but in good shape. Same with the transmission. And I save alot of money buy doing all the fab work myself. If your 230 is questionable, you virtually have no choice but to spend the money and rebuild it. Only you can decide if thats money well spent.

Good luck

[Doc Dave]

I'm realizing the 6bt will be too much for the m37. What's the downside to fixing the original engine?

Several people have used 4BT's successfully in the M37 as well as the civilian PW's. Over on Joe's PW forum Paul M has an image event album about this.
Have you thought of selling or trading your 6BT to acquire a 4BT? You would probably make out a little ahead money wise, and also have an engine that fits the truck well, including the power aspects.

[jeck2323]

just got my 4bt home. It came with power steering so I'm wondering what it would take to put a power steering sector on the m37. thanks for all the help steering me in the right direction.(pun intended)