GMC 211 engine and auto trans boost and smooth

[Gunfreak25]

Does your M135 bed have a tailgate? The beds themselves are not easy to find anymore, nevermind the proper tailgates.

 

[JackG]

It has a tailgate but it seems a little short width wise, it also has a step that swings out when released. I'll take a pic tonight and post it.

 

[M543A2]

My friend in the automatic trans shop that worked on the civilian and military versions of these transmissions, both repair and race builds, said that getting the valve body out of a car of the same vintage (Cadillac for one) that used the Hydramatic and changing it out with the military body would cure the harsh shift problem and give one more control over the shifts. I never got around to trying it though. He also advised to immediately get the engine oil out of the trans and put Dexron in it. I did that and never had a transmission problem in 20 years of hard farm use. I highly recommend this change! Be careful to never over-fill the trans or it will heat up. I had a trans temp gauge installed in mine at the "oil" plug on the pan bottom.
I also recommend draining the coolant at the "water" plug on the trans pan, taking off the front cover on the trans pan and checking for any crud that has collected in that compartment. It is a low point on the cooling system, so any "mud" or crud that is in the system settles there and restricts the ability of the oil cooler. You can wash it out with a hose, but a power washer might damage the cooler inside.
Keeping the bands adjusted, cooler clear, and using Dexron will make the trans a reliable unit. I get upset somewhat when I hear how these transmissions are guaranteed to be undependable. Proper maintenance and care is all they ask. I know that without a doubt from many years of trouble-free hard use with mine that was maintained the way I have described.
Regards Marti

 

[JackG]

Thanks Marti, I will do just that. I am still feeling my way around the truck. I have a manual on my computer but haven't printed it out to take down to the truck. As I read, I generally have more questions than answers. You folks have really been great help. I hope I can return the favor one day. I must say I that it is one hefty truck. I my opinion the M211 has a unique look to it. I will post more pix today. Thanks, Jack

 

[Gunfreak25]

The M211 borrows heavily from the CCKW in looks and in some ways, mechanically as well. Just remember, GMC stands for Generate More Cash.

 

[AMGeneral]

It has a tailgate but it seems a little short width wise, it also has a step that swings out when released. I'll take a pic tonight and post it.

Jack that would be the early style tailgate for the GMC M135 or M34 Reo,decently valueable if it's straight and functional.

I know where there is a decent M135 bed complete with the later style tailgate and troop seats here in NC if it hasn't been scrapped.

 

[135gmc]

Good luck finding a new muffler - the only source I think might have any is Alfa Heaven, in WI. I don't think any of the other surplus dealers have any left. A friend of mine was working on an M221 (2 1/2 ton semi-tractor), and wound up modifying an off the shelf truck muffler by moving the entry pipe. You mightalso try some of the canadian surplus dealers - the Canadians ran the GMCs much later than the US did.

Drive the truck exactly by the manual, except don't try to back up in high range - that was hard on the tranny, and the military told drivers to use low when backing up. Like all the gassers, the truck is underpowered for today's roads, but it will get you there. I found that wehn I tried to keep up with traffic, the mileage dropped to about 2 MPG, but if I took it easy, it would do about 6 MPG.

If you decide to use a rebuilt carb, be careful - some of the rebuilt surplus carbs were set up for use in an armored vehicle, and the acceleration pump needs to be reset. Move the acceleration pump plunger from the max stroke hole on the arm to the middle hole to change the pump for a wheeled vehicle.