The Stovebolt Site Forums The Shop Area Engine Shop Small 3 speed behind a 261

I have overhauled a 261 to install in my 1950 3100. I want to keep the “3 on the tree” shifter for nostalgic reasons. Will the current small 3 speed transmission carry the extra torque of the 261 under normal driving (no hot rodding) conditions? If not how do identify and locate a HD 3 speed that will carry the load and fit? Will I have to modify the shift linkage and/or driveline to install a HD 3 speed?

Thanks for your response in advance.

One thing to remeber is that you have a torque tube driveline. I don't think that there ever was a tt type heavy 3 speed. I may be wrong about that, though. Personally, I don't think that there'll be any problem with the tranny you've already got. These old trannies are really tough.

Actually, the shorter 3 speed was the heavy duty 3 speed. The longer one is the standard version. I don't think you will be able to tear up the HD 3 speed with a 261 unless you are running drag slicks on a heavy truck and winding it up before dumping the clutch. Lord knows it would be tough to power shift a column shifter. I had a fairly healthy 235 in front of HD 3 speed and it never gave any problem.

If youre still running the closed driveline,,the weakest point is the front u-joint. That'll break before anything else does. But,if youre not going to be hot rodding it,keep your three on the tree and enjoy.............
Marty

Bill,

There was a heavy-duty 3-speed 1/2 ton (torque-tube) transmission in 1954 but not in 1950. The '54 H-D 3-speed was available with different tailshafts for use on all 3000 series 1954 trucks (1/2, 3/4, and 1-ton).

On the 1/2 ton it was the same length as the regular 1/2 ton 3-speed. The column-to-transmission shift-linkages were slightly different. The two transmissions are easy to tell apart - the regular transmission's tailshaft is long and narrow and tapered; the H-D tailshaft does not have the long narrow taper.

My guess is that H-D 3-speed was not common on the 1/2 ton and might have more popular (but still uncommon) on the larger trucks that came standard with a 4-speed (". . . the convenience of a steering column gearshift on 1 ton models for those drivers who do not require the reduction offered by the standard 4-speed transmission").

A heavy-duty 3-speed transmission was available in 1950 on the Sedan Delivery (1508).

I doubt very much that the extra torque (+15%) of the 261 engine is enough to worry about with the standard 3-speed, unless you plan to drag race. I drove for years with no problems using a 261 and the standard 3-speed in a '54 Suburban.

Tim

That 3speed can handle a lot a abuse. I use mine on the strip since years without problems.

Let me quote Bill Fisher here to answer your question:

I think now u get the picture

Frank

That same basic tranny was used up into the early 1960's on Chevy trucks and cars,and was the standard non option tranny behind some powerful V-8's including the 409.
Not to say it's bulletproof,far from that,as young guys we found regular abuse on those tranny behind a 265 or 283 V-8 would mean a monthly trip to the wrecking yard for a replacement.
But old trucks have poor traction so the wheels will spin before the tranny blows,hopefully......

Thanks gentlemen for the info.

The early Chevy transmissions had bushings in the cluster gear and with hard use the bushing slipped from the front of the cluster toward the back, this let the gear slightly disengage and automatically removed the teeth from both the main drive gear and the cluster. Later (I think around '52 or '52 the improved transmissions had needle bearings at both ends of the cluster gear, making them less prone to failure. The way I broke dozens of transmissions was to "speed shift" from 1st gear to 2nd. I could keep the throttle floored and a quick "dip" of the clutch would allow enough time to cram the shift lever from 1st to 2nd, and very often break the trans. When I had a GMC 270 built up in my '39 Chevrolet I broke so many transmissions I carried a spare in the trunk and several times changed the trans at the curb. The bottom line is this, the stock (with needle bearings) 3 speed trans. will easily handle the 261 engine, but DON'T speed shift it!!
I am gathering parts to change the Hydramatic in my '54 GMC to a 3 speed, and the built up 248 engine will work fine with that setup.