The Stovebolt Site Forums The Shop Area Engine Shop 4 speed question...

Hello all!

The 261 is due back from the machine shop in about a week and a half. Patrick's is going to be smiling after they get my order.
I was under my truck today looking at the transmission. I noticed something that I thought to be strange. As I was looking at the output shaft, I noticed a smaller u-joint below and to the driver's side of the output shaft. To the left of that u-joint, I noticed a small, ummm... :confused: piston or actuator no more than an inch, maybe 3/4 in diameter and it had a piece of baling twine tied to it which was tied to the frame in a rearward direction. Is this a feature to be found on all factory transmissions or am I looking at a swap? 1953 Chevy 3600, factory 216, four-on-the-floor. As always, thanks for the help.

Congratulations, you found the PTO! The piston thingy is the shift rail, just attach a pushpull cable to it if you want to use it.

If it bugs you too much I'll trade you the PTO for a blank cover.

It runs off one of the idler gears in the transmission and it used for powering pumps and winches on trucks. They are rare on smaller trucks but they bolt to any SM420 transmission.

I'm going to guess it has an output shaft from a PTO. Is this right at the back of the transmission? Does it have a PTO (power take off)? Is this a pickup, or flatbed? Maybe the truck had some kind of power accessory once upon a time?

Josiah, Frank,

Have either one of you ever heard of a crank being turned 0.060 Main and 0.040 Rod? I was talking with Danese over at Patrick's Antique Cars & Trucks and she was just horrified. Do you know if she is well founded or what. I also talked with the machine shop tech and he admitted that it was well used but that in ordinary daily driving it "shouldn't" be a problem. What are y'alls thoughts? I am more inclined to believe what Danese has to say about this since Patrick's has such a wonderful reputation, but I am wanting someone else's input that doesn't have an interest in this situation. Thanks. Oh yeah, it is a 3/4 ton truck. Until yesterday, when I crawled under it, I wasn't aware of any PTO features. There are no signs of kind of linkage in the cab. How would it have been actuated? What could it have been used for on a truck? Thanks so much. -Shane

Shane, on the crank- if your machinist says it is OK and you can get the correct over size bearings, then I don't see any problems.It does sound like it is "well used" but it will still work in a "driver". If it is a 235 there is a lot of cranks around that haven't been "used" that much. Always trust your machinist first...

I forgot to answer the other question about the PTO.. Some times they included the PTO but didn't hook it to anything. It was there just in case you needed it. Remember- most of these old rigs were actually "farm use rigs". You could use the PTO to run a mower or baler or even a saw mill. Lots of "farm uses".

Oly,

Thanks for the reassurance. It does make me feel a little better. The machine shop can get the bearings to fit the grind, so that doesn't seem to be a problem. Patrick's can get me a crank for $175.00, which while added cost seemed like it might be a safer, more assured route. I like what you have to say though and I think I will give it a try with my crank as is. It is a 261, by the way, but it is my understanding that the 235 and 261's are similar in every aspect save the pistons, rings, and larger oil passages in the 261. Thanks again.

-Shane

As long as you're not building a high hp engine, the crank should be okay.

PTOs are mainly used for powering winches, and hydraulic pumps for things like dump beds. I've never driven a truck of this series with a pto, most that I've driven had either a cable control that mounted under the dash or a floor lever beside the tranny. If you aren't going to use it, I would suggest trading it for a side cover and letting someone use it that needs it. They are getting a little hard to find, but there are lots of side covers out there, so the pto is worth a bit more than the cover. Just how much, I don't know.

The only reason the pto would have been installed is to run somekind of equipment, like the others have said. It would not have been a Chevrolet option, though the truck dealer could have installed it when the truck was brand new. They are all after market made by names like Chelsea, Muncie, and others. It was never installed "just in case". It might be cool to know the history of the truck and what the pto was used for. I bought one listed in a swap meet ad about 4 years ago from a nice guy in Wisconsin for $45.
About your crank, .060 seems like too much to me as well. I did not know you could get bearings that undersized. My local shop quoted me $160 to turn the crank in my 235. I don't know how that compares to yours, but it's real close to Patrick's price. Good luck.

The crank is a pretty conservative design. As long as you have a good harmonic balancer and can get the bearings and oil seals to fit it will probably be fine, as long as you are not planning to rev it to the limits. The harmonics can be bad with a 4 main design and the thinnner the crank is the worse they get.

Thanks guys,

I think I will try the crank as is, 60/40, and just watch it real close and try to see how it acts after I run it in a bit. If it doesn't behave like it ought to then I suppose I could always go back in with a crank from the Patrick's source. I don't plan on maxing out the revs on the engine, but it will more than likely see some highway speeds 30-40% of the time. Thanks for all the input.

Frank, I will consider trading out that PTO...if I can't find something cool to do with it. Seems like a really neat feature to have. Do you think it would be possible to rig a shaft out the rear of the truck to feed PTO driven items like a log splitter? Hmm?....

Sure. Lots of tow trucks, military, etc. had mechanical winches and stuff running right off the pto. Running a hydraulic pump would be cool with quick disconnects at the front or rear for mobile or remote equipment, like a log splitter. Be sure to design your hydraulic system correctly and safely with a pressure relief/ by-pass valve, etc. That pressure has to go somewhere when it's dead-headed.

OK - this is exaclty what I have been looking for... Oly, or anyone else... I'm looking for more information on finding a mower that can be run from the PTO of an old farm truck... I've been wanting a bigbolt ever since John M. put that dump truck up for sale for $900 last December. And I'm finding reason to justify getting one, 'cause we have 10 acres of undeveloped land at church we have to mow, and we go through 30 yards or more of mulch and compost each year taking care of the 5 acres that is landscaped with gardens and trees... So I'm looking for a dump bed truck for the mulch/compost, and if I can dual-purpose the PTO to run a mower, than I'll be in hog-heaven cuz I really can justify getting myslef a nice big toy...


Should I move or repost this to the Big Bolts forum?

you might wanna make a parts wanted post, but I'd bet you'll never find one - the pto's ran hydraulics for dump beds and road plows, not 3 point hitch driveshaft equipment unless some haywire farmer [like Oly, who you won't be getting a mower or an answer from!] rigged them for some stationary use - you can justify the dump for the hauling alone, get a real mower for the grass instead of rutting up the fields with a truck

Bill

The tractor we currently hire out to mow the field has to weigh 4 thousand pounds, I'm guessing... and has those narrow tires... I didnt figure the additional weight of the truck, spread out over the dually rear wheels, would rut up the field any worse... We'll have no problem staying off of it when its wet, and when it's dry, this North Texas ground gets pretty hard... It's probably been 10 years at least since this particular 10 acres was plowed and raising crops, so its pretty hard...

But I was skeptical about a 3 point hitch rig... Was wondering if Oly was referring so something else... Apparently not... The imaginary "haywire farmer" in my head though, wonders about suspending the cutting bed underneath the chassis... Turn the thing into the biggest strangest riding lawn mower ever...

I guess I'll go back to "plan A", and keep building a small fleet of actual riding lawn mowers as we find them at garage-sales and swap-meets... Thanks Bill!

This may sound weird, but there were companies that made 3 point setups for trucks. I know for sure that they were made for Jeeps, both as factory equipment and aftermarket conversions. I seem to recall seeing a similar setup for the early Power Wagons, too. I don't know if there was one for other brand trucks, though, but there were/are kits for adding a 3 point to older tractors that were not factory equipped with one. I could potentially see someone adapting one to a truck, especially one that's been converted to a Doodlebug tractor.

I have the pto on my3/4 ton and we had a dump box. Our stock pick up box sat down on the frame and there was no hint at a dump truck unless you checked under and saw hydraulic oil storage and the cylinders for lift. Just took out oil storage and cylinders this past winter. Had heil cylinders and home made oil storge of about a gallon and one half. The 56 is just a pickup again!

This should get you going MacX:

http://www.film.queensu.ca/Cj3b/Tech/Mowing.html