The Stovebolt Site Forums The Parking Lot Big Bolts anyone put a modern auto trans into an old big bolt ?

i was thinking about the possibility of replacing the original CH465 trans behind the 327 engine in the 68 C-60 with a THM475 tranny that i have sitting here collecting dust

i know i would need to fab up a crossmember and driveshaft

but otherwise would i have any other issues, other than shift linkage and column ?

i cant see that i would have any other issues to deal with


and i think it would be pretty neat to have an auto in it

THM475 trans is about as heavy of an auto as you can get, cept for an allison or something else like that, but i wouldnt want one of those

and i dont need the trans parking drum brake deal either,


anyone here done it yet ?

thanks for anything

I think the TH475 was used in 1-ton trucks, but am not aware that it was ever used in anything heavier.

I have a P30 (1-ton truck) with a 12,300 pound GVW that has one. I don't know the rating of your C-60. Is it much more than that?

If you use this truck to capacity I'd want to do a little more research before assuming the transmission will last long in a bigger truck. If all its going to move around is the truck itself I bet you'll be fine.

But I'm just guessing I don't really know...

With-out the trans brake, what are you going touse for a parking/emergency brake?

Sound like a great plan on paper. Last I was aware, your required to have a parking brake of some kind, on any truck. A big bolt with none is just asking for trouble. Your may also have trouble with the parking prawl holding back a large truck. Empty might be fine, or on the flat, but anything much of a load or a hill and it won't hold. All our yard automatic trucks, come with a hand brake and no park in the trans. Empty they dont weight much more than my 47 does.

Put the biggest, baddest trans-cooler money can buy on it too,
Scott

One other concern would be getting a transmission yoke to fit the TH400 series 27 or 30 splines or whatever it is and be 1410 / 1460 series on the U joint. You will find that those yokes are much heavier and are for larger diameter shafts with 10 splines or so. Also they are not made as a slip yoke to fit like a car uses but rather are like a midship stub uses. I doubt anything is readliy available.

Frankly I don't think this is a good idea.

I have seen plenty of TH400-475 in motor homes that held up fine, school busses also used them before going to Allisons, big [censored] yokes are available new at driveline shops(but pricey), my bro went to huge 1460 on his blown pickup truck w/TH400. brian.

Just say NO to slushboxes!

I remember reading that a typical automatic tranny sucks up about 20hp.. if we're talking about a old bolt with something like a 90HP engine in the first place, that dosen't leave alot of 'ummph' left over for doing truck stuff.

Only time i've seen a slushbox in a bolt is usually when they've swapped the engine to something like a small block v8.

me personally i'd just say no to an automatic period i don't care for automatics at all really, love manuals except for newer manual trannies that run Auto Trans fluid in them i look at it is this way when an Auto leaks IT LEAKS don't like auto tranny fluid just cause its darn near just like water i think now a manual barely leaks even when the fluids hot unless theres one heck of hole but ya.... just don't like auto to many things to go wrong and just plain goofy that and its just so fun to just sit back and jam through the gears
Nate

For your driveline,use the front shaft from a 0ne ton w/automatic,and have a driveline shop remove the front end of it and splice it to your old driveline. Don't forget to replace your carrier bearing while you have the truck down. I don't remember the name but there's an outfit selling a carrier bearing with polyurethane in place of the rubber,has enough flex to soak up some vibration but lasts forever.
I agree with the guys about parking brake-remember,all the "Park" feature in your transmission is relying on is a little hunk of plastic or potmetal-that's all that keeps it from rolling away.A motorhome might have something that'll work without having to replace the rear end. I ALSO agree with the big-[censored] transmission cooler,and I'd wire in an electric fan for it too. Also,use one of the deep pans available for it,cast aluminum if you can get it. (A trans. temp. gauge would be a very good thing,too.) For the shifter,you can build a tower to mount over where the old shifter used to be from angle iron,and mount a cable operated shifter on it,and upholdter some thin plywood panels to cover the sides of it.
As was pointed out.they use automatics in motorhomes and school busses,so it oughts work okay in your truck.
Speed

there are allisons trans that will work much better than the one you are talking about and have the drum brake on them. old schoolbusses might be a good place to look, as well as some public service vehicles or utility trucks. with the allisons i think you will have to worry alot less about ripping the thing out under load.

maybe do a swap with someone for what ya got.

Don't they make 700R4 for 1 ton trucks?

The 700R4 has been replaced with the 4L60 series transmissions.

The 4L80 is the heavy duty automatic with overdrive. I'd like to replace the Tutbo 400 in my 1-ton with a 4L80 but it cost a pretty penny...

I think if the truck is going to be used like a truck you may want to stick with the existing transmission.

My TH475 has the transmission parking brake stuff on it. If yours does too, then I'd say go ahead and make the swap. Just be prepared to go back the other way if you load the truck and break the transmission...

Just my 2 cents, our 97 chevy 3500 HD has the 4l80 auto in it the truck weighs in at 12500 lbs empty and have towed a 3/4 ton pick with 5th wheel attached for thirty miles and several other jobs that are over the limit of the truck and the trans holds up well I think . Its got 220,000 on the odom and its only on its second trans first went at 160,000 change the fluid twice a year and go with the additional tranny cooler outside of radiator