The Stovebolt Site Forums The Shop Area Driveline What open drive line axle would fit a 54 Chevy 3100? Rear Tranny support?

Ok I have 2 questions. I am still trying to connect my non torque tube tranny to my torque tube axle. At the junk yard today I spotted a different tranny that I can rob the back plate and u joint off of and would I think do what I need. But I am still considering changing over to an open drive shaft. I am just torn because I am trying to stay somewhat original with the project but I don't want something that is going to be so slow or high maintenance that it is impractical to use. I want to have some fun with the truck but I also want to use it for typical home owner hauling jobs. Can some one tell me a good donor vehicle for an open drive axle? I would for sure like the same length as stock, same 6 lug hub pattern, and if possible the same brake components. In hind sight I should have changed over to 5 lug hubs and it would make this a little easier. But at this point I have the entire front end rebuilt and wheels bought so I just want the truck to be running and usable with the 6 lugs bolt pattern.

Also can someone explain or show me a picture of what supports the rear of the tranny? My truck has no cross member past the bell housing and neither did any truck at the junk yard today. Maybe they just didn't need any support for the rear of the tranny but I find that hard to believe especially since the torque tube appear to be held up by the tranny as well.

Thanks

The cross member under the rear of the engine changed in 1954. This allowed the elimination of the cross member and support at the rear of the manual transmissions.
http://www.1954advance-design.com/Documents/EngineeringFeatures/slides/Page49.html

Special cross members in those two locations were needed/used on trucks equipped with the heavy Hydra-Matic transmission.

The 1954 3100 rear end is a 3.90 ratio. A 3.55 R&P swap is possible in that enclosed driveshaft rear end. Check the Tech Tips on this site.

If you want to change to open drive shaft, find a 55-66 1/2 ton rear end. You may have to change the spring mounting perches or maybe not. get the drive shaft while your at it. Fairly simple swap and can be accomplished in a weekend if you have the tools and a handy helper.

When did the standard 3100 truck ratio change from 3.90 to a lower ratio?

I think there is a set of 3.38 R&P conversion gears for Task Force rear ends. However, if you have a 3-speed, 1st gear might be a little high?

Maybe someone who has done this will post info?

Ok so basically the engine supports the tranny and front of the torque tube axle? Thats surprising but I guess those are all stout parts and not like the plastic trucks they build today. Thanks for the link

I thought I read some where the ratio on a stock axle was 4.11? Or maybe I am confusing it with the 3/4 ton truck. Thanks for the year range , I will call the junk yards on monday and see what I can find. Whats everyones thoughts on the best axle ratio for these trucks? I don't think I will ever change the tranny out on this truck. I may on occasion haul some weigh in the truck or pull a medium weight trailer. I understand you can't have the best of both worlds but would the 3.38 give you some decent torque or is it all for speed?

Thanks again

If you have the original 1954 1/2 ton rear end, it is a 3.90

http://chevy.oldcarmanualproject.com/chevyresto/54132.htm

The rear engine support is under the clutch housing, which was changed in 1954.

If you use the 3.55 converted enclosed rear end, you might find the original enclosed driveshaft 3-speed might have too high a 1st gear if you are loaded. I have used that combination without problems, and I might go back to that (to get the floor space from removing the 4-speed shifter).

If you use the 4-speed enclosed drive-shaft rear end, you can start in first gear or second gear, depending on the load you are carrying. This is what I now have.

Ok good to know, not sure where I got 4.11. Thanks for posting that link. So it looks like my options are a 3.55 with the stock axle, or a 3.38 if I change out to a 55 or later axle. My 54 is actually a 4 speed also. Are torque tubes really that bad? I hear horror stories about them but if you take care of them and have a good seal after the u joint to keep oil in the tranny would they not be a reasonably reliable set up?

I see no need to change my from my torque tube. It has the 3.55 R&P and the parts kit. All parts in my front end and braking system are new.

I can cruise the Interstates all day at 65 mph at around 12-15 mpg. If I cruised at 60, I'd get around 15-18 mpg. I have impressed/astounded my friends by easily hitting 90 mph (but, I backoff immediately).

No horror stories from me. I still get a little drip under the u-joint housing until I re-tighten the collar ring.. I have gotten used to it ,and I top up the transmission fluid every year.

I cannot wrap my head around how one could possibly do this on a '54 3100.

If the transmission is an open driveshaft SM420 4-speed, a 54 or earlier SM420 rear cover and ujoint assembly for an enclosed driveshaft can convert the later SM420 to work with an enclosed driveshaft.

Thanks thats good to know. Thats what I was hoping for when I bought that SM420 from a 57 3100. I quickly found out that rear cover is impossible to find. I thought with people doing conversions from torque tube to the open drive there would be lots of those rear covers out there for sale. But I found not a one. I finally found a tranny in a GMC at the local junkyard that has that rear cover and u joint. They won't sell me just the cover but they said they would take $100 for the whole tranny so I guess thats not bad. I just thought I would consider an axle swap before I went that route but maybe I will just go grab that tranny next weekend. I thought I heard no one made higher gearing for these torque tube axles but I was proved wrong in this thread so all the more reason to keep the stock axle. I don't mind topping the oil off every few months if I have to.

12-15 MPG? Thats going to be hard to get used to after years of driving my 20 year old Honda that gets 40 MPG.

When you switch to the 3.55 R&P how do you keep your speedometer working accurately?

"When you switch to the 3.55 R&P how do you keep your speedometer working accurately?"

A speedometer ratio adapter that screws into the transmission. Do a search here on +ratio +adapter

Thanks Tim. Got my head all wrapped up now.

Today I stopped by the local junkyard and found a possible open drive axle for my 54 3100. Actually 2 different axles. One is sitting in the back of I believe about 59 3100 so I am assuming that's the truck it came out of. The other is in a newer truck but I'm not sure what it is exactly. That axle bolts to a triangular frame and uses coil springs. I am thinking it is a 60s 3100. It has some big spring perches I would have to cut off but that's an easy job for the cutting torch. I would for sure go with the 59 axle the problem is its missing the cover and one axle shaft. Also it looks like the pinion hit the spider carrier and left some gouge marks. From what I can tell the 60s axle looks complete and in better shape. I thought the 59 axle would be a bolt in but the spring perches are about 1.5 inches too narrow and they appear to be on the top of the axle, not the bottom the way my torque tube currently is. Anyone have any experience with either of these axle types? They are both the correct width and lug pattern.

Jonald, Is this the part you are looking for ?

photo@photobucket

http://i669.photobucket.com/albums/...204%20speed%20-GM_591679_zpsxuoiu4ut.jpg


I know where to get this part . It has been cleaned - media blasted and painted

no U Joint included.......he wants $120.00 & shipping


George
'54 3600

'54 3600, selling or offering to sell is a prohibited activity in the regular forums. Swap Meet Forum. In this case you should have just sent Jonald a Private Message. Sorry, it's just the site rules.

That part I actually have. I bought a whole tranny from the junk yard that has that plate and the u joint assembly. I thought I found exactly what I needed but unfortunately the u joint is a 10 spline and I needed a 17 spline. I am assuming the truck is a 3/4 but it was hard to tell. It was nothing but a frame engine and tranny sitting in a field. If I cant find that u joint in another week or so I am going to go ahead with the axle swap. In that case I will have a tranny, and complete torque tube axle with leaf springs to sell if anyone is interested.

Thanks for the offer

Ha Is that all you got for me? You're usually my expert on these issues.

Im still trying to figure out if a 59 or early 60s axle would work out for me. I don't see any reason it wouldn't but I thought maybe there was some things Im not considering. I wish the 59 axle was complete but its missing the cover, one axle, and the brakes. No matter what I get I will probably rebuild it with a 3.5:1 ring and pinion. The 59 might be a bolt in for me but it looks like the perches may be about an inch too narrow. But its not a big deal because I can get the conversion kit with new perches for $100 and I have a welder. I may see what kind of deal I can make on both axles and use the best parts from each. It seems like most people use axles that came from later novas but I want to keep the stock length, lug pattern and I dislike axles that do not have a removable carrier. Any thoughts?