Inliners International Forums General Discussion Truck Talk Torque tube replacement

I'm changing my 46 1/2 ton over to an open driveline, W/T5. I want to pull the torque tube and replace it with the a pumpkin from a 55-62 rear end.

Now I know that most 55-62 trucks came with a 3.90 rear but what other ratios are avalible?

Will a pumpkin from a car bolt up the same way as a truck or are they a different size.

Any advice would be most appreciated.

George

Dear George;

You'll need to change the whole axle assembly, not just the 'center section'.

Check with Patrick's for all the ratio(s) etc.

The T-5 shifter may be to far back to work in a P/U truck. Bryan or someone else will know about that.

Good luck.

Hey George -

I have finished my T-5 installation in my 37 Chevrolet 1/2 ton truck and I feel qualified to tell you a few things that you need to consider.

I know you are still running six lugs wheels, but you might want to consider going to Chevrolet car 49-54 hubs. Those hubs will slip right on you truck front spindles and you would be five lugs. With that problem solved, you can go to the Chevrolet car rear end choices and when you talk about 55-64, you are talking about a choice of 3.08, 3.36, 3.54 (Power Glide), 3.73 and 4.11 rear gears, the most common being the mid range ones. I used a 55 Chevrolet 3.54 car rear axle and with the Classic Performance Products kit advertised in Classic Trucks magazine. With that comversion kit you can easily convert that car rear axle to go under your truck. You can even make your emergency brake cable work for you. You can also use the car drive shaft with the T-5 yoke. The one problem you will have on your truck is your master cylinder. Because your master cylinder is plumbed on the transmission side, you are going to be very limited on just how you can make that master cylinder work with the T-5. It gets pretty tight between the T-5 and a master cylinder plumbed on the transmission side. I used a master cylinder plumbed on the outboard side and it was very easy. If you use a 1/2" thick adapter, your shifter will end up about 9 1/2" back from the stock location. That should work fine for you, although you will have to alter the S-10 shifter. Several of the guys who have put T-5's in their 41-46.5 trucks have had good luck with various shifters. I used a
B & M shifter in mine and altered it to work for me and my shifter ended up within four or five inches from my seat. Finally, let me say that if you don't already love your truck, you will fall in love with it after you do this conversion! It is a great upgrade! My truck performs so much better than it did - just can't tell you the difference it has made! Let me know if you need any help. I'll be happy to do all I can to get you going on this change and you'll love it!

Joe

Thanks for the info guys. Ive got the T5 but I'm still looking for a rear end. I would like to keep it as simple as possible. That's why I am looking at just replacing the pumpkin. If you haven't seen it, check out Steppenwood's great writeup on this over on the Stovebolt site. It seems like this would be the easiest and cheapest way to do it. Also everything in the rear I have now is new, bearings, brakes, brake cylinders everything. I really don't want to discard it all. With a pumpkin swap I can keep all the previous work I've already done.

Anyway that the direction I'm heading, I may have to stick with a truck rear, from what I'm hearing the pumpkin from a car isn't going to work.

Thanks
George

Car center sections won't work with the truck housing/axles.
There was a 3:36 gear available, but it's tough to find. They do make a repop of the 3:36 gear, though $$$$.

George;

Just look for a 55 & up pick up rear end, is all. Your wheels will all fit & the e-brake cables too.

You may need to move the pads + make a driveshaft.

Good luck.

George -

If you want to try to change out the pumpkin, you are on the right track. I don't know how easy it will be to find a truck pumpkin with the right gear, but it can be done.

I've done all the other stuff, so if you have any questions, let me know!

Joe

Thanks guys. I'll keep you informed on my progress.

George

Dear Joe;

The 46 Chevy P/U is a Spiicer 'rear end' and NOT the same design as the "pumpkin" style, where the axels are held in by the bearing retainer(s).

I suppose it could be "re-invented", but at what cost in time and money??

This guy is a novice at all this. :rolleyes:

John -

George wants to do the same thing to his truck that John Sandoval (Steppenwood) did to his 1945 pickup featured on the Stovebolt page. John changed out the center section on his 1945 1/2 ton pickup and installed a 1955 pumpkin, welded up the axle and now has an open driveline.

Joe

J;

That is a totally "Micky Mouse" procedure and potentialy dangerous!!

That type of advice could get someone killed when an axle comes out on the freeway from a broken weld while carrying a load. This is a truck, remember.

A novice might believe (MM is OK) is the real danger here.

We all need to be very carefull when giving advice in todays legal climate.

George,

First, making an adapter plate for the tranny to 46 bellhousing won't be necessary (like in the Stovebolt article) as Buffalo allready makes one for $120.

Second, the 55-62 truck center section can be used, but 3.90 and 3.36 were the only gears used. 3.36 can be bought new from Patrick's or Randy's ring and pinion, plus others.

Using a whole 55-62 truck rearend can be done, but it's several inches wider that the '46, so this may be an issue with you depending on the rims and tires. The '46 brakes are different than the '55-up, also. Changing the spring perches is still necessary.

To fix the rearend in place, Speedway Motors (and others) sell some spring perches for $12.95, see part #54585090 over at www.speedwaymotors.com . Remember that the rearend is not centered over the spring center bolt!

You'll need to come up with a driveshaft. Probably have to find one thats a little long and have it shortened and the rear yoke changed to match your rearend yoke.

Personally, I would go with what Joe suggests, and use a 55-64 car rearend. It's a little less work, no expensive aftermarket gears needed, 3.36 and 3.56 geared centers are readily available used. New wheel cylinders and shoes will run about $35 for comparrison.

John -

You misunderstood me. I wasn't endorsing what George wants to do, I was merely explaining what George wants to do.

As far as "Mickey Mouse", that's your opinion.

I told George what he needed to do a couple of posts back. Car rear axles fit very nicly under trucks like his. I just put a car rear axle (3.54) under my 37 and the cost of the project was less than $100.00 with new brakes and new wheel cylinders. A set of 55 Chevrolet car rear brakes is $15.00 and a two new wheel cylinders is $18.00.

Joe

I've been lurking long enough and I had to get in on this...
Mr. Meredith- With all due respect, there is nothing "Mickey Mouse" that I have done. The welding was done on the spring perches to the rear end housing (no welding on axles). There are several Inliner members (and Stovebolt members too) that have done exactly what I did to convert to an open driveline. The reason I kept the original rearend housing is 'cause the '55-'64 unit is too wide of a width. Also, you questioned the positon of the T-5 shifter, actually it's in perfect position for the '41-'46 pickup.

Steppenwood -

I appreciate you coming in on this and lending your input.

My approach to the open driveline / T-5 installation on my truck was done a different way than the approach you took, however, both are very well done and are not "Mickey Mouse" jobs. I have owned my truck for 30 years and before I do ANYTHING to my truck, I throughly investigate and study the procedure to the fullest. I spent about four years throughly investigating this alteration to my truck before I did it. I talked with everyone from Jack Halton on down that I thought would have information that would help me. I would put the job I did on my truck up against anyone's and I did it right!

Joe

Dear John;

There's nothing wrong with moving/adding perchs/mounts, or welding on the housing. It's done all the time in the industry and your photos show professional work.

Glad to see that the shifter position is okay too.

I was led to believe otherwise on the welding issue..

What puzzels me is why the spring mounts had to be moved if you were keeping the same housing for that truck and what axles were used to keep the 6 lug truck configuration.

The front of the torque tube housing is joined to the rear if the original transmission, the rear of the torque tube is part of the original pumpkin. So the original rearend mounts allows for slight (very slight) rotation of the whole rearend housing beings that the torque tube kept in position. The newly welded in spring perches is the only thing that keeps the rearend housing in position after the torque tube goes away.
My original axles fit perfectly into the '55 pumpkin with no modification.

Steppenwood and others : This was interesting to me, as I am doing a driveline conversion on my -39 gMc 1/2 ton pu. I do have a -55 1/2 ton rear that I can take the pumpkin out of, and do the conv. as you described, very informative pics! I want to keep the stock track width and the 6 lugs, as I have 2 sets of nice 6 lug rims. But my question is: Is it possible to ad a "possie" in the diff., and will the old stuff hold up the torq and power of a 302 with 10:1 comp,280deg. cam, 500cfm carb and th400 trans?

Gee Wiz I didn't realize that I was going to start a big controversy. John M is right I am a novice at this stuff, that's why I'm asking questions. I think that Steppenwood's approach is the direction I'm going. I want to keep the 6 lug axels. This keeps me from trying to find 5 new 5 lug wheels that will work with my orig. hub caps. Plus the width factor is important to me.

It just seems easier for this novice to swap out the pumpkin, get new perches welded on, and go from there.

I've got the T5 and have already straightened the shifter to workwith my seat position, plus I even shortened up the throw by redrilling the shaft to raise the pivot point. This part was easy. Now all I need to do is find a 55-62 rear end, a drive shaft, and an adaptor plate from buffalo and I'll be set.

I truly appreciate all the advice I get from you fellows, without your expertise I wouldn't have gotten to first base with my truck. It has been a learning experence for me, but all the hard work has been worth it.

Thanks
George

Steppenwood, I dont see how replacing the perches gained anything. Are you saying the old u-bolt and mounts have to be changed because the pinion angle changes? I cant see any other reason to remove what the factory had placed there.

John;

I understand this now. The 55 P/U center section (pumpkin) is a Spicer too and the axles from the 46 are the same, except for their lenght. This IS a great combination as there ALL truck parts, going into a truck.

I stand corrected for the "Micky Mouse" description as I thought a passenger car (non Spicer) center section was being used & the axles (somehow) welded, to stay in.

George;

The rear axle housing must stay stationary & that's why the new mounts, as the torque tube was solid and held it before.

The 1955 era truck 'rear ends' were designed for 200+/- Hp. engines, in commercial service. I would think if NOT abused it would "hold up" just fine. The 1939s were designed for 100 Hp. so your smart to change.

Good luck to all.

6inarow and John -

You guys should know that the rear axle on these trucks is just like the rear axle on the cars with torque tubes. The axle is "clamped" between two machined parts so the axle will rotate slightly during driving, When going to an open drive line, these two "clamps" must be removed and and spring perches welded to the axle so the axle pinion angle can be set for use with the open drive shaft. That's what John did on his truck and George wants to do on his truck.

Joe

Hi Joe,
I wasnt aware that the torque tube axle had some rotation to it. I assumed the design of the torque tube prevented any rotational movement. But now that you say that I can see why the perches would have to be installed and made like the open drive vehicles
Tom

The rear axle assembly does not 'rotate'.

It can't be a solid connection to the springs because the drive shaft/tube needs to be moveable when you go over bumps. The spring(s) need to move in this process too & this is why there is only one stationary mount on them.

To 'rotate' there would have to be a U-Joint in the rear.

It moves forward/backward-up/down when the springs change shape from road changes/the vehicles body movement etc.

Walt is right . . .

As understand it, in a torque tube setup the axle cannot be afixed to the springs - nor can the propeller shaft be afixed to the transmission - because both the driveline angle and length vary.

The pinion angle is dictated by the geometry within the tube. But as the axle rides up and down through spring travel the angle of the tube itself changes. This is why the universal joint is enclosed in a spherical coupling. This holds the distance between the transmission tail case and the rearend pumpkin constant - allowing the angle to change, and also allowing the propeller shaft to slide in-and-out on its splines as the axle moves up and down on the springs (end play).

With an open driveline the pinion angle is dictated by the perches. Driveline length is constant with universal joints at both ends.

As Steppenwood points out in his website - the torque tube spring perches are unsuitable for use with an open driveline - because they allow the axle to rotate which would change the pinion angle.

regards
stock49

HI Guys- Great to read all the solutions for this problem that we all go through as we change things on these old trucks. Biggest problem with the Chevs and torque tubes is that you can't easily change just one major component.

If you want a bone stock appearing truck that's just fine, but we can't leave well enough alone, I didn't.
FYI my 46 has had the following rear ends in the 30 years I've owned the thing:
Stock torque tube with 4:11 gears.
Passenger car torque tube with 3:55s, but 6 lug.
57 truck with 3:90s.
Now, 65 pickup rear with 3:08.

For my money the trans and rear end gear selection is just as critical to the enjoyment of the truck as is the motor.

Another plus in changing the entire rear axle is you'll step up to the more modern brakes. I also installed the 57 truck drums on the I beam, now have better brakes on all four corners.

Best of luck George.

This is correct.

The (new) open driveshaft one would 'rotate' as the torque tube is now gone.

Orginally the torque tube held it in place, while the springs 'walked' back & forth as their arch changed.

The 'ball shaped' transmission adapter does "rorate slightly" in the transmission's socket, as the driveshaft/torque tube slide in/out.

But It's not part of the rear axle housing.

I might have a line on a 61 GMC rear end. Are these the same as the Chevy?

George

Probably not, but check with Patrick's in Az.

It may work though. Just get out the tape measure etc.

The debate here was to keep things as 'orginal' as possible & still have an 'open' driveline so the later OD transmissions could be used.

Good luck.