open driveshaft for a torque tube tranny.

[Buick35]

Has anyone had any success in replacing the torque tube unit (it's for a 35 40series) with a different higher geared rear end and drive shaft retaining the same transmission? If so I would be interested in which one would work best using the same bolt pattern for the wheels. I know I could get an overdrive but really don't care to. Thanks.

 

[Guest]

Title and text are not quite the same. 

In answer to the "title", Any machine shop or driveshaft shop could convert the universal joint to a common spicer joint and make you a driveshaft.

The answer to the "text" is a bit more complex.  These, all from a simple Google search, might help.

 

https://www.jalopyjournal.com/forum/threads/buick-torque-tube-to-open-driveline.578566/

https://m.roadkillcustoms.com/1949-54-gm-car-torque-tube-to-open-driveshaft-conversion/

https://www.google.com/search?q=buick+torque+tube+eliminator+kit&rlz=1C1CHBF_enCA819CA819&oq=buick+torque+tube&aqs=chrome.1.69i57j0l5.10666j0j8&sourceid=chrome&ie=UTF-8

 

I wish you good luck with your modifications.

[joe_padavano]

Actually, this is the article you want to read. The problem is that the torque tube is the primary locating link for the rear axle. If you eliminate it, you need to basically design a new rear suspension. There IS one possible option. The third gen Camaros used a torque ARM suspension. Basically it functions like a torque tube to locate the rear axle, but it is an open C-section instead of a closed tube and thus uses a conventional driveshaft inside the channel. A pivot bracket on the back of the trans serves the same function as the ball on a torque tube. Since the Camaro (and Firebird) axles of this vintage have the mounting provisions for this torque arm cast into the center section, you might be able to fabricate a similar torque arm to fit the geometry of your Buick with minimal disruption to the rest of the chassis. The only alternative is a four link or leaf spring rear suspension conversion.

 

Here's what the torque arm setup looks like (OK, this is actually a Vega, but the Camaro is nearly the same):

 

 

 

There are actually aftermarket kits for installing a different trans in a car with a  torque arm suspensions. Many use a pivot bracket that looks like this:

 

 

And to come full circle back to Buick, the GNX turbo cars came from the factory with a torque arm suspension. In that case, they used a special rear cover for the axle that incorporated the torque arm attach points.

 

[Buick35]

Thanks for your reply,Greg.

[mcdarrunt]

Your 35 should have leaf springs so it simplifies an open drive line conversion. In the case of my 37 40 series the only hitch was the leaf springs had shackles at BOTH ends. This let the rear end shift forward or back either in unison or one side only. A set of  61 Chevy tie rods made light duty trailing arms that have lasted 30 years. Most leaf spring cars of that era had an eye bolt at the front of the spring which made a torque tube not necessary.

[joe_padavano]

1 hour ago, mcdarrunt said:

Your 35 should have leaf springs so it simplifies an open drive line conversion. In the case of my 37 40 series the only hitch was the leaf springs had shackles at BOTH ends. This let the rear end shift forward or back either in unison or one side only. A set of  61 Chevy tie rods made light duty trailing arms that have lasted 30 years. Most leaf spring cars of that era had an eye bolt at the front of the spring which made a torque tube not necessary.

 

The problem with using the two trailing arms and keeping the dual shackle leaf springs is that you lose the rotational restraint of the housing as the pinion tries to climb the ring gear under acceleration. There are still too many degrees of freedom in the suspension. Yeah, yours may have lasted 30 years, but that depends on driving style and luck. Eliminating the front shackles and using a single pivot at the front of each leaf is the better way to do it, as this eliminates the need for the two trailing arms as well as the torque tube. A pinion snubber might be a good idea, but I doubt the car will be doing an drag race launches off the line. 😁

[thegnu]

you may have an easier time doing that mod in your car , check my thread . in post war buick , 55 roadmaster complex suspension modification .  some of the gentlemen here brought up points that I hadn't considered.

 so whats your reasoning for wanting to swap to an open drive shaft ?

[Buick35]

Just to be able to install a higher geared rearend.I know I can get an overdrive installed.I wish I could just change the ring and pinion gears.Thanks,Greg.

[pont35cpe]

9 hours ago, Buick35 said:

Just to be able to install a higher geared rearend.I know I can get an overdrive installed.I wish I could just change the ring and pinion gears.Thanks,Greg.

Greg, i`ve been down this road with my `36 40 series, and realized the OD install(Lloyd Young did mine) in the torque tube was the best way to go. Both our cars have spiral cut gears in the rear-end, the pinion is at the same level as the axles, our engines sit level. Think of it like this, it`s a straight line thru the crankshaft, transmission, and torque tube to the axles and your u-joint in the tail of the trans is basically spinning not pivoting. If you go to open drive, i doubt you`ll find any open drive type rear-end with spiral cut gears, they`re all hypoid gears, which the pinion center line is located a couple inches below the axle center line. Cars with hypoid rear ends, the engine is mounted tilted to keep that straight line thru engine to the pinion. Your car, the straight line i mentioned, would have a big bend at the transmission to the rear end, this would really over work the u-joint and wear it out in no time. After i realized all this, the OD in the torque tube was the best way to go.

[Buick35]

Thanks,Greg.That makes sense.

[Steves Buick]

Which overdrive unit did you install? I'm looking at the Mitchel , any thoughts? many thanks. 

[pont35cpe]

6 hours ago, Steves Buick said:

Which overdrive unit did you install? I'm looking at the Mitchel , any thoughts? many thanks. 

Lloyd Young did mine before he passed away, grafted in a Borg-Warner R-10 which was common in Borg-Warner 3spd speed transmissions 40s-50s-60s. Here is a discussion on AACA about this subject.