Drive Shaft: Converting to One Piece Shaft?

[345 DeSoto]

I'm converting the 2 piece driveshaft in my 289 Sky Hawk, with 200-4R transmission, to one piece driveshaft. Would anyone with this combination have info on shaft length, series U-Joint, and shaft diameter? My Hawk and I are in two different locations, so I am not able to get this info on my own. Thanks in advance...

[Mike Van Veghten]

If I may say, it IS best if you do your own measuring.

While I have a similar combination, I'd hate to give you my measurements, and you have yours built to the same, to be an inch or so different than what YOUR car actually needs. Easy to happen.
While an inch doesn't sound like much, it could ram your yoke right up against the back of the trans. Or...it could pull the yoke out just far enough that while driving on the freeway at 75mph, it actually doesn't have the bearing support that it needs and whips out and trashes your trans., floor, drive shaft...and lots more.

So again, while you can do this, your car, your money (as another says !), I'd make the trip to your car with a good tape and get the dimensions from...your...car.

Mike

[tsenecal]

Maybe not feasible for you, but when I do a custom build, I haul the vehicle to the driveline shop and have him measure it up. He's the expert, and knows how much travel there needs to be in the slip joint. Have always had great luck this way.

[chet445]

I just had my drive shaft shortened. The fellow at the drive shaft place told me to put the shaft all the way in the tranny until it bottoms out then measure from the center of the u-joint on the tranny side to the center of where the the u-joint would fit in the yoke on the rear end. I did that and he took 1 inch off my drive shaft length, balanced the shaft and sent me out the door. It fits perfectly...$85 later. He reduced the measurement I gave him by 1".

[bensherb]

I have a 700R4/4L60 trans behind the original 289 in my '62GT, with the original Dana 44. My drive shaft is 55 1/4" long joint center to joint center, the U joints are Spicer 1310 at both ends 3.219" x 3.219" x 1.062" and the shaft is 3" diameter (the original was smaller and a bunch shorter). My shaft was made by Tatton's Driveline in Murray Utah and shipped to my door, balanced with new U joints installed, for $200.

Your 2004R is 3.062" shorter than my trans. Assuming your engine is in the same place as mine and the axle is too (which I doubt, I believe the springs are different), you should need a shaft around 58 5/16" long. This is quite a long shaft and many makers will not make one this long, particularly one as small as 3" diameter. You will almost certainly have clearance problems with a shaft any larger diameter, especially one that long.

We have a 3" shaft in our '53 with 700R4 and Ford axle, and it will occasionally contact the rear edge of the tunnel. It did the same when it had a Dana 44.

As mentioned by the others, MEASURE YOUR CAR, with the weight on the suspension. There are many variables that can affect the measurement and 1" can make a huge difference.

[Mrs K Corbin]

$85?!?! WOW shop in Nashville charged me $400 to do a 6 footer for my dodge truck. That was for me bringing in the measurements and my old shaft.

I just had my drive shaft shortened. The fellow at the drive shaft place told me to put the shaft all the way in the tranny until it bottoms out then measure from the center of the u-joint on the tranny side to the center of where the the u-joint would fit in the yoke on the rear end. I did that and he took 1 inch off my drive shaft length, balanced the shaft and sent me out the door. It fits perfectly...$85 later. He reduced the measurement I gave him by 1".

[Jeff_H]

Some possibly helpful reading here from my own adventures with driveshaft fitment:

https://forum.studebakerdriversclub.com/showthread.php?24820-Driveshaft-tunnel-mods-was-58-Hawk-HT-rear-floor

[sweetolbob]

$85?!?! WOW shop in Nashville charged me $400 to do a 6 footer for my dodge truck. That was for me bringing in the measurements and my old shaft.

Sounds like they wacked one end off and rewelded it back shorter. IAC $85 is an excellent price for that. The last drive shaft I had modified was like above with new u-joints and balanced $190 locally. For the 74 Avanti I bought one from a local speed shop that set me back about $240.

The OP will need to add a bit more as he will need a new slip yoke for the transmission. Based on my experience with my 74 i'll guess he will need about 61-62 inches so the least expensive route if he doesn't go new is find a Chevy drive shaft in a yard that is over 62" and have the shop graft on his old shaft rear or just use the Chevy setup and find a u-joint that has Chevy and Dana ends.

I wouldn't be shocked if what he wants fabricated by a quality shop with yoke, u-joints, fully assembled and balanced would be around $400.

Bob

[bensherb]

Here's a new yoke $44, https://www.summitracing.com/parts/sdh-2-3-6081x

As I mentioned the Stude shaft ends won't work, where they meet the shaft tube is too small. The ends of the two piece shaft are WAY too small.

Most makers will not make a 3" diameter shaft over 56" long. They will go to 3.5" diameter. Over 60" get's even larger. A typical 3"x .083" wall drive shaft 60" long only has a recomended safe opperating speed of 3092 RPM and a 1/2 true critical speed, (maximum cruise speed) of 2751 rpm. Even my 55" shaft is only 3680 rpm. With my 0.70/1 overdrive and 3.54/1 axle I'd be going 120 mph at 3680 rpm.

1/2 true critical speed1/2 true critical speed

All I sent Tatton (10 months ago, August 8, 2018) was the legnth I wanted, the U joint size and $200 via email and paypal. A week or so later a driveshaft was on my doorstep. It fit perfectly and works great.

[Lynn]

"If I may say, it IS best if you do your own measuring."

True times 4.

[345 DeSoto]

Measuring done...61 1/4" from end of trans tail shaft to middle of differential U-joint saddle...

[alpayed]

This thread is a bit old but why convert? what is the issue with the two piece shaft?

[345 DeSoto]

No matter what I or the Driveline Shop could do, we could not stop the center bearing carrier from "wobbleing" in the cross member. 100% new Stock parts, installed properly, shafts balanced/properly aligned, in phase, proper angles, etc.

[PackardV8]

No matter what I or the Driveline Shop could do, we could not stop the center bearing carrier from "wobbleing" in the cross member. 100% new Stock parts, installed properly, shafts balanced/properly aligned, in phase, proper angles, etc.

This is moot, because the decision has been made to give up and go one piece.
However, it's obvious some of the above only appeared to be correct. Millions of two and three piece driveshafts function correctly for the past hundred years. Drive alongside a medium truck at freeway speeds. Because of the low gears trucks run, the multi-piece driveshaft is spinning so fast it's a blur and narry a wobble.

Installing a one-piece driveshaft can bring its own problems. The early Stude tunnel is quite small, so the more desirable large diameter driveshafts cannot be used. Also, with passengers in the rear seat and/or a load in the trunk, on hard acceleration, the u-joints can hit the underside of the tunnel.

jack vines

[bensherb]

The early Stude tunnel is quite small, so the more desirable large diameter driveshafts cannot be used. Also, with passengers in the rear seat and/or a load in the trunk, on hard acceleration, the u-joints can hit the underside of the tunnel.

jack vines

It doesn't even take hard acceleration, just a decent "whoop" in the freeway. Actually it's the shaft that hits; about 6" in front of the rear U joint. That is with a 3" diameter shaft, any larger will take much less.

Raising the rear of the car, heavy duty or helper springs, and heavy duty shocks can help.