700R4 / One Piece Driveshaft Conversion

[pdawg]

Hey guys, I've got my fresh 700R4 in and am considering going to a one piece driveshaft. Are there any clearance issues with the back crossmember (where the carrier bearing usually sits) hitting the new one piece driveshaft ? It looks like it could be kinda tight. Thanks!
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[summitflier]

Considering doing the same... subscribed.

Are you running stock height?

[michael bustamante]

long or shortbed?

[pdawg]

Stock height, long wheel base.
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[leftybass209]

I don't know what help it will be, but I have a 1 piece on a 3/5 lowered shortbed and I have plenty of room around the entire driveshaft for full rear suspension articulation.

[pdawg]

Hey Lefty,

Thanks for the reply. I think the lowering & short will give you more clearance than I will have. I'm interested if anyone with a normal ride height long box has had any problems before I go to the expense of ordering my new driveshaft.
Thanks anyway !
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[67ChevyRedneck]

Tape a couple of broomstick handles together so they're the length of DS that you need and wrap something the diameter of the DS around it where the cross member is (like pipe insulation and tape).

The lower the truck, the more clearance you will have, that is correct. My DS has a ring scrape around it from my earlier years when I used to "jump it off stuff" (like railroad track humps). The suspension would drop from the jump and the DS hit the bottom of the cross member.

[hamjet]

It seems if its close on a stock height then when you jack it up by the bumper or frame it would hit. Thats why I stuck with 2 piece..

[pdawg]

Originally Posted by 67ChevyRedneck

Tape a couple of broomstick handles together so they're the length of DS that you need and wrap something the diameter of the DS around it where the cross member is (like pipe insulation and tape).

The lower the truck, the more clearance you will have, that is correct. My DS has a ring scrape around it from my earlier years when I used to "jump it off stuff" (like railroad track humps). The suspension would drop from the jump and the DS hit the bottom of the cross member.

Good idea - actually I've got a telescoping paint handle that would likely work. I'll give that a try once I lower it from doing the tranny install. Thanks for the idea!
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[brad_man_72]

3.5" diameter will fit through the crossmember. Od and a one piece driveshaft in a longbed is a bad combination.I wouldn't take it over 100mph depending on engine location, gearing and tire size.

[67ChevyRedneck]

Originally Posted by brad_man_72

3.5" diameter will fit through the crossmember. Od and a one piece driveshaft in a longbed is a bad combination.I wouldn't take it over 100mph depending on engine location, gearing and tire size.

Why is it a bad idea?

My modern extended cab Z71 has a one piece, it's a pretty long drive shaft.

[pdawg]

I was told it was best to go one piece - less chance of failure. I know drag strips won't allow you to use slicks with 2 piece driveshafts, so I figured they must be weaker.
This is why I'm asking the question before I swap!
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[WIDESIDE72]

Originally Posted by leftybass209

I don't know what help it will be, but I have a 1 piece on a 3/5 lowered shortbed and I have plenty of room around the entire driveshaft for full rear suspension articulation.

I am running the same setup as this in my 72 with no issues. I even had a pretty good load of parts when I headed to the swap meet this past April with no issues.

[WIDESIDE72]

BTW I am running a stock shaft out of an 86 or 87 swb I found at the wrecking yard. They don't haul cars around with loaders so I was pretty sure it wasn't bent. New u joints clean an paint and I was good to go!

[Dust Collector]

I tried to get a one piece made for my 72 long bed and the guy at the driveline shop said it was too long of a gap. I put a 700r4 in as well. Mine kept eating up the carrier bearing so he cut the back section in half and installed a slip yoke. Seems to be working better.
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[pdawg]

Originally Posted by WIDESIDE72

BTW I am running a stock shaft out of an 86 or 87 swb I found at the wrecking yard. They don't haul cars around with loaders so I was pretty sure it wasn't bent. New u joints clean an paint and I was good to go!

My '72 longbox has not been dropped, so I may have an issue with clearance. I'm most concerned with clearance when the suspension is extended, as that looks to be tighter. Thanks for the feedback !
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[pdawg]

Originally Posted by Dust Collector

I tried to get a one piece made for my 72 long bed and the guy at the driveline shop said it was too long of a gap. I put a 700r4 in as well. Mine kept eating up the carrier bearing so he cut the back section in half and installed a slip yoke. Seems to be working better.
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I guess that's also an option - thanks! I wouldn't have thought you'd use a carrier bearing with a one piece driveshaft. I'm starting to think I should stick with my 2 piece & just have it shortened. Unless I'm willing to drop the suspension it sounds like it could be a headache!
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[Hogshooter]

One piece will rub when suspension droops, I have one with a ring in it from that. I also had problems with transmission bushings because of this long drive shaft.

[pdawg]

Thanks Hogshooter! That settles it. 2 piece it is.
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[brad_man_72]

Originally Posted by 67ChevyRedneck

Why is it a bad idea?

My modern extended cab Z71 has a one piece, it's a pretty long drive shaft.

Its also made from 5" diameter tubing not 3.5" the larger the diameter tubing the longer the shaft can be at a specific maximum rpm.

[Ruscal]

Mine is a short bed with T400 and a 4" aluminum shaft. With a 6" drop and fully bottomed I had contact at the top of the xmember opening. I trimmed the top of the hole about an inch, and one side about a half inch and then formed some flat bar around the opening to replace the lip. It took a couple of hours to do. Including a little rattle can touch up. Pretty easy.
A drive shaft shop should be able to help you out with the length, diameter, horsepower, torque calculations.
Russ

[enigma]

I have a 67 long bed with 700r4 with one piece drive line. Had to buy lowering cross member from ccp and turn it up side down to make it work. JFYI

[summitflier]

I have a short-bed, stock height. My truck was originally a i6, but somewhere along the line parts were changed, when I got it had a 350 with a TH400 (long shaft). It has a one piece shaft. The transmission cross-member is a home made affair made from a piece if I beam. It still has the original cross member for the trailing arms. So far I haven't had any problems with it hitting or rubbing anywhere. The 700R4 (I haven't installed it yet) had a shorter tail shaft on it. It seems that would lower the height of the drive shaft in relationship to the frame. If I wanted to raise it back up, I was told they make the transmission yokes in different lengths. (up to 2 inches longer anyway).