2 ppiece drive shaft question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kaphillips · 10-08-2013, 10:05 AM

I have a 70 swb 350 th350 truck with 2 piece drive shaft. I am doing a big block conversion and th400 tranny swap. My question is what is the difference between the 2 drivelines. Is it as simple as just adding a th400 yoke on the front shaft or are the carrier bearing, cross member and shafts different on the big block set up. Thanks

**bigmac73** · 10-08-2013, 10:10 AM

the 400 tranny has a differnet yoke, I had to get a thick walled yoke and shorten the drive shaft about 2 inches or so , if I rememeber right, this was back in the early 90's,
but i rememebr being told by the garage that did the install to go find a thick walled yoke at a local junk yard, i think cars had a tinner walled yoke

geezer#99 · 10-08-2013, 10:48 AM

Get a new yoke for the T400 and then have a new one piece driveshaft built.

kaphillips · 10-08-2013, 12:19 PM

If I keep my existing original 2 piece driveshaft factory small block (1/2 ton) set up and change the yoke for a th400 then it would be exactly the same as a factory 2 piece big block would have come ? Correct?

**bigmac73** · 10-08-2013, 12:32 PM

no you would have to shorten the front shaft

Eddie H. · 10-08-2013, 02:49 PM

Another option would be just find a 2 piece driveshaft from a truck that was equipped with a TH 400 from the factory, install new u joints and carrier bearing and you're good to go.

geezer#99 · 10-08-2013, 04:43 PM

Best option is to have a one piece built. New joints, new tube, gauranteed not to be bent, balanced and fit perfect. Usually 250 bucks.
Or shorten yours, new steady bearing, get it balanced and checked for straightness and 3 new joints instead of two. Likely 200 bucks.
For 50 bucks more you're set.

ItsRandy · 10-08-2013, 11:34 PM

You could use the th350 and use the drive shaft you have as is. Using the 400 is a better idea. If you use the 400 just shorten the front shaft and change the yoke. There is probably a good reason the engineers at GM used a two piece shaft. I have a 502 and 4l85e with a two piece shaft and it works very well.

10-08-2013, 10:05 AM	#1
kaphillips Registered User Join Date: Jul 2013 Location: Amarillo Tx Posts: 502	2 ppiece drive shaft question I have a 70 swb 350 th350 truck with 2 piece drive shaft. I am doing a big block conversion and th400 tranny swap. My question is what is the difference between the 2 drivelines. Is it as simple as just adding a th400 yoke on the front shaft or are the carrier bearing, cross member and shafts different on the big block set up. Thanks

10-08-2013, 10:10 AM	#2
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: 2 ppiece drive shaft question the 400 tranny has a differnet yoke, I had to get a thick walled yoke and shorten the drive shaft about 2 inches or so , if I rememeber right, this was back in the early 90's, but i rememebr being told by the garage that did the install to go find a thick walled yoke at a local junk yard, i think cars had a tinner walled yoke __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

10-08-2013, 10:48 AM	#3
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,731	Re: 2 ppiece drive shaft question Get a new yoke for the T400 and then have a new one piece driveshaft built.

10-08-2013, 12:19 PM	#4
kaphillips Registered User Join Date: Jul 2013 Location: Amarillo Tx Posts: 502	Re: 2 ppiece drive shaft question If I keep my existing original 2 piece driveshaft factory small block (1/2 ton) set up and change the yoke for a th400 then it would be exactly the same as a factory 2 piece big block would have come ? Correct?

10-08-2013, 12:32 PM	#5
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: 2 ppiece drive shaft question no you would have to shorten the front shaft __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

10-08-2013, 02:49 PM	#6
Eddie H. Registered User Join Date: Mar 2001 Location: Paradise TX USA Posts: 1,200	Re: 2 ppiece drive shaft question Another option would be just find a 2 piece driveshaft from a truck that was equipped with a TH 400 from the factory, install new u joints and carrier bearing and you're good to go. __________________ "Negative people always seem to have a problem for every solution"

10-08-2013, 04:43 PM	#7
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,731	Re: 2 ppiece drive shaft question Best option is to have a one piece built. New joints, new tube, gauranteed not to be bent, balanced and fit perfect. Usually 250 bucks. Or shorten yours, new steady bearing, get it balanced and checked for straightness and 3 new joints instead of two. Likely 200 bucks. For 50 bucks more you're set.

10-08-2013, 11:34 PM	#8
ItsRandy Registered User Join Date: Nov 2010 Location: Grand Terrace, Ca. Posts: 1,607	Re: 2 ppiece drive shaft question You could use the th350 and use the drive shaft you have as is. Using the 400 is a better idea. If you use the 400 just shorten the front shaft and change the yoke. There is probably a good reason the engineers at GM used a two piece shaft. I have a 502 and 4l85e with a two piece shaft and it works very well.



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