Figuring Out U-Joint Needed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cebra · 12-05-2019, 04:31 PM

Continuing to work out some bugs on my truck as it is near complete. I have driveshaft vibrations going on and when I put a new rearend in, I noticed my u-joint that attaches to the rearend was too narrow (did not go from tang to tang on rearend). The truck was a 350/350 long bed with 2-piece driveshaft and 12 bolt rearend. It now has a LS and a new 1-piece driveshaft. It will need a hybrid u-joint; I can pull the u-joint and get the x measurements (cap and width to fit driveshaft) but how do I get the cap and width measurements for the y to fit my rearend? Was a standard u-joint used on all 12 bolt rearends? Can I measure ID tang to tang to get the y width, if so how do I get Y cap measurement? Thanks for any guidance.

**Steeveedee** · 12-05-2019, 07:25 PM

It's too late now (maybe), but the driveshaft shop could have welded on the proper end so that a stock u-joint could be installed. There are u-joints that do this kind of adapting, but I have no experience with them.

**tdangle** · 12-05-2019, 07:36 PM

Yes, they make conversion U-Joints. Had one in a dodge years ago after swapping the rear end out.

countr · 12-05-2019, 10:06 PM

I worked in the manuf. driveline business for a period of time. Not sure this will help. but if you go online for Neapco (made in Nebr.)conversion u-joints there will be PDF of the lockup conversion dimensions. these u-joints allow you to attach two different lockups together. Dim. are listed. need to match up cup od and the two different lockup lengths (if your lucky).
Thanks Russ

**kwmech** · 12-06-2019, 12:56 AM

Quote:

Originally Posted by cebra

Was a standard u-joint used on all 12 bolt rearends? Can I measure ID tang to tang to get the y width, if so how do I get Y cap measurement? Thanks for any guidance.

Yes, 90+ percent of the time it is a 1310 u-joint on the trucks. If the u-joint has a gap between the tangs then the yoke could be worn out. Have seen this quite often

**bigmac73** · 12-06-2019, 07:36 AM

i would call Denny's driveshaft or look on their website and see what they got.
https://www.dennysdriveshaft.com/

cebra · 12-09-2019, 02:15 PM

Quote:

Originally Posted by kwmech

Yes, 90+ percent of the time it is a 1310 u-joint on the trucks. If the u-joint has a gap between the tangs then the yoke could be worn out. Have seen this quite often

Perfect, I will measure the tangs and see if they are 3 1/4" or if they have worn to a bigger size.

*randy500* · 12-10-2019, 10:22 AM

1310 is most common, some use 1330, here are the specs.
http://www.driveshaftspecialist.com/...D%20Guide.html

12-05-2019, 04:31 PM	#1
cebra Registered User Join Date: Jan 2018 Location: Durham, North Carolina Posts: 782	Figuring Out U-Joint Needed Continuing to work out some bugs on my truck as it is near complete. I have driveshaft vibrations going on and when I put a new rearend in, I noticed my u-joint that attaches to the rearend was too narrow (did not go from tang to tang on rearend). The truck was a 350/350 long bed with 2-piece driveshaft and 12 bolt rearend. It now has a LS and a new 1-piece driveshaft. It will need a hybrid u-joint; I can pull the u-joint and get the x measurements (cap and width to fit driveshaft) but how do I get the cap and width measurements for the y to fit my rearend? Was a standard u-joint used on all 12 bolt rearends? Can I measure ID tang to tang to get the y width, if so how do I get Y cap measurement? Thanks for any guidance. __________________ My Daily Driver Build: http://67-72chevytrucks.com/vboard/s...d.php?t=755668

12-05-2019, 07:25 PM	#2
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,108	Re: Figuring Out U-Joint Needed It's too late now (maybe), but the driveshaft shop could have welded on the proper end so that a stock u-joint could be installed. There are u-joints that do this kind of adapting, but I have no experience with them. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

12-05-2019, 07:36 PM	#3
tdangle Senior Member Join Date: Mar 2005 Location: Jurupa Valley, Ca Posts: 1,209	Re: Figuring Out U-Joint Needed Yes, they make conversion U-Joints. Had one in a dodge years ago after swapping the rear end out. __________________ Terry 1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC

12-05-2019, 10:06 PM	#4
countr Registered User Join Date: Dec 2015 Location: Russell, Iowa Posts: 2,010	Re: Figuring Out U-Joint Needed I worked in the manuf. driveline business for a period of time. Not sure this will help. but if you go online for Neapco (made in Nebr.)conversion u-joints there will be PDF of the lockup conversion dimensions. these u-joints allow you to attach two different lockups together. Dim. are listed. need to match up cup od and the two different lockup lengths (if your lucky). Thanks Russ

12-06-2019, 07:36 AM	#6
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Figuring Out U-Joint Needed i would call Denny's driveshaft or look on their website and see what they got. https://www.dennysdriveshaft.com/ __________________ 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

12-10-2019, 10:22 AM	#8
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: Figuring Out U-Joint Needed 1310 is most common, some use 1330, here are the specs. http://www.driveshaftspecialist.com/...D%20Guide.html



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