Killing U-joints - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dirtboy488 · 11-15-2005, 12:32 AM

I have had the new motor in my truck for about two months now, and ever since the install I have consistantly killed my rear most u-joint on a weekly basis. (it's a two peice driveshaft) I have tryed a new center carrier but no change. It always kills the two sides of the u-joint that bolt to the rear end yoke. My question is could the torque be flexing the driveshaft enough to burn up the u-joint? Also does anyone know of a single piece driveshaft that will bolt in place? Or maybie somewhere that could make one at a good price?
Thanks in advance,

Terry

cableguy0 · 11-15-2005, 12:43 AM

believe it or not. a two piece is better than a one piece as far as drive line angles go. are you using greasable or non greasable joints? greaseable joints seem to fail a lot quicker anymore.i broke a bunch of greasables then went to none greasables and they seem to better

Green Machine · 11-15-2005, 12:54 AM

If you use the greasable ones, install so that the engine torque pushes the grease hole together insted of pulling it apart, think about which way it turns and study it a bit and you will see what I mean. Non greasble have no holes and are stronger anyway.

sdredneck · 11-15-2005, 01:38 AM

You might have a significant amount of axle wrap. I had the same problem and it was bending the crap out of the straps and then it would destroy the U joint. Now granted I was using wore out springs, 4.10 rear end and 450 hp 400 small block. All of that in a Blazer short wheelbase on a one piece drive shaft. That could of had something to do with it.

Green Machine · 11-15-2005, 10:21 AM

Hmm, I assumed coils in the rear.

shelby987 · 11-15-2005, 10:35 AM

stupid question, how do you know if you have toasted a u-joint?

*FormerMember* · 11-15-2005, 10:43 AM

Are you putting the joints all in phase with each other? I.E. They're all the same direction at the same time?

When you pulled the shaft apart, did you mark it with a line to make sure you put it back together the same?

woodridge · 11-15-2005, 12:26 PM

If the damage is only to the joint where it attatches the diff flange, check for damage or wear to the flange itself. If it is worn or damaged it will cause missalignment of the cups wich will cause joint failure.

11-15-2005, 12:32 AM	#1
dirtboy488 Registered User Join Date: Aug 2005 Location: Reno, NV Posts: 86	Killing U-joints I have had the new motor in my truck for about two months now, and ever since the install I have consistantly killed my rear most u-joint on a weekly basis. (it's a two peice driveshaft) I have tryed a new center carrier but no change. It always kills the two sides of the u-joint that bolt to the rear end yoke. My question is could the torque be flexing the driveshaft enough to burn up the u-joint? Also does anyone know of a single piece driveshaft that will bolt in place? Or maybie somewhere that could make one at a good price? Thanks in advance, Terry __________________ 1969 C10 swb 2wd 1970 C10 swb 2wd SOLD

11-15-2005, 12:43 AM	#2
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: Killing U-joints believe it or not. a two piece is better than a one piece as far as drive line angles go. are you using greasable or non greasable joints? greaseable joints seem to fail a lot quicker anymore.i broke a bunch of greasables then went to none greasables and they seem to better __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

11-15-2005, 12:54 AM	#3
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Killing U-joints If you use the greasable ones, install so that the engine torque pushes the grease hole together insted of pulling it apart, think about which way it turns and study it a bit and you will see what I mean. Non greasble have no holes and are stronger anyway. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

11-15-2005, 01:38 AM	#4
sdredneck The Crazy Kracka Join Date: Dec 2003 Location: San Diego, Ca Posts: 60	Re: Killing U-joints You might have a significant amount of axle wrap. I had the same problem and it was bending the crap out of the straps and then it would destroy the U joint. Now granted I was using wore out springs, 4.10 rear end and 450 hp 400 small block. All of that in a Blazer short wheelbase on a one piece drive shaft. That could of had something to do with it. __________________ My goal in life is to be as good of a person as my dog already thinks I am. 68 GMC LWB 396 BBC Camper Special 72 Chevy Blazer 4x4 with 406 SBC 73 Dodge Dart Sport with 340

11-15-2005, 10:21 AM	#5
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Killing U-joints Hmm, I assumed coils in the rear. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

11-15-2005, 10:35 AM	#6
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	Re: Killing U-joints stupid question, how do you know if you have toasted a u-joint?

11-15-2005, 10:43 AM	#7
FormerMember Account Suspended Join Date: Feb 2004 Posts: 3,051	Re: Killing U-joints Are you putting the joints all in phase with each other? I.E. They're all the same direction at the same time? When you pulled the shaft apart, did you mark it with a line to make sure you put it back together the same?

11-15-2005, 12:26 PM	#8
woodridge Senior Member Join Date: Feb 2005 Location: Maynardville, Tn Posts: 3,030	Re: Killing U-joints If the damage is only to the joint where it attatches the diff flange, check for damage or wear to the flange itself. If it is worn or damaged it will cause missalignment of the cups wich will cause joint failure. __________________ SEMA Network- Protect our Hobby! 71 C30 in pieces, starting to come together. Click here for A Place For Tennessee Truck Enthusiest To Meet



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