Help with Driveshaft

[gcburdic]

Hey folks....just looking at some pics I took this weekend of my exhaust I installed and noticed that the front drive shaft knuckles(???) do not match the rear driveshaft knuckles (???).....Do I need to line them up??...here's a pic

Thanks for any help!!!

[clay68c10]

They should line up. It's called having the u-joints 'in phase'. Just pull the driveshaft and separate the slip joint then clock it until the caps line up.

[gcburdic]

Originally Posted by clay68c10

They should line up. It's called having the u-joints 'in phase'. Just pull the driveshaft and separate the slip joint then clock it until the caps line up.

Hey Clay.....thanks.....I assume that if they are outta phase, I'll get a little vibration!!!!

Would I be able to remove it from the rear axle and turn it, or will I need to remove the whole driveshaft to get them back in phase??

[El Jay]

If that doesn't take out the vibration, try rotating one half, or the other, 180 degrees.

[cdowns]

i'd suggest taking to driveshaft shop and having it done and balanced its well worth the money

[clay68c10]

Pull the rear half from the rear diff pinion, that half has the slip joint.

[Sinisterspeed]

It looks like a solid driveline portion to me from the pictures. If not its an easy fix. As stated above you just pull the slip yoke and rotate. They should be apposed though. The second joint should be 90 degrees from the first one. I think El Jay was on the right track but just to many degrees. IF you did 180 degrees you would end up with the same thing as if you left it at 0. 90 would get them facing opposite directions therefore causing constant pressure rather since 1 joint would always be bending when the other is not. If they were exactly the same then you end up with vibration as well since you end up with both bending then both not bending at the same time. Hope that makes sense its the best way I could think of to explain it.

[El Jay]

I lust went out and climbed under my GMC.
Sorry no pics because no fancy digital camera.
The u-joint on the tranny is in the same relative position as the ones on the rear 1/2 of the shaft. (Obviously, the ones on the rear 1/2 are in alignment.)

I wouldn't be surprised if this is how it came from the factory. The truck only has about 40K original miles.

[gcburdic]

Originally Posted by cdowns

i'd suggest taking to driveshaft shop and having it done and balanced its well worth the money

Hey cdowns....Thanks for your input....I just grab my receipt from 2 years ago....it was taken to the driveshaft shop....They did replace all u-joints and balance based on the receipt I have....ummmm.....

Originally Posted by Sinisterspeed

It looks like a solid driveline portion to me from the pictures. If not its an easy fix. As stated above you just pull the slip yoke and rotate. They should be apposed though. The second joint should be 90 degrees from the first one. I think El Jay was on the right track but just to many degrees. IF you did 180 degrees you would end up with the same thing as if you left it at 0. 90 would get them facing opposite directions therefore causing constant pressure rather since 1 joint would always be bending when the other is not. If they were exactly the same then you end up with vibration as well since you end up with both bending then both not bending at the same time. Hope that makes sense its the best way I could think of to explain it.

Hey sinisterspeed....Thanks for this input...it is a 2-piece shaft.....so if they oppose each other then it's okay???...If that's the case....I'm okay....they are almost 90 degrees from each other....right??.....And yes, I do follow your explaination of the bending....Thanks again....

Originally Posted by El Jay

I lust went out and climbed under my GMC.
Sorry no pics because no fancy digital camera.
The u-joint on the tranny is in the same relative position as the ones on the rear 1/2 of the shaft. (Obviously, the ones on the rear 1/2 are in alignment.)

I wouldn't be surprised if this is how it came from the factory. The truck only has about 40K original miles.

Hey ElJay....thanks so much for going out and check under the truck, but now I'm confused again....so they should line up with each other???.....Sorry, for all the questions guys.....

[El Jay]

Hey ElJay....thanks so much for going out and check under the truck, but now I'm confused again....so they should line up with each other???.....Sorry, for all the questions guys.....

I'm not trying to be evasive because I'm certainly no drive line expert, but the u_joint at the transmission is oriented the same as the u-joints on the rear 1/2 of the drive-line on my truck. And I wouldn't be surprised if mine is the factory set up.

[Sinisterspeed]

If that was taken to a DL shop either someone messed up or that slip yoke has been off since its trip to the DL shop. It should not be balanced with it like that.


This is the best way I can explain how the drivelines I have had built are set up.


One more thing. This is a 2 piece DL with that top joint at the carrier. I have not done this set up before I am speaking from a 1 piece DL POV. If they clock one half way then the last joint the rest of the way it would be right the way it is. You have a 3rd u joint dont you? How is it in phase according to the others?

[El Jay]

Originally Posted by Sinisterspeed

If that was taken to a DL shop either someone messed up or that slip yoke has been off since its trip to the DL shop. It should not be balanced with it like that.


This is the best way I can explain how the drivelines I have had built are set up.


One more thing. This is a 2 piece DL with that top joint at the carrier. I have not done this set up before I am speaking from a 1 piece DL POV. If they clock one half way then the last joint the rest of the way it would be right the way it is. You have a 3rd u joint dont you? How is it in phase according to the others?

Good eye. I missed that.
I don't think I've ever seen a 2 piece driveline that didn't have the slip joint @ the carrier bearing.

[gcburdic]

Originally Posted by El Jay

I'm not trying to be evasive because I'm certainly no drive line expert, but the u_joint at the transmission is oriented the same as the u-joints on the rear 1/2 of the drive-line on my truck. And I wouldn't be surprised if mine is the factory set up.

Hey El Jay....by no means did I take your response as evasive...I'm with you...I am no driveline expert, and I appreciate your continued input.....

Originally Posted by Sinisterspeed

If that was taken to a DL shop either someone messed up or that slip yoke has been off since its trip to the DL shop. It should not be balanced with it like that.

This is the best way I can explain how the drivelines I have had built are set up.
One more thing. This is a 2 piece DL with that top joint at the carrier. I have not done this set up before I am speaking from a 1 piece DL POV. If they clock one half way then the last joint the rest of the way it would be right the way it is. You have a 3rd u joint dont you? How is it in phase according to the others?

Thanks so much for the illustration/ input Sinisterspeed.....here is the best pic I have right now for the rear axle u-joint....it looks like it is in the same position as the u-joint by the carrier, but my poor eyes can't make it out....guess I need another pic....thanks again for your time and input guys...

[Wrenchbender Ret]

They should line up like el Jay says. There is a 1/2 in bolt with 3/4 hex head holding them together. If you are lucky you can put a open end wrench in there & turn it out. Otherwise you have to take the U-joint apart.

[Sinisterspeed]

Those ones look like they might be in phase or may even be slightly off. I think it would defiantly be worth a trip to the driveline shop when you get a chance just to be sure. Just have one of their guys poke his head under it and make sure you have them all three phased correctly. The U joints should all line up when they are installed. The yoke itself is what I was talking about earlier. But, El jay is right on the money with the u joints they should all line up and yours clearly do not. I am pretty certain that the yoke should be opposite thought. When you get a chance I would have the DL shop look at it.

Here is what I see on that one. But, its hard to tell since you cant see the middle u joint clearly in this picture.

[gcburdic]

Originally Posted by Wrenchbender Ret

They should line up like el Jay says. There is a 1/2 in bolt with 3/4 hex head holding them together. If you are lucky you can put a open end wrench in there & turn it out. Otherwise you have to take the U-joint apart.

Thanks wrenchbender ret.....I appreciate your input....

Originally Posted by Sinisterspeed

Those ones look like they might be in phase or may even be slightly off. I think it would defiantly be worth a trip to the driveline shop when you get a chance just to be sure. Just have one of their guys poke his head under it and make sure you have them all three phased correctly. The U joints should all line up when they are installed. The yoke itself is what I was talking about earlier. But, El jay is right on the money with the u joints they should all line up and yours clearly do not. I am pretty certain that the yoke should be opposite thought. When you get a chance I would have the DL shop look at it.

Here is what I see on that one. But, its hard to tell since you cant see the middle u joint clearly in this picture.

Yeah Sinisterspeed....I think I'll get her over to the DL shop that did the DL balance and repair for a looky!!!....thanks again for your help....