2 peice driveshaft angle question.

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jmlcolorado

Well-known member
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Jul 23, 2010
Messages
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Location
The flat plains of Elbert County, CO
So I'm building my binder on a 68 gmc c10 chassis. ( http://www.ratrodsrule.com/forum/showthread.php?t=15930 )
I would like to keep the floor inside tha cab as low as i can without cutting much of a trans hump in the middle. I wanna put a jumper seat in the center for the kid and having a 7" chop and 3" section is cutting headroom low as it is.

My question is, i think a 2 piece drive shaft will help me do this. The factory setup came with a 2 piece design with a carrier bearing. If i mount the engine on the frame with -3 degrees of angle back, the carrier bearing is set at 0 degrees on the frame.
My question is at what angle should i set the rear end be in comparison to the carrier bearing angle?
The truck is going to be on bags with the frame laying on the ground when parked. So i will set the rear end pinion angle at ride height. My guess is i will want 3 degrees upward angle on the rear end right?

Thanks for your help folks.
 
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See if this helps.
 

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Great..... another useful diagram to paste to the garage wall :D
Thats exactly what i was looking for.
So this tells me that the engine and trans should be mounted with a 0 degree angle right?!
I guess with this diagram on the table, my next question would be, it looks as though both the tail shaft pinion as well as the diff pinion are set to 0 degrees. Would it beneficial to mount the diff pinion angle to a +3 degree angle so that when the centerline of all the drive line u joints become in line, the back one still has a slight angle to keep tension?! I cant figure out how to explain my question.

Also.....and im not questining the diagram, but, if a guy were using a 1 piece shaft, he would mount the engine with w -3 degree angle on the tail shaft and a +3 degree on the diff pinion, why would you not want the same contition on a 2 piece?
This is where my head is thinking. -3* on tail shaft, 0* at the carrier bearing, +3* on the diff pinion. Maybe im all wrong.
 
Depends on your engine, but you'll need to keep the carb level which would mean about a three degrees down angle on the engine and trans (in most cases). The crossmember that you bolt the carrier bearing to for your drive shaft will need to be paralle with that angle. Then your pinion will angle will need to be three degrees up.
 

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Ive attached a butchered image of the above diagram to help explane my thinking.
Please DO NOT use the atttached photo as a referance.
 

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Depends on your engine, but you'll need to keep the carb level which would mean about a three degrees down angle on the engine and trans (in most cases). The crossmember that you bolt the carrier bearing to for your drive shaft will need to be paralle with that angle. Then your pinion will angle will need to be three degrees up.

Sounds like you and i are on the same page. Ill mount my motor with -3* angle, my carrier bearing will need +3*, and the rear end will need -3*

Right?

Man, adding a second pivot is making my head spin [S
 
I've never really seen that setup....not sure if you would have a problem with deflection when you hit bumps and such with the rear tires. Although with the slip yoke on the carrier bearing you might not have a problem. Not 100% on this...do a little more research on. I'll let you know if I run across anything about. You might want to ask some guys on the Mini-Truck forums...I'm sure those guys have dealt with this before.
 
I've never really seen that setup....not sure if you would have a problem with deflection when you hit bumps and such with the rear tires. Although with the slip yoke on the carrier bearing you might not have a problem. Not 100% on this...do a little more research on. I'll let you know if I run across anything about. You might want to ask some guys on the Mini-Truck forums...I'm sure those guys have dealt with this before.

Good deal. Thanks for your help. You've already shed some light on a cloudy subject in my head :D
 
Sounds like you and i are on the same page. Ill mount my motor with -3* angle, my carrier bearing will need +3*, and the rear end will need -3*

Right?

Man, adding a second pivot is making my head spin [S

I think it will depend on if there is a u-joint on both size of the front part of the drive shaft. I've seen some with and without. If not then you only need the -3* down on the tail shaft and +3* up on the rear end. The main point is that the pinion angle and the tail shaft angle are offset and paralle for proper u-joint operation.

I know how you feel...at the same point in my build.[S
 
I think it will depend on if there is a u-joint on both size of the front part of the drive shaft. I've seen some with and without. If not then you only need the -3* down on the tail shaft and +3* up on the rear end. The main point is that the pinion angle and the tail shaft angle are offset and paralle for proper u-joint operation.

I know how you feel...at the same point in my build.[S

I see what your saying. that make sense. I guess ill have to wait and see what the factory shaft looks like since the chassis didnt come with one.

Man....all this thinking makes me wanna go to a 1 piece shaft :rolleyes:
 
Its amazing how much work it is to add 1 u-joint! There are so many variables its crazy!
On my 03 Dodge Ram with a 5.9 cummins, i had a 2 piece shaft with a large harmonic balancer on the #1 shaft. The hard rubber mounting the balancer went bad and caused HUGE vibrations in the truck. I converted the shaft to a 1 piece 6" aluminum shaft and eliminated the carrier bearing with no ill issues for 60k plus miles.
I guess i just lucked out at having angles that worked well with each other by doing that.
If i would have read all this informatin before i did that swap, i probably would have scared myself and spent the extra $400 over the cost of the swap to keep the extra u joint and carrier bearing (which i constantly had problems with failing) with the 2 piece shaft.

Im really leaning towards doing a 1 piece shaft after all this information now :confused:
Im starting to think that having a 2 piece isnt worth the headache of getting angles that work well together through the entire suspention range. Especially since the truck is sitting on bags and has about 8 inches of travel.
 
perhaps i can throw a little info out there to clear some foggy minds. the reason you have to match the u joint angles is due to the momentum created as the joint works itself back and forth in operation. when the angles are the same on both u joints of the same shaft, the momentum created by one is cancelled out by the opposite motion of the other joint, giving you vibration free operation :)
but this is not the end of this discussion, when assembling a driveshaft you must be sure to properly phase the u joints, and by this i mean that the drive shaft yolks must be clocked in the same position, this is not a concern with a single piece shaft because the yolks should be welded on in line, but if you have a drive shaft with a slip joint that you let fall apart, you cannot just slide it back together all willey nilley like, it must go back together with, for example, both u joint yolks at the 12 o clock position.....
that was a bit long winded... sorry, but hope it cleared some issues up for you all
 
There is nothing wrong with a long winded reply when it's full of valuable information.
I was kicking around a 2 piece shaft on a bagged binder pickup to keep the floor at stock height and avoid a large trans hump but the more info I get (like yours) about the science involved, I'm hesitant to go that way.
Especially since the driveline angle will be changing drastically through suspension articulation due to the bags.

The rear end will see 8-10 inches of change depending on what the bags ate set at.

Both dodge rams I've had both had a 2 piece system and I always had carrier bearing and u joint failure. Probably from improper installation.
I have since replaced my 3" 2 piece shaft on my 03 crew cab long bed for a 6" aluminum 1 piece shaft and will never look back. I've lost the "launch shudder" in the truck now as well as getting rid of 1 extra u joint and a carrier bearing.

I think people (including myself) are pretty blind to the science of rotational mass when it comes to that long stick that attaches to my transfer case and rear end. :D
 
i didnt even mention anything about a variable hieght situation encountered with bags.... but there is a way of thinking it through, you just have to set your angles to be correct at your comfortable ride hight. but if your using a four link for the rear axle the drive line angles are a non issue because a properly set up four link will keep the diff at very close to the same angle weather its at the top or bottom of the travel. so as long as the engine and diff are on the same plane you wont have any problems :) just remember that as long as both joints operate at the same (but opposite) angle, all is well
 
Granted with most rear suspensions there will be a change of angle during travel, this angle could be side offset instead of up and down. The point I remember is not being lined up too perfect, This will not let the bearings in the u-joint move the grease around. We also tried to keep within +- 4 degrees.
 

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