Why did Dodge build it this way?

[JTurben]

Hi all:

I joined TDR, found a nice 93 D350 CC auto for sale, went with a buddy to look at it, and HE bought it, with my blessings as I think I want a single cab. Now we have it up on the hoist fixing about 99 things we found wrong (and it's a nice truck) Standing back and looking down the drive line (two piece driveshaft) I notice that it is not straight I. E. it takes a little turn at the midship bearing on its way to the rear end. Why was this done? Is straight better? Muffler clearence? I want to slide that center mount over but someone stop me if I shouldn't. This site is great and I want to say thanks to all who take the time to share, with it we have killed the KDP, turned the screws, put in a gov. spring, a 16 housing, pressure tested and switched out a verrry holeyyy charge air cooler(-0- air build at test) plus many more things. I have some guages to install then it's off to the mopar show in Vegas (april 1-3) towing a car and trailer from Michigan with the 93, Black truck black trailer, wave If you see us.

Jerry

 

[Greenleaf]

Isn't the diff carrier off set a tad on the ax. assy???



GL

 

[JLEONARD]

To answer your question, an u joint will last longer at zero degrees than if needlessly operated at an angle.

From what I gather you want to move the bearing/driveshaft to eliminate the left/right angle?? So it must now go one way after the bearing, then go into the axle at the opposite angle, thus making an unecessary "jog"?

 

["Mad Max"]

Hey Jerry -

We're also going to Vegas for the show - where U stayin'? We're at the Sahara - bunch of the gang from the club here in the Springs are going, and I'm taking the Magnum.



On your question, not sure - Sounds like GL said, or maybe the carrier bearing got relocated for some reason.



- Sam

 

[Grey Wolf]

My sons '90 D250 is straight! The C Bearing is bolted up right next to the fuel tank... ...

 

[dan brooks]

I don't have a center bearing - just one long shaft that runs straight from the trans to the diff.

... a u joint will last longer at zero degrees than if needlessly operated at an angle.

Actually, there needs to be a slight angle to promote lubrication. If continuously operated at zero angle the rollers can't spread the grease and the U-joint will wear prematurely.

 

[Greenleaf]

This is what I'm told and is said to be the honest truth... ... ... . so I'm told.



The drive shaft DIRECTLY behind the trans HAS to be straight, no angle what so ever. The ONLY shaft that is "allowed" to have any angle to it is the last one. The one that is attatched to the diff yoke.





So I'm told by the old school guys... ... ... .....



My buses have like four separate shafts. They are ALL straight EXCEPT the last one. It's off center and sloped downward.



Some of our buses had to be "re-aligned" cause the shafts leading to the rear most shaft were not in perfect register with the engine crank shaft.



Sounds dumb but true.



The only u-joint that goes bad on the bus fleet is the most rear u-joint, right at the diff yoke.



For what it's worth.



I have no idea what my truck shafts look like in terms of angles... ... ... ... ... .



GL

 

[paccool]

I agree with Dan, need to have a little offset to keep things greased. At least that was what I was taught. Lord knows I may be wrong, had that happen a time or two!

 

[1stgen4evr]

joint angle

Technical 'best practice' will dictate that the joint have minimun angle. This will however be for a joint that is operating at or under its load design. In practice, I have seen multiple segment drive lines that will show more wear at the minimun angle joint and less wear at the steeper angle joint. I believe that this manifest due to overload and the fact that the zero angle joint has no action to keep the needles from eroding into a single knife edge line.



Failure on the joint will be from overload and angle operation that exceeds the clearance of the joint. I have had this problem on my 93 from just that, overload and extreme angle at the differential. The two front joints lasted a very long time. The joint at the transmission was replaced only a few k miles back at about 425k. I don't think you will have a problem at stock hp if the drive line is in its original position.





James

 

[JTurben]

Hey Sam, We might be sleeping in the trailer as we havn't booked rooms yet. We went last year and pulled the black trailer with a 90 something borrowed suburban diesel. We got a whopping 6 mpg all the way out and back. The exhaust broke on the pass side going up a hill (mountian) so we lost the turbo (no pressure to spin it on a V8) but we got all the fuel. It put out so much black smoke we allmost caused a wreck, and it was at night to boot. We are fixing everything on this 93 that even looks worn. We showed a silver1968 coronet r/t and took 2nd place with it so we fixed a few things and are going to show it again (stock class) this year. Stop by and say hi, we will be the two pale yankee's first day, pink the second and red the third

Jerry

 

[wtrenholm]

The front shaft it probably straight on the trans centerline because there is only one joint to work with, no cancelling angle. The rear shaft will have some angle but the two joints cancel the each others angle (if the front is 2 degrees the rear will be darn close to 2 degrees) so the front shaft and rear pinion turn consistant speeds, the rear driveshaft actually does a speed up/slow down cycle every rotation. (this is normal action for a cross style joint). The driveshafts are phased together for proper operation. If you start messing around with angles, you may end up with a vibration or accelerated joint wear, this is assuming that angles are actually correct now. The working angle also has to take into consideration that the rear pinion angle is changing whenever the truck is under load/accelerating.



My buddy put a gear vendors overdrive unit in his truck and they were very specific on which driveshaft had to be shorted. If I remember right he had to shorten the front shaft and move the support bearing crossmember.



This is my understanding, look around there is better info available.



Wayne