Bad day...Dyno

[JLEONARD]

that is plain u-joint alignment, not the sine waves and loads

Same thing.

 

[dpuckett]

I stand correected. So, if Cade kept his stock driveshaft, how could the u-joints have gotten out of alignment? Or are you saying if it was 1/10 of a degree off true from the factory (bean counters wont stand for quality, you know), it would be magnified at the greater angle from the lift?



DP

 

[CSchafer]

All that is very true Jay. I have read many suspension geometry books that have all said that. However I have been in countless off road rigs with the pinion pointing straight at the transfercase to get rid of harsh angles. These trucks did not have a viberation. When I built my 12in lift I had the pinion tiped up straight, i. e. angles were no were near off setting and there was no vibration. I beat the snot out of it in mudd and on the street also. When I broke it I tried launching too hard, It twisted the axle up so bad it bent the leaf springs and went beyond the limits of the u-joint's movement thus shearing off the bolts holding it to the rear end. Slaming it off the ground that hard probobly wasnt good for it. Now with it's current setup, I have about 5-5. 5in lift. I set pinion angle with angle blocks just about the same as the angle as the output, i. e. off setting eachother to kill vibration. actually I had to build taller blocks anyway so I angled them correct because that's what the book's say. My transfer case in lowered 2 inches and my pinion set accordinally it has the same if not less angle on the driveshaft then stock. So in conclusion I understand why the u-joint angles should be the same but have went agianst it there were no vibrations. The current suspension is set up properly and it vibrated, it viberated enough to break so I think it was more then 1 deg difference in angles. I do believe that the shaft was bent from before and that's why it broke, not the lift. I will know when it gets put back together, it will have the same angles so we will see if it viberates.

 

[bgilbert]

Lifts are for gassers:-laf:-laf !

 

[JLEONARD]

Or are you saying if it was 1/10 of a degree off true

No. . that is not significant. 10 degrees would be significant.

 do believe that the shaft was bent from before and that's why it broke

That would cause it for sure.

 

[CSchafer]

Lifts are for gassers:-laf:-laf !

Stacks are for semi's, Dyno's are for drag cars anything else I should go agianst the grain on?:-laf

 

[cojhl2]

that is plain u-joint alignment, not the sine waves and loads

Same thing.

I think what dpuckett was referring to was the phase of the yokes being in time. It is not the same thing as what you were describing Jay.



BTW, regardless of what may be observed, ie:vibrations etc, to be correct the two ends of u-jointed (non cv) shafts must be at the same anglewith the intermediate shaft to eliminate the issue described by jleonard. Pointing the pinion shaft directly toward the xfer case is not correct!



You either have to have the shafts parallel or implement a "broken back" design.



edit: You only run into the timing of the u-joint problem if you are the one building the intermidiate shaft.

 

[dpuckett]

Stacks are for semi's, Dyno's are for drag cars anything else I should go agianst the grain on?:-laf

I agree with ya on the stacks :-laf :-laf But I agree with Bill on the lifts.

 

[MMiller]

AHHHHH, nobody here is going to like me anymore. Both my trucks have lifts, both have bigger tires then stock, one has dual stacks, one has dual tailpipes, and I suppose somebody will tell me I don't need dual CB antennas!!!!! And heck, my gasser isn't lifted, and doesn't have dual cb antennas! I'm going to be an outcast. :-laf



Having u joints out of phase, or alignment would be the same as having the angles wrong, as the joints being in phase and in the correct angles cancel out each other. If they are not phased roght, they can't cancel each other out. One thing I don't understand, is both of my unmolested dodges the pinion pointed right at the output of the transfer case, and the rearmost joint has little or no angle to it, and that was factory.



Besides, lifts are ok, as long as they stay under 6" or so. If its a tow vehicle then it should get little to no lift. If you want to run bog tires for offroad, you should be prepaired to cut or remove copious amounts of sheetmetal! Thats my opinion, now I'm going over to the corner for breaking too many rules... ... ...



Michael

 

[cojhl2]

Having u joints out of phase, or alignment would be the same as having the angles wrong, as the joints being in phase and in the correct angles cancel out each other. If they are not phased roght, they can't cancel each other out. One thing I don't understand, is both of my unmolested dodges the pinion pointed right at the output of the transfer case, and the rearmost joint has little or no angle to it, and that was factory.



Michael

That is correct and probably what dpuckett was saying. I implied that it was not the same because I was looking only at implementation. I shoulda bin more broad in my thinking.



Also, If there are splines on the intermidiate shaft for a slip joint they usually have a spline missing so the joints can't be misaligned. If this is not the case then the installer must be careful to time the joints.



Re the factory pinion shaft pointing toward the xmission output,, just loose engineering. It still is not correct!!