Driveshaft angle....slack in the couplers good enough?

I am putting a crower/lenco in a plueger chassis with a 6b cummins in front of it. The problem is that with a in-line 6.....they just dont hang as low,ive got a dry sump on it & there is no more room to be gained there. ive built my midplate to match the old one but when i do the nose of the pan drops down too low. If i raise the nose up a little the driveshaft isnt "dead on"..... i do think the shaft will have some slop to it back & forth but i know it will not be straight as an arrow...is that ok? I dont want to sit on a u joint if i can help it....Whats the limit there? Thanks in advance.

 

Can't remember for sure but I think it was Virgil Hartman told me one time you could have up to 3 degrees total variance from top to bottom. The couplers might could stand a little more than that but the pinion and tailshaft bearings would probably suffer more from the misalignment over time.

 

You can use couplers , male/female on both ends of the driveshaft.
Ricky

 

you need a long piece of 1 1/2" round stock a couple main bearing spacers to fit it into a block . 1 1/2 fits into the bach pinion bearing in a 9" and a spacer to fit the 1 1/2 to the the front of the 9 ' ( a dummy pinion support). If you have a rear end other than a 9" you need to make dummy pinion bearings to fit the round stock to it. Weld the holes up in the rear end brackets and drill new ones.

 

if i do that the pinion angle will have to change a bunch !! isnt there some connection between pinion angle traction/launch properties? is the 3 degree number in stone or do you think i could sneek 5 degrees of angle into it.

 

if you use a constant velocity joint

 

The amount of misalignment depends on the length of the drive shaft, coupler-to-coupler.

Example:
12" length @ +/- 3 degrees = 1.254" total
36" length @ +/- 3 degrees = 3.763" total

 

i guess it would ....i wasnt thinking about it that way. i do not have the trans in yet but it is going to be pretty short, 18 " maybe. keep in mind im not running near the hp as alcohol cars...1400 or so but the torque is over 2k.
thank you for your input. any more thoughts are appreciated.

 

do yourself a favor and figure out a way to get the motor and pinion lined up correctly. some people will say you can get away with this number, or that....but that doesn't make it right. just raise or lower the rear end like Creech said and line everything up. i would set the pinion angle around 1-2* down in the front and put the motor the same.....that will work fine. just my 2 cents
Darren

 

Over the years we've run dragsters with the motor from 2 degrees down to 4 degrees up. With the moter 4 degrees up and alot of power (screw blower) they tend to wheelstand to much and need wieght in front wing wieghtbar but with the wieght of a diesel it would probably like it. If you have missalignment with a coupler shaft (no ujoint) it will tear up the pinion, esp. with the torque of a deisel.

You should probably leave one set of bolt loose in the rear end (either the top or the bottom) to keep the rear end aligned. level the moter to the rearend and could possibly just drill new holes for the others just behind the original set in case you ever want to put it back like it was. We have two sets of holes in the rear end brackets and two sets of motor plates for our dragster; dead level and 1" up at the front of the crank, just in case I think we need more bite I can move the motor up an inch.

 

thanks for the input....im goining to have to modify the front gear cover in order to get her to nose down any at all.she is dead level right now...im going to heed the advice & get her dead on.