rear end setup ?

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phils

Member
Joined
Jun 7, 2009
Messages
24
Location
Isanti, MN
Rear end question: I am not sure if this is good enough to run. Need some advice.
Car is sitting right now at ride height and the ladder bars are adjusted so the coilover shocks (upper & lower mounts) are parallel, but I think we welded the coilover mounts in the wrong spot on the 9" axle. (See pic shows tranny & driveshaft pointing down and angles, but pinion is pointing up). With these angles, shouldn't the pinion angle be pointing down?
If that is true, then I will need to break the welds and reposition the coilover mounts after the pinion angle is correct? Because now, if I adjust the ladder bars and put the pinion angle down 5 degrees towards the ground, it swings the lower shock mounts up and puts the shock bushing in a position that is going to wear them out in a hurry. Any thoughts appreciated!
2010Mar8HR.jpg
 
This is something that sparks a lot of discussion in different circles. Everyone seems to have their own opinion on this, but my tried and true way is to have your transmission output shaft and the rear pinion in the same plane. I set everything at 3 degrees. Tranny is 3 down (this also keeps the carbs level), and pinion is 3 up. This keeps the universals working properly and everything working smooth. If both the tranny and pinion are down it will bind the U-joints and wear them prematurely. The only time the pinion should be pointing down is in a race-type application where extreme wrap is accounted for. Not necessary on the street.
 
B.E.D.,
I've read through the really good thread that was posted on this 'shift it, grind it, pop da clutch' forum that was posted last year, as well as other discussions and there does seem to have alot of opinions out there.
The main reason for my post was that the ladder bar brackets instuction sheet for the Comp Engineering (and Speedyway, too) both recommend pointing pinion down 2-4 degrees. I can only assume, they are assuming the folks putting their brackets in their cars, will be driving their rigs 1/4 mile at a time.

My concern was having this pinion sitting 5 degrees up...to bring it down 2 more degrees is still going to 'stress out' the shock mount bushings. I think my choices are: run it as is and see what happens, break welds and reposition lower shock mounts, or switch upper shock mounts to heims?
 
most people say to have the pinion 2-4 deg down and the reason is that under acceleration (load) the pinion will climb due to bushing/suspension flex or movement. if you are starting at 2-4 deg up then under load it will go to 6-8 deg and it will either bind the u-joint or at the very least have a horrendous drive line vibration. Ideal situation is to have the pinion at 2-4 deg down and the equal but oposit angle at the transmission end. This will make the draiveshaft run without any vibration.
 

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