Pinion angle

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TripleL

TripleL

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Why is the pinion angle so critical on these cars while say a 4x4 can have alot more angle with no vibration
 
I think if the car’s stance is close to original, it’s close enough. See how it rides, and if it vibrates try shimming the axle up or down a tad and run again. I’ve been in cars with the *** end obnoxiously high, and didn’t notice any vibration.
 
The angle of the driveshaft (4 X 4s) doesn't hardly matter at all. What matters is the angle of the engine crankshaft/trans relative to the rear end pinion angle.....WATCH:

 
THAT was quite an example, hard to wrap my head around it. I just assumed all parts would be moving equally. So on a lifted 4x4, with an extreme driveshaft angle, all is well if the rear end yoke and tranny are in line?
 
SplangJ said:
THAT was quite an example, hard to wrap my head around it. I just assumed all parts would be moving equally. So on a lifted 4x4, with an extreme driveshaft angle, all is well if the rear end yoke and tranny are in line?
Click to expand...
Well you're close............??? Normally the angles (engine and yoke) are set so that when there is a load on the drive train (during acceleration) the tranny and yoke are at the same angle. So if you set your pinion angle with the car sitting still (static) you need to have the yoke about 2 1/2 degrees down relative to the engine/tranny angle. Now other people might say 2 degrees and some might say 3 degrees ....to each his own. The point is that when you accelerate the pinion yoke will rise up a degree or 2 at which time it will be at the same angle as the engine/tranny. Make sense??
 
Yes! You would really notice any vibration while cruising, but not notice necessarily while under WOT. Great post Treblig!
 
Remember, when you hit the gas the rear end (yoke) will rotate up (changing the pinion angle). The type of rear suspension (loose or tight) will determine how much the pinion needs to be pointed down relative the engine/trans angle.......Here's another explanation:

pinionangle-1pcshaft-jpg.jpg
 
SplangJ said:
Yes! You would really notice any vibration while cruising, but not notice necessarily while under WOT. Great post Treblig!
Click to expand...
Thanks...there is a "HAPPY PLACE" for the pinion yoke as demonstrated by all factory cars (no vibration at all). That's why they invented pinion angle shims for us hot rodders!!!!
 
Surely. With a snug pinion snubber you might see some housing twist at launch, but settles back down with less torque at speed, leading towards no vibration at all, like cruising. No one will notice a driveshaft imbalance at low driveshaft speed for a few seconds
 
That video is excellent. The "simple story" is that with a common 1 piece shaft like A bodies use, the two end shafts (trans and pinion) MUST BE PARALLEL under load. You will find a 4x4 does the same thing. The shaft speeds up and slows down every 1/4 turn, and that is cancelled at the "other end" IF THE angle is the same at both ends.

You can "feel this" for yourself with a socket drive U joint.
 
Thanks for the great info. Thats just one reason I'm not designing cars.
 
Thats why they created the CV joint "constant velocity" for the FWD half shafts.
 
My 3 point post hole digger does the thump and bump at certain angles when drilling so same concept. Learn something every day
 
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