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Last winter we finsihed a backhalf project that I purchased that was 50 percent complete. it has dana 60 with a 32" tall tire and 4 link so the ride height is low and less than 2 deg rake. I kept the powerglide setting on the stock cross member. The crank/tailshaft point down 1.5 degs, drive shaft runs "uphill" 1.5 degrees. not the traditonal downhill. It took a few trips to the track to set the pinion angle to remove my bad vibration, but did make huge progress.

several people told me that drivehsafts can run uphill to the pinion but my tailshaft has to point up ??? I have the motor out now and looking to improve my situation ?? any help ?
 

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Last winter we finsihed a backhalf project that I purchased that was 50 percent complete. it has dana 60 with a 32" tall tire and 4 link so the ride height is low and less than 2 deg rake. I kept the powerglide setting on the stock cross member. The crank/tailshaft point down 1.5 degs, drive shaft runs "uphill" 1.5 degrees. not the traditonal downhill. It took a few trips to the track to set the pinion angle to remove my bad vibration, but did make huge progress.

several people told me that drivehsafts can run uphill to the pinion but my tailshaft has to point up ??? I have the motor out now and looking to improve my situation ?? any help ?




Take a look at this, should clear things up a bit ..............

looks like you need to drop the pinion one degree .............



http://www.rosslertrans.com/Pinion Angle.htm
 

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Discussion Starter #3
example

Thanks Chris for response, I have seen this chart before and actually it would suggest that my pinion should be 1/2 degree up(1 degree for 4 link). but with most charts its shows the tailshaft at higher elevation than the pinion. Most things that I have read is that the tailshaft should be pointed at the pinion and what ever that angle is you take one from that,lower the pinion by that amount. Would also like to hear from guys that run a similar setup with a driveshaft running up to the pinion. just looking at the mechanics I would think that if the pinion is higher than the tailshaft the tailshaft angle should be up in degrees(pointed at the pinion) lets say its 1 degree up then the pinion would be set at -2 and axle wrap to -1 off setting the front ujoint angles.

my present alignment is tailshaft down 1.5 degrees, drivehsaft then runs uphill 1.5 degrees to the higher pinion which is 1/2-1 degree up. Doesnt sound effective at transfering power. I was able to remove vibration at higher speeds over 130 but I think its effecting launch and power transfer.
 

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ref : if the tranny is pointing down 1° then the pinion sould be pointing up 1°
in other words, they should be parallel.
then dial in your pinion angle from there.

my driveshaft goes up to the pinion also .

ROGER
 

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most charts or diagrams don't take into account lowered cars or taller tires.. just make the pinion 1 degree down from parrallel to the crank centerline .. in your case it should have been about .5 degrees up... this would give minimal vibration & frictional loss.
 

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most charts or diagrams don't take into account lowered cars or taller tires.. just make the pinion 1 degree down from parrallel to the crank centerline .. in your case it should have been about .5 degrees up... this would give minimal vibration & frictional loss.




YUP ......... Tech guy is spot on ........ I misread your initial post, I thought you said 1.5 down on the trans and 1.5 up on the pinion. The drive shaft is irrelevent in checking pinion angle. Ask ten guys how to check pinion angle and you'll get eleven different answers LOL .................
 

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With a 4-link you want roughly -1º pinion angle. Take the driveshaft out of the equation and forget it's even there. If your engine/trans slopes down in the rear by 2º, then you want your rear yoke pointing up 1º in order to get -1º pinion angle.

Here's an excellent drivetrain setup guide: HERE
 

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most charts or diagrams don't take into account lowered cars or taller tires.. just make the pinion 1 degree down from parrallel to the crank centerline .. in your case it should have been about .5 degrees up... this would give minimal vibration & frictional loss.
Especially if a driveshaft goes up and the rear is higher than the trans.
 

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The crank/tailshaft point down 1.5 degs

Using your measurements and allowing for 1 degree of pinion climb, the static measurement for your pinion should point ½ degree up. Tune it from there but this is the baseline adjustment.

Your u-joints should not operate more than 1 degree out of phase which yours won’t. My leaf spring car has to operate 2.5 degrees out of phase to allow for pinion climb.
 

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Let me ask a question that no one ever seems to address. Everyone talks about equal and opposite. That only works if the rear is lower than the engine. On a tube chassis car, you can jig the car to set engine angles and where the rear is. On a street car, the rear is generally below the engine, so you can set your pinion angle on that. But a backhalved, stock front stub car is a mess. The engine sits at the stock engine angle built in from the manufacturer. Mostly pointing down at the tailshaft. Unless you jack the back of the car up, the rear will be set higher in the car. So a driveshaft will have to go from low to high in the car. You can try to raise the rear of the trans with a taller mount, I raised mine a little with a poly mount. But it still points down. A rear end, regardless of 4 link, ladder bar etc, WILL try to roll up in the car under acceleration, though the amount may be less depending on set up. The general chassis setup rule has always been to set your pinion to be at a downward angle to the driveshaft. This is so that under acceleration the acting angle between driveshaft and pinion is ALMOST zero. Granted you need an angle for the joint to work. With all this information, how can it be suggested setting a pinion pointing up to a driveshaft? Adding angle to a u joint increases drag on the joint.
 

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It works regardless of whether or not the rear is higher or lower than the transmission. The goal here has nothing to do with the angle of the pinion to the drive shaft. In a steady state cruise condition ideally you would want both u-joints to operate with the same angularity to each other or in other words “in phase”. They should never be more than 1 degree out of phase or operate at an angle more than 3 degrees. Now introduce hard acceleration into the equation and you will have to make a compromise. My leaf spring car has to operate at cruise about 2.5 degrees out of phase (according to Calvert Racing) so when I accelerate the car the driveline is in phase during the acceleration. Four link cars don’t have as much slop so they only need about 1 degree to compensate when the pinion climbs the ring gear.

My transmission tail shaft is 2.5 degrees down angle at ride height. My ideal pinion angle would be 2.5 degrees up angle for vibration free highway cruising. Because I consulted with Calvert, I set my pinion angle at zero in relation to the ground so when I accelerate it will be at 2.5 degrees up when the driveline sees the most stress. The u-joints will be operating at the same angularity and will therefore be in phase.

Here is a link to an article that helped me a lot.
http://www.dragzine.com/tech-stories/chassis-safety/drivetrain-angles-increase-torque-and-improving-hook-2/

Steve
 

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The general chassis setup rule has always been to set your pinion to be at a downward angle to the driveshaft. .

these "general" rules assume an engine level to the ground...

any engineering principle or drive line theory or power transmission theorist will tell you 2 u-joints must be in phase for minimal loss or vibration. both u-joints must be acounted for .

what I find many people get confused about is the difference between pinion angle & u-joint angle.

pinion angle is the difference between the angle of the engine (power output) & the angle of the pinion ( power input), in degrees.

u-joint angle is the angle from the transmitting shaft across the joint to the input or output.

example:
jacked up 4x4 truck.. engine level to ground 3 feet higher than pinion which is also level to ground.
pinion angle = 0 degrees
u-joint angle = 35 degrees

same 4 x 4, but engine is down in back 5 degrees to ground, pinion is up 3 degrees from ground.
pinion angle= 2 deg. down
u-joint angles =20 front 24 rear

hope this helps.. my fingers are tired from typing...
 

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With all this information, how can it be suggested setting a pinion pointing up to a driveshaft? Adding angle to a u joint increases drag on the joint.
Forget about the driveshaft, pretend it's not even there. You are just connecting two different points with it. However those points have to be parallel or close to parallel with each other.

It the engine/trans is pointing downhill 2º then the pinion needs to point uphill 2º to be 0 pinion angle. For -1º angle, it still needs to point up, only 1º.

In our ProMod, the engine trans actually points up in the rear, so the pinion points slightly down in order to achieve -1º pinion angle. It's a 4-link so doesn't require much.
 

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Discussion Starter #18
thanks

ok I understand crank/tailshaft and pinon angle should be equal under load , so at rest with a 4 link -1 pinion angle. my setup= tailshaft down 1.5 so pinion goes up .5 so under accel it rolls to up 1.5 equalling the tailshaft down1.5 degrees. at rest my drivehsaft runs up 1.5 degrees, I know it doesnt matter , but please read on

So here is my Million dollar question, all Im asking your OPINIONS.
WIth my motor now out and off season here. My Thoughts from Some quick measurments, distance from dampner to tailshaft is close to driveshaft length. So if I raise my tailshaft slighlty(not much room i have original floor pan) but i think i Can get to zero angle, then the driveshaft would be near zero, then I could lower my pinion angle to one degree down and be more conventional and have near zero angle during accel. I also have an offset pinion so I will still have an angle that will make the cups rotate.
 

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I like to have a little down pinion angle even under load. It helps with the rear bite all the way down track. I think you are missing the point...it doesn't matter what angle the driveshaft is at...pretend it's not even there. As far as offset, if your pinion is offset then so should the rest of your drivetrain. In early Nova's, it's usually offset to the passenger side, meaning engine/trans & pinion all ALL offset. When guys put many of these aftermarket front clips on, they center the engine in the car, so now the drivetrain is crooked compared to the pinion. I'm not getting why you want to move anything other than setting pinion angle to get where you need to be. What do you think you are gaining? As long as there's a degree or so of angle, the U-joints are going to lube fine, if it's zero, not so much.
 

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Ok, I can understand the in phase of the joints. I will agree with that. That was not really looked at back when I started doing this. It was always focused on the rear. But what still isn't being talked about is a rear that is higher than the trans. Are you saying that instead of allowing the pinion to roll up to a zero angle between driveshaft and pinion, that todays thought is allow the pinion to roll away from the driveshaft increasing the angle between the 2? I wish I could post a picture of it to illustrate this. I will fully agree that the theories will apply to a setup that is in line or the trans is higher than the rear. But somebody, please draw a setup with a down pointing trans and the pinion higher than the trans and show me HOW you would set this up for a drag car with hard acceleration.
 
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