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LIS20
02-29-2012, 11:43 AM
This is an elementary question but i have found three different answers -- what is the correct way to measure pinion angle when the car is at ride heigths??? Thanks in advance.

hpmaster
02-29-2012, 03:10 PM
Add driveshaft angle to pinion plate angle to get total pinion angle. Thats how I been doing it. JMHO

Dirtrunner35
02-29-2012, 08:47 PM
7 degrees or 6 degrees does it really matter? When you look at videos of the pinion and drive shaft and see how much it really moves, static setting is just a place to start. I have a video of my axle and I'm not worried about it statically, set it and forget it lol.

I have heard both ways also, so not sure. I wonder why someone when setting pinion angle, adds the drive shaft angle?? I don't get it lol

hpmaster
03-01-2012, 07:35 AM
7 degrees or 6 degrees does it really matter? When you look at videos of the pinion and drive shaft and see how much it really moves, static setting is just a place to start. I have a video of my axle and I'm not worried about it statically, set it and forget it lol.

I have heard both ways also, so not sure. I wonder why someone when setting pinion angle, adds the drive shaft angle?? I don't get it lol


The pinion angle is set in relationship to the drive shaft, what is actually driving the pinion thru the u joints, not level earth. It really isn't hard to understand. To ignore 3 degrees or so of drive shaft angle when the needed angle to minimize wear and power loss is say 6 or 7 degrees total is to accept being almost 50% off. Set properly this angle will almost completely eliminate the possibility of u joint failure. The Spicer web site used to have a very complete explanation or Goggle it I am sure you will find some good facts, ck it out.

I found this hope it helps.
http://www.pirate4x4.com/tech/billavista/PR-shaft/measurin.avi

http://www.pirate4x4.com/tech/billavista/PR-shaft/index4.html

AmickRacing
03-01-2012, 11:07 PM
That makes sense (the angles added). Now for as long as I can remember, the pinion angle was always 6 deg (on the pinion), never a cumulative degree.

What is the optimal number you're looking for with the 2 combined?

spiderma4
03-02-2012, 12:09 AM
no math skills needed just go off rear end cover or j bar mount set 7 degrees

Dirtrunner35
03-02-2012, 08:43 PM
The pinion angle is set in relationship to the drive shaft, what is actually driving the pinion thru the u joints, not level earth. It really isn't hard to understand. To ignore 3 degrees or so of drive shaft angle when the needed angle to minimize wear and power loss is say 6 or 7 degrees total is to accept being almost 50% off. Set properly this angle will almost completely eliminate the possibility of u joint failure. The Spicer web site used to have a very complete explanation or Goggle it I am sure you will find some good facts, ck it out.

I found this hope it helps.
http://www.pirate4x4.com/tech/billavista/PR-shaft/measurin.avi

http://www.pirate4x4.com/tech/billavista/PR-shaft/index4.html

I agree to a point, but how can anyone say where it should start static, if you don't know where it ends dynamic ? Some rear axle videos look like the u joint is going to exploded when on the gas.

hpmaster
03-03-2012, 02:36 PM
What I have given is the right way to set it. This is as simple as I can explain it.

Rule of thumb is that if the total of pinion angle and drive shaft angle gets around 11 degrees total both added together you are comprimising wear and power or if you go the other way around 5 degrees total or less between the two, pinion angle and driveshaft, you once again comprimise wear and power. The idea is to have the pinion and driveshaft very near straight underload or as we say on the throttle. To have it angled away from straight UNDERLOAD UP OR DOWN more than a few degrees lowers the amount of load the ujoint can handle drasticly while increasing wear.
Now if you run a 600 hp 510ft lbs of torque motor thru a u joint set at 11 degrees total you have alot less stress on it than a 750hp 690ftlbs of torque motor thru the same u joint.

When you back off the gas the housing rotates down alot BUT you are also NOT underload.

Personaly I do not take offense if you don't agree, do what you want. Or as my dad used to say "you can lead a horse to water, one will drink, one will not and sooner or later one will drown."

Dirtrunner35
03-03-2012, 06:55 PM
So really everyone should have a video of there rear pinion to set it when on the gas. I know mine goes way past being straight in line when on the gas. I think it was the Harris rear axle video that the angle will scare you, lol.

hpmaster
03-04-2012, 10:30 AM
I agree after watching a few videos it's a wonder this stuff doesn't all fly apart all the time.

dualdj1
03-05-2012, 04:36 PM
well you actually never want it completely flat, even on load. u-joints are built to run with some angle to eliminate vibration (which can also break things). You just can't get too much in it.

hpmaster
03-05-2012, 04:51 PM
[QUOTE=dualdj1;1503895]well you actually never want it completely flat, even on load. u-joints are built to run with some angle to eliminate vibration (which can also break things). You just can't get too much in it.[/QU

This is what I said earlier, read the 3 line down and I am done expalining and reexpalining this.

By setting shaft to be as straight as possiable under load so you don't use HP to move roller bearings to adjust for angle under full load. The loss is not great but does happen, 10 to 15 hp as I remember. By straight as possiable at full load but it can't be too straight or you can ruin the needle bearings because of no load on them, just like you ruin them with too much angle and load. This horsepower loss is part of what is called parasitic loss in the drivetrain. This loss starts with how the transmission is aligned to the engine all the way back to the bearings on the axles and finaly the seals and their drag plus every bearing surface and gear matting surface in between. As for drive angles like everything else there are therories, such as matching the load angles of both front and rear u joints to be working at the same angle under full load. But just as soon as you think you have that all figured out most late models when you move a engine right or left you set up what is called a 2 plane driveshaft, with the drive shaft angled not only up and down but right and left. Talk to chassis dyno operators, its part of trying to get every last drop of power out a car you can.