[35terraplane]

Originally Posted by 5 CWT

Pinion angle is a complete myth + or - 3 degree makes no difference in power,vibration or drivability

I sure wasn't checking the pinion angle for nothing, every time we changed the 4-link in our Pro Stock car.

Bob

[RatPin]

Originally Posted by user151

If the trans down angle and the pinion up angle are set equal, that is good... then raising (or jacking up) the vehicle will increase those angles, but they will still remain the same and opposite.

So the rule remains true: the trans down angle and the pinion up angle should be the same.

Of course, too large an angle will result in short U-joint life.

Actually in almost all setups, when you raise the whole car the trans output angle does not change. The rear pinion will definetely change as your 4 link setup will either pull the axle closer or away to the output shaft of the trans. This really is not that difficult to understand. I'm surprised there is so much false info floating around.

To make things more difficult, take into consideration the rear axle lateral movement from a panhard bar as you raise and lower a car. Mind blowing stuff isn't it....? (sarcasm)

[Centerline]

Originally Posted by 5 CWT

your post in my view is invalid due to lack argument! good job your"e not a barrister....

There's no argument to make. Its real simple... when it come to driveline setup, you have no idea what you're talking about....... as those who have posted on this page have already pointed out.

Centerline
HotRodsAndHemis.com

"The difference between genius and stupidity is that genius has its limits." - Albert Einstein

[NEW INTERIORS]

I set all mine at 3* down on trans, And 3* up on pinion.. (On a everyday street car)

On my Hotter street cars,(race cars)
I have the trans down at 3*, and the pinion at level to 1* up.... Never had a problem yet...

[MARTINSR]

Originally Posted by SSedan64

Without any arguing, look at the 1st 2*-degree example in this link and explain how raising or lowering the vehicles Body will change the Drive line angles of the Trans & Rear. >> http://www.rosslertrans.com/Pinion%20angle.htm

Just in case someone doesn't go to the link I think this really needs to be seen. It spells it out so clearly.

Brian

Credit to web site. http://www.rosslertrans.com/Pinion%20angle.htm

[UPandComing]

Ok i have a question, looking at your image posted here im seeing the pinion can be placed in a -3* position which is more angled towards the ground. What kind of set up would require something like that, iv never had to get into 4 links or ride heights YET but knowlege is power. I know when i see jacked up trucks their pinions a angled very steep to meet with the tail shaft. I dunno im just trying to get an underatanding for this being i stumbled accross the thread

[35terraplane]

Originally Posted by UPandComing

Ok i have a question, looking at your image posted here im seeing the pinion can be placed in a -3* position which is more angled towards the ground. What kind of set up would require something like that, iv never had to get into 4 links or ride heights YET but knowlege is power. I know when i see jacked up trucks their pinions a angled very steep to meet with the tail shaft. I dunno im just trying to get an underatanding for this being i stumbled accross the thread

Well I will try to answer this from what I remember, but I have not touched a 4-link in almost 40 years. How they set them up now, could be way different than back when I did it. Pro Stock was a new class, and there have been many changes.

You could run the pinion at that angle as the 4-link system did have mounting holes that low, but I don't really know why you would want to, because of the way the car would drive, or better yet the way the car would be pushed.

With a 4-link, you look at the 4 bars as pushers, so it is where to push the car is what you are trying to find out with your practice runs. this of course is decided by traction.

you set your bars up, now they are in the holes that they were in the last time you ran at that track, if you have not run there before you go from your neutral point. the bars are a little bit up or a little bit down, now if you could run a string from each bar end and go forward, those strings will cross, both sides should be in the same spot, side by side. where those string cross is where you are going to push on the car, if they are set right they should be straight ahead in front of the car, now you have a starting point.

From there you can set the bars to push the nose into the ground, or stand the car on it's back bumper, which I did once, before we had wheelie bars, not pretty.

Once you put your bars where you want them, each bar has two heim joints with long threaded ends and lock nuts this is when you set the pinion angle, you turn each bar the same, once set and you lock the nuts, you should be able to grab the bars and wiggle them or turn them a little back and forth, if you can't the bars were not turned the same and your rearend is not straight. It won't be off by much, but it is off.

You set these as close as you can, as you dump the clutch at 9000 RPM, you can't have them off at those RPMs.

A 4X4 with the steep angles will work, but it is very hard on u-joints. They will turn easy until you get to the biggest part of the bend or angle and it will loop over it. I have seen it in steering columns, when they put too big a angle in the u-joint on the shaft, you can't help but notice it.

Like I said I hope this still applies, I don't really know how much it has changed, I'm sure someone will correct me if I'm wrong. I think the basics are still there.

Bob

[5 CWT]

I ran a street car with 580 bhp,changed the rear end several times for better gears and suspension set ups including stick axles and jag irs,always kept the pinion angle at 0 degrees and never had a problem!

[35terraplane]

Originally Posted by 5 CWT

I ran a street car with 580 bhp,changed the rear end several times for better gears and suspension set ups including stick axles and jag irs,always kept the pinion angle at 0 degrees and never had a problem!

And your point being, 0 is good as long as trans is the same.

Bob

[MARTINSR]

Originally Posted by 5 CWT

I ran a street car with 580 bhp,changed the rear end several times for better gears and suspension set ups including stick axles and jag irs,always kept the pinion angle at 0 degrees and never had a problem!

One of the first lessons I learn long, long ago as a youngster just because "it has worked" doesn't mean it's right. You could have lucked out, or you could have not known if it was exactly 0 degrees. What ever the case when automotive theory is telling me to set them at a couple of degrees, that is what I will do.

Brian

[5 CWT]

There is not a single man on the planet that can accurately dictate the degree of pinion angle for any given setup,it is all based on theory and previous trial and error usually more error!

[MARTINSR]

You put this device.....


on the yoke flange on the rear end and the transmission and it will tell you EXACTLY (within reason here, "exactly" is relative) what degree it is at. My 10 year old daughter could do it.

Buy them here... http://www.northerntool.com/shop/too...6974_200276974

Brian

[Centerline]

Originally Posted by 5 CWT

There is not a single man on the planet that can accurately dictate the degree of pinion angle for any given setup,it is all based on theory and previous trial and error usually more error!

I guess I'll have to take the time to educate you on this subject. Whether or not you listen is another story. After all you can lead a horse to water but you can't make him drink.

Driveline basics:

Drive shafts in rear wheel drive vehicles have "U" joints at each end that transfer the rotational energy from the output shaft of the transmission to the driveshaft and then from the driveshaft to the differential. All "U" joints rotate in an elliptical motion, unless the operating angle is exactly zero which is almost never the case. So, this means the "U" joint at the front of the driveshaft and the one at the rear both speed up and slow down twice per rotation. That's why they need to be installed "in phase". Each "U" joint must speed up and slow down at exactly the same time as the other. If they are not in phase vibration is inevitable.

Not only do "U" joints rotate elliptically, the ellipse changes as the angle of rotation changes. In order to keep from creating undue vibration the "U" joint angle at each end of the driveshaft needs to match the other as close as possible so the ellipse the "U" joints travel in are the same. In other words, the angle of the output shaft of the transmission and the differential pinion gear input shaft need to be in the same plane. This helps keep the rotational angles for both "U" joints equal. Differences here will create driveline vibration because as the rotational angle of the "U" joint changes the elliptical path changes and when one "U" joint travels in a different ellipse than the other, vibration is created. Also, the greater the operating angle of the "U" joint, the more distorted the ellipse becomes and the greater the torsional vibration. This is why most "U" joint manufacturers recommend an operating angle of 3 degrees or less. Operating the "U" joint at greater angles is possible but it will cause premature "U" joint failure and driveline vibration due to excess torsional stress.

In summary, for a street driven vehicle the transmission output shaft and pinion input shaft need to be in the same plane, (or parallel) and the angles need to be kept at 3 degrees or less for optimal longevity. Lower operating angles also minimize driveline vibration introduced by the elliptical rotational pattern of the "U" joints. Drag racing and specialized rear suspensions will require different settings but the "U" joints will still operate under the same laws of motion.

Consider yourself educated. Proper driveline angles, when it comes to "U" joints and driveshafts, are critical to effectively transmitting torque and power from the trans to the differential without creating vibration.

Centerline
HotRodsAndHemis.com

"One of the problems with stupid people is they very rarely realize just how stupid they really are." - Anonymous

[user151]

Originally Posted by RatPin

Actually in almost all setups, when you raise the whole car the trans output angle does not change. The rear pinion will definetely change as your 4 link setup will either pull the axle closer or away to the output shaft of the trans. This really is not that difficult to understand. I'm surprised there is so much false info floating around.......

Hi ratpin. I guess you are addressing my comment in post 15 where I said "then raising (or jacking up) the vehicle will increase those angles, but they will still remain the same and opposite."

I agree that raising or lowering the chassis will pull the axle closer or away to the output shaft of the trans, but since the 4 links are a parallelogram I don't think the pinion angle would change. (If I am wrong I would like to know why; aways willing to learn.)

[RatPin]

Originally Posted by user151

Hi ratpin. I guess you are addressing my comment in post 15 where I said "then raising (or jacking up) the vehicle will increase those angles, but they will still remain the same and opposite."

I agree that raising or lowering the chassis will pull the axle closer or away to the output shaft of the trans, but since the 4 links are a parallelogram I don't think the pinion angle would change. (If I am wrong I would like to know why; aways willing to learn.)

How will raising the car increase the angle of your trans output shaft? Unless you only raise the front.That's what I was addressing.
As far as rear pinion angle goes. On a parralel 4-link there are many factors to take into consideration, but if your bars are less than 36", there will be a change on a 6" stroke like you might find with a bagged setup.