Notta... its just to counteract wrap up to increase drive train efficiency.

 

They must have serious flexing going on

 

-10 is just an example. I'm just looking for opinions in general on pinion angle having effects on traction.

 

I guess the extreme angles COULD kill enough h/p to help hook.....hahahahaha

idiots......

 

Pinion angle does nothing for traction.

.

 

Pinion angle does nothing for traction.

.

It does on certain cars.

 

Only there to gain a 0 if set right....

 

It is very common to do this in dirt track racing with leafs or torque arms.

 

Changing the pinion angle in a triangulated 4 link like a fox body will also change the instant center.

 

I was at a Dave Morgan seminar years ago and the discussion was concerning excessive pinion angle and it's effect on traction. There were people in the audience who were dead certain that it (lots of angle)had helped their car hook, and Morgan agreed with them. I then asked a question which in a nutshell was "Why?". Everyone agreed that it worked, but how? 4 links can be explained, as can ladder bars, but I had never seen a force-vector diagram of pinion angle. SOMETHING had to be pushing down on the tires.

That something, as explained to us, was bind. Lots of torque being transferred thru a u-joint with excessive angularity tends to stiffen the joint up, so as the mass of the car rotates, the joint tries to straighten out, and a force is fed thru the driveshaft directly to the rear end, bypassing the suspension.

I'm still not sure I understand it 100%, because it seems to be something that can't be expressed as an equation, and that puts it in the "Black Magic" area, for me at least.

Mark

 

I was at a Dave Morgan seminar years ago and the discussion was concerning excessive pinion angle and it's effect on traction. There were people in the audience who were dead certain that it (lots of angle)had helped their car hook, and Morgan agreed with them. I then asked a question which in a nutshell was "Why?". Everyone agreed that it worked, but how? 4 links can be explained, as can ladder bars, but I had never seen a force-vector diagram of pinion angle. SOMETHING had to be pushing down on the tires.

That something, as explained to us, was bind. Lots of torque being transferred thru a u-joint with excessive angularity tends to stiffen the joint up, so as the mass of the car rotates, the joint tries to straighten out, and a force is fed thru the driveshaft directly to the rear end, bypassing the suspension.

I'm still not sure I understand it 100%, because it seems to be something that can't be expressed as an equation, and that puts it in the "Black Magic" area, for me at least.

Mark

I have found that moderate amounts helped my ladder bar car. It was years ago when I played with it, but it had a very definite effect even when keeping other factors the same. The theory above is the best guess I had for the response.

 

Ask Jerry Bickel or Tim McAmis about their thoughts on this... it does affect it.

 

4 link T/S car in signature 2460#...we run 1.5* pinion angle. Our understanding is that it does help with off the line launch traction, but it might reduce HP/Trq, & cause the suspension to be looser (less traction) down track...again, no expert, but our understanding.

 

Pinion angle affecting traction has nothing to do with the u-joint. Nothing against Dave Morgan, but Ive ate dinner with him before so I know he's a little out there at times. Dropping the pinion decreases the angle between the lever arm ( 4 link bracket) and the top bar. This will increase hit, which may or may not increase traction.

 

But we are still trying to achieve a perfect zero after launch, have seem dirt drag trucks with as much as 7 degrees, that sir in my opinion is dangerous...

 

severe angles eat up torque through the joint......kill torque=traction......

try useing a swivel at full angle to loosen your lugnuts...
then straighten out the angle and try again......BIG difference.

 

I agree John. You might increase traction but you are eating up HP to do it. Instead of fixing a problem you are creating another problem.
Just my 2 cents......................

 

When changing pinion angle you are changing pressure angles on the suspension links.. Pinion angle is just the reference number you use to tell how much of a change you are making. If The only way you could see if pinion angle itself had any affect would be to build a year end that you could change just the pinion angle without changing anything else.

I do believe you would have to make some drastic pinion angle changes for it to be able to make a big change in the toque the pinion was seeing from the driveshaft

I have often wondered about how the 4 link brackets are clocked are many housings and it being the cause of many racers traction problems. I have seen alot of cars that the pinion was set to what we all believe to be correct and the lower 4 link bar to 4 link bracket has a very undesirable angle to it.

I have seen some pretty good improvements on a few vehicles when we ran car set up with positive pinion angle (peaked when checking between the pinion and driveshaft)

 

racer9899, what you said about pinion angle being what they thought it should be and it makeing the lower 4 link bar at an undesirable angle, could a ride height change correct that.

 

Not enough I imagine, You would just have to check and see as you made changes..

 

What is the best process to check your pinion angle?

 

Measure your engine/trans angle either at the motor plate, valve covers etc., then measure your pinion yoke angle. The difference between the two is your pinion angle.

Example 1: If your engine/trans is 2° down and your pinion is 1° up, your pinion angle is -1°

Example 2: If your engine/trans is angled up 1° and your pinion is angled down 2½° your pinion angle is -1½°

Example 3: If your engine/trans is 2° down and your pinion is 2° up, your pinion angle is 0°

 

Thanks Mike

 

I gotta disagree with mike. What he is measuring is an important number, but I dont think it's pinion angle because you're leaving out crank CL. Real Pinion angle is just the difference between the driveshaft angle and pinion yoke angle. Like 9899 said, it's just a reference. Mikes number is important because it tells whether you end up with a broken back setup or not among other things. Dave Morgan and others have said u can't run the broken back, but guys have done it. The reason you have to consider crank CL is that you could have the engine and rear end both pointed level, but if the engine sits way high with a short driveshaft you would have a really steep pinion angle.

 

Like bjs344 said, pinion angle is the difference between pinion and driveshaft, the actual angle of the universal joint.
Having negative pinion angle plays a bigger role on cars that have suspensions that allow some movement, like a 'stock' class car. In brief, the driveshaft plays a bigger role in this than you give credit for. When the clutch is dumped the driveshaft tries to snap straight out - it don't like any kind of an angle and wants to be at 180deg from the tailshaft, go play with a gyroscope and you'll feel how much force a spinning mass can have, .5mass X velocity squared = kinetic energy.
If the snout of the pinion is below the contact patch of the rear gear then the driveshaft tries to lift the pinion snout (at the universal) and that rotates the rear and tries to drive the rear tires into the asphalt. Go watch a stock class car launch, you can see it happen. If you go positive on the pinion angle the reverse happens an dthe rear tire will try to rise - i believe fox bodied mustangs came from ford with positive pinion angles and that is part of the reason they can light them up so easy.
Just factor in the driveshaft and think about how it is transmitting torque and you will soon figure it all out, the snout of the pinion is the fulcrum and the contact patch of the gear is the pinch point of the lever (lever is the force being applied via the driveshaft).
A procar - top sportsman for instance - has the engine located below the pinion. the driveshaft runs uphill into the pinion and the rear is situated by massive control arms that won't allow any rotational movement - other than propellar type).
Sorry, got wordier than intented.

 

The driveshaft doesn't even need to be in the car when setting pinion angle.

Reference these:
http://www.rosslertrans.com/Pinion angle.htm
http://www.iedls.com/asp/admin/getFile.asp?RID=5&TID=28&FN=PDF

 

Mike, are you saying you set the pinion angle like in Rosslers tech sheet and then never change it for different track conditions?

 

I don't adjust it unless I make a 4-link adjustment. Should I be? I set it at -1 to -1.5 and leave it. I'm sure you have a lot more expertise in that area than I do. What's the skinny?