Just curious. How do you set your pinion angle in your door cars and dragsters?

How much angle?

Why do you set it at that angle?

SL...

This message has been edited. Last edited by: DragRaceResults,

On my dragster, I used this Tim McAmis video on YouTube as my guide:

https://www.youtube.com/watch?v=Yss6Uf3AwNM

I don't recall exactly what number I landed on, but I was targeting 1.5-2.0 degrees of negative angle at the driveshaft compared to the pinion.

I don't have any original thoughts as to why that number. Somebody must have told me that, or I read it somewhere.

This is a good video and funny too. He uses sprockets and a playing card to show what actually happens to the driveshaft.

https://www.youtube.com/watch?v=YgNZfIR-8Ng&t=870s

First thing you have to do when checking pinion angle is take the driveshaft out and put it somewhere out of the way. People confuse pinion angle with ujoint operating angles.

On my Nova, the engine is at 0* and the pinion is down 2*. This is checked at the balancer and yoke flats. Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

This video is old but a great way to understand u-joint operating angles.

https://youtu.be/gmV4qwLfOMY

quote:

Originally posted by TomR:

Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

Tom, how do you verify this?

-1.5 degrees for a 4-link dragster

quote:

Originally posted by CURTIS REED:

quote:

Originally posted by TomR:

Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

Tom, how do you verify this?

Many videos and pictures of the car, rear separation with ladder bars.

quote:

Originally posted by TomR:

quote:

Originally posted by CURTIS REED:

quote:

Originally posted by TomR:

Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

Tom, how do you verify this?

Many videos and pictures of the car, rear separation with ladder bars.

I really shouldn't have called you out specifically. I should have asked everyone. I understand you can video the movement of the parts what I am wondering is how we can say it is at zero with certainty?

Probably trial and error made most arrive at a given negative number but I was curious how one would know exactly?

Also, separation on a 4 link shouldn't cause an angle change correct?

I run a lot of negative pinion angle. I think it helps keep the tire planted down track. I take a measurement from the ground and zero the gauge and the top of my diff is flat to pinion. I adjust it accordingly

It all depends on the length of your rod.

goob- iykyk
goob2-spmv

I think Carl Rosslers instructions are the best, I made a science project out of pinion angle trying to run down a vibration. There is a lot of misunderstanding with pinion angle including incorrect instruction I have read. Rosslers dispels all the myths and is excellent.

quote:

Originally posted by BG7X77:
I think Carl Rosslers instructions are the best, I made a science project out of pinion angle trying to run down a vibration. There is a lot of misunderstanding with pinion angle including incorrect instruction I have read. Rosslers dispels all the myths and is excellent.

Don't keep us in suspense, what are Carl's instructions?

quote:

Originally posted by CURTIS REED:

quote:

Originally posted by TomR:

quote:

Originally posted by CURTIS REED:

quote:

Originally posted by TomR:

Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

Tom, how do you verify this?

Many videos and pictures of the car, rear separation with ladder bars.

I really shouldn't have called you out specifically. I should have asked everyone. I understand you can video the movement of the parts what I am wondering is how we can say it is at zero with certainty?

Probably trial and error made most arrive at a given negative number but I was curious how one would know exactly?

Also, separation on a 4 link shouldn't cause an angle change correct?

No worries, I don't mind questions, its how we learn and grow. Mine has ladder bars, so I jack up the body to match pictures and video so I could try to zero it.

A four link with four equal length bars won't change pinion angle. A four link with two longer and two shorter bars will change pinion angle.

The most extreme example of this is GM and fox body mustangs with short upper arms and long lower arms.

quote:

Originally posted by TomR:
First thing you have to do when checking pinion angle is take the driveshaft out and put it somewhere out of the way. People confuse pinion angle with ujoint operating angles.

On my Nova, the engine is at 0* and the pinion is down 2*. This is checked at the balancer and yoke flats. Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

This video is old but a great way to understand u-joint operating angles.

https://youtu.be/gmV4qwLfOMY

Couldn't have explained it better.
The driveshaft for some reason drives everyone crazy so the best deal is to remove it.

quote:

Originally posted by Eman:

quote:

Originally posted by TomR:
First thing you have to do when checking pinion angle is take the driveshaft out and put it somewhere out of the way. People confuse pinion angle with ujoint operating angles.

On my Nova, the engine is at 0* and the pinion is down 2*. This is checked at the balancer and yoke flats. Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

This video is old but a great way to understand u-joint operating angles.

https://youtu.be/gmV4qwLfOMY

Couldn't have explained it better.
The driveshaft for some reason drives everyone crazy so the best deal is to remove it.

I tried to do my dragster that way, and I ran out of threads on the 4-link bar before I could get it right. I don't know that I can make sense of the "why" but I used the McAmis video I posted above to compare driveshaft angle to pinion and it worked out just fine.

Thanks Tom

quote:

Originally posted by Lenny5160:

quote:

Originally posted by Eman:

quote:

Originally posted by TomR:
First thing you have to do when checking pinion angle is take the driveshaft out and put it somewhere out of the way. People confuse pinion angle with ujoint operating angles.

On my Nova, the engine is at 0* and the pinion is down 2*. This is checked at the balancer and yoke flats. Under load the pinion is zero to match the engine and the ujoint operating angles match each other at 1.5*.

This video is old but a great way to understand u-joint operating angles.

https://youtu.be/gmV4qwLfOMY

Couldn't have explained it better.
The driveshaft for some reason drives everyone crazy so the best deal is to remove it.

I tried to do my dragster that way, and I ran out of threads on the 4-link bar before I could get it right. I don't know that I can make sense of the "why" but I used the McAmis video I posted above to compare driveshaft angle to pinion and it worked out just fine.

That video is good, but he is measuring rear u-joint operating angle, not pinion angle. Pinion angle is the pinion shaft centerline angle relative to the crankshaft centerline angle, they should be within .5° of each other.

https://www.markwilliams.com/d...shaft-measuring.html

This message has been edited. Last edited by: "The Bender",

Pinion Angle

Angle from the center line of the crank to the center line of the pinion. When view from the side, 4 links should have about 1 degree of angle and if you extend the lines parallel to both the crank and pinion, they would form a V. Ladder bar cars, 2 to 3 degrees and leaf springs 5 - 7. The goal is to have the lines parallel under power.

U-Joint Angle are the drive shaft to the pinion or crank/trans tail shaft. You want these equal under power. Without a shock movement sensor/data logger, you don't know how much the rear travels up or down so how do you set this angle at rest? Can't without assuming something.

I haven't had vibration issues with my 4 link dragster. One key item I feel is the trans tail shaft support which Dan Page Races makes and sells. It's a double roller bearing support so it provides at least twice the support to the DS yoke as all the rest out there. These are more critical with short DS like 4 link dragsters use.

In general, I haven't heard of many real issues with DS vibrations with either door cars or dragster, but there are some out there. Obviously, the DS need to be balanced!

-1 to -5 and never saw any difference