Pinion angle

Could some one explain to me theory of pinion angle why posative or negative,what situation is one better over the other? my car is 289" RED, BBC,Powerglide. Thanks

 

maybe this helps...seems like a decent article
http://www.buickperformance.com/Pinion.htm

 

That's a very good article and quite correct.

One thing it doesn't say is that it is ideal to have a little bit of angle on the engine/trans, and hence the pinion as well. This means the bearings in the U/Js will be constantly moving and not sitting in one spot.

Paul.

 

I think the question is targeted to a 289" wheel base dragster. No 4 link, shocks, spring rates or universal joints. So it might be a bit confusing for someone to relate the article to a dragster application. Although the "instant center" would still be out there and apply.

Not discrediting the article, just not sure if he will see his answer as it relates to a dragster in that application.

I just went through this in my dragster after converting to alumium block. Wacked the weight transfer and had to change engine angle to get the leverage back.

Blessings.............Ron Clevenger.

 

Ron, are you saying the engine/trans angle (crankshaft center-line) in your car is different to your pinion center-line angle?

Even in a car with a fixed rear end the pinion angle must be the same as the crankshaft center-line angle, if you are running a driveshaft with U/Js. The reason is because of how a U/J affects the driveshaft. If the crankshaft and pinion aren't exactly in line, the driveshaft will be on an angle (I know, Driveline 101). This means the U/Js will be earning their pay, but output RPM from a U/J is not even, it fluctuates.

After the first U/J the driveshaft RPM speeds up and slows down twice with each revolution. The second U/J cancels these fluctuations out, providing the U/Js are 'in-phase'. But, the crankshaft and pinion centerlines must be the same for the second U/J to cancel out the first U/J equally. Otherwise the fluctations will remain and slow you down (not to mention break things ).

Happy Motoring!
Paul.

 

Paul, most dragsters on this board (exclude bracket rear suspended) don't run any drive shafts with U/J's. Just use a male to female coupler from trans to rear end with crank centerline running through pinion centerline, mine included.

Blessings.........Ron.

 

For sure. I had that in the old FED I used to run. I got the wrong impression from your first message and went off on a tangent!

If Wudcobbler is doing the same (and one must assume he is) then he should have the whole lot lined up as you've said, and then it's just a matter of getting the centerline angle right to get the weight transfer right.

Paul.

 

Thanks guys, That helps, lets go one step farther, The theory of center line angle as it applies to weight transfer, This is 289" RED hardtail,Dart Big M iron block (heavy) ,and a powerglide. Ron did you increase angle when you made the switch to aluminum Block? I'm A little confused as how to figure IC with no working arms ,or traveling suspension.

 

please expain more about the weight transfer, with more or less angle, moving the engine up or down on it center line does it also change the center of gravity? the four corner weight?
thanks steve m.

 

Sorry for not following through sooner, been busy in shop and also wanted to talk with a friend of mine who has a Race chassis/fabrication to validate terminology correctly so as not to be confusing.

The term "IC" is not correctly applied to a dragster or fix'd rear end chassis'd car. So my reference to it in relation to a dragster chassis would be misleading, sorry about that. Even though the theroy is still applicable the "IC" in a fix'd rear end chassis would be "infinity". So it's sorta point less as a term.

The general base line set up for a dragster is for the centerline of the pinion through the centerline of crankshaft to be parallel to the bottom frame rail. This would be the standard setup. Now, for slight variations the overall combination and total power can deviate from a slight negative (front engine lower, less transfer)) to a slight positive ( front engine raised, more transfer).

In regards to my raising the engine. The whole story is, about 7 years ago I went from a SBC engine (centerlines parallel to frame) to a 632 nitrous motor with the driver compartment right up against the motor. Car was pretty violet on the starting line so I dropped the engine angle one degree. It helped claim the car down. After that I changed to a blown gas engine and needed 15" to be added between the engine and driver for centrifical blower and gear drive. This is 75 lbs hanging on front of engine. The weight transfer wasn't to bad until I recently went to an alumium block and that -100+ lbs put me over the edge. So I have now returned the engine back to parallel to bottom frame rails. I'll see June 26-27 how it worked.

Hope that helps, and if anyone else can contribute or comment I'm sure it would be appreciated.

Blessings...........Ron Clevenger.

 

Thanks Guys, that helps ,I got a little better understanding now.