Pinion/engine/tranny angle
 

I'm setting up my rear end swap in my 1st gen and I'm unsure of how to set my pinion angle in reference to my engine and tranny angle.
I was originally going to set the pinion angle of the rear up 2* and the angle of the tranny down 2*. But since this is a drag car
for track use only, I am wondering if setting it to 0* and setting the engine and tranny in a perfect strait line with the rear
end pinion is a good idea.

If I lower my engine and set it so the tail shaft of the transmission is centered to the pinion, could this translate to more power to the wheels?


*This is still a stock chassis 1st gen. No mini-tub or anything like that either. The car is being built for all motor. And if I did my measurements and math correctly, I should have a 70% anti-squat if that matters...

for drag racing 6 degrees is a great angle,you only need to measure the drive shaft and the 3rd member.so get a magnetic angle finder and put it on the bottom flat of the diff,and then on the bottom of the drive shaft and and you should have x number of degrees.the diff at angle should be pointing downward.the idea is under load on launch,as the tires rotate forward the rear end is rotating the opposite and the pinion angle will then be at 0.hope that made sense.

that angle will also depend on what type of ends you have on the links, you will need less angle if you are using heim joints as opposed to stock rubber or polyurethane. Key here is that on a first gen at stock ride height you do not want to run rubber with the pinion having positive angle. I have 5 dents in the trans tunnel you can use as reasons...

I am using chromoly endlinks. No rubber. Just steel on steel. But I did a little more reading on the whole squat/anti-squat thing associated to pinion angle. I’ll give a basic break down. This could get very in depth, but this is a VERY basic overview.


Squat:
-The rear of the car will lift and the rear tires will be forced down. This does give more traction, but it's wasting horsepower doing it...
-When you accelerate forward, the axle has the tendency to rotate (causing pinion angle change) a certain way causing it to move upwards to the frame.


Anti-squat:
-The rear of the car will squat and the suspension will lift giving "less" traction or “lightening” the rear end.
-When you accelerate, the axle has the tendency to rotate a certain way causing is to move downward away from the frame.

From my measurements, I should have around a 70% anti-squat. Which is about where I wanted it. But, according to what I posted above, my pinion angle should become more negative rather than raise itself. So I should actually set my pinion angle to about 2-3* positive instead of negative. This way, under acceleration, My pinion angle should lower itself to 0* ideally.

Think you have squat and anti-squat backward. A high anti-squat value will cause the body to lift, commonly called separate, from the axle at the hit. If the body squats, it has a low anti-squat percentage.

An FD IRS has an anti-squat value of around 10%, and we've all seen how much they squat in the rear at the hit.

A high value anti-squat suspension will cause the body and axle to separate. We see this in the body raising slightly while the axle is driven into the ground.

This is where I got most of my squat/anti-squat information. Among many other places.

Tuning 4 Link Rear Suspensions for the Drag Strip


This is the calculator I used to verify my measurements anc calculations.

Instant Center Calculator for Mustang drag car suspensions with Prolaunch upper control arms.

If you read my post right above yours again, you can see we are in agreement just worded different. You called it "high value anti-squat". I just call it squat. You called it "low anti-squat", I just call it anti squat. But we are in fact both agreeing that anything over 100% makes the car lift. And anything under 100% will make the car squat.

http://www.jimnyclub.gr/gallery/d/55...anti-squat.jpg

Anti-squat is when the car (body) lifts and suspension is pushed down.

Squat is when the car (body) 'squats' and suspension moves up. You had the two described backwards.

Some anti-squat is what you want as it will put more pressure on the rear axle and keep the front tires from lifting, maintaining more traction in the rear -from the very limited knowledge I have on the topic.

I see said the blind man. I'll try to re-wrap my head around squat and anti-squat.

OK, so the more I read on squat/anti-squat the more confused I get, lol.


The way it is currently set, the car has 57.21% anti-squat. Meaning the point where the end links would meet if I drew a line collinear with each link, they would meet up below the anti-squat line a little below and short of the front wheel center.

My 100% stock chassis car should weigh in around 1600-1700 lbs without me. I weigh about 180. I plan to use either a 10.5" or 8.5", 26" tall slick. The car is all motor (no nitrous).

Right now, I can only adjust the height of the body mounted upper link. And I can only do it this one time. After its all set and welded in, there will be no adjustment (except for lengthening and shortening the links). So I want to get it right the first time. Everything is set up ready to weld, I just want to get the squat/anti-squat the best I can before it's welded in for good.

Would some of you more experienced guys recommend raising or lowering my 57.21% value to get the best traction without wasting HP?

Oh, and just so I got this right... Under 100% anti-squat the pinion should be pointing down at rest. And over 100% anti-squat the pinion should be pointing up at rest?

Up and back on the lower mount should give more AS. Take this question to yellowbullet.com and stick it in the chassis forum. There are some sharp minds over there.

I really need to measure mine out to see what I can do about the short uppers at the diff. Trying to keep stock mounting points.