Not another pinion angle question!

I read all thru the old threads and there are as many theories as questions. Then if you ask a drag racer they will give you an entirely different answer. My question is, if the car is going to run a pretty healthy (450HP+) motor, manual trans and leaf spring rear what are your thoughts on running the pinion down a couple degrees (from where it should be) to compensate for axle wrap. This will be primarily a street car but will see some weekend drag racing hopefully. I will also probably end up running some Caltrac bars on it. Thanks Mike.

 

Set it up to compensate for spring wrap and the only time it will be correct is when the springs are wrapped. Simple right ?

The only time the spring wraps is when you launch hard and have your foot deep into the carb. Simple right ?

 

Are you going to trailer it?
Then go for the down angle.
Hiway driving...3* up....

 

X2. If it's street driven and you don't want that annoying wwamp wwamp from the drive shaft at speed, keep the angles close on both ends at ride height. If anything maybe put 1 more degree down at the rear.

 

Thanks for the reply. It seems simple, but I would imagine it actually wraps a little even under moderate acceleration on the street too. With a manual trans and fairly aggressive gearing should you try to meet it in the middle? I've seen ******* bars move quite a bit on the street. Thats the problem I guess trying to set it up for 1 or the other when you want to do both.

 

Main concern for me would be cruising at freeway speeds. Very little to no load and with a traction or ladder bar, the deflection would be pretty much nil.

 

Generally I have found that dual purpose set ups do neither very well or are extremely complicated.

 

I am probably over thinking it, I definately dont want any rumble at highway speeds. I was on another OT forum last nite there was much debate about this.

 

You are overthinking this, 3 degrees up, ****** three degrees down, makes for no annoying hum under your ***. If you're gonna street it, set it up for the street, if you're gonna track it, then set it up for the track. If its both, invest in or make a nice set of traction bars you can install at the track. On the street, axle wrap isn't a concern unless you've got REALLY wimpy springs under it. Even if it wraps a little, its not gonna hurt anything, unless the springs are so wimpy you pull the yoke out of the ******. I'd set it up for the steet and enjoy driving it.

 

I would just fix the suspension properly. You will still get wheel hop. Mopar sells super stock springs for these types of problems. They also had a shorter front segment on their leaf packs in most all their cars to help with axle wrap as well as a pinion snubber. You could try similar tricks on your leafs.

 

This is part of what has me worried about it its a 40 Ford coupe with CE parallel spring kit. So the springs are a bit of an unknown.

 

Wont the cal tracks get you what you want ? Back and forth in just a few mins

 

Calvert's recommends a pinion 4-5* down pinion angle on their Caltracs? Thats why I was asking.

 

I run neg 5 degree's of pinion angle in my 4 speed Falcon g***er, it has ******* bars, doesn't make any humming noise, it hooks and books on 295/50/15 radials. I drove it over 3000 miles last year with no problems. I'm setting my Jeep pickup at a neg 7 degree's, will be running a 4 speed in it with 550hp big block. I would go with what Calvert recommends. Some of the serious stickshift dragcars run upwards of neg 9 degree's to plant the slicks.

 

Calvert has been doing it for a long time. Also with a proven product. Follow his advice.

 

I just got off the phone with Calverts they said I should be able to go 2* down with no problems at highway speed. He actually said they have many street strip cars running more than that without problems but since I was concerned about vibration and wasn't a serious racer the 2* with their bars would still prevent wheel hop and still help launch better at the track although it would take some trial and error adjusting to get it optimized. I also figured if only off by 2* I can shim it back to 0* without much problem. Thanks for everyone's input if I remember I'll post how it works out.

 

subscribed....

 

I welded the perches on and after welding them the rear end ended up being down 1.7* (the motor/trans is 4.7* down the rear is 3* up). We'll see what happens.

 

This has worked for many years for me and I own a 9.0 sec car that shifts at 9,000+ RPMs. If you do it wrong there could some terrible injuries.
Normbc9

 

The working angles of the U-joints are what's important, not the engine or pinion angle.

 

YES! Bingo...the correct answer for street driving.

 

The last 3 posts ( 4 including mine ) are the only ones to pay attention to. People always refer to a certain degree up or down, but mention nothing of what that measurement is in relation to. Just saying 3 degrees down means little. 3 down from what---the ground, frame, engine, trans, shifter, windshield, gas tank, or radio?


Ideally, the angles between the transmission output shaft and driveshaft, and between the driveshaft and the pinion will be equal and opposite.

 

buy an aluminum wedge for the springs to use at the track, take it out when not using---bought mine at local speed shop but i think it is a moroso...

 

In regards to the picture "perfect" is anything but perfect and "absolutely not" is actually perfectly fine although not normally recommended. U-joint pairs (meaning sets of them) will cancel out the vibration IF the angles are the same - angle being the u-joint's working angle. There is of course a limit -the reason for that is that the drive shaft speeds up and slows down every 1/4 revolution. The magnitude of this increases with working angle - eventually the m*** catches up with you and even a matched set of angles will vibrate.
Go to a reputable manufacturer and follow THEIR directions - they will steer you in the right direction in terms of how little angle you want (zero is actually bad) and how much you can stand.

 

Equal and opposite would be the picture captioned " absolutely not". So since you say to ignore all the posts ( actually you said it a little differently) beside yours and three previous posts - what are we do with contradiction conundrum that's been created now ??

 

Its not a contradiction at all. It just means that if the trans to ds angle is 3 degrees , then the the ds to yoke angle should be 3 degrees----just in the opposite directions. Or think of it like this. Trans 3 degrees down --- yoke 3 degrees up. Up and down are opposites last time I checked.

 

To clarify, my motor/trans is 4.7 degrees down towards the rear in relation to the ch***is. I understand about the equal and oppisite working angles. I welded my perches so the rear is up 3 degrees also in relation to the ch***is, this gives me a pinion down 1.7 degrees from perfectly parallel. I agree that equal and oppisite (actually parallel) angles are Ideal, and I would normally set my street cars up like this. But on this car I plan on drag racing it fairly often and due to the fact that it has what I consider less than strong leaf springs I think allowing for 1-2 degrees of flex out of the spring is not a stretch. I also dont think a degree or two off of equal and oppisite will hurt much. If I set it up at exactly equal working angles and since its a pretty healthy motor and manual trans with fairly aggresive gearing dont you think that much of the time even under moderate acceleration street driving the springs would flex enough causing it to be unequal (pinion up). I doubt there are many cars out there that maintain a perfect equal and oppisite working angle during acceleration, deceleration and suspension travel, especially leaf spring cars. so I thought Id try this and see how it works out. I've seen others recommend allowing for some movement when setting up the pinion angle too Curry,Moser, Mark Williams ETC. I thought I would try this which is a bit of a comprimise of both theories and see how it works out. If I am completely wrong a 2* shim should make it right.

 

What you described should work fine. Good luck with it.

 

Let me help you out here :
Your equal but opposite Statement It is a contradiction to the "absolutely not photo"

You're statement of only needing to pay attention to the the last 4 posts yours included is wrapping the contradiction with another contradiction of pay attention to that contradiction by ignoring the photo which states its caption "absolutely not"

It's either a contradiction or you are not more than reasonably certain of the difference between parallel and equal but opposite

Hence the conundrum as measured off the radio

Parallel means the lines will never cross and never grow further apart , ever into infinity both directions.
Equal but opposite means the lines will intersect at exactly the center of the origin points and continue to grow further apart at exactly the same rate

 

I just sent your post via text message to my high school English teacher, my high school geometry teacher, and my high school physics teacher.