Thread: Driveline Angle

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Just don't really see any reason to get all fussy about matching the angles... Too many launches with a 0 degree tranny and 3 degree down pinion, and that's with slicks and big horsepower. Seems if it's a good driveshaft and joints it will work just fine within about 5 degrees or less.

I know all the "science" and "theory" behind it, and even understand what all the engineer's are talking about. Just haven't seen a lot of problems in application. Our
Comet drag car, for example. The engine sits level at launch, which leaves the trans angle a couple degrees down...The pinion angle is set a 3 degrees down. The car was built 10 years ago, gets about 100 passes a summer, new U-joints every winter, and has never had a failure or a vibration in the driveshaft...Everyone will tell you those angles are all wrong, but it works just fine!!! Look at some of the oddball angles on 4 wheel drive stuff, and they survive...

Maybe all the angles is more important on light duty parts, but I sure haven't seen any problematic failures with angles being not exactly right when quality parts are used... Heck, our old Late Model had 9" of travel on the rear suspension, think how "incorrect" those angles got, and again never a failure???

Maybe I'm just lucky?

Originally Posted by Dave Severson

Just don't really see any reason to get all fussy about matching the angles... Too many launches with a 0 degree tranny and 3 degree down pinion, and that's with slicks and big horsepower. Seems if it's a good driveshaft and joints it will work just fine within about 5 degrees or less.

I know all the "science" and "theory" behind it, and even understand what all the engineer's are talking about. Just haven't seen a lot of problems in application. Our
Comet drag car, for example. The engine sits level at launch, which leaves the trans angle a couple degrees down...The pinion angle is set a 3 degrees down. The car was built 10 years ago, gets about 100 passes a summer, new U-joints every winter, and has never had a failure or a vibration in the driveshaft...Everyone will tell you those angles are all wrong, but it works just fine!!! Look at some of the oddball angles on 4 wheel drive stuff, and they survive...

Maybe all the angles is more important on light duty parts, but I sure haven't seen any problematic failures with angles being not exactly right when quality parts are used... Heck, our old Late Model had 9" of travel on the rear suspension, think how "incorrect" those angles got, and again never a failure???

Maybe I'm just lucky?

Completely agree! this is what i tried to say earlier, figured i would get blasted for it, but i know what i am talking about, i'm one of those engineers that knows and understands the theory behind it too. No reason to fuss over it, i've never had a failure in the dirt late model either and there's no way that thing is ever any where near "correct". Use good parts, and you have no worries, quality U-joints/drive shaft are cheap insurance when you look at the cost of the damage it could cause if it comes apart.

Dave and TooFast,
I would make a guess that in either of the applications cited you would never even realize that there is a driveline harmonic Launching for a 1/4 mile pass and banging gears, or tearing around the dirt oval with angles going everywhere are about as far away from a steady state cruise down the interstate as one can get, and I believe that is where the harmonic vibrations come into play. Sure, I want the thing to hook up on an occasional launch, but I'm much more concerned with a smooth ride on the street and highway, plus long term reliability - changing u-joints in the AutoZone parking lot on a car sitting 4 or 5 inches off the ground, chasing a driveline shake is not a good trip highlight! Your racing applications point out that the setup is not going to break u-joints, and I agree 100%. This is a street/cruise question to me, and one where the high speed NASCAR experience on asphalt may provide some insights, but drags and dirt tracking are probably not really relevant. Just my opinion, and I may be wrong. Thanks for the input, anyway. Everything goes into the decision hopper.

Originally Posted by rspears

Dave and TooFast,
I would make a guess that in either of the applications cited you would never even realize that there is a driveline harmonic Launching for a 1/4 mile pass and banging gears, or tearing around the dirt oval with angles going everywhere are about as far away from a steady state cruise down the interstate as one can get, and I believe that is where the harmonic vibrations come into play. Sure, I want the thing to hook up on an occasional launch, but I'm much more concerned with a smooth ride on the street and highway, plus long term reliability - changing u-joints in the AutoZone parking lot on a car sitting 4 or 5 inches off the ground, chasing a driveline shake is not a good trip highlight! Your racing applications point out that the setup is not going to break u-joints, and I agree 100%. This is a street/cruise question to me, and one where the high speed NASCAR experience on asphalt may provide some insights, but drags and dirt tracking are probably not really relevant. Just my opinion, and I may be wrong. Thanks for the input, anyway. Everything goes into the decision hopper.

Guess i just have to run it wide open all the time if i am off a degree... Thats more fun anyways.