Does Drive shaft angle really matter?

I've looked all over the internet and cannot find any examples where an "intersecting" angle is construed as a proper setup for a double-joint, single shaft driveline which will not vibrate. I have found plenty that agree with the way I believe is correct, which is equal but opposite angles. For my own education, could any of you that truly believe you can have equal and SAME (vs opposite) angles in a single shaft driveline operate without vibration please point me to some evidence? Just saying so isn't going to change my mind. I live fairly close to Missouri, so you'll have to show me.....

Forgive the links to non-HAMB friendly sites, but drivelines come in all shapes, sizes and vintage. I'm only posting three that support my view, but there are dozens more, including some that have already been shared on this thread:

http://www.prostreetcamaro.com/dshaft.shtml

http://www.carcraft.com/howto/91758/index.html

http://www.iedls.com/asp/admin/getFile.asp?RID=10&TID=28&FN=PDF

In my voyage through the ether, I found this very interesting tidbit that demonstrates how much the rotational speed varies, twice per revolution, on a u-joint operating at 30 degrees. From a tractor-trailer site, but nonetheless applicable:

Koedam has measured the variation in velocity as driveshafts rotate. When a u-joint is placed at a 30-degree angle and rotated at a constant speed of 1000 rpm, the driveshaft actually speeds up to 1300 rpm and slows down to 700 rpm.

 

Say if your tailshaft/ output shaft angle is 4.5 degrees your pinion angle needs to be 5.0 degrees or atleast 1 to 2 maybe 3 degrees close. Which the reason for that is axle twist which is a big deal when running stock or some what modified leafs with a built engine. Pinion angle plays a big role with this. Also when you hit a bump giving the pinion a little anlge to play with is good as well it will give less strain on u joints. Which running a single u-joint compared to a double cardan you need some play with the angle.

 

this is a VERY useful post.

 

but what about if you throw carrier bearings into the mix like on GM x-frame cars?

 

Yeah, if you think that's complicated try adding two hangers and tandem axles like a big truck has.

With a single driveshaft 98% of the time you'll be just fine if your transmission output shaft is parallel with the pinion input but I also agree with Norfab and Hackerbilt that opposite angles can also work.
The parallel setup is usually the preferred method but you can sometimes reduce the working angle of the u joints by using the "broken back" configuration.
That "broken back" setup is commonly used on the short driveshaft that runs between the tandem axles of large trucks.
It seems weird but it actually works.

 

subscribed

 

Driveshaft angle matters only in relation to the driveline itself, not to the ground. In the simplest example 4* down at trans , 4 * up at pinion, those cancel each other out but the driveshaft still needs a working angle. U-joints need at least 1/2* degree working angle to rotate other wise they would wear out very quickly without the rotation. Usually 1/2 to 3 1/2? is acceptable.

 

It certainly is. I am running this setup on my A. It has a T56 with a fixed yoke, a double-cardan shaft running to the pinion yoke, which is 4" above the trans yoke, and pointed directly at the trans yoke. It has radius arms, so the pinion yoke angle moves on a curve when the suspension cycles.

It is the upside-down version of what is on the front and rear of my 4x4 rig.

Drilling and tapping an output shaft is not that hard. Some are already drilled and tapped (the T56 was). Fixed yokes can be had for most all shafts.

 

theres a 32 in my shop and the trans is pointed down about 5 degrees and the pinion is up 2, the trans is lower the the dif, you would think it would vibrate, the guy says no and its been driven for years like that, lots of miles put on it, go figure.

 

The answer seems obvious to me, IMO, 7 or 8 degrees is no problem so long as the ****** and pinion are = and opposite. Seems to be the consensus here also.

I want to say that 11* is the realistic working limit for a typical conventional u joint. So you might be pushing it at 10.

= and opposite is the way that u joint surging balances itself out, not completely, but good enough. this balancing becomes less effective at greater driveline angles.

 

I'm not suprised. When I was building a rod in the later 70s, I worked as a used car mechanic at a new car dealer. I looked at a lot of the used cars, checking driveline angles to copy......very few cars had the same front and rear angles.. no bull.

 

I could also shim both to have a parallel angle of 0 degrees and have the angle of the driveshaft be the working angle for both becuase the driveshaft will be angled upwards...

 

http://www.jalopyjournal.com/forum/showthread.php?t=445498&highlight=out+of+phase
PM and ask here, please, for other info.
The two piece carrier bearing type driveshaft like 63 Impala is not a good answer. Good to try on thinking. BUT, I built a driveshaft for a chopped, Z'd, 39 Buick w/BBC/700rR4/9" that had a two piece driveshaft with a CV head at the rear to allow for pinion nose down for Z and tunnel clearances. Try that trick on for size and make it run smooth, I barely did.
Oh, the car is dark blue and in Rod & Custom Magazine. Bodys by Bob built the car.

 

Here's the biggest deal.
What angle is your engine/transmission set at? I call nose up because the balancer is higher than the ****** tail.
What angle is your pinion intended to be set at. I call nose up if the yoke is higher than the gear on the TAIL of the pinion..
What is the angle of the driveshaft between? Then math jumps in.
Operating angle thru the front u-joint (A) vs angle thru rear (B). On a two u-joint shaft, they must be within ! degree of each other for max u-joint life and least vibration.
You can have an engine sitting at 3 degrees nose up, driveshaft running nose down at 3 degrees, with the pinion pointed nose down at 9 degrees-------and have complimentary angles. In this situation, you need to have your construction solid, not much room for error.
The Q about suspension movement causing arcing and angle change is extremely valid. Your suspension design needs to compliment how u-joints work.
Case in point, OT but will describe.
75 or so Caprice/big GM car with 4 arm coil spring suspension. Changed to hydraulics. Customer brings car in because he complains of driveshaft vibration when the car is lifted to it's highest, squawks more than ............ The suspension makes the pinion nose down hard when hiked up, nose up hard when sat down. The CV head, mind you, is being worked harder than a jacked up 78 Chevy 4WD, when hike up, ma**ed out, metal to metal. No happy medium other than to change the length of suspension arms, etc. The suspension mounting points and arm lengths cause the suspension to make pinion angle change dramatically with ride height. This can also make suspension induced bad driving/handling characteristics.
Another piece of math. 1/4" rise at 1 foot, (slightly less) equals one degree of angle change. 1" at 4 feet is the same. You can modify off of this to know how much change is needed at a known distance.

 

Norfab has it RIGHT. When you operate a u-joint at let's say 5 degrees - it creates a speed variation (positional variation) during a rotation. The driveshaft actually speeds up and slows down during rotation. By using a COMPLIMENTARY U-joint angle on the second Ujoint - you effectively cancel this speed variation out and the output to the rear end is now once again a smooth aplication of speed (no variations - no vibrations)

The deal is simply this - the SECOND Ujoint has no idea if it is being operated at +5 or -5 degrees (either way causes the exact same variation) so whether or not the input and output shafts are parallel is NOT the ONLY way to achieve the desireable COMPLIMENTARY U-joint angle. Parallel input/ output may be desireable for several other reasons, but it ain't the only way to skin this cat.

 

Correct HemiRambler.
The technical term is angle cancellation. Drive steady rotation speed is converted to oscilliating (sp) speed, back to driven steady speed thru proper u-joint angles.
Not always this easy.

 

Lot's of good info. here and some mis-info. Rather than explain, I've always used the tech data found here (4x4 site, but works well for hot rod applications). http://www.4xshaft.com/index.html Click on the "tech info" link in the top right corner, then "geometry 101." Also check out the "what type of driveshaft" link. I believe someone else posted diagrams earlier in this thread that appear to be from the same site, but read the text. Good info and it's never let me down and I've built Jeeps with some very short and severe driveline angles without vibration or failure. Rock crawling is a lot tougher environment that street car use as well.

 

Yes

 

Guys, I gotta tell you, the crow I'm eating right now is tough, and not very tasty either. But after I chucked up a borgeson steering u-joint in my lathe, along with a pair of degree wheels, I now realize that what I've been thinking for years is not the only way that a driveshaft can be set up, and that the "broken back" config does basically the same as far as cancelling the ellipsis effect on a shaft. I had set out to prove some others wrong, when in fact I was.

My apologies to Norfab, JohnEvans, Hackerbilt, and anybody else that I may have suggested were wrong. Thanks for continuing to insist that "Parallel" isn't the only option for pinion to tailshaft relationship. I learned something from it.

 

I don't see a need for apologies, but I certainly thank YOU for going the extra mile and testing the configuration!
Nothing like having someone you can trust try it out rather than just argue the points back and forth.

Crow isn't so bad...I know I've had my fill of it over time!

 

My concern was live axle. Say you have a 4' driveshaft and 3* down on both trans and rear. I" of movement is 1*. So if the rear end moves up 3". now you have 6* at the trans and 0* at the rear. If it drops 3" you have 0* at trans and 6* at rear. Fine for cruising at a static height but if it squats when applying power you might get a vibration or lose a joint. If typical rod suspension of only an inch either way it would work.

 

None needed. Many times I've found out I'm wrong by trying to prove I'm right. That's what makes these discussions valuable. I've worked up quite a few recipes for crow over the years because of it.

 

That's another can of worms. Very rarely does a rear move up and down with no rotation. They rotate around an instant center that's determined by the suspension linkage. If there's much travel you need to address this too.

 

Somewhere, this thread lost its direction as I read it. So, my input. No, the angle does not make a difference as long as it is within reason. If the joints can turn without bind, there is no specific concern. Case in point. A threepoint hitch on a tractor can change the shaft angle from 0 dg to 30 or more degrees up and down, but the drive shaft does not notice this as long as the alignment factors are correct. This swing through a 60 dg angle makes no noticable difference the operation of the joints. I have seen a tractor running a 6" water pump for months with a shaft angle of almost 45dg with no problem. Nobody made any extra effort to make sure the shafts were parallel though they were reasonably close.
The reality of it is that theory and perfectionism can make problem out of anything. As in hand grenades, mechanical close counts in nonprecesion applications.

 

So exactly --erhh I mean approximately how much is "within reason" ??

"no bind - no problem" ? Maybe for a steering column, but I'm thinking it will eventually catch up with you if you start to zing that driveshaft any. I say this because even though you can cancel out the speed fluctuations by phasing the ujoints and using complimentary angles - the eventual reality is that the driveshaft is STILL speeding up and slowing down multiple times a revolution - as the ujoint angle is increased the magnitude of the fluctuation increases as well - eventually you get to a point where the inertia of the whole thing causes a vibration and we stand back scratching our heads wondering why. YMMV


Threads like this always make me hesitate to post - usually I

 

He was asking about a 7 dg driveline angle. If the output and input angles are compatible and the shaft is balanced, it should not be a problem which is the question he was asking. If there is a problem, it is more than likely to be harmonics which can be treated with a cardboard liner in the shaft.

 

There's a whole different world between agricultural driveshafts spinning at 540 or 1000, compared to automotive stuff spinning at 2500 rpm plus at sustained highway speed. At the slower speed, you can run more angle, but within limits. Drag a drawbar attached rotary mower and turn a corner too tight, you will HEAR what too much angle sounds like.
In the automotive world, 3 to 5 degrees opeating angle through a u-joint should pretty much be the maximum and still be able to have mazimum life from a u-joint. Stock Chevy K5 Blazers up to about 1990 have 11 degrees angle through each of the rear u-joints--stock u-joints last about 150K miles, replacements 10K-12K miles. WHY short u-joint life? Too much operating angle.
I have made a twenty year career of trying for perfection in my mechanical repairs and driveshaft rebuilds. That's why my customers keep coming back and why I get jobs and calls on problems nobody else can figure out, even from sister stores from three states away.
You would be very surprised at how little it takes to make a driveshaft tear up bearings and gears in heavy truck stuff because someone didn't understand how to build a truck with proper driveline angle setup. Hotrod stuff is just a little smaller and a little lighter, same affect. Wear pattern insdie automatic transmission clutch packs, manual transmission gears, ring and pinion sets will show if driveline angle setup is improper. You can find troubleshooting pictures in roadranger.com literature online if you want to look at what I'm speaking of---Failure ****ysis Handbook.
Dana Corporation has a torsion vibration ****ysis program I use if I have trouble with a pickup or big truck, it's in their Dana Expert online help stuff.
Drag race pinion down setup is good for short term use. Dirt car guys do stuff that will screw up on the street. Dirt car guys will also throw in so much pinion down, the bearing journals will melt and bend like you bending your finger.
I'm not throwing a fit or slamming my keyboard around. Just trying to provide useful info to y'all. It's good for people to ask questions and learn.

 

Any angle, up, down, side to side, will work good and last a long time as long as the extremes of suspenstion travel don't result in the U Joint yoke shoulders coming in contact with each other.

 

Well just a little update... I pulled the whole rear end and moving all my brackets... So thanks to all you to gave me info on setting it up. got a busy weekend planned!

 

Set the rear at 3 down and trans at 3 down... driveshaft is at 6.5... hope this works... maybe my feet wont fall asleep on my way to Ventura!