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Zero CV joint angle

Zero CV joint angle

Zero CV joint angle

(OP)
Just wondering what the pros/cons are with setting up a driveshaft with zero angles through the CV joints? Should one end of the shaft be slightly offset to intentionally create an angle through the CV or is it ok to run a CV at small to no drive angle?

RE: Zero CV joint angle

U-joints die early if their internal needle bearings don't roll  far enough to distribute the lubricant, e.g. far enough that their tracks overlap.

Minimum angle in degrees = 360 / number of needles


Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle

(OP)
Sorry Mike, should have specified that I was talking about ball type CVs on front wheel drive or IRS applications. Thanks.

RE: Zero CV joint angle

Take 'em apart.  You'll find needles.

Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle

Ah.  I thought he was talking about double- Cardan or two- ball or tripod joints.

The Rzeppa joint is different.  It needs even more angulation to avoid false Brinelling than do joints with needle bearings.

If he's talking about an _axle_ shaft, where angulation is guaranteed by suspension travel, then the static angle doesn't greatly affect joint wear.

If he's talking about a _drive_ shaft, which is what he said, then the Rzeppa joint wouldn't be my first choice.

Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle

(OP)
Sorry guys, yes I'm actually talking about an axle shaft and Pat's link is the type of joint I'm talking about. So I take it from what you're saying Mike, suspension travel should be enough to overcome any problems that may arise from having little or zero static angle? Having said that, I guess it wouldn't hurt to have some offset at one end of the shaft to ensure articulation of the joint??

RE: Zero CV joint angle

If the height of the diff is set by ground clearance and interior space or CG requirements so it's output spline or flange is at wheel centre height, fore and aft displacement also works and may even benefit total possible suspension travel if it is thought relative to the fore and aft movement of the wheel during suspension travel.

Regards

eng-tips, by professional engineers for professional engineers
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RE: Zero CV joint angle

It shouldn't hurt.



Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle

In production cars, with say +/- 20 degrees of suspension articulation, our usual problem is running out of articulation, as opposed to needing more.

For a race car I wouldn't sweat it - you'll get more than a season out of a stationary CV joint, at a guess.

Cheers

Greg Locock

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Zero CV joint angle


I doubt offset will change things much in that situation. Suspension movement should be enough. The AWD Jeep Grand Cherokees have a Rzeppa front joint with no visually detectable angle at ride height. It's actually a fairly long shaft so I don't really know why they went that route. It may very well have been done due to the lack of angle.
Still being very tight at 180,000 miles suggests that they made the right decision.

RE: Zero CV joint angle

(OP)
Thanks for the help guys... much appreciated.

Cheers, Brett.

RE: Zero CV joint angle


Steering lock? It would be obvious on axle shafts. Can you shed some light on how it relates to the drive shaft?

RE: Zero CV joint angle

Oh, I hadn't realised you meant the prop shaft. I call them prop shafts and half shafts.

You'll notice alot of propshafts run very small angles in their joints - and I really don't know why we get away with it.

Historically some companies offset the diff in plan view on IRS installations.

Cheers

Greg Locock

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Zero CV joint angle


The Jeep is solid front axle, so there is some up and down on the prop shaft(!). The forward facing 4-link makes the slip joint, just behind the CV, virtually not move at all.



RE: Zero CV joint angle

By an odd coincidence, my 2002 Explorer (Eddie Bauer V8 2WD)  developed a new noise/ vibration from the rear axle (IRS), a munch/crunch at driveaway that is more pronounced if the front wheels are turned.  It goes away at a couple mph, and there are no symptoms at highway speeds, except maybe a little more gear noise on float than I remember from last month.

It was just noticeable and not localizeable until halfway through a 1500 mile trip, wherein it's gotten progressively worse.  Examination showed the left halfshaft can be moved radially a mm or two.  This does not seem like a good thing.

The last 200 miles of the trip was in hilly country, and the noise seems to have abated, at least temporarily.

IN MY IMAGINATION, it's the sort of noise/ graunch/ vibration that a Rzeppa joint would make if the ball cage were fractured.  I DO NOT KNOW if there is in fact a Rzeppa joint in the halfshafts.  The inner joints are Tripods; the outer joints are smaller, and of course enclosed.

We are taking it to the Ford dealer on Monday for diagnosis.  In the meantime, anyone care to speculate?

Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle


I hate to keep mentioning the Jeep, but they can bang/munch/crunch if you change rear lube without adding the proper type and ampount of additive for the anti-slip differential. At very low speeds, it can feel like someone bumped the car from behind, even while moving in a straight line.


RE: Zero CV joint angle

I've lived with a Posi.  Not this problem.  

It feels like a Cardan joint with missing needles, at a crawl, then it goes away as you get rolling.




Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle


Let us know what they find.

RE: Zero CV joint angle

Well, Fabrico, it appears that you were right.  They found nothing, except a service bulletin that mentions the diff clutches may lock up in cars that don't turn much.  I thought it was an open diff.

As it happens, the last 35 miles of our trip was on a fairly twisty road, and that was enough to fix the problem.

The service manager asked if I had changed the lube.  I hadn't even checked it.  She had spoken to my wife earlier, and mentioned a non-OEM color, which is about when my wife decided to wake me.  The dealer is going to add some friction modifier.  

Mike Halloran
Pembroke Pines, FL, USA

RE: Zero CV joint angle


I wasn't about to argue about posi rear ends. I too have owned a few muscle cars and full size 4WD's with limited slip differentials. They chirp, they bump, and do funny things but none of them do anything close to what a Jeep, and aparently some others, can do. I have not studied the differences but the Jeep can definately store up a sizable amount of bind and release it when it feels like doing so. In summation, if you haven't experienced it, you wouldn't believe it. Glad it didn't cost you much.



  

RE: Zero CV joint angle

"Much" is a relative thing.
labor        120.00  
new axle oil  46.02
additive       4.44
brakleen       4.25
waste disp     1.00
tax           13.62
total        189.33  USD

The labor includes three road tests, and inspection of all the u-joints and halfshafts, which were declared just fine.  

I'm used to GM posis, which exhibit fewer weird symptoms as they age.  Not so for Fords, I guess.

Thanks for the help.




Mike Halloran
Pembroke Pines, FL, USA

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