Driveline Vibration/Harmonic

MDW

MDW

New member
Joined
Dec 7, 2006
Messages
643
Looking for some input.
In our ProStreet truck we are seeing a new problem.
We are getting a vibration in the front of the driveshaft as in goes in the trans.
At about 3500rpm the shaft is deflecting a lot. Maybe an inch.
It comes on at 2500 to about 2700 then goes away and comes back at 3500.
Its very violent.
The truck is a reg. cab short bed so we had a driveshaft made shorter and balanced. The shaft is one piece steel. Don't know the thickness or the length yet as it's raining.
We did the test on jack stands without tires. We changed the yoke even though it looked good. The u joints seem tight and fine. We tried the test in overdrive with the converter locked and unlocked and it still vibrated. We also tried 3rd gear locked and unlock and it didn't vibrate.

At 3500rpm with overdrive I believe the shaft is seeing 4550rpm?
Are we getting to critical speed as they call it?

Any thoughts/help would be appreciated.

Michael
HRD
 
Here's some more info:
Length 46.5"
Weight 30.5lbs with trans. yoke.
Wall thickness .065
Diameter 4"

Michael
HRD
 
put a full tube of gun grease in it, drill hole and weld back shut or tap and plug it

it will balance it at all times
 
46" at 4" is good for almost 9,000 rpm...

Was that shaft re-balanced with the new slip yoke after you put it on?

The shafts are balanced with the slip yokes, also have them remove that extra weight up there on the slip yoke before they balance it...


When you say 1"....are you saying that when the shaft is spinning it is spinning out 1 inch, as if it was a crankshaft ?
 
I talked to the drive shaft shop today and he brought up the same question.
No it wasn't rebalanced after the yoke change.
Yes it is wobbling out about an inch or so. Lets just say I'm not getting close enough to measure it :)

I'm thinking of going ahead with a new output shaft setup that will need a longer shaft by a few inches, seems like the right time to do it.
Kill 2 birds with 1 stone sort of thing.
 
If it is wobbling an inch that is the problem, what's causing it to wobble is what needs to be fixed, is the bushing in the tail housing ok?
 
Just got back from the drive shaft shop.
The yoke end is out of round is the only way I can think to describe it.
I'm going to wait to have it fixed as I'm going with a different output shaft setup that will require a longer shaft by a few inches.

Any thoughts on aluminum or carbon shafts surviving in this application?
 
AL or CF will work, and benefit you in performance...

What is the app? drag racing?

The shaft is made up of a shaft tube, 2 weld yokes (at each end), 2 joints, and a slip yoke and some shafts have a flange yoke...
Which part was out of round ?
Have them remove the entire balancer assembly from the slip yoke when they balance it....added bs weight to slow you down...


.
 
Drag Racing
The new shaft will have a different yoke from Mark Williams.
Any idea how much a carbon shaft would cost?
 
If you reuse your slip yoke it'll be somewhere between $600 and $800...

Which series are you using...

Also that slip is very strong, unless you are using a roller tail housing
 
Would it not be better to build the slip into the shaft itself? That way you have yokes that bolt on both ends?
 
I have the new output shaft setup coming along with the trans. yoke from Mark Williams.
The new trans. yoke is going to be 1350 u joint and the pinion yoke is 1410 so I will need a hybrid shaft I believe. Any thoughts on this?
The drive shaft shop I'm working with says he will make me a 1350 on one end and 1410 on the other in steel, sound good?
Mark Williams says they are working on making the same style yoke in a 1480 joint but its a few months away.

Any different ideas would be appreciated.
Hey Supershafts, do you make carbon shafts?

Michael
HRD
 
Why can't they make it in 4" AL with 1410 and 1350....
I do all types of shafts

I never seen the factory slip break..

AS for Lower's question.......

You don't want a LD style shaft on anything performance related if you DO NOT have to, it simply increases the weight and hurts performance..

On a deep trail truck a LD style is ok for the ONLY reason being that if you break the shaft you can continue on 1 axle without losing all the trans/t-case fluid...

In the performance world......if you lose the shaft....who cares if you can keep the fluid in.... YOU LOSE either way...
 
wouldnt aluminum be a bit softer on the rest of the driveline also?
lightness would hurt at all either
 
Alright, fair enough. I have 2 transmissions and one is the LD and the other is slip and I was unshure of which tailhousing to use. Now if they will interchange i'll be set.
 
Supershafts said:
Why can't they make it in 4" AL with 1410 and 1350....
I do all types of shafts

I never seen the factory slip break..

I twisted 4 of them so bad they got stuck in the trans.

All the parts are on the way I will update as soon as it's moving again.
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