80 series driveline noise question (1 Viewer)

[enox]

Hi, I have a strange noise that only occurs on the freeway 50mph+ i have checked phasing and u-joints which appear to be fine.

heres what happens and only with these conditions - i can be going flat at highway speeds foot on the accelerator and under load. in the seconds when i release my foot or let up on the accelerator and the vehicle speed is slightly faster than engine load, it sounds like grrrrrr with a small vibration in the pedal (nothing in the wheel) now when engine braking takes over it stops. once the vehicle goes from the change in velocity relative to load is when i hear and feel the issue. its those seconds of unloaded driveline when its transferring the torque from an increase or decrease in torque.

sorry for the exclamation if it doesn't make sense, trying to put it into words ....

thanks in advance for any thoughts or suggestions!

 

[f5driver]

My 100 does the same thing. Happened right after the tcase seals were replaced so I’m thinking that’s it.

 

[enox]

My 100 does the same thing. Happened right after the tcase seals were replaced so I’m thinking that’s it.

Weird...the only thing I've done to my t-case was pull the viscious coupler, it seems to get better after I hit the zirc fittings on the driveshaft with grease...I don't want to overload those so next step would be pull the front and rear shafts - separate them and regrease the slip yokes.

But yeah it only happens for those brief seconds when there is a change in load, weather it's an acceleration or deceleration...

 

[landtank]

what lift and caster correction. This is typically solved with a DC shaft under the right circumstances.

 

[bajaphile]

I'll bet $5 its your front or rear drive shaft u-joints.

You can pump the joint of grease and see if it temporarily goes away. Most people run a DC front with 3"+ of lift.

Also the rear joint on the rear shaft tends to require replacement even on stock trucks...try pumping in grease and see if it changes it. If so, you may want to replace it.

 

[enox]

what lift and caster correction. This is typically solved with a DC shaft under the right circumstances.

ome 3.5 front and 2.5 rear with castor correction plate kit..

 

[enox]

I'll bet $5 its your front or rear drive shaft u-joints.

You can pump the joint of grease and see if it temporarily goes away. Most people run a DC front with 3"+ of lift.

Also the rear joint on the rear shaft tends to require replacement even on stock trucks...try pumping in grease and see if it changes it. If so, you may want to replace it.

okay thanks, so maybe the yanking on the driveshaft wont give me a difinitive answer on bad u-joints... ill grease em and see if that helps..then like you said, if so ill know to replace those...

 

[landtank]

ome 3.5 front and 2.5 rear with castor correction plate kit..

who's plates?

 

[enox]

who's plates?

*Slee*

 

[landtank]

*Slee*

you need a DC shaft.

 

[enox]

you need a DC shaft.

Dang.. okay thanks tank! I'll have to source out a shop to convert mine...

 

[BILT4ME]

When you're checking the play on the U-Joints.....Are you doing it with the driveline UNLOADED? That means, wheels chocked, transmission in neutral, no parking brake. THEN you check for horizontal / vertical / rotational movement on the DS on each end.

What you're describing sounds to me like the output bearing on the T-Case IF the u-joints have been properly checked.

 

[enox]

When you're checking the play on the U-Joints.....Are you doing it with the driveline UNLOADED? That means, wheels chocked, transmission in neutral, no parking brake. THEN you check for horizontal / vertical / rotational movement on the DS on each end.

What you're describing sounds to me like the output bearing on the T-Case IF the u-joints have been properly checked.

thanks for this, i have not checked in that manner. i checked by crawling under there in park - ebrake on - how i would normally park anywhere...

 

[BILT4ME]

thanks for this, i have not checked in that manner. i checked by crawling under there in park - ebrake on - how i would normally park anywhere...

Lots of people check the driveline as you did and always state no problems, only to find out it was a VERY bad U-Joint.

You're not the first....won't be the last. That's why I post that information frequently.

Good luck!

 

[enox]

Lots of people check the driveline as you did and always state no problems, only to find out it was a VERY bad U-Joint.

You're not the first....won't be the last. That's why I post that information frequently.

Good luck!

thanks BILT! appreciate the info - purchased this truck about 6mo ago bone stock, have had a lot of fun taking it out and working on it. I keep tackling one thing after another, so far the only thing i have hit a big snag with is changing the dang tie rod ends..had them come when i purchased the lift among a few other things. Broke one puller already, then put the tie rod ends back in the box for another day... ill diagnose the u-joints in the manner you outlined when i get home today. once again thanks for the info & a big thanks to this available community!

 

[BILT4ME]

What puller are you using for the tie rod ends? Do NOT use the pickle fork.

Use this style:

You install it by hand, tighten with a wrench or impact.
Hit the nut end of the stud with a hammer (like you mean it!) inline with the stud.
Then tighten it again
Lather, Rinse, Repeat.

You can rent these from O'Reilly or your local FLAPS (Friendly Local Auto Parts Store)

 

[enox]

you need a DC shaft.

Sourced a shop, approx 300 without seeing it to do the conversion. Takes about 24hrs to complete. I'm going to double check the u-joints first..

 

[enox]

What puller are you using for the tie rod ends? Do NOT use the pickle fork.

Use this style:


View attachment 1799364


You install it by hand, tighten with a wrench or impact.
Hit the nut end of the stud with a hammer (like you mean it!) inline with the stud.
Then tighten it again
Lather, Rinse, Repeat.

You can rent these from O'Reilly or your local FLAPS (Friendly Local Auto Parts Store)

I used the style that is a tripod shape with adjustable legs..I'll have to pick one of these up when I tackle those next! Thanks!

 

[jonheld]

FWIW, a sloppy slip yolk on either driveshaft will exhibit these exact symptoms, regardless of lift.
Under load in either direction, the splines are tight. When coasting at highway speeds, the 2 halves of the shaft can flop around causing a very noticeable "buzz" until a load is applied in either direction.

 

[enox]

FWIW, a sloppy slip yolk on either driveshaft will exhibit these exact symptoms, regardless of lift.
Under load in either direction, the splines are tight. When coasting at highway speeds, the 2 halves of the shaft can flop around causing a very noticeable "buzz" until a load is applied in either direction.

Your description is spot on to what I'm experiencing...