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29 replies

Drive Train Clunking

R rrs1Member
I have a clunking noise that is coming from either the ZF or the drive shafts. It happens on acceleration either from a standing start, or if coasting and then getting back on the gas. It's as if some slack is being taken up before the drive is actually put to the ground, so it's kind of a slapping/clunking sound.

It also happens to a lesser extent upon deceleration.

With the wheels off the ground, and turning one wheel back and forth I notice there is quite a bit of play/slop, maybe 1/2" before the axle flange turns. I know there is some play, but how much?

The transmission shifts fine. Is there something else that can happen inside a ZF besides shifting problems that would cause this noise?

Is there a way to know or test if the drive axles could be causing this besides looking for the "ring of death" snap rings turning into the metal? I don't know if it applies on a Pantera, but it feels like U joints are worn.

Thanks for any insight.
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rockyrockyMember
Just saw an ad in the POCA Newsletter (Pantera Parts Connection, Carson City) for U-Joints at $36 each. Or you can get the halfshafts complete at $300 each (with exchange).

Might be worth looking into after you check your U-Joints.


Rocky


PS - I just saw the ad, not sure if there are other deals out there.....
rockyrockyMember
There's a lot of things going on in there, that might be making noises....

There's only a few things you can get to without pulling the box out.

I agree with at least doing the check JFB mentioned. At least find out if its the same on both sides.

If this is really correct, and you mean the Axle flange on the side of the box, I would be very surprised... I thought that the connection between the wheel and the Axle was very solid.

With the wheels off the ground, and turning one wheel back and forth I notice there is quite a bit of play/slop, maybe 1/2" before the axle flange turns...


That would say it's in the connection inside the bearing carrier.

See this picture - I think if you can turn the wheel without any motion on the driveshaft - you have a problem between part #7 & #16......

Wilkenson Catalog
bosswrenchbosswrenchMember
Just a thought- I've seen one Pantera- used for drag racing with a highly modified engine- that twisted the sliding splines inside both halfshafts. In this car, the sliding length-adjuster splines were sloppy-loose from the dumping of the clutch, along with apparently not ever being greased, as the factory zerks were missing.
jfb05177jfb05177Member
if you have the wheel rotate 1/2" on the tires outer diameter, the ZF flange rotation expected would only be ~0.07" on its outer diameter with no lost motion in the half shaft

EDIT;
SORRY I forgot about
quote:
Originally posted by RRS1:...when turning the mounting flange on the ZF. I can recreate the noise with a swift twist as the slack is taken up.


I was still thinking
quote:
Originally posted by RRS1:
With the wheels off the ground, and turning one wheel back and forth I notice there is quite a bit of play/slop, maybe 1/2" before the axle flange turns..

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  • clunking
rockyrockyMember
You can take the side covers off, and as I recall, you could visually inspect the splines on the INSIDE of the input...

But if the slop in the rotation is not going into the ZF, I am not sure that would help.

You will also need new gaskets, and seals (both of which you can get from several vendors, RBT, SACC, Ipsco).

Be very careful on torqueing the side-plates back, if you overtorque, the aluminum case can yield.

If you pull those side covers, I feel you will just get an unsatisfactory look at the tip of the iceberg... But at least you can inspect the splines.

I concur with Forest about calling Lloyd at RBT. He was very helpful to me. I had the best luck calling about 0900 - 1000 California time.

Here's a picture of what you will see if you pull the side cover.

Rocky

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  • 12-23-2015_ZF_Reassembly_(3)_(Small)
rockyrockyMember
Here's what you won't be able to really get a good look at (you'll get an idea, though).....

  • Splines Inside the Carrier
  • Broken Bolt Heads on the R&P
  • R&P Engagement
  • Output Bearing Condition
  • Condition of Clutch Packs
  • Condition of Spider Gears & Differential

    I've got bigger pictures - PM me with an email address, and I can send you some.

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    R rrs1Member
    Thanks Rocky, I did find that both axle nuts were loose and that has been corrected with a torgue wrench and socket. It can be tightened on the car easily. Unfortunately that did not correct the clunking, which at this point I'm sure is transmission related. I don't ever think I've heard of removing a transmission that shifts perfectly though. Frowner
    jfb05177jfb05177Member
    finding and correcting the lose axle nuts is at least a good thing out of hearing this clunk.

    being in the transaxle, has me wondering that could it be an "acceptable" amount of back lash accumulation between all the gear teeth?

    I don't have my freshly rebuilt available to me to check, but it does look like there would be some acceptable limits of back lash by holding two of the shafts and measuring the rotation back and forth of the third. then you could compare yours.

    it reminds me of my expected "clunk" I look for when driven the truck/suv up loose gravel slopes. I apply light throttle with a little wheel spin till I hear/feel the "clunk" of the differitail locking up, then I can apply more throttle and go on

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