Left rear hub area makes a distinct "clink" under torque application

[Vic]

Got a weird one here...

Imagine your left rear wheel is only held on by one lug nut, (or, all lugs are loose) and the wheel is shifting on the axle, when you apply torque, either forward, or in reverse. That's the best way for me to describe what I hear on my GTS, how and when it occurs.

If I let the clutch out normally, the left rear wheel area emits a distinct clink, or clunk. Sounds like the medium tone of a casting shifting, like my SSR rim shifting on the axle, or the bearing shifting in the hub. Or maybe the control arms are shifting on the mounts. Tried torquing the lug nuts down on all four corners, no help.

If it clunks initially when going forward, it will not clunk again, unless the direction of torque applied changes from forward, to reverse. Like when you let of the gas, under engine braking, where the kinetic energy of the car is pushing the wheel to turn, it will "re-clunk". Or, if I make it clunk when backing up, it won't clunk again, until I go forward. Then it "re-clunks". Only the intial application of torque in a given direction initiates the clunk. If the torque is not reversed, it will not clunk again. But as you know, torque is alternately applied forward, and reverse, even when just driving forward, as you alternately step on, and then off the gas. Somtimes the engine drives the car, and then again, the wheels "drive" the engine, when you are using the engine for braking. The torque then reverses on the axles. So while I'm driving, if the torque in either direction is suffcient, there are many "clunks" and "re-clunks" during the drive. I can really make it happen severely, if I stay in 1st or 2nd gear, and stomp on the gas, then let off abruptly. Clunks like a mfr.

My diff has been serviced by Unitrax, (this problem was extant BEFORE I ever brought it to them), and all four half-shaft U-joints were replaced. I even brought it back to them to check if the U-joint straps were tight.

Only the left rear side does this. No noise from the right side at all.

Guess I'm gonna hafta jack it up, pop the wheel off, see if anything is visible.

Anybpody had this exact problem before?

Car is a 2001 GTS, 55,000 miles, 580 rwhp/590 rwtq

 

[SingleMalt]

First, you need to check ALL of the 3rd member mounting bolts and ensure all suspension bolts are tight in the rear of the car (left and right). It's a very common issue and usually it boils down to a bolt that worked loose.

Failing that, you may have a cracked half-shaft but check all those bolts first. I'm betting it's the simpler of the two possible issues.

 

[dave6666]

Check the rear stub axle nut torque sans special axle holding tool dave made to hold axle. 250 ft lbs if me remembers.

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[SingleMalt]

That's pretty cool. I didn't know Dave made a tool like that. We always just used an impact wrench. Great pic too!

 

[Vic]

Wow, thanks guys.

Great ideas.

Dave, your Viper makes me sick. Can't you let it get all dirty? I know I'd feel a lot better....

 

[AndyMac]

Dave, as usual, is right. Check your axle nut, it is most likely loose. I had to put my impact to the R/R years ago.

 

[bluesrt]

your wheels can also make this noise, loosen and retork the wheel... (just a thought cause iv seen it happen)

 

[Vic]

If I apply the e-brake fairly hard, and leave it locked up, the clink/clunk noise doesn't occur to anywhere near the same degree. If I slip it through the pads a bit, I can get it to make the noise, but it's much harder. In this case, with the ebrake applied, the torque goes through the axle, through the rotor, and the twisting force is transmitted to the ebrake caliper, and back to the hub, then through the control arms, (but not identical to driving), then back to the frame rails (also not identical to driving).

The wheel never receives the twisting force, since it is taken up by the rotor and pads. So the wheel is not trying to push the hub forward, and so the rear toe link is not under tensile force. But if I release the ebrake, the clink/clunk occurs again all too easily, even at slight throttle. I think my toe link is shifting, where it is bolted to a sheetmetal boss on the frame. The wheel wants to pull the hub forward, but the toe link is under tension, holding the hub at the factory rear toe-in preset. Could be other things too. I won't be looking into it again until next w/e.

I would think the axle nut isn't the issue, since the torque is present whether the ebrake is applied or not. If it was the nut, I wouldn't think applying the ebrake would make any difference, but hey, who cares, i'll try tightening it as well!


Blue SRT, thanks for the idea. I did try to torque all lug nuts, to no avail. Also removed the wheel on the offending corner, and retorqued, no help. But thanks.

 

[Jack B]

If I apply the e-brake fairly hard, and leave it locked up, the clink/clunk noise doesn't occur to anywhere near the same degree. If I slip it through the pads a bit, I can get it to make the noise, but it's much harder. In this case, with the ebrake applied, the torque goes through the axle, through the rotor, and the twisting force is transmitted to the ebrake caliper, and back to the hub, then through the control arms, (but not identical to driving), then back to the frame rails (also not identical to driving).

The wheel never receives the twisting force, since it is taken up by the rotor and pads. So the wheel is not trying to push the hub forward, and so the rear toe link is not under tensile force. But if I release the ebrake, the clink/clunk occurs again all too easily, even at slight throttle. I think my toe link is shifting, where it is bolted to a sheetmetal boss on the frame. The wheel wants to pull the hub forward, but the toe link is under tension, holding the hub at the factory rear toe-in preset. Could be other things too. I won't be looking into it again until next w/e.

I would think the axle nut isn't the issue, since the torque is present whether the ebrake is applied or not. If it was the nut, I wouldn't think applying the ebrake would make any difference, but hey, who cares, i'll try tightening it as well!


Blue SRT, thanks for the idea. I did try to torque all lug nuts, to no avail. Also removed the wheel on the offending corner, and retorqued, no help. But thanks.

Let me give you a couple more possibilities:

1. A half-shaft is slightly twisted and the noise is the shaft breaking loose as the wheel separates from the diff.

2. One of the two main diff arm bolts was loose at one time and has elongated the the bolt hole, therefore, allowing the arm to move up and down in the slot.

 

[Vic]

Hadn't thought of that...

Thanks!

 

[99 R/T 10]

I had one that clunks going forward then rear. Turned out that U-joints were shot. Check the end caps to see if the neddle bearing are still good and re-grease.

 

[dave6666]

Dana Spicer u-joints are $23 each. Just replace 'em if in question. Greasing a dry joint is temporary delay of the inevitable.

 

[Stonep185]

I had a front wheel hub go out and made some clicking noses. Jack up the offending corner, leave the wheel on, and see if there is any play in the wheel.

 

[Stonep185]

Dave 6's where did you get your u joints and do you replace the ujoint straps at the same time?

 

[Dan Cragin]

This sounds like the "axle crack noise" that was a big issue on Gen 1's but also bled over to Gen 2's. The splines in the hub and snub axle are worn and shift making a crack noise only when you go forward or reverse. Changing the rear bearing should get rid of it, but you might want to replace the bearing and the snub axle. Of course it will most likely last forever, making that same noise.

 

[dave6666]

Dave 6's where did you get your u joints and do you replace the ujoint straps at the same time?

Here's the joint in the pic below. Google that info to find the best deal. I have not bought any in a few years but last time I did they were under $25. Dealers (and so on) will sell you repackaged joints for many times the real price. I buy the strap / bolt kits from the dealer though as they are reasonable and have the correct bolt thread. Some of the kits have the wrong thread sans metric versus english. The car is one of those threads, some of the kits are the other thread. And yes, you should always replace the straps, but if you reuse the bolts, loctite them. The come new with a threadlocker patch. Have good sockets too. Those little bolts are tight. 5/16 or 8mm either will work.

In regards to the hubs making noise, I had both my front hubs go out within a few months of each other. Seems a little odd for a car of not that may miles, but the squealing noise and pad knock back were the signs. I confirmed one side with a roller tipped dial indicator on the perimeter of the hub, and the side that had the pad knock back was wobbly loose via grabbing the wheel. BUT... the one side that I checked with the indicator could not be detected by grabbing the wheel. I would suggest if you suspect the hubs are worn and have runout, to use a dial indicator.

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[dave6666]

This sounds like the "axle crack noise" that was a big issue on Gen 1's but also bled over to Gen 2's. The splines in the hub and snub axle are worn and shift making a crack noise only when you go forward or reverse. Changing the rear bearing should get rid of it, but you might want to replace the bearing and the snub axle. Of course it will most likely last forever, making that same noise.

Good to see you posting Dan. How's the new shop arrangement working out?

 

[bluesrt]

or if you dont want to spend any money(the cheap way out) dissasemble and lightly grease splines, but you didnt hear that from me...

 

[dave6666]

or if you dont want to spend any money(the cheap way out) dissasemble and lightly grease splines, but you didnt hear that from me...

Hillbilly...

Dana Spicer u-joints are $23 each. Just replace 'em if in question. Greasing a dry joint is temporary delay of the inevitable.

Versus engineer...

LOL

 

[Vic]

Thanks a bunch, everybody.

How are things, Dan?

I hear Dave Jenkins is over at Hennesseys' shop in Lake Forest.

 

[bluesrt]

yeeee haaaaaaa!!!!!!!!

 

[Vic]

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This is the left rear stub axle. You can see the rouge, even after I brushed off all the loose rust dust.

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This is the hub, where the wheel bearing sits in a casting, that is bolted to the hub carrier. You can see the splines, where the stub axle inserts. Looks like that spline is just an insert, pressed or sweated into the inner race of the wheel bearing.



So here's the funny thing- I take this stuff apart, clean the rust off of it, and put some high temperature grease on the splines. Bolt it all back together, take her for a test drive. (Boom-chika-wow-wow! "Test drive", get it?)


So the clunk/cracking noise goes away!


Why does this bother me? Because, when the suspension flexes, the distance between the diff and the wheel bearing can change. And this change is supossed to be taken up by the sliding splines that are engineered into the half-shafts, mid-way between the U-joints on each shaft. You can see the rubber boots, mid point, that covers the splines. They have a huge range of motion, in and out. That is what is supossed to slide in and out as the suspension flexes, not the spline at the wheel bearing. As far as I can see, the wheel bearing spline just keeps the axle from spinning in the bearing race, to ensure the bearing spins, and the axle doesn't gall up, spinning in the bearing. Or to make a standard size bearing inner race i.d. fit the end of the axle o.d.. Ok, dem's just theories. I don't really know. This is the first time I've gotten into this.


Also noticed that the half-shaft splines have a noticeable rotating play in them, maybe a degree or two. So here's my theory #2-


Since the half shaft splines are so worn, that when torque is applied to them, they "lock up", permitting no in and out movement. Since we have rearward weight transfer upon application of torque, the suspension wants to squat, which means the half-shaft splines want to compress, and shorten the half shaft, to let the suspension flex. But they can't, because they are worn, (and possibly rusty under the boots) If the half shafts don't get shorter, the suspension freezes. It's just basic geometry.

So the axial compression force is transmitted outward to the stub axle spline, at the wheel bearing. As we know, they were rusty as hell, and don't want to slide in or out easily. So the clunk/clicking noise, was the stub axle spline refusing compress while under torque, until the torque forces the issue. At first, it binds up, but then lets go with a metallic clunk/click noise. (Is that even possible, with the axle nut tight?) If the nut firmly "marries" the stub axle to the wheel bearing, then maybe this axial force is "slide-hammering" the bearing, peening a wider berth, where the outer race of the bearing is held by the casting. Whatevah....

Anyway, all I did, was to grease the stub axle spline, on the left rear of the car, where the sound was coming from. No more noises. I also rotated the bearing carrier 180. Not sure if that helped, like if the bearing was shifting in the casting.

Although the stub axle splines were rusty, unbelievably, they show no signs of wear, no rotational slop at all. Not like the half shaft splines, where there is a hugely obvious, easily detectable rotating slop. If you grab the inner and outer section of the half shaft, one in each hand, and twist them back and forth against each other, you can produce like a degree or two of movement. That sounds like badly worn splines to me. Anybody got any first hand experience with this?

Looks like I do need new half shafts. Which is the 800 pound goriila here, as well as stub axle rust. No way the half-shafts are supossed to have that rotational slop in the spines, right?

 

[dave6666]

Or, it could jst be that your axle nuts are properly tightened after the inspection and reassembly.

 

[Dan Cragin]

This noise is pretty common and most likely will come back. If you replace the splined yoke and bearing it will not happen again. I have never seen a failure because of this, but it is annoying.

Things are going well for me, the new service facility will open in October and I will let everyone know the details. Our internet site is still open working as Modifiedviper.com.

Yes Dave Jenkins from Victory Vipers is now the production manager at Hennessey west coast. Dave is a stand up guy and I wish him all the best.

I am look forward to VOI and seeing everyone.

Take Care

 

[Vic]

Or, it could jst be that your axle nuts are properly tightened after the inspection and reassembly.

Possible. However, the nut was tight, when I took it off.
???

Thanks for reading this. Appreciate any and all input.

 

[Vic]

Dan,

What do you think about the half shafts? Should they have that 1 or 2 degree backlash in the splines?

Looking forward to details on your next venture.

This noise is pretty common and most likely will come back. If you replace the splined yoke and bearing it will not happen again. I have never seen a failure because of this, but it is annoying.

Things are going well for me, the new service facility will open in October and I will let everyone know the details. Our internet site is still open working as Modifiedviper.com.

Yes Dave Jenkins from Victory Vipers is now the production manager at Hennessey west coast. Dave is a stand up guy and I wish him all the best.

I am look forward to VOI and seeing everyone.

Take Care

 

[GTS Warp]

Same problem here just on the left rear. Already torqued the axle nuts. Guess I'll pull it apart this weekend. Suspected the bearing or u-joints, but you guys have confirmed it. Glad I'm not crazy!

 

[Vic]

GTS Warp-

Let us know how it turns out!

 

[Camfab]

Vic it's been a while since I pulled the rear end out. Though I do remember grabbing the half shafts and dealing with them. I really don't recall any axial slop in them.

 

[dave6666]

Possible. However, the nut was tight, when I took it off.
???

Thanks for reading this. Appreciate any and all input.

The final torque value is 250 lb ft for the rear axle nut. You could have had a torque value some fraction of that, that upon disassembly, would have felt like a lot. But it could have been "loose" given the target of 250.

In either case, no noise, no prob right?