A Clunk

[pgermond]

Lately if noticed a slight clunk now-n-then when starting off in 1st gear. At first I thought it might be the locker in my differential, but know I don't think so because it does it when I'm not only turning, but starting off and going straight. I have the rear of the car in the air and will crawl under it tomorrow to insure nothing is loose.

With it off the ground and in gear, does anyone know how much play should I have when moving the rear wheel back and forth?

The rear-end hasn't been abused, well, every once in awhile I might melt some rubber, but nothing regular or radical.

Thank in advance.

[TurnpikeBoy]

If you grab a rear wheel at the 12:00 and 6:00 positions, and try to tilt it (top and bottom) in and out you probably will feel some slop, likely as much as 1/16" or so. Note that this is when trying to tilt the wheel - not slide it in and out. You should have NO back-and-forth movement in the horizontal plane, and you should have NO movement inward-and-outward.

The vertical slop is movement designed in (HO! HO!!) by Jaguar to allow less heating of the bearings in the hub. Somehow this always seemed dubious to me, but what the h*ll do I know.

Don't have any loose shocks, right?


-Roger

[peter]

How much play is acceptable? I have close to 1/8 at the edge of the tire.

[Justin Upchurch]

Phil,

I had a slight clunck when stopping, it turned out that the mount for the side pipe was a little loose, my fault.

Justin

[pgermond]

Roger - thanks. Everything is just as you said it should be. Maybe I'm just paranoid, but I just doesn't seem that it should be making the noise I'm hearing. With the rear wheels off the ground - If I rotate the rear tire forward and backward with the transmission in gear there is a certain amount of play and it replicates the noise I hear.

I don't know if that is normal or not :confused:

[TurnpikeBoy]

Pete - you're probably OK with as much as 1/8"; all of these things have some. Do keep an eye on it, although it won't likely increase any time soon. You could peel the hubs apart and redo them, tightening up the stubshafts and doing new seals, but it is a good winter job.....and you better be prepared for some serious grunt work too; they are a b*tch to take apart. Remember that you're measuring that 1/8" out at a 14" (or so) radius from the centerline of the shaft, so it's not as nerve-wracking as it seems.

PhilG, the compilation of tolerances in the gearbox and rear can allow what seems like a lot of slack but is normal. Still, I dunno if you would hear takeup of that slack as much as maybe feel it. I wouldn't think that stack-up of tolerances would amount to more than, oh, say about 1" to 1-1/2" of rotational distance at the tire tread, give or take. No broken trans mount? Bolts in the driveshaft are there, and tight? U-joints (drive and half shafts) still good and tight too? Any loose bolts in strut arms or mounts anywhere along the driveline? Shifter linkage hitting the side of the tunnel? If you're hearing the klunk, it might be worthwhile to keep looking to see just where it's coming from.


-Roger

[pgermond]

Rod Jacobsen gave me a call this afternoon and we compared notes on the amount of play when rotating the rear wheels back and forth. Thanks Rod for the call..... after talking to you and reading TurnpikeBoys reply, I think I'm okay.

Roger - you said something that is so simple and may well be the culprit. "Shifter linkage hitting the side of the tunnel?" I'm feeling a little punk today and I'm going on a wood cutting/splitting journey for a few days tomorrow, so I'm trying to rest up. But the cars is in the air I'll check it out when I get back.

Thanks for all the suggestions! :)

[spd4me]

Speaking of noises, the only noise I hear every once and awhile is in the rear end when I'm making a slow 90 degree turn. I think it's the normal sounds of the posi track rear end clutches. I rebuilt my huds and rear end half shaft axles once on another cobra I had. Losts of fun if you have the patience.
Bob

[pgermond]

The "clunk" in the rear-end as been persistent to the point it was driving be nuts and had to be corrected. Digging through the cobwebs I remembered a post a few years ago regarding a similar issue - sure enough, Russ Dickey posted in 2004 and had the same type of "clunk". The solution - anti-friction additive. I had used this when I changed my rear-end gear oil several thousand miles ago, but only added one 4 oz tube. A couple of days ago I drained the rear, and refilled with fresh oil and two 4 oz tubes of anti-friction additive. Wallah! Problem solved :)

Here's the link if anyone is interested - http://www.uniquecobra.com/forums/showthread.php?t=5761&highlight=anti+friction

I really like it when something can be fixed by squirting a tube of whatever in it :D