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Loud "POP" then clackclackclack. Diff? U joint?


usafdarkhorse

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Hi,

 

I've just now got the Z back on the road for about a month after some issues with my charging circuit and Megasquirt, and I was on my way back from a drive to Nashville over the weekend when I got about a mile from my house ( thankfully! ) and something in the rear of the car goes "POP!" Then it made a "clankclankclankclank" sound all the way to a stop, decreasing in frequency with the speed.

 

Checked under the car. No fluid. No random hanging pieces. Rolls forward and backward just fine. So I babied it the 1 mile home ( about 10mph ) with it going "clank clank clank clank" the whole way.

 

At first I thought either the rearend or a U joint, but now I'm thinking something in the differential is probably not the culprit.

 

Ideas? I'm going to pull the rear wheels and get a good look at the stub axles and joints tonight and make sure everything in the rear is up to torque spec.

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I broke a stub axle in my 240Z while making a normal slow take off from a stop sign. There was a loud bang and some clicking noise. I drove the car for about a week not realizing what had happened until I checked the clicking noise. I could move the right side half shaft and flange with a screw driver from side to side. So I pulled the half shaft and the flange and stub axle nut came off with it. The stub axle broke right at the bottom of the nut that holds the shaft on (typical). The only thing holding the stub axle in was the bearing. It was amazing that the half shaft and flange remained in place without making noise other than the clicks.

 

I replaced both half shafts.

 

Miles

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Hi,

 

I've just now got the Z back on the road for about a month after some issues with my charging circuit and Megasquirt, and I was on my way back from a drive to Nashville over the weekend when I got about a mile from my house ( thankfully! ) and something in the rear of the car goes "POP!" Then it made a "clankclankclankclank" sound all the way to a stop, decreasing in frequency with the speed.

 

Checked under the car. No fluid. No random hanging pieces. Rolls forward and backward just fine. So I babied it the 1 mile home ( about 10mph ) with it going "clank clank clank clank" the whole way.

 

At first I thought either the rearend or a U joint, but now I'm thinking something in the differential is probably not the culprit.

 

Ideas? I'm going to pull the rear wheels and get a good look at the stub axles and joints tonight and make sure everything in the rear is up to torque spec.

Does it sound like a metalic grinding or just clank clank clank? I'd Check your Wheel Studs and makes sure the lug nuts are tights and i would double check your u-joints cause its possible they're shot. This sounds like my car about a month ago and it was both of these things. Make sure your wheels rae bolted down tight and your Axles aren't grinding.

~J

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Jacked the car up and got a good look under the rear end.

 

Nothing looked out of whack and everything felt pretty tight and normal.

 

I think my left rear brake calipre was sticking so I shimmed it from the bracket and fixed it mostly. It's not the lugs since I retorqued them and the U joints felt pretty tight like mentioned before. Dropped the car and went for a drive.

 

Clanking is still there, although it appears to show more in the higher speeds ( over 20mph or so ) and it sounds like it's coming from directly beneath me ( like as in driveshaft or front diff mount area ).

 

Sounds the same way. Like a card in bicycle spokes or like a helicopter if that helps. I'm going to raise the car again and get a good look at the driveshaft where it meets the diff.

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UPDATE:

 

I've pulled the driveshaft since the noise presents itself in any gear at a higher speed, and from the car the sound was coming from right under me.

 

There was a little play in the U joint, but once I pulled it out I noticed that the U joint moved fine in one axis, and little to none in another axis ( IE will move up and down, but not side to side ).

 

The yoke has a few slight wear marks on it as well, so I'm having the U joints in the driveshaft replaced and I may go with Spicer joints with the grease fittings. :flamedevi

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  • 2 weeks later...

UPDATE:

 

BOTH U joints in the driveshaft were dead. Had about 140,000 miles on that part of the drivetrain with about 20,000 miles of boost, so I'm not surprised.

 

A shop here in TN is building me a new shaft with Spicer joints. Hopefully everything will be good when I throw it back in.

 

Wish me luck!

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