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1978 280z
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Discussion Starter · #1 ·
I've been having this problem since I bought the car. When I put it in reverse it makes a terrible grinding and clunking noise. I attached a video. The sound it alot worse when the car is on the ground and it wont even reverse. I'm thinking the diffrential is bad.

 

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How do you know it's not the transmission?
 

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1978 280z
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Discussion Starter · #3 ·
How do you know it's not the transmission?
I dont see why just the reverse gear would be the problem since the rest of the gears feel and sound fine.
 

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Does the car make the same grinding noises when in neutral rolling backwards? I would think if the differential were toast, even rolling backwards in neutral would produce the same noises. If this doesn't happen, I would suspect the transmission. Reverse is on a different shaft from the forward gears, which would explain why the forward gears sound fine.

Also, drain the fluid for both the transmission and the differential. If you see metal chunks in either of them, you know where the problem is.
 

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1983 280ZX Turbo
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I dont see why just the reverse gear would be the problem since the rest of the gears feel and sound fine.
Perhaps you've never been inside a transmission. It's quite easy or the reverse gear to be bad, or for the bearing next to the reverse gear to fail and cause problems in reverse.

Drain the transmission gear oil and I'll bet you find metal pieces in it.

I think tranny more likely than diff, since I'd expect the diff to have problems in forward gears as well. Try draining the gear oil from the diff and see what you get in the oil.

You ought to be able to get under it and find the noise provided you get it up securely and safely on jackstands.
 

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Drivers side rear tire is flat spotted pretty good too.
 

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1978 280z
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Discussion Starter · #7 ·
Perhaps you've never been inside a transmission. It's quite easy or the reverse gear to be bad, or for the bearing next to the reverse gear to fail and cause problems in reverse.

Drain the transmission gear oil and I'll bet you find metal pieces in it.

I think tranny more likely than diff, since I'd expect the diff to have problems in forward gears as well. Try draining the gear oil from the diff and see what you get in the oil.

You ought to be able to get under it and find the noise provided you get it up securely and safely on jackstands.
Yup, drained the fluid and sure enough metal chunks came pouring out as the magnet on the plug was covered to capacity. I was planning on doing a 5 speed swap anyway. Thanks for the help!
20200502_141419.jpg
 

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The semi-circular piece of metal in the center of the picture looks to be part of a bearing .
 

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The semi-circular piece of metal in the center of the picture looks to be part of a bearing . More accurately, that big piece of metal is part of the bearing cage and you can bet that it's from the rear counter shaft bearing because it's a 4 speed. If it were a 5 speed then it would be the middle counter shaft bearing. Z man of Washington
 
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