Sergio146 Posted January 6 Report Share Posted January 6 As a person who hasn't had much experience with rear differentials, how does one go about the tools and equipment needed for setting the backlash on my 1980 datsun 720 4x4. Reason is because when I am driving at a certain speed (about 30~35mph), i hear a roaring noise on the rear of my truck but only when I accelerate. After I let go off the accelerator, the noise is gone. I have to remove the differential either way to check it but are there other things that I should look into while I'm there? Quote Link to comment
Stoffregen Motorsports Posted January 6 Report Share Posted January 6 There aren't really any special tools, other than a dial indicator. But, if the backlash is excessive, the gear is likely worn out. You can't really just tighten up the backlash and make the gears quieter. It's probably just a bad pinion bearing. Quote Link to comment
datzenmike Posted January 6 Report Share Posted January 6 Check the oil level. Could be a wheel bearing. Quote Link to comment
Sergio146 Posted January 6 Author Report Share Posted January 6 I'll look into it because as both of you have mentioned, there is play on the pinion when I grab the deiveshaft and move it up and down. I'll keep you posted on what I find. 1 Quote Link to comment
datzenmike Posted January 6 Report Share Posted January 6 It should not move other than to turn. I ran my 620 out of oil over the minter and that's what happened. The pinion bearing was so bad that the gear lash destroyed the ring and pinion. The ratio will be stamped on the outside edge of the ring gear when you get it off. 4x4 should be 35:8 or 35 divide by 8 or 4.375* *unless it's a long bed then 37/8 or 4.625 1 Quote Link to comment
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