17brpeterson1

Although I've never driven another s30, I've driven plenty of older stuff with lots of noise, and mine has it as well. It's just the diff noise is massively overwhelming.

Yeah, no clutch type lsd additives in the fluid I'm using.

Next time I go out ill will whip a blanket over the whole trunk area just to see what it does to deaden the sound.

75-140

I would think if it were a bad bearing, the noise would be fairly consistent with load and just change with speed. The way mine whines drastically changes under different load conditions as well. 1) I have had the car along some hard corners and from what I can tell the noise was consistent from side to side while in and out of the corners. Would a louder noise to one side in a corner point to a bad wheel bearing? 2) Ive had the car up on stands and in and out of gears at different speeds, makes the same noises. 3) I was under the car as well with it running and felt the diff all over for vibration. From what i could tell, it was coming from the gears and not anything on the pinion end. 4) Yes same set of stub axles, however, when I was under the car listening I know for certain it was not coming from them. Ive had them off multiple times and checked the joints each time. Not a bit of slop in them and no notchy feel when moving them with a load on them. I felt bad u joints before with pits on the inner race, I am confident that the half shafts are in good condition. Ive had my spare out and all the metal in the trunk area is solid. It may be running fine but just a noisy diff I will have to live with for the moment.

Sorry for the delay but here is a video. Its the best i could get with my phone. You can really hear it at the end where I cruise at 60-70mph. https://photos.app.goo.gl/9eYmMMQzgDpRsHGGA

Update Went one size down on the shim size according to the fsm. That brought me to .002-.003" of backlash, a little tight but I figured I would try it anyways given the circumstances. The gears patterned good, both drive and coast side of the teeth. But alas, still overwhelming noisy. A slight difference in its characteristics, whines on acceleration, still a whine on coast too. Unfortunately, this means I'll probably abandon the r-200s I have for a ford 8.8. Which will be better anyways with cv axles, better mount design, and better aftermarket.

Well, I checked and unbolted all my bushings and mounts and they look good. I slipped some 1/8" rubber in between the body and mustache bar mounts and where the front mount bolts up to the body and cradles the swing arm pivot. Test drove and no noticeable difference. I think my next step is going to be messing with the backlash. With both of my diffs, they were on the higher end of the tolerance with backlash at .007". I also noticed that it whines a lot louder while coasting. While under power, its not bad, something I could live with. From what Ive researched, it appears that too much backlash can cause a whine while coasting. The tight end of backlash tolerance is .005", Ill try and aim for that.

I should be able to do a few tests this week checking those and making up some rubber washers and insulators. Does anyone happen to know if rubber, not urethane, bushings are still available? Would there be much a difference between the two?

Nothing unusual, all stock. I'd say it whines the most while coasting, in limbo between engine braking. But there is still a pronounced whine in all situations.

I've had the half shafts off and the wheel bearings seem fine as well. The transmission is rebuilt with all new bearings and nothing wrong with the gears. I am almost certain it is the diff based on the sound and location of the noise. The u joints feel smooth with no slop, but even then the sound is a definite gear whine.

It appears the factory rubber has been replaced with urethane. I've had the front mount off a handful of times and can see no issues there. I'll have to unbolt and check the mustache bar mounts, but they looked fine from the outside. If I can make some rubber insulators to stick between the bushing and body, I'll try that just to see if anything changes.

So, I am at my whits end with making a r-200 diff work in my 1978 280z with a 5-speed. When I first bought the car, it had a really loud noise coming from the diff. This is no slight whine either, it is OVERBEARING. The car is straight piped right now and it is still overbearing. Later on I tore into it and found nothing really wrong at all. Installed an M-factory helical diff and rebuilt the whole unit with all new bearings. I closely followed the factory service manual. Almost the same exact noise occurred with the same volume. I gave up and had a shop tear in and rebuild the diff, install and it was exactly the same. Bought a whole unit off ebay with the same ratio, checked backlash, everything looked ok. Same story, unbearable noise. The car has the factory mounts but with urethane bushings. Everything else looked and felt good, u-joints, mounts, wheel bearings. The noise I am hearing is from the differential as it changes under load, being the loudest when the car is coasting. I'm not sure where to go next, ive already wasted 2k trying to have a functioning differential. Any and all tips or suggestions would be greatly appreciated at this point.

So, I am at my whits end with making a r-200 diff work in my 1978 280z with a 5-speed. When I first bought the car, it had a really loud noise coming from the diff. This is no slight whine either, it is OVERBEARING. The car is straight piped right now and it is still overbearing. Later on I tore into it and found nothing really wrong at all. Installed an M-factory helical diff and rebuilt the whole unit with all new bearings. I closely followed the factory service manual. Almost the same exact noise occurred with the same volume. I gave up and had a shop tear in and rebuild the diff, install and it was exactly the same. Bought a whole unit off ebay with the same ratio, checked backlash, everything looked ok. Same story, unbearable noise. The car has the factory mounts but with urethane bushings. Everything else looked and felt good, u-joints, mounts, wheel bearings. The noise I am hearing is from the differential as it changes under load, being the loudest when the car is coasting. I'm not sure where to go next, ive already wasted 2k trying to have a functioning differential. Any and all tips or suggestions would be greatly appreciated at this point.

I am just wondering if one would be able to swap this carrier: https://www.z1motorsports.com/differential-upgrades/tomei/tomei-technical-trax-300zx-limited-slip-differential-lsd-non-turbo-p-2547.html into a R200LN with 10mm ring gear bolts from a 280z. Does anybody know if that carrier has 10 or 12mm holes? Thanks