Noisy R-200 Woes

[17brpeterson1]

On 10/30/2021 at 9:41 AM, Sanchez said:

Just listened to the video it’s definitely a pronounced whine which has me partially agreeing with @bunkhouse.

But maybe a few more questions and tests would help pinpoint the problem area. 
1) Find a good long on/off ramp to a highway that has a good curve to it where you can safely keep the the speed where it whines throughout the turn. Does the whine change, get worse, or go away?

2) Lift the rear end so all weight is off the suspension, start her up and take it through your common drive cycle where the whines occur. Does it go away or still persist?
3) If you have a friend who can safely get under the car with a stethoscope they may be able to pinpoint the exact area the whine is coming from. I’m sure I don’t need to stress this safety point but do it safely with a 2 post lift, not with the back on jack stands.

4) You said you replaced all the bearings in the diff and have tried 3 different ones, but did you reuse the same stub axles between all of them?

 

My next thought is that from my understanding is the R200 is just a very noisy diff even when everything is totally fine with them. The cars they came in had a lot more sound deadening and thicker metal in the trunk so if your car is untouched/unrestored maybe start probing around the trunk area for some rust holes (spare wheel well most likely culprit) or missing material that could be letting excessive noise in. The tar insulation and undercoating combined has a history of making the car look solid until you press somewhere and find a softball sized hole.

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.

[17brpeterson1]

On 10/30/2021 at 6:01 PM, walkerbk said:

What kind of diff fluid are you using? Diff fluid can make a huge difference. 

75-140

[17brpeterson1]

On 10/30/2021 at 10:24 AM, NewZed said:

 

This is rational.  My diff noise reduced a surprising amount when I lined the back deck with bubble foil insulation.  As Sanchez says, the less material you have over the metal deck the more noise will get through.

 

 

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.

[jhm]

Sorry to hear that this nagging issue hasn't come to resolution for you.  It sounds like you have isolated it to the differential, and have tried everything I would suggest to fix the issue.  Maybe the additional sound deadening in the hatch will help.

 

Just curious....have you driven in other S30s for comparison sake?  I don't know if you're new to these cars or not; but nothing is quiet about them.  Most of my Zs have sounded like they're falling apart and dropping pieces all over the road.  You can't compare them in any way shape or form to a modern civilized-riding automobile.  I know that doesn't make the driving experience any less irritating for you; but at least you might be able to decide that your current diff is functioning "normally", FWIW.

[walkerbk]

8 hours ago, 17brpeterson1 said:

75-140

Not what viscosity but what brand; royal purple, red line...

 

Is it made for LSDs (if I'm not mistaken you don't want a dedicated lsd fluid in a helical lsd. Lsd gear oil is made for clutch based LSDs).

[17brpeterson1]

On 11/2/2021 at 7:07 PM, walkerbk said:

Not what viscosity but what brand; royal purple, red line...

 

Is it made for LSDs (if I'm not mistaken you don't want a dedicated lsd fluid in a helical lsd. Lsd gear oil is made for clutch based LSDs).

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

[17brpeterson1]

On 11/2/2021 at 4:09 PM, jhm said:

Sorry to hear that this nagging issue hasn't come to resolution for you.  It sounds like you have isolated it to the differential, and have tried everything I would suggest to fix the issue.  Maybe the additional sound deadening in the hatch will help.

 

Just curious....have you driven in other S30s for comparison sake?  I don't know if you're new to these cars or not; but nothing is quiet about them.  Most of my Zs have sounded like they're falling apart and dropping pieces all over the road.  You can't compare them in any way shape or form to a modern civilized-riding automobile.  I know that doesn't make the driving experience any less irritating for you; but at least you might be able to decide that your current diff is functioning "normally", FWIW.

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. 

[NewZed]

On 10/20/2021 at 6:01 PM, 17brpeterson1 said:

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.

 

On 10/20/2021 at 6:01 PM, 17brpeterson1 said:

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.

 

On 10/27/2021 at 6:05 AM, 17brpeterson1 said:

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. 

 

Don't overlook the transmission mounts.  They have rubber bushings also that can sag and let metal to metal contact occur.

 

One option that seems to work well is to use an RTz style mount with the diff nose hanging from the GM transmission mount.  Then you can completely eliminate the bottom mount and any noise transmission there.

 

https://www.technoversions.com/DiffMount.html

 

I went back through your thread and see that you didn't really address the diff mounting issues.  A 1/8" piece of rubber?  And you never came back with what happened if you insulated the rear deck.  Also see that you've had the diff apart and reshimmed the carrier.  Generally, from what I've read, almost any operation on the diff will cause it to be noisier.  People have problems even just getting the pinion shaft nut retightened after a seal replacement without creating more noise.  

 

In sum though, you're having a problem that most people don't have.  My setup with a stock open diff, unmolested, was quiet enough that my main noise concern was the noise the mirrors made in the wind when I had the window open.  Not kidding.  Overall, you're just doing small things to try to get rid of the noise, with gear oil, and thin pieces of rubber in strange places.  It seems like what you have now is essentially the same as what you started with.  Make some big changes.  Good luck.

[Jlhalsey3]

I have had some experience with R200 being noisy, especially when coasting. Had it rebuilt w same ring and pinion by a local shop, just as noisy. I located a low mileage R200 and had the ring and pinion transferred to my case by the same shop. It is now dead quiet. Very happy with it. The challenge is finding a ring and pinion in the right ratio that isn’t worn out. I couldn’t find any new OEM, i think there are some aftermarket available in Japan but very expensive. I got lucky and found a R200 seller who claimed the unit was out of a low mileage car he was parting out. I am using the OEM rubber trans mount that mounts under the front of the diff. Previously used a solid billet mount there but changed to rubber in quest of lower noise. Helped a little but the big change was switching out the worn ring and pinion gears. Not sure if there is a way to test or inspect the gears to determine wear, my old gears looked ok but when i found a unit from documented low mile vehicle ( i think 30k ish miles) i made the decision to purchase. Luckily it worked out great.

[Invincibleextremes]

Back when I had an r200 in the common 3.54 ratio I drove thousands of miles in a given trip without noise.  I think a big part of it is the fact that less common ratios are unavailable and tend to be worn out when they get replaced in peoples project cars.  Even Ford had issues with their explorer differential that howled constantly because of a pinion bearing issue.  I'm not entirely sure using sound deadening will help much, because all of my customers with the mustang differentials use the poly bushings my kit comes with, and the only ones that come back with noise complaints are those who got unlucky with a worn diff with bad bearings.

 

Speaking of bearings, if your gearset isn't worn out, which is likely so, considering the lash being on the large side before adjustment, a worn pinion bearing could result in noise as it allows minor deflection in the gearset mesh under load or coast.  This same bearing could itself not contribute to the noise if the rollers themselves aren't noisy, but contribute to the small amount of deflection.

Edited November 19, 2021 by Invincibleextremes
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