Suppression of Diff Whine
 

Can ring/pinion whine be mitigated with Dynamat-type material applied to the rear floor area?

If you are getting differential gear whine, your gears are either worn out, or they are wearing themselves out.
Doug

Roger that -- but was wondering if anyone had determined what's the main transmission path of the noise and whether it can be quieted down until it's corrected.

The entire underside of the car and transmission tunnel are like the body of a guitar and will act as a sound board. The cure for the whine is to repair the cause of the whine. If you don't want to fix it, wear ear plugs. Everybody OUTSIDE the car is going to hear it coming from miles away.

I don't know how you define "whine" - my 63 coupe is perfectly healthy but you can hear a lot going on back in the rear with just some fiberglass and carpet between the moving bits and your ears.....I found these additions "dumbed down" a lot of the mechanical sounds, an acoustical liner covered by a cargo mat:

https://www.corvetteforum.com/forums...post1597901209

You can read farther down in that thread to see the items installed in my car...you just lay them in - no cutting or glue.

Of course, if you really do have a "whiny in the hiny" from mechanical issues; they need fixed.

:iagree:

I had friend with a '64 T-Bird whose gears were wearing out, you could hear him about 3-4 blocks away, it was easy to tell if he was coming, or going, or just passing by on some arterial street. The gears finally broke and the car didn't move anymore after that.

Doug

Where did you get those, Frank?
Thanks,
Doug

Both items are from Mid America Motorworks...

Back in 1963 I rebuilt a 3:36 in my 59 pass car for a trip to CA from IL. I didn't space the pinyon to the ring exact. It whined all the way there and back. It never failed in the 5 years I drove it But if one starts whining it's a differen't story.
This may be horse pucky but the GM rep told me after approving a warrantee job I did, he asked me what the spacing was between the ring & pinyon. There was a shim pack and a range of spacing. This is what he said! Station wagons got the best at the factory because there wasn't a trunk and back seat to muffle a possible whine. I do know that a whine noise can travel thru the drive shaft. That guy fixed it with a screw driver. He punched holes in his muffler.

Dom

I can hear a light whine in the differential of my '63 convertible with the hardtop on. With the top off you can't hear it. Either way, I'm not gonna' get too excited about fixing something that likely will still be working way past my time with the car.

I'd think sound deadener would help some or even a lot, depending...............................

Maybe even a pint of 90W gear oil.

I had my diff rebuilt back in 2008 after I backed out of the garage and it simply locked up. I took the diff out myself and took it to a well known diff-drive line specialist. He rebuilt it and we went with the original 3.70 gearing. Since then, I've always had a very,very, faint whistle sort of sound coming from the diff but seems to disappear somewhat as the it warms up. Sometimes you can't hear it at all. I ain't going to do nothing because I don't think its worth the work and agony of removing it and having it diagnosed. I'm sure the diff will last longer than me. Just saying. Sometimes its better to let sleeping dogs lay.

Same here -- just took it for a cruise with the top down, and I wasn't bothered.

Beautiful day for a drive through the wine country of Temecula. All was well until I remarked to the wife how much smoother the car rode with her in the passenger seat.....

That oughta' do it!

I lived right on a major US highway when I was a kid. I spent a lot of time on the front porch tallying how many of which brand of car/truck would go by. It didn't take long to see a pattern and it also didn't take long to recognize repeat sounds.

Every day at the same time, this early '50's Chevy would come by. Differential howling with a very loud, high pitched whine. Not on coast but on drive side. Same car went by, making the same noise for at least three years. Never seemed any better or any worse.

You got it right - sorta; its GTR1999...

No the last Dodge I had was a '70 Dart "swinger" 6 cly automatic.

Gear whine, to a degree, can be expected with any gear set. In fact the best set made today and last in the USA for Tom's has a spec sheet mentioning gear whine is to be expected. Now with a vette you're sitting behind the diff BUT even so GM gears were not noisy and Tom's gears are not typically but it all comes down to setup.

Other then Tom's gears, (US Gear) the others are imported. Suppliers rebox gears so you won't know what you get until you look at them out of the box. Tom's always has a "G" inside a shield logo on the side of the ring gear. Yukon don't have anything, Richmond had Double Diamonds, and I don't know about Motive. I only use Tom's, his wife is still running the business and has new USA made gears in stock now BUT you have to know how to set them up or you will get whine with any of them.

Example of why I only use Toms. 6-7 years ago I built a 79 diff for a local guy using new usa made Richmonds, dialed in perfectly. They were terrible, whined badly. I broke down the diff to see if there was anything I did wrong the first time and found nothing I would have changed. The lash, preload, and the pattern were PREFECT. I replace the Richmonds with Tom's and installed all new bearings, did the same setup and they also dialed in PERFECT- only no noise in use. I stopped using any other gear set since. I just got in a new set of Tom's 373's, they are still 5 cut gears. NOTE- Toms are 373 not 370, the only new 370 ratios are imported gears now.

Robert - if you took it apart several times now and still have a whine I would not bother anymore, get Tom's gears, a new master kit with USA Timkens, and setup the posi correctly. The pinion shim should be about 024-026 and the lash 5-7, total preload 10 in/lb over the final pinion preload.

Mike; I've no doubt you know this and need only be reminded that long term it is never a good idea to drive through mechanical noise. Mechanical noise always comes with wear and eventual failure it being only a matter of time and place. Dynamat is good to use in any old car it will fit.
Get the rear end fixed and you will sleep better.

Dan