Technical Drivetrain Whining Noise

Yesterday installed new u-joints and differential seal on my '50 Ford Custom. Also replaced the diff oil. Now there is a whining noise when decelerating. Any idea what the specific cause could be? Any help would be greatly appreciated. Thanks.

 

Did seal kit have a new crush sleeve? If not torqued up the pinion can move some on the ring gear and vibrate, leak and whine…

 

Maybe the U joints weren't installed correctly? I usually smack them each sideways to press the cups outward after install.

 

Dropped a needle ?

 

Wining during deceleration could be the front bearing in the transmission.

 

Most likely not enough or too much preload on the pinion assuming you replaced the pinion seal. See if the pinion moves in and out, up and down slightly.

 

Thank you for your responses. Yes, it was the pinion seal that was replaced (photo below). There was no crush sleeve. Should the pinion be able to move in and out, up and down slightly?

 

No. Check torque specs. On 55 Chevy took me 120 lbs to get it right.

 

Second on the NO vote. I'm going to ask; did you tighten the nut by hand or with an impact gun?

 

By hand, but not using a torque wrench.

 

While I might be mistaken, that then is the problem. By hand for sure... No torque I'd live with if it was rapped on by the force of an impact wrench.

 

The crush sleeve is in between the Inner and outer pinion bearings. You won’t see it unless you take the entire diff apart. I’ve done it in the past where I mark the pinion nut and the pinion gear where the nut threads on. Then when removing the nut counting the turns it take ls to get it off. That will then give a place to try and get back to where it was when you started. Once the marks are lined up and it’s the right number of turns on the nut the. I give it just a hair more tight to take up a little slack in the worn bearings. Maybe an 1/8th of a turn.
If you didn’t mark things when you took it apart. The one not right way to fix it is to pull the third member out remove the differential (mark everything before disassembly) and tighten the nut so it has the right rotational torque setting on the pinion bearings. I think it s 5 to 9 inch pounds rotational torque, set with an inch pound torque meter or inch pound torque bar. Then put it all back together. The wrong pinion bearing preload will cause the bearings to go bad and destroy the ring and pinion gears.

I’ve rebuilt hundreds of rears both in hot rod stuff and as a tech in GM dealers and independent shops. Ring and pinions are not tough to do, but they have to be set up right or they will eat themselves.

 

Had a whining noise in my car. Pulled over and the wife got out and looked under the car. Whining noise had stopped. She got back in the car and the whining started again

 

I have a similar problem except I get a knocking noise on deceleration.

 

I guess I'm under complicating the job with my approach to doing things...

 

I removed the whining noise from my car by divorcing my ex wife!

 

ONLY...with a new crush sleeve !
With NO...sleeve, there's no way to accurately get the torque correct. A solid sleeve, or a crush sleeve is required to space the two pinion bearings apart.

A solid or a previously crushed sleeve only needs about 10 lb.ft. of torque to hold things together.

Mike

 

Nailhead Jason - Thanks for your detailed suggestion. The workshop manual states bearing pre-load should be 13-18 inch-pounds. Will give that a shot and keep my fingers crossed.

 

Because you have the drag of the pinion bearings as well as the ring gear etc. That torque spec is useless without disassembling the differential . Getting the pinion nut back approximately can best be described as a " feel" thing .

 

I agree about the “feel” thing. At this point, (because you didn’t mark the pinion nut). I suggest you loosen the pinion nut until you feel a little play in the bearings by wiggling the yoke. (I’m guessing that yours is already loose.) then tighten the pinion nut a little bit at a time until there is zero play in the bearings. Then tighten the pinion nut a tiny bit more to preload the bearings slightly. It’s the same procedure you use when adjusting a front wheel bearing. In the future, mark the pinion nut before you disassemble it, as Nailhead mentioned. Then retighten it to the same spot and make sure the bearing preload feels about right.

 

The way I do pinion seals and it works great is .

I count the threads coming out of the pinion .

Then I use a dial type torque wrench to check preload.

the loosen the pinion nut with the dial torque wrench to see break away torque .

then tighten it up to between breakaway torque and the torque required to loosen it while keeping the same thread count sticking out of the nut.

always works for me , taught to my by and old timer when I got into the trade .

 

I’m willing to bet you didn’t get the yoke back on correctly .
I did that several years ago in my ot truck .
The pinion nut was dimpled at the top into the shaft so it wouldn’t back off .
I marked the socket so I would know exactly how many turns I backed it off to remove it .
Then after a couple of days driving ,,,the rear started roaring,,,,,,I wondered what I had done .
Dropped the drive shaft again,,,,counted how many turns I made with the nut .
Yep ,,,you guessed it,,,,it was the nuts fault,,,,,,I was the nut !

I had put the pinion nut back on 1 turn shy of being tight !
I put it back to the correct count,,,,,it has been perfect for over 200,000 miles now,,,problem solved .

Tommy

 

Thanks for everyone's suggestions. I have a lot to work with now and will let you know how it turns out. I knew I should have gotten the 75 year extended warranty.

 

Just wanted to let you know all is good now. Whining noise is gone. Backed of the tightness on the nut and that did the trick. As others have said, it was definitely a "feel thing" to get the torque just right.