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School this rookie: "RRRRRR" sound from rear diff... #2104205
07/05/16 01:20 PM
07/05/16 01:20 PM
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Albany, NY
67SATisfaction Offline OP
The member whose name is actually Art
67SATisfaction  Offline OP
The member whose name is actually Art

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Albany, NY
This might be a very basic question for someone whose familiar with stock 8-3/4 inch rear diffs, but I've never been in this territory before...

The stock diff on my car is making a "RRRRRRR", growling sound when driving it.
The sound level is definitely louder than last summer, which triggered my concern this year.
The sound level goes down when I brake.
The sound follows the speed of the roadwheels, not the driveshaft..
The diff case isn't TOO hot to touch after a hard drive, but it's definitely warm.

I restored the car a couple years ago. Never opened the diff, but I did replace the case oil with factory spec oil up to the level of the plug. I have not noticed any leaks from it, but I haven't checked the current oil level.

I've got a stock '65 Satellite big block, the rear diff is the stock "open" 2.76 ratio (standard on an A/C car).

What do you guys think? (I'm a bit embarrassed I haven't even checked the case oil level yet or the FSM troubleshooting section..

I've never had a Mopar diff "fail" before. My old '66 Dart slant six had a similar "growl", but it never got worse and stayed the same for 200,000 miles. I was going to ignore this one too, but it's def getting worse over time and no apparent oil leak.

I doubt my skills to rebuild and reinstall the pumpkin. What kind of shop would do a rebuild? I have a couple performance shops around here. Or is it a machine shop I'm looking for?

Thanks for your input,
- Art



Last edited by 67SATisfaction; 07/05/16 01:21 PM.

65 Satellite hardtop 361/4bbl console 727 2.76
67 Satellite convert 383/2bbl column 727 3.23
67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd
67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd
71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd
82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle
75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF
77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF
07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104216
07/05/16 01:34 PM
07/05/16 01:34 PM
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I would start by pulling the shaft & moving the ujoints back & forth in their planes of movement & checking for roughness. First see if the straps are a slight bit loose/quick visual on the ujoints when you get under there. fluid level/freeplay on the yoke (not sure if that would produce noise but it'd take 5 seconds & then you'd have that info if others say it is critical). EDIT trans mount in good shape/bolts tight

Last edited by RapidRobert; 07/05/16 01:36 PM.

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Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104217
07/05/16 01:39 PM
07/05/16 01:39 PM
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I'ts not a 489 case so that is a good thing , you should be able to find a 2.76 case fairly easily, and fairly cheap, to swap out to determine if that is the issue , I probably have a few of them ??

Art , did you pull the axles out during the resto ?


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Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104239
07/05/16 02:21 PM
07/05/16 02:21 PM
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I'd put the car up on stands and run it to determine if I'm dealing with a third member or a wheel bearing and or axle thrust adjustment?


When is the sound?, constant, more on acceleration, de-acceleration, cornering, etc

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: DAYCLONA] #2104273
07/05/16 03:18 PM
07/05/16 03:18 PM
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Originally Posted By DAYCLONA

When is the sound?, constant, more on acceleration, de-acceleration, cornering, etc


iagree

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: TJP] #2104275
07/05/16 03:20 PM
07/05/16 03:20 PM
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Worded a bit differently,

does the noise change under the following 3 conditions at 30+ MPH,

1. Acceleration
2. Deceleration
3. Cruise, IE: in between accel and deccel

beer

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104299
07/05/16 04:06 PM
07/05/16 04:06 PM
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The rear axle bearings are lubricated with wheel bearing grease, not the rear axle gear oil. Folks seem to never repack them. I have had a car make a sound like this and it was a dried up wheel bearing, the differential was just fine.

Running it on stands with no load on anything may not help you decide anything. Be very careful of the rotating tires and driveshaft when doing this test.

Removing the axle shafts is pretty easy thing to do to check the wheel bearings.

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104352
07/05/16 05:46 PM
07/05/16 05:46 PM
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Originally Posted By 67SATisfaction

The sound level goes down when I brake.
The sound follows the speed of the roadwheels, not the driveshaft..


Could be an axle bearing; does the noise change when turning sharply right/left at the same speed?


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Re: School this rookie: "RRRRRR" sound from rear diff... [Re: NANKET] #2104374
07/05/16 06:21 PM
07/05/16 06:21 PM
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You should check the axle bearings before you drive it any more. The shop that restored my Road Runner didn't put any grease in the bearings on my Dana, and it cost my over a $1000 to fix.

Last edited by 71birdJ68; 07/05/16 06:22 PM.
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 71birdJ68] #2104529
07/05/16 10:28 PM
07/05/16 10:28 PM
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Art if it is the bearings just needing greased, the needle attachment for your grease gun works the best. No need to pull the axle all the way out but if you need to for whatever reason be sure to wrap the splines in past the seal with some brown grocery sack paper BEFORE you pull the splines out past the seal. Holler if needed


live every 24 hour block of time like it's your last day on earth
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104667
07/06/16 02:58 AM
07/06/16 02:58 AM
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Better remove the axles, clean out the old grease with solvent, then brake cleaner. Then put in new grease with the needle.

When removing the shaft and you are getting near the splined end, lift the axle and do not slide it over the seal.

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104756
07/06/16 09:52 AM
07/06/16 09:52 AM
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Albany, NY
67SATisfaction Offline OP
The member whose name is actually Art
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Thanks guys, RR, Robert, Mike everyone,
Glad to learn about the possibilities, I hadn't thought about a wheel bearing.

THE SOUNDS:

I recall the sound is there in both accel and decel. It's pretty loud when I'm just cruising along, constant throttle, on the highway.

Like I said above, the frequency tracks the wheel speed, not the driveshaft speed - it doesn't vary with gear shifts.

I recall very clearly that I could make the sound go way down when braking - not trailing throttle, but actually braking.

I do think the sound changes in cornering - making right turns, but not left turns. I'll double check this. I have to go get it out of storage today, so I'll pay close attention when I drive the 10 mile trip.

I'll start checking the suggestions you offer and read the FSM, I'll post back here when I can.
Thanks again, cheers,
- Art


65 Satellite hardtop 361/4bbl console 727 2.76
67 Satellite convert 383/2bbl column 727 3.23
67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd
67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd
71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd
82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle
75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF
77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF
07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2104805
07/06/16 11:21 AM
07/06/16 11:21 AM
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Originally Posted By 67SATisfaction
Thanks guys, RR, Robert, Mike everyone,
Glad to learn about the possibilities, I hadn't thought about a wheel bearing.

THE SOUNDS:

I recall the sound is there in both accel and decel. It's pretty loud when I'm just cruising along, constant throttle, on the highway.

Like I said above, the frequency tracks the wheel speed, not the driveshaft speed - it doesn't vary with gear shifts.

I recall very clearly that I could make the sound go way down when braking - not trailing throttle, but actually braking.

I do think the sound changes in cornering - making right turns, but not left turns. I'll double check this. I have to go get it out of storage today, so I'll pay close attention when I drive the 10 mile trip.

I'll start checking the suggestions you offer and read the FSM, I'll post back here when I can.
Thanks again, cheers,
- Art


Sounds like the wheel bearings , stop driving it till you get it figured out , the bearings may already be damaged though.

Do yourself a favor and put the stock style tapered bearings back in it , it's a little more work , and money , but worth it in the long run.


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Re: School this rookie: "RRRRRR" sound from rear diff... [Re: JohnRR] #2104849
07/06/16 12:19 PM
07/06/16 12:19 PM
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Quote:
Sounds like the wheel bearings , stop driving it till you get it figured out , the bearings may already be damaged though.

Do yourself a favor and put the stock style tapered bearings back in it , it's a little more work , and money , but worth it in the long run.


iagree

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: JohnRR] #2104907
07/06/16 02:10 PM
07/06/16 02:10 PM
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Originally Posted By JohnRR
Originally Posted By 67SATisfaction
Thanks guys, RR, Robert, Mike everyone,
Glad to learn about the possibilities, I hadn't thought about a wheel bearing.

THE SOUNDS:

I recall the sound is there in both accel and decel. It's pretty loud when I'm just cruising along, constant throttle, on the highway.

Like I said above, the frequency tracks the wheel speed, not the driveshaft speed - it doesn't vary with gear shifts.

I recall very clearly that I could make the sound go way down when braking - not trailing throttle, but actually braking.

I do think the sound changes in cornering - making right turns, but not left turns. I'll double check this. I have to go get it out of storage today, so I'll pay close attention when I drive the 10 mile trip.

I'll start checking the suggestions you offer and read the FSM, I'll post back here when I can.
Thanks again, cheers,
- Art


Sounds like the wheel bearings , stop driving it till you get it figured out , the bearings may already be damaged though.

Do yourself a favor and put the stock style tapered bearings back in it , it's a little more work , and money , but worth it in the long run.





If it's the wheel bearings, I'd be more inclined to go with Green Bearings, from Dr Diff, eliminate all the factory tapered/adjuster crap, yes crap...the only time I see an issue with Green Bearings, it's an installation error on the installers behalf

mike

Re: School this rookie: "RRRRRR" sound from rear diff... [Re: DAYCLONA] #2104919
07/06/16 02:19 PM
07/06/16 02:19 PM
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Originally Posted By DAYCLONA
Originally Posted By JohnRR
Originally Posted By 67SATisfaction
Thanks guys, RR, Robert, Mike everyone,
Glad to learn about the possibilities, I hadn't thought about a wheel bearing.

THE SOUNDS:

I recall the sound is there in both accel and decel. It's pretty loud when I'm just cruising along, constant throttle, on the highway.

Like I said above, the frequency tracks the wheel speed, not the driveshaft speed - it doesn't vary with gear shifts.

I recall very clearly that I could make the sound go way down when braking - not trailing throttle, but actually braking.

I do think the sound changes in cornering - making right turns, but not left turns. I'll double check this. I have to go get it out of storage today, so I'll pay close attention when I drive the 10 mile trip.

I'll start checking the suggestions you offer and read the FSM, I'll post back here when I can.
Thanks again, cheers,
- Art


Sounds like the wheel bearings , stop driving it till you get it figured out , the bearings may already be damaged though.

Do yourself a favor and put the stock style tapered bearings back in it , it's a little more work , and money , but worth it in the long run.





If it's the wheel bearings, I'd be more inclined to go with Green Bearings, from Dr Diff, eliminate all the factory tapered/adjuster crap, yes crap...the only time I see an issue with Green Bearings, it's an installation error on the installers behalf

mike


argue spank


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Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2105003
07/06/16 04:16 PM
07/06/16 04:16 PM
Joined: Jan 2003
Posts: 7,538
Albany, NY
67SATisfaction Offline OP
The member whose name is actually Art
67SATisfaction  Offline OP
The member whose name is actually Art

Joined: Jan 2003
Posts: 7,538
Albany, NY
Thanks guys,
I surfed around YouTube to get a feel for what's involved at the axles and bearing(s).

The diff case is 742.

Before I read your suggestion NOT to drive the car, I went and drove the Satellite home and observed the following during the drive;
- The exhaust is too loud to hear much from the rear until I'm going 65mph, and the "RRR" sound is clear.
- The sound changes a little in corners, but doesn't go away.
- The sounds vanishes almost completely when braking.
- At low speeds the sound can be heard just a bit, and it seems to go away taking right turns, but not left turns. Hard to tell for sure though.
- The temperature of the wheel hub on the driver's side is warmer than the passenger side. I'll check brake shoe advance mechanism on the passenger side.

I loosened the lug nuts but kept the tires on, and jacked the rear up off the ground. The lugs are tight enough that the rim isn't loose:
- There is some "play" in the rear wheels, it is about equal on both sides and I detail it as follows:
- I grab the tire tread top and bottom and did Push/Pull get about 1/8" of play.
- With the same grip on the tire treads, I tilted it up, Tilt it down, Tilt it towards the front, and towards the rear. Each side had some play in most directions - enough to make a tiny "clunk" sound when wrestling the tire with my hands.
- Rotationally I get 1" of play before the driveshaft or opposite wheel moves.

The play is enough that if this was my front, I'd be tightening the wheel bearing end-play nut.
I WILL CHECK the level of oil in the case, somehow it "sounds dry" in there. Can't explain why, it just seems harsh, not dampened.

After that, I'll take the wheels off and get a look at the play of the shaft at the bearing plate area. So that might reveal something.

If nothing shows up clear, I'll run the engine in D and listen for the problem.

So far haven't messed with the driveshaft U-joint.

I'll come back here in a few.
- Art


65 Satellite hardtop 361/4bbl console 727 2.76
67 Satellite convert 383/2bbl column 727 3.23
67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd
67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd
71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd
82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle
75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF
77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF
07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2105027
07/06/16 04:44 PM
07/06/16 04:44 PM
Joined: Jan 2003
Posts: 7,538
Albany, NY
67SATisfaction Offline OP
The member whose name is actually Art
67SATisfaction  Offline OP
The member whose name is actually Art

Joined: Jan 2003
Posts: 7,538
Albany, NY
So I took the tires and brake drums off and the play at the axle flange is clearer;

The passenger side end-play (in/out) is maybe 1/16", and there is some play in the bearing, less than 1/32" I'd say. The gap where the drive shaft enters the bearing plate is dry and clean.

The driver's side is very different. Same end-play, but much more play fore/aft and up/down at the bearing, nearly 1/16". The gap where the shaft enters the bearing plate is wet with oil, not dripping exactly but close.

I checked the oil in the diff case and it is both clean and full.

So I will now read the FSM about axle bearing replacements, they may have tolerances for the bearing play, but I bet it's less than my 1/32" to 1/16" .

I appreciate both of your opinions on bearing type John and Mike, thanks for keeping it respectful, I'll replace both sides with the type that works for me.

I'll check for comments and get back here with any issues.
- Art


65 Satellite hardtop 361/4bbl console 727 2.76
67 Satellite convert 383/2bbl column 727 3.23
67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd
67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd
71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd
82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle
75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF
77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF
07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: 67SATisfaction] #2105031
07/06/16 04:47 PM
07/06/16 04:47 PM
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Originally Posted By 67SATisfaction
Thanks guys,
I surfed around YouTube to get a feel for what's involved at the axles and bearing(s).

The diff case is 742.

Before I read your suggestion NOT to drive the car, I went and drove the Satellite home and observed the following during the drive;
- The exhaust is too loud to hear much from the rear until I'm going 65mph, and the "RRR" sound is clear.
- The sound changes a little in corners, but doesn't go away.
- The sounds vanishes almost completely when braking.
- At low speeds the sound can be heard just a bit, and it seems to go away taking right turns, but not left turns. Hard to tell for sure though.
- The temperature of the wheel hub on the driver's side is warmer than the passenger side. I'll check brake shoe advance mechanism on the passenger side.

I loosened the lug nuts but kept the tires on, and jacked the rear up off the ground. The lugs are tight enough that the rim isn't loose:
- There is some "play" in the rear wheels, it is about equal on both sides and I detail it as follows:
- I grab the tire tread top and bottom and did Push/Pull get about 1/8" of play.
- With the same grip on the tire treads, I tilted it up, Tilt it down, Tilt it towards the front, and towards the rear. Each side had some play in most directions - enough to make a tiny "clunk" sound when wrestling the tire with my hands.
- Rotationally I get 1" of play before the driveshaft or opposite wheel moves.

The play is enough that if this was my front, I'd be tightening the wheel bearing end-play nut.
I WILL CHECK the level of oil in the case, somehow it "sounds dry" in there. Can't explain why, it just seems harsh, not dampened.

After that, I'll take the wheels off and get a look at the play of the shaft at the bearing plate area. So that might reveal something.

If nothing shows up clear, I'll run the engine in D and listen for the problem.

So far haven't messed with the driveshaft U-joint.

I'll come back here in a few.
- Art



It's the axle bearings , an 1/8" is .125 , axle endplay is about .012 MAX ...

Hitting the brakes is centering the bearing, the fact that you can move it in all directions tell me it's too loose.

Did you have the axles out to redo the backing plates during the resto ?

A7 is the number for the bearing Kit , you need 2 , there is also 2 seals , one in the axle tube , the other in the axle retaining plate.

If you go with Greens buy them from Dr. Diff , and buy 2 sets so you have them on hand when you have to replace them again ... wink


running up my post count some more .
Re: School this rookie: "RRRRRR" sound from rear diff... [Re: RapidRobert] #2105082
07/06/16 06:16 PM
07/06/16 06:16 PM
Joined: Jan 2003
Posts: 9,108
Tucson, AZ
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Originally Posted By RapidRobert
if you need to for whatever reason be sure to wrap the splines in past the seal with some brown grocery sack paper BEFORE you pull the splines out past the seal. Holler if needed


I'm not clear on this Robert. Are you suggesting pushing paper through the seal before sliding the splined portion of the axle out?

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