Re: 8 3/4 Rear Pinion Noise
[Re: ben-dart]
#2210523
12/09/16 04:22 AM
12/09/16 04:22 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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Circle Track
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Posts: 36,040
Lincoln Nebraska
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Tapered roller bearings on axle shafts are newly greased and endplay is correct. I've heard that pinion gear is higher pitched, but could use some help on whether ring and pinion need replace. Not my area so a BTT for ya but more info, I was wondering if it was bad & you did the greasing/endplay to try & correct it? when did it start? any parts changes preceding this?
live every 24 hour block of time like it's your last day on earth
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Re: 8 3/4 Rear Pinion Noise
[Re: ben-dart]
#2210877
12/09/16 08:46 PM
12/09/16 08:46 PM
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Joined: Jan 2003
Posts: 20,171 Park Forest, IL
slantzilla
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Park Forest, IL
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A pinion bearing bad may or may not make a rumbling noise, but a loose bearing will make the pinion pattern change and make noise.
"Everybody funny, now you funny too."
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Re: 8 3/4 Rear Pinion Noise
[Re: slantzilla]
#2211014
12/10/16 01:11 AM
12/10/16 01:11 AM
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Joined: Jan 2003
Posts: 15,311 Omaha Ne
TJP
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I Live Here
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Omaha Ne
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A pinion bearing bad may or may not make a rumbling noise, but a loose bearing will make the pinion pattern change and make noise. Either the pinion bearing is loose/ worn allowing it to go forward under acceleration, or the differential side bearings are worn/ improperly set. Either situation will allow the pattern to change and cause the noise you are experiencing.
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Re: 8 3/4 Rear Pinion Noise
[Re: 1969ronnie]
#2211124
12/10/16 10:58 AM
12/10/16 10:58 AM
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Joined: Feb 2007
Posts: 26 Aylett, VA
ben-dart
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ben how old are you u joints? ronnie The rear u-joint is new. The front u-joint is from before I bought the car 3 years ago. There's no play in either u-joint. Also, per my 1970 Factory Shop Manual, driveshaft length is correct.
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Re: 8 3/4 Rear Pinion Noise
[Re: RapidRobert]
#2211130
12/10/16 11:11 AM
12/10/16 11:11 AM
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Joined: Feb 2007
Posts: 26 Aylett, VA
ben-dart
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[/quote] Not my area so a BTT for ya but more info, I was wondering if it was bad & you did the greasing/endplay to try & correct it? when did it start? any parts changes preceding this? [/quote]
The story is that I bought a 1970 Fury with bad rust for a parts car. I did drive it, but not at very high speed. I didn't notice problems with the 3.23 8.75 sure grip axle. My 1970 Fury convertible had an 8.25, 2.71 gear, open. I cleaned and painted the 8.75 rear from the parts car. I installed the rear in the convertible as prep for a big block conversion, which I have not yet begun. The axle shafts had a tapered roller bearing on one side and a non-adjustable bearing on the other, which was a mismatch. I had a tapered roller bearing installed on the side with the repair bearing, greased both sides, and set up the end play after I had installed the axle on the car. The noise appeared immediately with the replacement axle. I removed the pinion shaft nut and tightened to factory spec. I drove the car again and the noise remains.
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Re: 8 3/4 Rear Pinion Noise
[Re: cudaman1969]
#2211134
12/10/16 11:20 AM
12/10/16 11:20 AM
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Joined: Feb 2007
Posts: 26 Aylett, VA
ben-dart
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I want to hear the answer too, I have a 741-3.55 sure-grip and does the same thing, same speed. Mine is a used set and thought it was bad run in before I got them. All ears. MANY THANKS to TJP and Slantzilla. It sounds like the problem is the pinion bearings (or diff side bearings). Nobody is saying gears. I guess the good news is that I can keep my ring and pinion, but the bad news is that the center section has to be pulled and rebuilt. I'm only about an hour away from Fredericksburg. If you know a good rebuilder in our area, I'd be very interested in that info.
Last edited by ben-dart; 12/10/16 11:43 AM.
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Re: 8 3/4 Rear Pinion Noise
[Re: ben-dart]
#2211145
12/10/16 12:00 PM
12/10/16 12:00 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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Lincoln Nebraska
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The axle shafts had a tapered roller bearing on one side and a non-adjustable bearing on the other, which was a mismatch. I had a tapered roller bearing installed on the side with the repair bearing. The noise appeared immediately with the replacement axle. Not my area of knowledge but offhand that would lead me to believe that the problem was related to the endplay/thrust spacer areas rather than the gears cuz that was what was altered (tho you did say you did not run it up very high before the swap). Holler how it turns out
live every 24 hour block of time like it's your last day on earth
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