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Old 01-06-2016, 03:42 PM   #26
c1800
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thanks,will pursue it further. not a winter driver.
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Old 01-07-2016, 01:52 AM   #27
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Quote:
Originally Posted by JerryJS8 View Post
I had a 240 with a constant differential whine relative to cruising speed, and the bearing eventually melted together bringing the car to a screeching stop on a dirt road.
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For the safety of those around you, I suggest you stop driving the car and fix the thing. Diff failures can cause you to spin out.
Yikes, you've got me worried now!

My '85 245 GLT AW71 has had a rear end whine since I bought it last March. The whine is fairly constant, starting to be noticeable at ~20mph and increasing a bit to highway speeds. There is only a slight difference in whine between cruising at 60mph in gear and coasting at 60mph with auto shifted into Neutral.

On jack stands, I didn't hear the whine while reving to lower speeds in the garage (I was chicken and didn't rev it up to 60mph). If I spin a rear wheel by hand (other wheel spinning in opposite direction), I hear a clicking at ~15 clicks per wheel rev. If I wedge the other wheel, so only driveshaft spins, the clicking is at ~half the rate. It's a factory turbo AW71 with a 3.91 ratio (43 and 11 ring/pinion teeth?)

I drained the gear oil and it seemed OK (black, but no noticeable metal flakes, fill level OK). There were some filings on the magnetic plug. I replaced the oil with high-vis lucas, but haven't had a chance to drive it much since then (too much snow and now gravel on the roads).





What does this seem like? Gears? Bearings? Too wimpy of a stereo?

What else can I do to diagnose the whine?

Thanks!
Bob
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Old 01-07-2016, 02:10 AM   #28
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Try the synthetic Lucas, needs to be hypoid for the diff.
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Old 01-07-2016, 02:20 AM   #29
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Pop the cover off and inspect and measure backlash with a dial indicator with magnetic base. Backlash that is too loose will cause whining.

Bearings can go bad, shims can wear down, gears can wear, all sorts of stuff to fail back there. gotta get in there and inspect/measure. Replacing bearings is a large job and requires a press.
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Old 01-07-2016, 02:51 AM   #30
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Thanks,
Can you point me to a decent document, link, or video showing what I should inspect and measure? My Bentley manual falls far short of normal on this topic - a mere 4 pages for the entire Rear Axle section. The only greebook I could find (link) devotes 5 pages just to list the special tools required, but then is really weak on inspection/measurement. Alternately, I can (weather/frostbite permitting) pull the diff cover this weekend and shoot pictures of what I find and then post them here for expert review.
Cheers,
Bob
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Old 01-07-2016, 03:17 AM   #31
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http://www.differentials.com/technic...n-instructions

Spec says 6-10 Thousandths backlash for the Dana 30. If it is too loose, it will whine. Too tight it will burn up. As things wear, backlash can get sloppy and cause whining.


Tip: Do NOT use Harbor Freight vice-grip base flex dial indicator. Pure junk. Use magnetic base.

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Old 01-07-2016, 06:28 AM   #32
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What is being measured? how much freeplay the crown wheel has before it engages the pinion?
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Old 01-07-2016, 10:21 AM   #33
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Default Ring gear to drive pinion backlash

I think there may be 5 million articles on the internet about it. ;- ) You measure it, and if it's off, you shift the entire diff/ring gear one way or the other to change the adjustment. Certain axles have a screw to adjust (Ford 9" and some Japanese stuff), many use shims, such as on our Volvo. Do your research.







Here are two videos I found that I liked that I have filtered thru on the millions of articles/videos available. This is a Ford 8.8, but it's the same concept:

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Originally Posted by ZVOLV View Post
Dial indicator for measuring backlash. On the 8.8 it is adjusted by shims on the sides of the carrier bearings. Too loose it will whine. Too tight it will burn up.

Pinion depth is also a dial indicator measurement. End result is measured with the marking compound to check toof engagement.

Need inch pound torque wrench to setup pinion bearing preload. It took almost 300+ ft/lbs of torque for us to crush the new crush sleeve to get the preload correct.







Last edited by ZVOLV; 01-07-2016 at 10:49 AM..
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Old 01-09-2016, 01:45 AM   #34
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Thanks for the pics and links!

I didn't know if I could measure backlash by hand or if I needed to [somehow] lock down the yoke and torque the gears before measurement.

Since the weekend forecast, for the unheated garage, is a high of 18 and a low of 8, it may be a while before I can pull the cover, visually inspect, and measure the backlash.

Cheers,
Bob
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Old 01-11-2016, 10:56 PM   #35
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The weather warmed up enough so that I was able to measure/inspect my whining diff. The ring gear backlash is ~ 7.25mils. Greenbook spec for adjusting backlash after disassembly is 5 to 7 mil, but set "as near to 6mil as possible". I didn't see anything obviously damaged on either side of the visible gear teeth (I couldn't see back-side of pinion, and am not sure if I saw all the spider teeth).



I also tried measuring the spider backlash -- I wedged one wheel, held the ring fixed, and moved the other wheel. I measured the backlash on the spider gear on the moving axle - so axle spider, to carrier spider, to other axle spider, to wedged wheel. This was about 18mils, but was a somewhat vague measurement and might be a few mils less.

By hand, I didn't feel any play in pinion gear seating, or in the u-joint.

Some folks have mentioned the drive shaft carrier bearing as another source of whining. To me, it sure sounds like my whine is from the rear axle. Do they sound similar?

What else should I inspect/measure?

Thanks,
Bob
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Old 01-14-2016, 10:52 AM   #36
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If your backlash spec is only 6 thousandths that isn't the cause of your whine. I had a Mustang 8.8" at 30-40 thou on accident and THAT made loud whining. Wait,,, you say 6 mil? 6 mm?? That doesn't make sense. Let's keep it to SAE units here.
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Old 01-14-2016, 10:58 PM   #37
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Sorry, I guess I'm old school. 1 mil = 0.001", and from Jr.High Power Mechanics class (aka lawn mower engines), a sheet of typing paper is ~3.5mils thick.

The local autoparts stores didn't have any gear marking compound, or at least not without buying a rebuilt kit to get the little packet of compound, so I tried white lithium grease. It didn't work very well -- hard to tell the mesh patterns and these pictures are after only a single rev.




At this point, I'll probably take it to the local Volvo shop and see if they can diagnose the source of the whine with a stethoscope while spinning the wheels on a lift. Volvo carrier bearings seem reasonably replaceable but good luck finding a shop that can replace and warranty the pinion bearings.

Unfortunately, it's a factory turbo AW71 with a 3.91 ratio (43/11), so I may not be able to find a good used replacement axle if needed. I guess I could go to the more common 3.73, and swap speedo and tranny speedo drive gear, but I'd prefer keeping it original.

Thanks,
Bob
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Old 01-16-2016, 10:40 AM   #38
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We have the corded version at the shop, but these are fun to play with:




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Old 09-03-2019, 11:48 PM   #39
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3.5 year bump.

Status update: After checking the backlash and finding it was OK, I ended up swapping the whole rear axle for a good junkyard 3.73 rear axle in the Spring of 2016. No more whining.

The original rear axle has been taking up space in my garage ever since. This last weekend, I finally tore it down and inspected the parts:



The front pinion bearing rollers are obviously pitted. The outer race has some shallow damage (hard to photograph). I assume that this was the source of the whine?



I didn't see any other bearing damage. For the ring and pinion teeth, what should I look for in terms of wear patterns to see if the 3.91 is still good?

Thanks - Bob
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Old 09-04-2019, 11:43 AM   #40
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I got nuthin on gear inspection, but those pinion rollers sure look like they would make noise.
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It's always better to get into a turbo volvo and drive.
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Old 09-04-2019, 09:40 PM   #41
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yeah, those rollers look bad up close. When I had my true track installed. It was with all new bearings in there both diff and pinion and filled with red line. After about a year it was whining loudly. I took it back to the shop that installed it and they told me they stopped using synthetic redline. So I tried the Lucas stuff that reads that it stops whining gears on the bottle. After about a year or so the whining went away and the diff has been fine. That was at 250k miles, now at 340k miles on an 82 turbo. My true track is worn and clanks though. It's an early no preload version so that is the deal with no preload.
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Old 09-08-2019, 11:46 AM   #42
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Thread jack #3!

My rear axle sounds like it’s full of rocks and makes the most horrible sound for the first few minutes of driving every time the ambient temperature drops below -15*C. It’s fine all of spring, summer and fall but always does this in the wintertime.

But why?!
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Old 09-08-2019, 01:38 PM   #43
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Wear in the spider gears would be my guess?
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