quote:

Originally posted by Bill N.Y.:
Hey Bill H, what do you think about...

Bill N.Y.

I have had bad luck diagnosing rear end noises, perhaps due to my hearing. I wear two hearing aids, so not much good there. Sometimes I end up breaking it down before I find the bad bearing by feel. I do know that backlash much over .010 is bad, swarf is bad and sharp edges on teeth are bad. Spray clean the ring and pinion and do a pattern check with white lead from an old fashioned paint shop. Most manuals have good pictures to compare.

A magnet will detect any swarf in the bottom.

Going back to the original post, it is described as a "knocking noise". Of course, the lexicon here is not standardized, but my description of a ring and pinion problem is a whine that changes from power to trailing throttle. My description of bearing failure is a grinding or crunching noise. My description of spider gear noise is really bad crunching around corners. I have not experienced a "knocking noise" from a rear end.

It's a shame we can't all listen to it.

What we need is to all go for a ride with the floor pulled up so we can listen and say, "hmmmm".

If the outside pinion bearing gets sloppy, a seal would likely start to leak. If the inside pinion bearing goes, I suspect a backlash check would reveal that. Or a pattern check.

Ah heck, a diff professional is going to look at it.

I think there's probably room for 8 or 10 of us, ears-down to the floor....

ISSUE:
Some vehicles equipped with the DANA 80 rear axle may exhibit a popping or audible chattering noise. This popping noise/feel results from the clutch plates and discs (in the limited slip differential case) sticking and then slipping. The condition can occur in either forward or reverse, or both, when the axle is required to differentiate, i.e. during vehicle turning.

ACTION:
To verify the chatter condition, drive the vehicle in very sharp turning maneuvers at very low speeds, i.e. foot on brake, creeping. Testing should be done in both forward and reverse, both left and right turns, on flat, dry pavement. Frequent stops and slow starts are also recommended to determine presence of Chatter. Refer to the following Service Procedure.

SERVICE PROCEDURE:
Remove rear axle carrier cover plate and drain fluid. Clean sealing surfaces of both carrier and cover plate. Reinstall cover plate with High Performance Silicone Sealant TA-29 and torque cover plate bolts to 54-68 N-m (40-50 lb-ft). Allow 15 minutes for silicone sealant to set-up. Refill carrier with 2 bottles (8oz.) of additive Friction Modifier XL-3 and 0.84 gallons (107 oz.) of XY-75W90-QLS Rear Axle Lubricant. Drive vehicle as outlined above until chatter is gone. Additionally, allow vehicle to set for one (1) hour or longer and road test again, using same procedure.

If chatter is gone, return unit to customer.

If chatter is very slight, (and deemed acceptable) explain to customer that some chatter feel is normal in limited slip axles as greater differentiation forces are present.

If chatter is still unacceptable then...

Replace the clutch pack assemblies inside the limited slip differential. Obtain service part 3C3Z-4880-AA and continue with the following Service Procedure.

Not that your going to do this but some might find this an interesting read - This is where it gets VERY boring - technical babble - This is why most people take there coach to a competent repair shop and no playerslight77 I will not do this on the side of the highway - Walmart parking lot would be better as they are well lit - If it's raining you would have to pull under an interstate overpass

REPLACING CLUTCH PACKS ON DANA 80 LIMITED-SLIP DIFFERENTIAL

DISASSEMBLY OF DIFFERENTIAL FROM AXLE:

Remove cover plate and drain axle oil.
Refer to Workshop Manual Section 205-02C for axle shaft removal.
Clean sealing surfaces of both the carrier and cover plate.
Clean ring gear and pinion, visually inspect for damage.
Measure the differential ring gear and pinion backlash at three (3) equally spaced points.

CAUTION: DO NOT SPREAD THE DIFFERENTIAL HOUSING MORE THAN SPECIFIED. USING THE SPECIAL TOOLS, SPREAD THE DIFFERENTIAL HOUSING TO THE SPECIFICATION, THEN REMOVE THE DIAL INDICATOR GAUGE WITH HOLDING FIXTURE. SPECIAL TOOLS 205-001 CASE SPREADER AND 100-D002 DIAL INDICATOR, SPECIFICATION 0.25 MM (0.010").

Note positions of the mating letters stamped vertically and horizontally on the bearing caps and differential housing before removing the bearing caps. Remove bearing caps and bolts. Save for reuse during reassembly.

CAUTION: IT WILL BE NECESSARY TO USE LARGE PRY BARS TO REMOVE THE DIFFERENTIAL ASSEMBLY FROM THE DIFFERENTIAL HOUSING. DO NOT DAMAGE THE DIFFERENTIAL RING GEAR WHEN CARRYING OUT THIS STEP.

Carefully ease (pry if necessary) the differential out of the axle assembly. Set differential assembly on bench with differential bolt heads showing.
Note spacers in each carrier bore. Be certain to maintain the spacers in their original bore position.

DISASSEMBLY OF DANA 80 LIMITED SLIP DIFFERENTIAL:

The differential assembly has two halves (flanged or gear half and button half). Mark the flanged half, button half, and cross shaft positions for installation reference. These marks will be used during the rebuild procedures to insure the case halves and cross shaft are reassembled in the exact same position as original.

Remove the case attaching bolts and remove the button half (part of differential without the ring gear). Save the bolts for reuse during reassembly.

Once the button half is removed from the flanged half, there should be one side gear and clutch pack clearly visible. Remove the clutch pack and discard (save the side gear for reuse). Inspect the space in the button half where the clutch pack resides. Remove and discard any clutch discs or plates that may be stuck in the button half.

Remove the cross shaft and pinion mate gears (4 gears).

Once the cross shaft and pinion mate gears are removed, the flange half side gear is clearly visible. Remove the side gear clearly revealing the flange half clutch pack (save the side gear for reuse). Remove and discard the clutch pack from flange half.

REASSEMBLY OF DANA 80 LIMITED SLIP DIFFERENTIAL:

The clutch packs are replaceable as complete sets only. Do not reorient the clutch pack. You must use the clutch pack orientation as received. Remove the shipping wire from the clutch pack. Lubricate each component with Friction-Modifier XL-3 (both sides of all plates and discs).

Assemble clutch pack into flange half in exactly the same arrangement as removed. The convex side of the belleville washer should be visible.

Make sure the clutch plate lugs enter the slots in the case. Also make sure the clutch pack bottoms out on the case.

Install the flange half side gear into the clutch pack in the flange half.
Install pinion mate shaft and pinion mate gears. Make sure pinion mate shaft is correctly installed according to the alignment marks made during disassembly.

Install button half side gear with splined hub end facing vertical.

Lubricate the second clutch pack in the same manner the flange half clutch pack was lubricated, refer to Step 1. Install clutch pack to the side gear with the belleville washer's convex side touching the side gear back face.

Correctly align and assemble button half to flange half. Install case body screws finger tight.

Tighten body screws alternately and evenly. Torque screws to 122-136 N-m (90-100 lb-ft.).

REINSTALLATION OF DANA 80 LIMITED SLIP DIFFERENTIAL INTO AXLE:

Verify that spacers are still present in their original differential bearing bore.

Install differential into the carrier housing. Use rubber mallet if necessary to seat the differential into the carrier.

Install the bearing caps, aligning the letters with those on the carrier housing. Tighten the bolts to 95-122 N-m (70-90 lb-ft.).

Remove the differential housing spreader.
Install dial indicator.

Recheck the backlash to verify reading taken at the beginning of the procedure.

Refer to Workshop Manual Section 205-02C for axle shaft reinstallation.

Apply High Performance Silicone Sealant TA-29 to cover plate and reinstall to carrier. Torque cover plate bolts to 54-68 N-m (40-50 lb-ft.). Allow 15 minutes for the silicone sealant to set-up.

Refill carrier with two (2) bottles (8oz.) of additive Friction Modifier XL-3 and 0.84 gallons (107 oz.) of XY-75W90-QLS Rear Axle Lubricant.

Drive vehicle as described ACTION section until chatter is gone.

---PART NUMBER AND PART NAME---
3C3Z-4880-AA Kit - Clutch Pack
XL-3 Friction Modifier
XY-75W90-QLS SAE 75W-90 Synthetic Rear Axle Lubricant
TA-29 High Performance Silicone Sealant

That would be a very good idea if these Rv builders would place a floor hatch over the rear end area. Sure would make life easier. I had thought about strapping myself underneath and letting my wife drive down the road but for sure if there was any obstructions in the road she would run over it.

quote:

Originally posted by bigcat:
That would be a very good idea if these Rv builders would place a floor hatch over the rear end area. Sure would make life easier. I had thought about strapping myself underneath and letting my wife drive down the road but for sure if there was any obstructions in the road she would run over it.

I believe I read of a similar situation on an annual Darwin Awards mailing. I didn't even involve obstructions.

quote:

Originally posted by Bill N.Y.:
ISSUE:
The condition can occur in either forward or reverse, or both, when the axle is required to differentiate, i.e. during vehicle turning.

I love it. "When the vehicle is required to differentiate." What tortured prolix! I can't believe that one got past the tech writing editor.

Anyway, does the noise occur only during turning? I don't remember reading that. My previous mention of spider gears assumed that the noise was when going straight. Did I miss something?

But, yes, there is no doubt that a posi could do that. I have a Detroit Locker that scared me until I got used to it. But it is silent going straight. Oh, yeah, "in a non-differentiating event".

Thank you for all the posts. Have learned alot here. I don't understand why so many people need to throw out to the world that they are smarter than everyone else by making it a point to show some misspelled words when the meaning is there. Anyways I found the problem which is a couple broken teeth on pinion gear. Now you all can point out all the misspelled words.

Glad you found the issue!

Please don't be offended (or take it personally) by questions and responses arising from misspellings - in the only case I saw, the reponse was an attempt to clarify and further help if possible.

There's no one on this forum that snipes at anyone for grammar, spelling, or calling truck parts "thing-a-ma-jigs" because they are not knowledgeable (not dumb, but rather unfamiliar) about Things Mechanical. The ultimate endeavor is to either help someone diagnose and repair a problem, or to ensure they don't get ripped by a repair shop.

The wealth of knowledge and the willingness to share it unselfishly is a hallmark of this forum.

I wonder where the broken teeth went. Did you stick a magnet in the bottom of the diff?

Hey Bill H - To paraphrase an Ethel Merman song from the 1940s (some of you are old enough to remember who Ethel was). Why do they call a differential a differential if it doesn't differentiate? And what does it do if it doesn't differentiate?

quote:

Originally posted by olroy:
Hey Bill H - To paraphrase an Ethel Merman song from the 1940s (some of you are old enough to remember who Ethel was). Why do they call a differential a differential if it doesn't differentiate? And what does it do if it doesn't differentiate?

Roy, I wish I were still a tech writer or instructor. I would run that by our editors. I believe it would be circulated and held up as an example of adding complexity (even inventing a new usage) where a simple and direct description would better serve. That sentence, using "when the axle is required to differentiate" instead of "when turning corners" just struck me as humorous. As in edu-speak or government-speak, or just plain cant. In my departments, a usage like that would be regarded as vastly entertaining, at the least. I would expect at at the minimum, a memo chiding me for such usage. Perhaps other corporate cultures are different.

I don't want to get into Clintonian parsing, but I have some question as to whether that is even correct usage. But I'll just tease it a little by positing that a differential doesn't differentiate as much as it allows a differential of rotational displacements to occur.

Geeze, my majors were philosophy, electronics and business. Any English majors here?

Our Airedale just ripped the windshield curtain track from its mountings.

That tech writer was fixated on what happens inside that round gizmo full of funny looking gears in the back of the truck, not what the gizmo is supposed to do when the truck goes around a corner. He's obviously an engineer, and neither an English major nor a driver.

Having said that, and having referred to three different dictionaries, I find that to be perfectly proper we'd have to to call the gizmo a "differential coupling," or "differential gear," not simply a "differential."

What the gizmo does, however, is not mentioned in any of the definitions for the word, "differentiate," so Bill's right, it's not correct usage. The man also has good instincts for proper English, as well as lots of other stuff.

Airedales can be cranky, whether in motor homes or on the decks of aircraft carriers.

quote:

Originally posted by bigcat:
I removed the cover and found nothing. No broken teeth no metal lying in bottom oil level OK and oil did not smell burnt.

You were running out of things to check so that's why I posted a tech piece I found.

quote:

Originally posted by Bill H:
Anyway, does the noise occur only during turning? I don't remember reading that. My previous mention of spider gears assumed that the noise was when going straight. Did I miss something?

I know he didn't say anything about turning but I thought I would throw it out there just in case.

quote:

Originally posted by bigcat:
Anyways I found the problem which is a couple broken teeth on pinion gear.

Were did the teeth go bigcat?

quote:

Originally posted by Rusty:
Please don't be offended (or take it personally) by questions and responses arising from misspellings

Seeing that Bill H. was picking on me (not really) can I take off-fence with that Rusty? I actually found it rather amusing once Bill H. posted that.

Can we just make "differentiate" (when talking about rears) a Barthism and call it a day?

I now know how to differentiate the meaning of SOB, POS and PIA thanks to this site!

Bill N.Y.

quote:

Originally posted by Bill N.Y.:
Seeing that Bill H. was picking on me
Bill N.Y.

Nah, Bill, I wasn't picking on you. I knew you didn't write that. I was criticizing the tech writer's usage. As a former tech writer, and a father who still proofs my kids' papers in grad school, perhaps I glommed on it with a little too much alacrity. But a couple of us had a good laugh over it, I think. (I hope)

However, it was a great post, and I will file it and probably refer to it if diff trouble pops onto my radar screen.