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post #1 of 37 (permalink) Old 10-30-2018, 04:00 PM Thread Starter
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Diff fix?

Full disclosure: I'm the laziest Alfa owner...ever.

Among many issues accumulating on my 2-Do list is addressing an annoying clunk coming from the 120k diff which, except for a new front seal and fluid changes, has never been opened.

A few months back, Wheeler Dealers worked on an '87 Quad and their efforts included dropping the axle and R&R'ing the clutch packs, obviously not a trivial matter.

With that in mind, I'm wondering if anyone has discovered a "Diff Repair in a Bottle" solution that may save me the effort of doing a proper repair, or at least reducing the clunk sound enough to be drowned out by the cacaphony of noise from other sources (also on 2-Do list).

I'm thinking maybe Bunker C or, what the heck, go all the way with Texas Sweet Crude. Extra Virgin Italian Olive Oil? Peanut butter?

All reasonable suggestions will be considered.

Hey, I'm desperate here.

Thanks.

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #2 of 37 (permalink) Old 10-30-2018, 05:32 PM
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Is it clunking on takeoff? If so that might be the driveshaft smacking the body (typically because of a worn center support) rather than the diff.

Tom

1963 Giulia Spider (1750 engine)
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post #3 of 37 (permalink) Old 10-30-2018, 07:25 PM
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Quote:
All reasonable suggestions will be considered
.
Back in the day sawdust was the magic stuff for quietening transmissions, usually prior to sale of the vehicle.
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post #4 of 37 (permalink) Old 10-30-2018, 09:24 PM Thread Starter
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More ideas!

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Originally Posted by alfaparticle View Post
.
Back in the day sawdust was the magic stuff for quietening transmissions, usually prior to sale of the vehicle.
Hmmmm. How long can sawdust be expected to last?

Do you recommend sawdust from any particular tree? There is an isolated grove of Bristlecone Pine on a mountaintop not too far south of my home, and they have endured for thousands of years. Gotta be a plus but I'd have to sneak past the Rangers.

Maybe oatmeal?

Gubi, thanks for the suggestion of checking the center carrier, but it was R&R'ed a few years back and at last inspection, was sound. Also, I've replaced all universal joints.

Sigh, may have to fix this the traditional way...

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #5 of 37 (permalink) Old 10-31-2018, 02:53 AM
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In the dear old UK, bananas used to be the trick in the 60's....................
Trouble is, they don't grow 'em thin enough to go through the hole.

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post #6 of 37 (permalink) Old 10-31-2018, 10:42 AM Thread Starter
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Time to end this silliness!

OK, we've had some fun speculating on ways to quiet a clunking diff, but time for me to end the hilarity and move on to researching a repair. A long winter approaches.

On the other hand, if I put the bananas in a blender and added sawdust from a Bristlecone Pine ....

Oh, never mind .

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #7 of 37 (permalink) Old 10-31-2018, 11:40 AM
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It would probably be helpful if you better described the problem. When does it clunk? Every launch? Only hard launches? When driving when you come on/off the power? At regular intervals?

Normally a worn diff will whine. Clunks in a Spider I’d be looking at the driveshaft first: either center support and bearing (even if done at some point in the past) or maybe the splines.

Tom

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Former: 1987 Milano Gold
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post #8 of 37 (permalink) Old 10-31-2018, 12:16 PM Thread Starter
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Details, details...

Quote:
Originally Posted by Gubi View Post
It would probably be helpful if you better described the problem. When does it clunk? Every launch? Only hard launches? When driving when you come on/off the power? At regular intervals?

Normally a worn diff will whine. Clunks in a Spider I’d be looking at the driveshaft first: either center support and bearing (even if done at some point in the past) or maybe the splines.
Gubi,

Thanks for your thoughtful reply.

Frankly, after doing considerable research on repair of our differentials, I fear the challenge (including special measuring tools) is beyond my feeble abilities, although complete R&R of the axle is not out of the question.

To answer your question, driveline clunk in my 120k Quad has existed since I bought her @70k and over the years, the problem was attacked through replacement of the center bearing (much improved, since the bearing had been movable by hand), R&R of all universal joints (also were loose), Guibo (cracked and dry), and front diff seal (leaking). R&R of the tranny mount also helped considerably, and I feel foolish for enduring that problem for so long.

Guidance on the driveline forum indicates only 1/4" (or something?) of lash should be felt using fingertips with rear of drive shaft disconnected at diff. Without disconnecting, I have probably 1/2" (!) in each direction.

Clunk presents on each take off and all on/off throttle conditions.

I have come to accept the issue as "character" and franky, unless something breaks during Autocross, feel disinclined to pursue the matter further.

So why am I posting, you may ask?


See my comments on "repair in a bottle".

Again, thanks for your interest.

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)

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post #9 of 37 (permalink) Old 10-31-2018, 12:35 PM
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The good news: It is highly unlikely that this "clunk" is coming from inside the differential. As Gubi wrote, "Normally a worn diff will whine. Clunks in a Spider I’d be looking at the driveshaft first: either center support and bearing (even if done at some point in the past) or maybe the splines". My advice would be look at the giubo or U-joints first, but sure, it could also be the center support or splines.

The bad news: Nothing in a bottle is going to fix this. Having said that, stuff in a bottle rarely fixes anything (exception: Bars Stop Leak, though I wouldn't put that in a diff).

Jay Mackro
San Juan Capistrano, CA

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'65 Guilia Sprint GT
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post #10 of 37 (permalink) Old 10-31-2018, 12:43 PM
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Quote:
Originally Posted by Stevew View Post
Guidance on the driveline forum indicates only 1/4" (or something?) of lash should be felt using fingertips with rear of drive shaft disconnected at diff. Without disconnecting, I have probably 1/2" (!) in each direction.
That doesn't sound too atypical. That isn't ring and pinion lash (which should basically be zero) that's just lash in the other gears. On both my '91 and my '63 you can get a surprising amount of hand turning in the driveshaft before you feel the diff gears engage (with a clunk, I might add) and neither diff clunks or whines when driving.

I'd check your driveshaft splines for play and also inject some grease into the splines, see if that makes any difference.

Another possibility: shot motor mounts or transmission mounts? If those are worn things'll bounce around a lot and you'll get thumps.

(When I got my Spider it would thump on hard takeoff. New driveshaft support improved things, but it still thumped. Years later I replaced the support again and now it doesn't thump at all. So just replacing something doesn't mean it fixed the problem sometimes!)

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #11 of 37 (permalink) Old 10-31-2018, 03:22 PM
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Just a note of warning from a lifetime paranoid: Clunks are not normal in any part of a car. It means somewhere metal is hitting metal, not gently. That always means some erosion. You have 50K miles on this clunk - you might be lucky something hasn't broken or exploded. It would not hurt to drain the Diff and Tx (and refill with Redline 90/75 NS, while checking the drained oil for metal particles.

There are a few other places in the drive train that can clunk that haven't been mentioned yet. One is wear on the "olive" on the output of the TX. The diff front end has a bushing that fits over this; it's common to find some wear if this hasn't had some lube.

You also have splines in two places. One is at the flywheel, where the TX input shaft couples to the clutch. The other is in the drive shaft where the two parts slide to accommodate the changing spacing as the suspension moves. My Duetto had a Zerk fitting at this joint to easily add lube.

Also, the center driveshaft bearing can be fine but the rubber suspension around it can be worn out, or just flopping from age. (NO from the smog in LA dissolves most of the rubber parts of out cars).

it's also easy for the clutch assy to be making a clunk that seems to be coming from farther rearward.

It's always a detective problem with out Italian cars.


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post #12 of 37 (permalink) Old 10-31-2018, 04:55 PM Thread Starter
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Re-check in order.

Tom and Robert,

I believe you are both correct that I should presume nothing and evaluate all the areas you have mentioned...from scratch.

Will make an opportunity to back up on the ramps, disconnect the drive shaft at the diff and check everything.

Record keeping became sketchy after writer's cramp set in and things I thought I had just done, turned out (often based on a tattered receipt, which I generally throw in the Alfa folder) to have been done much further back than I thought.

I'll report back soon.

Muchas gracias.

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #13 of 37 (permalink) Old 10-31-2018, 05:09 PM
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Clunking inside Diff

Clunking comes from excessive play in the LSD unit. The ramps the spider gears rotate on move inward towards the lsd`s center to either lock or partially lock the clutch plates with the floater plates to move the axles.

Clearance should be no more than .010 on a 2 disk (stock) lsd. It`s just wear causing the play. The floater plates come in lots of thicknesses to shim up the clearances correctly.
No lube will solve the problem, but when it is rebuilt the correct gearlube for the LSD IS Redline 75-90 NS.
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post #14 of 37 (permalink) Old 10-31-2018, 05:32 PM Thread Starter
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Frankly, I'm inclined to agree.

Quote:
Originally Posted by Alfar7 View Post
Clunking comes from excessive play in the LSD unit. The ramps the spider gears rotate on move inward towards the lsd`s center to either lock or partially lock the clutch plates with the floater plates to move the axles.

Clearance should be no more than .010 on a 2 disk (stock) lsd. It`s just wear causing the play. The floater plates come in lots of thicknesses to shim up the clearances correctly.
No lube will solve the problem, but when it is rebuilt the correct gearlube for the LSD IS Redline 75-90 NS.

But as advised, I'll be checking the basics again as well.

In the Wheeler Dealer episode, the mechanic added an extra plate to the new ones he installed and all was well.

Just don't wanna have to go there

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #15 of 37 (permalink) Old 10-31-2018, 06:23 PM
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Quote:
In the Wheeler Dealer episode, the mechanic added an extra plate to the new ones he installed and all was well.
He read about that somewhere. Russ Neely described it in Alfa Owner many moons ago. Richard understands this stuff better than me and he rebuilt both of my LSD's without the extra plates. I trust him a lot more than Ant on Alfa Romeo's.

Ed Prytherch
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85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

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