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Discussion Starter #1

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I'm not the expert here, but what I can tell you is the difference between our LSD and the video is that we only have 1 clutch disk per side and do not have the spring in the middle. Everything else looks the same.

Looking forward to the thread.

Good luck,

Vin
 

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Discussion Starter #3
Thanks, Vin!

I'm looking forward to a positive outcome on this project. LSD clunk has been a major bug stain on the windshield of my life for far too long...
 

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But Mad North-Northwest
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You sure it's the LSD? Every single time someone has had "differential clunk" on here, I think it's turned out to have been something else.

Well, except for one time where it was some broken pinion/ring teeth. But besides that...
 

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Discussion Starter #5
Hi Gubi and thanks for your observation.

I agree Differential Clunk (hereafter referred to as DC) is often misdiagnosed and found to be the result of other driveline failures.

As I mentioned earlier, considerable research here, as well as repair/inspection of common trouble areas (too numerous to recount) has led me to conclude LSD issues. Perhaps the most telling test was removal of the drain plug (BTW, I have Redline in the diff) and locking the internals with a screwdriver, while turning the input shaft (behind the universal joint) has convinced me the problem resides within.

With winter finally creeping up on Northern Nevada today, the car will be out of service till conditions improve, so now is the time to attack my long-standing DC headache.

Film at 11. :)
 

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But Mad North-Northwest
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I don’t think that test necessarily tells you anything. There’s a surprising amount of play in the cage and spider gears. But your call.
 

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But Mad North-Northwest
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...and you didn’t state your problem, but if it’s “clunk or thump on hard takeoff” then you’re very likely chasing the wrong thing.
 

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Discussion Starter #8
Starting to wish I took Gubi’s advice.

After two months of thinking about the challenges ahead I finally began removing my LSD and unfortunately, found some advice here that somewhat oversimplified the situation. A lot more needs to be removed than I anticipated...

Pulling nuts off the left side of the diff and should have the LSD on my workbench soon.

Here’s a glamour shot of progress:

58BF2F77-1D42-4929-A119-35C40E83B1D5.jpeg
 

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But Mad North-Northwest
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Starting to wish I took Gubi’s advice.
I often wish I took my advice. Typical weekend:

STATUS: IT IS WORKING
"Yeah, but I think I can make it better."
<several hours pass>
STATUS: IT IS F-ED UP
 

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71 Berlina 74 GTV 17 Giulia Q4
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Each lsd side has one internal blade and 3 external blades and unless something is really messed up won't "clunk". What can happen is the lash and preload on the bearings and pinion will be out of spec and it will "whine" under load. Even then it's not a common problem on a unmolested diff. The outer pinion bearing is the only bearing (only the bearing not the race) that can be replaced without going into the inner bearing, pinion gear, ring or crown gear, and left and right inner side bearings. You might have a trunion bushing that has gone south or trailing arm bushings that might cause a thunk aside from the driveshaft components.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Here is some of my foray into the rear end...
 

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But Mad North-Northwest
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Yeah, but my money is still on engine/transmission mounts or center driveshaft support.
 

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Discussion Starter #13
Thanks for the input guys.

And Gubi, engine mounts are aluminum units and center carrier was clunking when I got the car. R&R’ed and is solid.

OK, Now I’m confused about the clunk.

Scroll down about 1/3 this page to Diff Clunk. The 411 provided is what has convinced me to go in:


Also, my trailing arms, with only the fronts attached, can be moved through 18”. I know I have a lot of leverage but that seems a bit much. R&R’ed in ‘08.

”You might have...trailing arm bushings that cause a thunk aside from the driveshaft components.”

Hmmmm.

Finally, I stopped keeping a log years ago, but have discovered many of my efforts resulted in visits here and are preserved in the Archives. Sweet!
 

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Discussion Starter #14
FF1A9467-FA34-4E70-905A-3C469B5B95D0.png
 

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Discussion Starter #15
Soldiering on with my LSD project and because of considerable slop in both trailing arm front bushings, I pulled the left and knocked out the offending bits. Center bushing tube was loose. Thought I R&R’ed when I did the rear TA bushing, but unlikely these fronts failed in 30k and no witness marks of earlier mayhem. Two on order.

Also, since no metal on metal, would this “clunk”?

32EC8363-72B1-4570-A494-F2FC942F7926.jpeg
B3368459-89E8-4D11-B4EF-2CCA3F33BDC9.jpeg


I used the drill method to remove rubber around the center tube, then a hacksaw to cut a section of the outer. Had to go all Yosemite Sam on it for final removal.

Wondering if this has been my problem, but in for a penny...
 

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If it were me, (and ive rebuilt a few diffs) the very first thing I would do is all the rear trailing arm bushes (like you are) and the sway bar bushes, and check the conical rubber bush that mounts the diff. Give the T bar a solid yank and see if its loose-- probably not.

If the pinion nut is loose, you can get some slop in the lash. Check the pinion nut on the diff, 75 ft/lbs roughly. If you have the pinion nut tight, and you still have more than a tiny amount of lash in the diff when you lock the crown gear, then its time to pull the covers off and check things out.
 

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Discussion Starter #17
Thanks Goats (if that is your real name :)).

This thread is getting long so I’ll forgive you for not reading everything before you replied.;)

New conical bushes are on the workbench, rear TA bushes appear sound, and as noted front bushes are in process. New units arrived today.

T bar supports appear to be in good shape as well as anti-sway bushings.

A screwdriver through the filler hole locking the crown gear reveals no play at the diff input but when removed, considerable slop.

Im’a goin’ in!
 

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So pinion to crown wheel has minimal lash. This is good. If you pull the big cover off you can pull the LSD unit right out. I’d advise to not change any diff bearings unless absolutely needed. If you watch those yahoos wheeler dealer episode on spider you will see that guy added extra clutch plates to the lsd. My advice- don’t do it
 

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Discussion Starter #19
Thanks for the advice. If you review earlier posts, there is a link to advice about simply reconditioning existing clutch surfaces...my plan.
 

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Discussion Starter #20
One of the benefits of being retired is having the luxury of being able to walk (or in this case, crawl) away from my repair efforts and chill for a bit. Did just that a bit ago as the LSD removal chore progresses. Oh, for a lift!

Here are some photos of today’s festivities, as the left drive tube came off, revealing a sight no Alfisti should ever need to see.
B4506EFC-9D9E-407B-8AC4-391C88638353.jpeg
FB38D78D-A403-41E2-B955-9905D2A48D7A.jpeg
DEB24F92-9258-4D10-A3FA-156AC39DAB81.jpeg
 
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