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Spent a week shutting down my South Florida Condo for my yearly spring drive to back up to Connecticut for the summer. Hitting the road I suddenly noticed a clonking sound coming from the rear end. I was not too far from Auto Veloce in Miami so I pulled it to see whats up.

On the lift we rotated the rear wheels and heard a distinct clunk, clunk coming from the inside of the diff. It clunks approximately once with each tire rotation. For sure, the noise is inside the diff. It only makes the clunk sound at very low speed. Driving speed its find and smooth. I was tempted to just risk it - but FL to CT is lot of miles in Alfa-less lands.

Lucciano (at Auto Veloce) recommends changing the diff. So, I am looking for a replacement:

Its a 73 formally 1300 (now 1600). I think the ratio is 41:8 but I'm told a 41:9 will also work.

Anyone out there have anything to help me out?

Thanks!
Fred
 

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Fred, check the owners manual . I think it is 43/9 if it matters (I have the same ' 72 model Giulia Super 1.3), The 1.6 version was 41/9. It's a small matter but you might see a drop in torque.(???//). I think. Either way .. finding the exact ratios might be a test because these cars were not imported to the US (1.3).. It might be worth a tear down to find the problem without releasing the shim package on the pinion and ring gear .. perhaps one axle tube. Where in FL are you stuck? PS I assume you have a 1300.. disregard if not and anything goes. The 4.56 (41/9) is ubiquitous.
 

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Any diff at all will fit, if you're swapping the whole axle. Any 105/115 Ate will work. If you're replacing just the gears etc inside that's a different matter.
Andrew
 

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Thanks for the reply guys,
I could not find anything in the owners manual. I'd rather not loose any low end and my 1600 upgrade from the 1300 is lots of fun blasting around. I'd prefer a tear down rather then buying an entire rear-end. APE has a 456 posi-traction complete rear with brakes and all but its pricey, used and needs truck shipping .

I'm in Key Largo - back at my Condo. The car drives like a dream at high speed; no noise or vibration. But, the thought of an exploding diff or lockup haunts me.

1973 is about as late as the supers get. So sounds like 9/43? How would a 9/41 be on the low end?
 

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You'll be fine with the common 41/9, (4.56) found on US cars I think all the way to Bosch injection. Especially with the 1.6 engine.
Jethro Bonner of YT fame did just that on his TI.
It'll be 3k=60mph. 4k=80mph
 

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Fred, a garden veriety non LSD 4.56 will work just fine with your 1600 motor. This ratio was standard in most 105 Alfas commonly sold here in the 'States. Similarly, so will later 2 liter 4.56 with LSD. There may be some sizing differences with driveshaft bolts but your shop should be able to take care of that pretty easily. Our generation 1300 Supers (my '72 anyway) had 4.77 rear end ratios which are not at all common here. The big difference is that you'll be turning a few hundred fewer rpm at highway speeds.
 

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Discussion Starter #8
Again, thanks for the great replies. Gear ratios have my head spinning. I just got off the phone with a good buddy down here in Florida - he's got a 456 rear from a Berlina - and he's close to the shop in Miami so things may be working out. 4k at 80mph is a bit lower then what I'm seeing now. Will be good on long trips.
 

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Discussion Starter #9
1681714
 

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Fred simple answer is ..The Gearbox and RE ratios were calculated for a difference to each other..1.3/ trans/RE vs 1.6 trans/RE combos...slightly different ratios up front to the RE's...If you are going to put a 4.56 in the rear end and not change the trans you half half of the total equation... I don't believe you will notice much difference with the exception of a nano-difference at 75 MPH vs. RPM experienced before.. It's probably more pronounced with different tire sizes so it isn't a big deal. Just my take on it. The clunk is more really the question mark IMHO.
 

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Thanks.
I've been running the 1.3 rear end and trans with the 1.6 engine for years now and almost 90k miles since the restoration. On the highway at 70-80 it revs pretty high but I've been enjoying the low end. Its probably for the best that I go with the 4.56 and someday when the trans needs a rebuild I can change things in the gearbox.

Yes, the clunk.... I'm eager to find out what that is.
 
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With a stock 1600 I would not want more gearing than 4.56. I have 4.10 in my Super but it has a strong 1750.
It is from APE, Larry Jr knows what he is about, but yes, cost and shipping add up.
Andrew
 

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Discussion Starter #14
Larry was very helpful, even though my lack of understanding ratios would frustrate him.
Hopefully the local 4.56 will work out and I can hit the road again back up to Connecticut.

On an unrelated note, its getting difficult to drive these old Supers with the overt reactions from other drivers. Sudden horn honks and people pulling up along side to give "thumbs up" are somewhat startling at times.
 

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Thanks for the reply guys,
I could not find anything in the owners manual. I'd rather not loose any low end and my 1600 upgrade from the 1300 is lots of fun blasting around. I'd prefer a tear down rather then buying an entire rear-end. APE has a 456 posi-traction complete rear with brakes and all but its pricey, used and needs truck shipping .

I'm in Key Largo - back at my Condo. The car drives like a dream at high speed; no noise or vibration. But, the thought of an exploding diff or lockup haunts me.

1973 is about as late as the supers get. So sounds like 9/43? How would a 9/41 be on the low end?
Larry was very helpful, even though my lack of understanding ratios would frustrate him.
Hopefully the local 4.56 will work out and I can hit the road again back up to Connecticut.

On an unrelated note, its getting difficult to drive these old Supers with the overt reactions from other drivers. Sudden horn honks and people pulling up along side to give "thumbs up" are somewhat startling at times.
I snapped the differential carrier in my TI back in the 70's drag racing a Saab 99, but was still able to drive it from Gainesville Fl to Miami, 360 miles. The pieces kind of lock up and one can continue. I remember a replacement from Milano cost 150. Called ricambi directly in Milano and they shipped it to the dealer. They were quite upset that they didn't get their cut!
Yeah Fred, I've had the TI since 73 and while it used to be one could go about incognito, just an old car, now its people taking pictures while driving , and one guy stopped in front , got out of the car and came over to give a 5humbs up at an i tersection, THAT was a bit scary.
 

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Good luck.. been checking the same sources your guy is ( RML daytona ) for fixes and parts.so we are shaking the trees. I don't know the achilles heal of diffs but if it a broken tooth of any kind wouldn't it be found when you remove the bottom cover of the diff? Seems simpler than going after axle tubes for inspection. Spider gears rise to my prime suspects. May I ask what type of Guibo you have in the drive line? I've always contended that non-compliant guibos and fatter tires could put stresses in places not intended. .. but that is just an uninformed speculative opinion. It reminds me of a time when a Peterbuilt twin axel with a heavy load snapped a drive shaft while I watched him start up a residential hill when he popped the clutch. Driver just shrugged his shoulders and was on his way a couple hours later. Seems the drive shafts are made of aluminum and are cheaper to replace than a differential.
 

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You'll be fine with the common 41/9, (4.56) found on US cars I think all the way to Bosch injection. Especially with the 1.6 engine.
Jethro Bonner of YT fame did just that on his TI.
It'll be 3k=60mph. 4k=80mph
I just watched that Jethro Bronner video with interest since I have the 1300 trans and rear too. Like Jethro, I have a 1750 now. What interested me in the video was I was expecting more of an RMP change, but as others have said - the 1300 trans gearing, plus the rear end from a 1600 or 2000 makes for a mid-step.

Fred, I'll be following your story. Good luck!

Edit - by the way, one of those people giving you thumbs up and paparazzi stalking you was a friend of mine. Apparently his in-laws live somewhere near you in Key Largo? He kept texting me pictures of this Giulia he kept seeing near him, it looked familiar :)
 

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Discussion Starter #19
I snapped the differential carrier in my TI back in the 70's drag racing a Saab 99, but was still able to drive it from Gainesville Fl to Miami, 360 miles....
I was VERY tempted to just deal with the clunking sound and hit the road but I'm not on any schedule and its still cold (for me) up in Connecticut, so I'll have to endure it bit longer down here in Key Largo :p


a broken tooth of any kind wouldn't it be found when you remove the bottom cover of the diff? Seems simpler than going after axle tubes for inspection. Spider gears rise to my prime suspects.

May I ask what type of Guibo you have in the drive line?
I think its more substantial then a tooth. When it clunks, I can feel it in the drivers seat. Lucciano at the shop also suspects the spider gear.
Not sure what Guibo is in the car but I always look for the best parts from our friends in the UK and Germany.

Fred, I'll be following your story. Good luck!

Edit - by the way, one of those people giving you thumbs up and paparazzi stalking you was a friend of mine. Apparently his in-laws live somewhere near you in Key Largo? He kept texting me pictures of this Giulia he kept seeing near him, it looked familiar :)
Thanks
Your friend introduced himself to me several weeks back. I was quite surprised that someone in this tiny community in the same condo complex knew of my car. He told me he had a friend on the BB and mentioned he was from Pennsylvania.
 
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Apologies for the cyber-stalking! As soon as Neil sent me pictures of your super, I sent him a link to your thread on the BB. Small world. I had no idea how fantastic the car scene was in in Key Largo.... aside from all of the electric Mokes ;)

Link to The Jethro Bronner video - its informative.

 
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