Clitiky-clank noise from transaxle - Alfa Romeo Bulletin Board & Forums

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post #1 of 50 (permalink) Old 07-14-2015, 12:20 PM Thread Starter
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Wink Clitiky-clank noise from transaxle

Hello forum; my 1982 GTV6 2.5L has been completely restored in the engine and suspension areas, with high-grade original or aftermarket parts.
The only item left is the transaxle. It hasn't been touched since 2006 when I got the car with 39k miles on it. I just reworked and fitted a balanced driveshaft with new Guibos and bearings, but to my amazement I get every time I drive, especially when idling a "clateky-clack" noise from the transaxle as if something is loose and bangs around.

I have done the mounts on the transaxle, new springs, CV joints, wheels bearings, brake calipers, new torsion bar, mounts, etc. There is nothing back there that is loose or banging mechanically (even checked the rubber buffer over the clutch case that stops the trasnaxle from hitting the bodywork). the noise is internal of the transaxle. It sounds like metal pipes
banging together.

It only happens when idling and never under power, no matter the speed. I read once a post by another GTV^ owner complaining of the exact same thing, and an Alfista answered his query with: "it could be th gears banging each other or a clutch issue".

I have to say, when I owned another 1982 GTV6 back in 1984, it did the same thing.

Does anyone know what this noise is, and if known any measures or trick to minimize it, eliminate it or re-design anything so it would not do it?

Thanks for any feedback!

Trooper

Last edited by Trooper; 07-14-2015 at 12:38 PM.
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post #2 of 50 (permalink) Old 07-14-2015, 12:54 PM
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My car, '85 GTV6 (which also just went though a lot of mechanical work including new driveshaft, synchros, etc) does the same exact thing. The word on the street is that they all do that and there's nothing really wrong. Though my mechanic tried to trace down the issue to no avail.

At idle, if you push in the clutch, it sorta goes away. And it never occurs under power, even if it's very light acceleration. But yeah I'd like an answer (if there is one) as well.
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post #3 of 50 (permalink) Old 07-14-2015, 01:58 PM
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Do a web search for "neutral rollover noise". This is the most likely cause if it only happens at idle in neutral, gets worse when the transmission is warm, and completely goes away if you push in the clutch. It's very common and not harmful, just annoying.

Basically there's a little slop designed into the gears, and any unevenness in the idle causes them to rattle together. If you've got a rough or uneven idle that can make the noise worse. My Milano has S-cams so it idles a little lumpier than usual, and I get a decent amount of rollover rattle from the transmission at hot idle.

Tom

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post #4 of 50 (permalink) Old 07-14-2015, 02:42 PM Thread Starter
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Gepetto and Gubi: Thank you for proving I am not going nuts!

Now I never had a brand spanking new GTV6 so I would be curious to know if they did make this noise from new or only when it gets worn out.

If when new it did not make any noise, then it might be fixed bu checking clearances and the like. If not, then I need to fix my idle, becuase yes, my idle is rough due to the AAD leaking. I am planning using a thermostat mounted on the right bank valve cover and control a vacuum actuated dash pot valve. Hopefully that will fix the idle.

Thanks,

Trooper
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post #5 of 50 (permalink) Old 07-15-2015, 02:11 PM
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I don't agree with Gubi in that the noise is in the clutch, not the gears. Although he is right in that it happens to many different models (BMW etc) and even some front-drive vehicles. On our cars it is most likely due to engine harmonics because of imperfect tune, or loose clutch damper springs (old/worn), or perhaps the driveshaft connections fore and aft. In front there is the pinch bolt and in the rear a centering bush - also alignment is important on the driveshafts with giubos. Try raising your idle from 900 to 1100-1200rpm and see what happens.
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post #6 of 50 (permalink) Old 07-15-2015, 02:15 PM
But Mad North-Northwest
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I thought it might be in the clutch as well. Until I had the clutch replaced with a new complete assembly and the noise was exactly the same.

If it's in the pinch bolt or the clutch input you will still hear it in neutral with the clutch pushed in. If it goes away with the clutch pushed in then it ain't either of those parts.

Tom

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1963 Giulia Spider (1750 engine)
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post #7 of 50 (permalink) Old 07-15-2015, 03:31 PM Thread Starter
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Cool

Well I took notice of some of the comments on this forum and adjusted my idle to 1100, tunned the spark plugs tighter and adjusted the AAD to completely shut-off and the idle smothed out, which along with the higher revs (it was 850RPM before), the cliteky-clank went away.

Thank you all for the suggestions!

Trooper
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post #8 of 50 (permalink) Old 07-15-2015, 03:42 PM Thread Starter
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Cool

Well I took notice of some of the comments on this forum and adjusted my idle to 1100, tunned the spark plugs tighter and adjusted the AAD to completely shut-off and the idle smothed out, which along with the higher revs (it was 850RPM before), the cliteky-clank went away.

Thank you all for the suggestions!

Trooper
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post #9 of 50 (permalink) Old 07-15-2015, 04:23 PM
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Yes, a smooth idle is always desirable. However, it's a matter of time until it returns, even at 1,100 rpm. To eliminate the noise, remove the 30mm prop shaft yoke nut ("Spider yoke"), clean and dress all threads, reinstall and torque to specs using Locktite.

Jim

Last edited by La Voce; 07-15-2015 at 04:32 PM.
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post #10 of 50 (permalink) Old 07-15-2015, 04:31 PM
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3 of 4 cars I have interacted with that exhibited this noise were low on transaxle gear oil. I topped up with new fluid and the noise almost completely vanished...

If you drive your car regularly over longer distances, you can use a mildly higher viscosity gear oil. 75w90 NS redline is excellent oil but it is pretty "thin" (this used flexibly as viscosity and behavior under stress doesn't correspond with absolute thin-ness or thickness).

My track car doesn't idle smoothly and uses redline oil and it's quite noisy back there at idle sometimes.
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post #11 of 50 (permalink) Old 07-15-2015, 04:41 PM
But Mad North-Northwest
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Guys, in this case it ain't the pinch bolt. You can make the pinch bolt rattle with the clutch pushed in because the shaft is always spinning. If it only does it with the clutch out then it's most likely rollover rattle.

Yeah, 850 is too low an idle. Spec on the 2.5 is 950 +/- 50. I should probably raise mine up a bit as the lumpiness from the S-cams does make the rattle worse (I don't think it did it with the original cams).

Unfortunately I already know my gearbox oil is full. Anyway, rollover rattle doesn't hurt anything, it's just annoying.

Tom

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1963 Giulia Spider (1750 engine)
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post #12 of 50 (permalink) Old 10-30-2015, 10:35 PM
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I am new to the forum so am probably repeating what many others have offered. I have spent the past few months tracking noises and vibration in the drive train of my 1977 Alfetta GTV. When purchased it had a loud thump under the floor when crossing small road imperfections, a strong vibration at idle that got worse at above 2000 rpm, wriggling under braking and a gearbox rattle at idle accompanied by a loud growl when throttling off. The only visible deviation from standard was the rear giubo which had a larger centre hole. The locating piece in the drive shaft had been built up to compensate. We started by having the shaft assembly balanced. No change was noted in any of the problems. New bearings were fitted to the clutch housing but this also changed nothing. Early rear giubos are currently unobtainable so a good used one was fitted. The offset appeared different as the centralising bush is carried on a separate steel spider. This seemed to limit the front to rear clearance on the shaft when fitted and removed the vibration. At this point, all other defects remained. A spare gearbox was fitted with new mounts and the chassis locating hole welded up and returned to round. This removed the overrun growl, the brake wiggle and the loud thump. Rebushing the suspension removed sundry other squeaks.

Michael Findlay
1971 Alfa Romeo 1750 GTV
1977 Alfetta 2000 GTV
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post #13 of 50 (permalink) Old 10-31-2015, 04:58 AM
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It's the clutch disk damper springs shuddering at low idle. it is not the gear set.
The gear set is "constant mesh" and any backlash sounds are muted by the gear oil, usually the only sound you hear from inside the transaxle are the dog teeth crunching when the synchros are wearing
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post #14 of 50 (permalink) Old 10-31-2015, 06:02 AM
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My center YOKE was loose this summer causing the noise you describe. Had to take the rear shaft off to fix it, but all better now. It's always forgotten and overlooked I did it myself. When I took it apart I could loosen the 2 nuts by hand. Got to make sure the 30mm nut in the center is tight. The Fetta has 2 nuts, not sure of the GTV-6.

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post #15 of 50 (permalink) Old 10-31-2015, 07:19 AM
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I had a similar problem with an Alfetta I used to own. Turned out to be the nut that holds the yoke that connects to the driveshaft had come loose. By the time I got to it the threading was toast and I had to weld it in place.
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