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Discussion Starter #1
Hello
have 71 gtv that is giving me the crappers!!!
I thought is was a diff rumble that appears when running in neutal at any speed--nearly down to walking pace, and diminishes or maybe even disappears with throttle /acceleration, but not diff..
I have changed axels, changed diff, changed wheels and tyres, checked for rubbing but the noise persists. The tail shaft has both new yokes uni joints .
Gearbox was rebuilt by prevoius owner, looks like new centre bearings and rubber diablo...- but wondering what does a bad output bearing sound like ???. does it sound all the time or only in neutral while rolling under light load???

Note i put a alfaholic suspension kit in so car lower-- in desperation i put old springs back in rear with no change.
regards
 

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Does the rumble go away when you hold the clutch in?
 

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But Mad North-Northwest
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If the inner & outer transmission rubber boots are torn, even a perfectly good Alfa transmission will make a LOT of scary noises in the cabin.
 

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Seconding what Gubi says. In fact the GTV he is now driving suffered from exactly that before I sold it to him. I was prepped for a gearbox rebuild due to what I assumed was a terrible bearing hum coming from the gearbox. But then I decided to check the boot (single boot on a 74 GTV) and found it close to disintegration. Replaced it and drove it happily for months after that with nary a noise of any sort.

So give it a check and maybe you'll get lucky like I did.
 

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Discussion Starter #5
Thanks so far, noise still there clutch in or out, very noticable when coasting with no load -neutral or in gear-will check boot and have a really good look today at tailshaft--gearbox mounts-centre bearing mounts .
Will also have good shake of output area of gearbox.
I know what it should sound like as i have a 1600 that has no noise ( i swapped the diff and all rear axels, wheels out of this to rule out that part (s).
 

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Discussion Starter #6
I am pretty sure the noise is still there with engine off- rolling- will check ...
 

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Discussion Starter #7
ok boots fine. went for drive with mechanic today and he said..
sounds like wheel bearing - i said had three axel sets in it and three diffs so that rules that out.
Agreed noise in rear-- maybe centre..( or sounds like it)
Mechanic suggested check all rubbers in case metal to metal contact somewhere..i am sure they are all new!!- but will recheck.
I will Swap out full drive shaft , just in case bad uni , bearing etc ( even though all new).
maybe noise is at at front and resonating to bake ????
So noise is low rumble, makes you think some kind of rubbing - causes a very slight vibration through feet, may be maybe??- ever so slight.
Noise there In neutral coasting and underlight load, appears to dissappear fast but maybe other normal noise muffle it out. Noise there Ignition on and off when coasting
Put car on axel stands rear and ran car-- cant hear it then!!!
oh well= pulling hair out. Funny my old clunker 1600 gt has no noise and this one that has had a fortune spent on rubbers, suspension, gearbox etc has the problem, bet its a small thing in the end!!! ha ah
cheers
 

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Could be bad bearings in the transmission. Especially if it was ever run low on oil.
 

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Discussion Starter #9
Thanks for ideas,.
This noise was not there i am pretty sure when i purchased the car and i have only done 100km in it... but have had two new uni put in tailshaft, new alfaholics roard suspension kit.
New transmission just before i purchased, never run low oil since rebuild. most say transmision bearing would get louder under load. Noise worse in neutral - so out put bearing spinning but not many others ?. Not an expert though by any means.
 

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Discussion Starter #10
i will take out tailshaft tomorrow and start car with no prop shaft-- in gears to check gearbox for noises
 

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When the trans is in neutral four out of the 6 bearings will be spinning. With the clutch pushed in. Nothing in the trans is turning. This is with the car sitting still. With car moving in neutral prop shaft will be turning the gearbox.

A good way to check is with the car parked. Start it. Leave it in neutral. With the clutch out. Put your ear on the shifter knob so you can hear the noise inside the trans better. move the clutch in and out to see if noise gets better or worse.
 

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Discussion Starter #12
thanks Jim, i will check that. i know there is a small input bearing noise that has been there since purchase but not like this noise. (my 1600 gt has the same input bearing noise), whiring noise slight in neutral= goes when clutch pressed in- does not get louder when running car in gear - actually dissappears.
will listen through gearstick for other noises as suggested.
 

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Discussion Starter #13
Jim would running car with tailshaft removed = listening should rule out gearbox also? (hopefully). And mecahnic is saying rear or middle...
Next step get it running up on a hoist i suppose..
 

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Should work
 

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I had a gearbox rebuilt with new bearings coz I had a road speed dependent noise (versus engine speed) which I assumed was the gearbox output shaft bearing.
It wasn’t.....One new centre bearing later....all is good.
i can point you to a local gearbox man who said “next time, bring it in: I’ll tell you if it’s a gearbox noise or not”.
He said you get a LOT of noise transfer with the tail shaft, leading you to mistakenly think ‘gearbox’.
If you already have the driveshaft out...spin the bearing. Any roughness/grumble at all is a pointer. Worth replacing in that instance anyway. You’ll need a good press. Steve C can do that.
Gimme a call If you wish to pursue gearbox man.
Paul.
 

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Discussion Starter #17
Thanks, t bar not moved-no shims changed etc, just usual bit of up down flex to get diff out. Bushes look new and so do shims. I suppose if one of those shims broke on the side you would get a noise.
Paul will give you a ring.
 

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Discussion Starter #18
Took the diff and transmission rebuilt guy for a drive ( thanks Paul-it was Phil in Moonah), Phil decided after three diffs in car it leaves nothing but output end of box, after hearing noise ruled out tailshaft.
Bummer but a job i was half expecting. I will remove tailshaft first and give it a good look over though!!!
Have a pile of receipts for gearbox rebuilt from PO but that was 5 years ago( car only done 500km since).

Keep you informed on outcome- doing my head in this one ...
 

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Discussion Starter #19
before i pull the gearbox out is there anything i have missed..
just to overview of the situation again..

THE NOISE IS ....a low grumble / grating type noise that maybe very so slight vibration through your feet ( very so so slightly if at all). It seems to be coming from misddle to rear of the car ( not the front). It is there in neautral coasting , with engine on or off. It is very obvious even when the car is at fast walking pace. When you are running down a hill in neautral quite fast it is quite loud, i.e it seems to have a rythym that gets faster and slower in sync with the speed of the car as it travels. BUT when you put your foot on the accelerator even slightly,, the noise decreases ( less audible ) significantlty or even may dissapear. ( i can not tell which)

  • i purchased the car about 1 year ago..i have a pile of receipts( parts list) for a rebuilt gearbox to value of $2000 and done 500km since
  • i am almost certain this noise was not there when i purchased the car.
  • it did have a whine in the diff
  • i focussed on the diff noise as a project and purchased a new / rebuilt diff , now installed and whine is now gone.
  • while diff was out and new one being rebuilt I 1. put alfaholics spring kit in front and back, 2. had new universal joints installed in tailshaft . new rear wheel bearings.
  • ON first test drive after this i noted the low grumbling noise that i am convinced was not there before and still persisits and is driving me crazy.
Note I can can not replicate the noise on jack stands or with back diff jacked up
  1. i now know it cant be the diff because since that first diff replacement i have put three different diffs in it and the noise has persisted through all.
  2. i have also put the original rear springs back in to test and the noise persists.
  3. back A frame bushes fine,
  4. had 3 mecahnics with 3 opinions. Front wheeel bearings, diff, and harmonic noise from metal to metal contact. All these are ruled out.
  5. The mechanic i had on a test drive was a experience gear box / diff man mechanic.. he said "it sounds like diff... but as i know it isnt you woulkd have to suspect the gearbox."
TODAY i removed the tailshaft completely and inspected centre bearing ( it looks new and felt fine).
ALSO i rigged up a device with a drill and managed to get the front section tailshaft rotating very quickly whilst i laid under the car to listen - much to my dismay i could not hear the noise ( i expected i would as this replicates the car coasting down the road in neautral)..
Also i ran the car quite fast with with only the front section tailshaft and while underneath i could not here anything unusual..

So even though i have tested the out put end of the gearbox in the above mannner...could it still be the gearbox...??
I beginning to think removing and sending gearbox off is only option left...

I am dreading removing the box and the potential time and expense this might cause, only to discover that the noise still; persists..

Before i do this can anyopne think of anything i might of missed?
regards
 
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