Rumbly, Vibratey Gearbox
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Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Re: Rumbly, Vibratey Gearbox
Just a thought it might not be the gearbox. Could it be excessive end float on the crank? Lightly pressing on the clutch would have the effect of pre-loading the crank eliminating the end float. I haven't checked the end float yet but it's a fresh engine with about 10k miles on it so should be ok. What do engines with excessive end float sound like?
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Piledriver
- Moderator
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- Joined: Sat Feb 16, 2002 12:01 am
Re: Rumbly, Vibratey Gearbox
They make expensive sounding noises 
Pull the distributor drive, if you see play pushing the front pulley fwd/back, it's expensive noises.
Not entirely unusual on a T1 esp if you have a HD pressure plate.
Try loosening the clucth adjustment a few turns just to make sure the TO bearing isn't still lightly loaded?
Pull the distributor drive, if you see play pushing the front pulley fwd/back, it's expensive noises.
Not entirely unusual on a T1 esp if you have a HD pressure plate.
Try loosening the clucth adjustment a few turns just to make sure the TO bearing isn't still lightly loaded?
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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Piledriver
- Moderator
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Re: Rumbly, Vibratey Gearbox
Might not really be the transmission at all.
Hmmm.. I'm beginning to get similar sounding rumbly noises at idle.
Kinda rhythmically comes and goes...
99 and 44/100th% sure it's the input shaft bearing in my T4 flywheel.
Fits your symptoms as well, if I read the description right.
On T1s it's part of the gland nut, but can easily be replaced w/o breaking the nut loose for around $6.
Side with the lettering goes OUT towards the trans.
(the inner lip is paper thin)
Might be a good time to replace the seal with a genuine VW one and check your endplay, pull the dist drive if you pull the flywheel as a precaution lest you dork up the brass drive gear.
EDIT: Mine ended up being a loose alternator tension arm, 10mm bolt in a nyloc nut, not tightened up and allowing some vibration
(the one on the pivot, not the other end that holds tension, on a T4 w/GM alt)
Still:Your symptoms still fit a failing input shaft bushing.
Hmmm.. I'm beginning to get similar sounding rumbly noises at idle.
Kinda rhythmically comes and goes...
99 and 44/100th% sure it's the input shaft bearing in my T4 flywheel.
Fits your symptoms as well, if I read the description right.
On T1s it's part of the gland nut, but can easily be replaced w/o breaking the nut loose for around $6.
Side with the lettering goes OUT towards the trans.
(the inner lip is paper thin)
Might be a good time to replace the seal with a genuine VW one and check your endplay, pull the dist drive if you pull the flywheel as a precaution lest you dork up the brass drive gear.
EDIT: Mine ended up being a loose alternator tension arm, 10mm bolt in a nyloc nut, not tightened up and allowing some vibration
(the one on the pivot, not the other end that holds tension, on a T4 w/GM alt)
Still:Your symptoms still fit a failing input shaft bushing.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Re: Rumbly, Vibratey Gearbox
Still can't get my head around how just taking up the clearance between the thrust bearing and the clutch cover can eliminate the noise. Conversely I can't imagine how having a small amount of clearance between them can create so much noise. I still suspect end float on the crank as just taking up the clearance could apply significant axial load on the crank. When I consider the mechanical advantage of the clutch mechanism just 0.5kg load on the pedal could be 5kg on the thrust bearing and plenty to pre-load the crank and take up any end float. I guess I need to measure it and get my faithful assistant to press the clutch pedal while I look at stuff.
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Ol'fogasaurus
- Posts: 17759
- Joined: Mon Nov 13, 2006 10:17 pm
Re: Rumbly, Vibratey Gearbox
http://www.garrettwade.com/x-hd-screwdr ... /05R01.03/ This is what a lot of the old time mechanics used to hunt noises; aka a hundred-year screwdriver. Put the screwdriver down in the area then put your ear to the handle. Only this type of the metal chassis screwdriver with the chassis going the full length with the wood grips on the side will work well.
They also used a short length of rubber hose like a fuel line to "hear the engine". The way it works is similar to above.
I also have a mechanics' stethoscope that works OK. You just have to be careful putting the long probe down and not banging it against things on the way (and out of moving stuff) as your ears will take a beating.
Sometimes the sound your are looking for is obvious but other times it is hard to tell the bad noise from the good noises.
Lee
They also used a short length of rubber hose like a fuel line to "hear the engine". The way it works is similar to above.
I also have a mechanics' stethoscope that works OK. You just have to be careful putting the long probe down and not banging it against things on the way (and out of moving stuff) as your ears will take a beating.
Sometimes the sound your are looking for is obvious but other times it is hard to tell the bad noise from the good noises.
Lee