Rumbly, Vibratey Gearbox
- Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Rumbly, Vibratey Gearbox
The DC gearbox in the Bonito is getting noticably noisy and vibratey when in neutral when standing still. It all goes quiet when the clutch pedal is pushed down and all the gears work ok. Engine is a mild 1776 driven sympathetically. Does it sound terminal, is it just a bearing going bad or is it time for a chnage?
- trbugman
- Posts: 119
- Joined: Mon Apr 01, 2002 12:01 am
Re: Rumbly, Vibratey Gearbox
Sounds like it could also be the throughout bearing. Put it in neutral with the clutch out then slowly push on the clutch but not enough to disengage it. If the sound goes away then it is the throughout bearing, if it doesn't then it is probably in the trans axle.
2333(103x70) Type 4 DTM MS3+X on 73 Karmann Ghia ignition only with LS2 truck coils firing in sequential, fuel next.
- Marc
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Re: Rumbly, Vibratey Gearbox
If the cable's adjusted to afford pedal freeplay, the release bearing should be at rest until the pedal's depressed - a noise that shows up as the pedal's depressed would likely be from the release bearing, but not one which goes away when the pedal's down.
Most likely culprit here is the forward mainshaft bearing; it can be replaced without tearing the trans apart if you can borrow/rent the special puller designed for the job (it has fingers which go twixt the balls and grab the inner bearing race). If the trans truly works OK in all other respects, it could be worth the investment to replace that one bearing and change the fluid. If it's a pre-mid`72 trans the bearing is 113 311 123A; Chinese-made go for <$30, quality/longevity is sporadic but for a "patch job" it's all I'd want to spend. German/OEM will run you 2-3 times that if you can find one.
Most likely culprit here is the forward mainshaft bearing; it can be replaced without tearing the trans apart if you can borrow/rent the special puller designed for the job (it has fingers which go twixt the balls and grab the inner bearing race). If the trans truly works OK in all other respects, it could be worth the investment to replace that one bearing and change the fluid. If it's a pre-mid`72 trans the bearing is 113 311 123A; Chinese-made go for <$30, quality/longevity is sporadic but for a "patch job" it's all I'd want to spend. German/OEM will run you 2-3 times that if you can find one.
-
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Re: Rumbly, Vibratey Gearbox
In the past I've wanted to get that special puller Marc talked about, but not anymore.
I'll go out on a limb here and say that any gearbox with a bad mainshaft ball bearing, has plenty of other badly worn parts. I've never taken apart a gearbox and found only a bad MS bearing.
I'll go out on a limb here and say that any gearbox with a bad mainshaft ball bearing, has plenty of other badly worn parts. I've never taken apart a gearbox and found only a bad MS bearing.
- Marc
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Re: Rumbly, Vibratey Gearbox
It's a $40-50 gamble (including fresh fluid). I've had much success, never had one that failed to give many more miles of service after mainshaft bearing replacement (even using Chinese bearings). But you've got to do a little symptom elaboration...a pinion bearing will make more noise in 1st/2nd (but none when stationary) while the mainshaft bearing is typically louder in 3rd/4th; pinion & differential carrier bearings will make noise that can be heard when coasting down from ~45 MPH with the engine off (and the latter usually will change as you toss the car back & forth from lane to lane)...if you've got noises with the engine off and clutch pedal out - which means the mainshaft isn't revolving - a new mainshaft bearing won't fix those.
It's a moot point if there's no local VW shop willing to rent out the tool, and as costly as they are you can't blame them for being reluctant to do so...but it never hurts to ask.
It's a moot point if there's no local VW shop willing to rent out the tool, and as costly as they are you can't blame them for being reluctant to do so...but it never hurts to ask.
- sideshow
- Posts: 3428
- Joined: Mon Oct 27, 2003 11:00 am
Re: Rumbly, Vibratey Gearbox
Hmmm, I recently retired this box in favor of a fresh one rebuilt with a quaife. But more importantly it has the main bearing noise symptom and no other issues.
So assuming I have time but no proper tool, no hurry, can I just tack weld a puller to that bearing? Seems like a fun thing to try.
Yeah some may call it overkill, but you can't have too much overkill.
- Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Re: Rumbly, Vibratey Gearbox
The only sympton I've noted is that there's no noise or vibration with the clutch pedal depressed but there is with the pedal released. I'll try it under the other conditions today.
- Marc
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Re: Rumbly, Vibratey Gearbox
Yes (other than the fire hazard), but there's another bearing at the other end of the mainshaft that can cause a similar noise - and that one's not so easily accessible. If the noise is notably worse in 4th gear, odds are that the front bearing is the bad one, but it seems strange that the builder didn't catch that - it only takes a moment to do a visual inspection before installation.sideshow wrote: Hmmm, I recently retired this box in favor of a fresh one rebuilt with a quaife. But more importantly it has the main bearing noise symptom and no other issues.
So assuming I have time but no proper tool, no hurry, can I just tack weld a puller to that bearing? Seems like a fun thing to try.
- sideshow
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Re: Rumbly, Vibratey Gearbox
The red box is a random swap meet sourced I assume is entirely stock and I added the thrust plate and two bolt nose cone, and color matched it to the car.
The black box is in there now, I paid a professional to rehab it.
The black box is in there now, I paid a professional to rehab it.
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Yeah some may call it overkill, but you can't have too much overkill.
- Pablo2
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Re: Rumbly, Vibratey Gearbox
Both those mainshaft bearings should be replaced any time the box is apart. The needle bearing is cheap, and the ball bearing is in a low oil circulation zone.
aka Pablo, gears, Geary
9.36 @ 146 in '86
9.36 @ 146 in '86
- Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Re: Rumbly, Vibratey Gearbox
I've tried to pinpoint when it makes the noise and it seems quiet when coasting in 1st/2nd, 3/4th and neutral. I can only hear the noise and feel the vibration when its ticking over in neutral. If I just take up the slack in the clutch cable it goes smooth and quiet. The clutch pedal has about 3/4" movement before the thrust brearing contacts the clutch. Any thoughts? It seems the be trust bearing but I can't imagine it could make that noise and create that vibration.
- Marc
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Re: Rumbly, Vibratey Gearbox
If the clutch is still engaged (as it would be at the point where the freeplay is just taken up) the mainshaft's still spinning, so this would exonerate the mainshaft bearing - sounds like we're barking up the wrong tree....if not in the wrong forest
Do you note any flutter in the pedal as contact is made? That would point to a problem with the cover (uneven release lever height). An early cover with one detached bale on the thrust ring could allow the ring to contact the release bearing enough to make noise even though there seems to be adequate freeplay.
Consider that as you start to depress the clutch, the force is ultimately exerted against the crankshaft and into the case via the thrust bearing; the crank gets pushed rearward - if the pulley's contacting the breastplate tin, it could be just enough to provide clearance and make the noise quit. Still no explanation for "vibration", but without experiencing it in person that can be hard to diagnose.
Are all four engine-to-trans bolts/nuts tight?
Do you note any flutter in the pedal as contact is made? That would point to a problem with the cover (uneven release lever height). An early cover with one detached bale on the thrust ring could allow the ring to contact the release bearing enough to make noise even though there seems to be adequate freeplay.
Consider that as you start to depress the clutch, the force is ultimately exerted against the crankshaft and into the case via the thrust bearing; the crank gets pushed rearward - if the pulley's contacting the breastplate tin, it could be just enough to provide clearance and make the noise quit. Still no explanation for "vibration", but without experiencing it in person that can be hard to diagnose.
Are all four engine-to-trans bolts/nuts tight?
- Piledriver
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Re: Rumbly, Vibratey Gearbox
Solid mounts?
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.
- Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Re: Rumbly, Vibratey Gearbox
No to solid mounts but it does have a Kafer brace.
Haven't checked the four engine fixings but will do. I'd be suprised if the were loose though.
There is no interior or sound deadening in the car so maybe I'm hearing a noise that's always there but others don't hear. I have done a lot of miles in the car and haven't noticed it before but maybe it's one of those things you tune into and cant stop hearing.
Haven't checked the four engine fixings but will do. I'd be suprised if the were loose though.
There is no interior or sound deadening in the car so maybe I'm hearing a noise that's always there but others don't hear. I have done a lot of miles in the car and haven't noticed it before but maybe it's one of those things you tune into and cant stop hearing.
- Piledriver
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Re: Rumbly, Vibratey Gearbox
They usually don't loosen up in street use, but they can go away and you can easily get metal-on metal if they sag or split... completely..esp likely if you bit on the red urethane versions..
The kafer brace (good idea) will simply transfer the noise in that case far more efficiently.
Rubber !> urethane if the mounts are stock replacements.
They don't make them like they used to.
(well, they probably DO still make quality HD stock style mounts, but they probably do not come in an EMPI blister pack)
The kafer brace (good idea) will simply transfer the noise in that case far more efficiently.
Rubber !> urethane if the mounts are stock replacements.
They don't make them like they used to.
(well, they probably DO still make quality HD stock style mounts, but they probably do not come in an EMPI blister pack)
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.