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Rebuilt transmission (from Mofoco) leaking -- not sure why
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nsracing
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PostPosted: Sun Dec 06, 2015 5:33 pm    Post subject: Re: Rebuilt transmission (from Mofoco) leaking -- not sure w Reply with quote

Nice!

First of all, you had a trans built and cooked it on an application other than a car engine where it was supposed to mount.

I will address the leak first. If you filled this trans while it was upright -YOU WILL GET ALL KINDS OF LEAK.

2nd, the alignment issue. The trans bellhousing centered on a 'lip on the case and secured by 4 bolts. If you are going to adapt the transmission to some other powersource, you MUST reproduce ALL of the specs of the engine case to accept the bellhousing.

For centering, you machine that red coupler you made w/ the same 'lip' dimension as the engine case. Otherwise, you will not be able to align.

...or you can use dedicated 'studs' or dowel pins to maintain center for the input shaft. then the bolts will go on just as usual.

You were probably better off w/ the BUS bellhousing as an adapter to the electric motor. And use a spacer machined centered to the electric unit, mount/studded to the bellhousing.

The input shaft has to go inside the bellhousing same depth as the stock engine where it will mount to pilot bearing w/c can be in the rotor shaft of flywheel (like in some busses).

The issue is w/ your RED adapter. I will just cut the weld, machine the diameter on the mill and mount/couple inside the trans bellhousing. See how much depth you want, and weld the shoulder where it sits.

Well, seems you are a machinist too. Cannot forget the basics, mounting, coupling, alignment, all the good studs.

my 2 cents.
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corbin_dunn
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PostPosted: Mon Nov 30, 2015 8:17 am    Post subject: Reply with quote

gears wrote:
While it may seem that you're operating only slightly above design parameters, the VW trans can easily be pushed too far. For instance, we've learned that rotary engines which operate at much higher rpms than VW will often fry the late model mainshaft needle bearing. The little needles literally weld themselves at a sustained 9,000 rpm.

In the OP's case, when held at high rpm in 2nd, a lot of heat is continually generated right next to a needle bearing that may have been set at only .004" clearance. Had the builder known the OP's use, he could have set at the high end of the factory's recommendations .. or even much higher without consequence. I'm not saying that I absolutely know this is the sequence of events, but at least I know what I'm looking at (a fried 1st gear needle bearing, not a failed R&P), and I hope I'm shedding some light on the possible cause.


Hi,
I never said I held the transmission at high RPM in 2nd. I don't go around driving the car at 5000 RPM constantly, and I rarely (if ever) hit that RPM. I said I don't use first. I start in 2nd gear (which means a lot of torque -- but I never push it too hard to break traction), and shift before specific RPM points; usually around 4500 RPM (specifically, before 40MPH I shift to 3rd, and before 65 MPH I shift to 4th). These are safe RPMs and within the original engine's guidelines.

The failed R&P couldn't have had anything to do with this -- that failure happened after ~20 miles on the freshly rebuilt transmission.

To follow up on the original leaking problem: I did a lot of work to ensure the alignment of the main shaft was dead center with the adapter I use. That seems to have fixed the problem; I have about 800 miles on this setup so far, and it isn't leaking. More details at: http://corbindunn.com/plugbug

corbin
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gears
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PostPosted: Fri Nov 06, 2015 8:27 pm    Post subject: Reply with quote

While it may seem that you're operating only slightly above design parameters, the VW trans can easily be pushed too far. For instance, we've learned that rotary engines which operate at much higher rpms than VW will often fry the late model mainshaft needle bearing. The little needles literally weld themselves at a sustained 9,000 rpm.

In the OP's case, when held at high rpm in 2nd, a lot of heat is continually generated right next to a needle bearing that may have been set at only .004" clearance. Had the builder known the OP's use, he could have set at the high end of the factory's recommendations .. or even much higher without consequence. I'm not saying that I absolutely know this is the sequence of events, but at least I know what I'm looking at (a fried 1st gear needle bearing, not a failed R&P), and I hope I'm shedding some light on the possible cause.
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EVfun
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PostPosted: Fri Nov 06, 2015 7:50 pm    Post subject: Reply with quote

My transaxle has been handling EV duty since 2000, full of Redline MTL. Running at 45 mph in second gear (5100 rpm) isn't really that extreme. That is about what I hit running 70 mph in 3rd too (though I don't do that for very long.)

You should let your transaxle builder know it's an EV, but unless one is building a drag strip EV the power levels and the rpm range are not much different than stock. The extra low rpm torque, that mostly eliminates the need to use 1st gear, is about the only difference.
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gears
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PostPosted: Fri Nov 06, 2015 4:45 pm    Post subject: Reply with quote

I think it's unfair to any trans builder to withhold information that could dramatically affect the longevity of his product. I would surmise that this transaxle has been held in 2nd gear at high rpm for long periods of time. Otherwise, the 1st gear needle bearing wouldn't be completely fried (which in turn led to any other damage).

A transaxle can be built for EV, but expecting an off-the-shelf unit to withstand being held @ 5,000 rpm in 2nd gear is folly.
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EVfun
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PostPosted: Fri Nov 06, 2015 3:10 pm    Post subject: Reply with quote

The DC motors used in most home built EVs really don't rev that high, with a rev limit typically between 5000 and 7000 rpm. Series wound motors often have peak power down in the 3000 rpm range and a best efficiency a bit above that. So I'm going to guess he runs it similar to the way I do, 2nd gear from 0 to around 45 mph, 3rd gear from there up to around 70 mph.
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gears
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PostPosted: Fri Nov 06, 2015 11:22 am    Post subject: Reply with quote

I have to ask the OP .. Are you leaving this transmission in 2nd gear, and revving the motor to kingdom come?
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PostPosted: Fri Nov 06, 2015 10:27 am    Post subject: Reply with quote

corbin_dunn wrote:
Volks Wagen wrote:
Good progress. Is it now running with the noisy tranny or the previously leaky tranny?


It's the "previously leaky" transmission, which was a fresh rebuild. So far I have about 300 miles and it isn't leaking. I'm pretty sure it was leaking by this point. So, alignment was likely the issue.

Thanks again for the help from everyone! I'm a happy VW driver again. (And this one has zero emission scandals).

corbin


So there was nothing wrong with the transmission we built? This was all an alignment issue?
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corbin_dunn
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PostPosted: Wed Nov 04, 2015 7:59 pm    Post subject: Reply with quote

Volks Wagen wrote:
Good progress. Is it now running with the noisy tranny or the previously leaky tranny?


It's the "previously leaky" transmission, which was a fresh rebuild. So far I have about 300 miles and it isn't leaking. I'm pretty sure it was leaking by this point. So, alignment was likely the issue.

Thanks again for the help from everyone! I'm a happy VW driver again. (And this one has zero emission scandals).

corbin
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Volks Wagen
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PostPosted: Sat Oct 31, 2015 5:45 pm    Post subject: Reply with quote

Good progress. Is it now running with the noisy tranny or the previously leaky tranny?
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corbin_dunn
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PostPosted: Tue Oct 27, 2015 6:01 am    Post subject: Reply with quote

Hi Volks Wagen (and others),
Thanks for the replies! I don't have any pictures of the adapter shaft (pilot bearing part) on hand. Next time I take it apart I'll be sure to take some pictures of it.

Here is a blog post on what I did:

http://www.corbinstreehouse.com/blog/2015/10/plug-bug-try-3-with-the-transmission/

Indeed, the adapter bolt holes don't quite line up. I never had a real issue with this before (I got ~39,000 miles out of it this way), but for some reason it is causing issues with this newer transmission. So (as seen on the blog), I used my mill to trim out one hole, and align everything really well.

I also installed a new main shaft seal; the previous one definitely had some damage to the spring underneath it.

I only have about 55 miles so far, but it doesn't seem to be leaking (knock on wood). Time will tell if this worked or not.

If it doesn't work, then I have a feeling it is the location of my pilot bearing and/or flywheel that is causing the problem.

Thanks again everyone for the help!

corbin
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ROCKOROD71
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PostPosted: Tue Oct 27, 2015 5:59 am    Post subject: Reply with quote

Any progress on the tranny issues? Inquiring minds want to know.....
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PostPosted: Tue Oct 27, 2015 5:56 am    Post subject: Reply with quote

pb_foots wrote:
Holy crap, I know this car!

I've seen you parked in front of Mariani 3. Loved seeing the row of Teslas, etc. and right in front was this red bug.

I posted a pic a couple years ago

http://www.thesamba.com/vw/forum/viewtopic.php?p=6934162&highlight=#6934162

Good luck with your leak.


Yup! It's been charging at IL longer than any of those others existed (except the roadster).
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Volks Wagen
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PostPosted: Mon Oct 19, 2015 1:39 pm    Post subject: Reply with quote

pb_foots wrote:
Tesla could make that car go 150 MPH, and Apple could make you line up all night for the next version of it that's almost exactly like the current one.

The PO however, is having issues. I merely pointed out that he has very smart friends. The average IQ at Mariani 3 is just slightly higher than average. Laughing


The way I understand this is that the electromotor shaft has the flywheel mounted.
So, either the flywheel is not on straight and perpendicular to the shaft and centred on the shaft or it is.
Then there is a pilot bearing in the flywheel/motor/shaft assemply also centred.
Then there's the adapter/mounting plate between the motor and gearbox - to check for centres alignment between both the gearbox and the motor, the adapter plate can be attached one at a time to the motor or the gearbox, and the centre of each shaft measured relative to 3 points on the mounting plate to give a 3D point within the bellhousing where the gearbox input shaft sits; or alternatively for the motor, where the pilot bearing sits... BOTH of these points should coincide within VW tolerances. If not then the adapter plate needs to be remachined.

The fixings for the adapter plate should be rock solid.

Finally the clutch and pressure plate should be attached and centred using a clutch centering tool for about $8. Assuming that none of the components are MASSIVELY out of balance then that should do it right?
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pb_foots
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PostPosted: Sun Oct 18, 2015 5:30 pm    Post subject: Reply with quote

Tesla could make that car go 150 MPH, and Apple could make you line up all night for the next version of it that's almost exactly like the current one.

The PO however, is having issues. I merely pointed out that he has very smart friends. The average IQ at Mariani 3 is just slightly higher than average. Laughing
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Volks Wagen
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PostPosted: Sun Oct 18, 2015 1:40 pm    Post subject: Reply with quote

So, the folks at Apple and Tesla cannot successfully put an electric motor in a beetle. Come on, you've got to fix this.
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pb_foots
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PostPosted: Sun Oct 18, 2015 5:23 am    Post subject: Reply with quote

Holy crap, I know this car!

I've seen you parked in front of Mariani 3. Loved seeing the row of Teslas, etc. and right in front was this red bug.

I posted a pic a couple years ago

http://www.thesamba.com/vw/forum/viewtopic.php?p=6934162&highlight=#6934162

Good luck with your leak.
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EVfun
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PostPosted: Sat Oct 17, 2015 7:55 pm    Post subject: Reply with quote

A good look at the pilot bearing or bushing, along with the shaft adapter it's in, would help understand the setup. I suspect there is a length issue, where the input shaft is butting up to the end of the motor shaft as the adapter is tightened down. I don't see how slight misalignment (up, down, left, right) will cause any short term problems unless the error is large -- the stock setup is not very tight tolerance. Oil leaks would be easiest to cause by having the input shaft run slightly eccentric to the motor shaft. That usually causes out of balance noise.

The motors we are using are 100 lb. or more lighter than the stock Bug engine. I have no rear support and I have not heard of any Bug conversion having rear support. This should only be an issue if the adapter is allowing flex.
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PostPosted: Sat Oct 17, 2015 6:16 pm    Post subject: Reply with quote

first, listen to gears, he is your tranny guru, your best bet at solving your problems. Pilot bearing is another piece to the puzzle.

Just a thought after looking at your pictures: In the first few you mention a "balancing point" This may be something to examine. The german engineers, in their infinite wisdom, had it figured out as to where to put the engine/transmission hanger. Even if the gasoline engine is heavier, how is the weight distributed? The pressure plate, clutch and flywheel are pretty heavy on an ACVW engine and they are closer to the center where the hanger is. Even if your motor is lighter, if there is a lot of weight on the rear side it is putting exponentially more force downward on the motor. Think of it like an axe, even if it is a 5 pound axe if the handle is 6 feet long its hard to lift it up level and hold it there....

Again, just spitballing here, maybe you need some support on the outside (rear) part of the motor?
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI
79SuperVert wrote:

30 years from now, the next guy may not want your girlfriend, but he may want your classic car, depending on how nice you were to it.


asiab3 wrote:

Careful guys, a petulant child can grow up to be president these days.


**winter drivers: no survivors!**rust warrior**#keepbodyshopsbusy**
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gears
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PostPosted: Sat Oct 17, 2015 7:51 am    Post subject: Reply with quote

^^ +1 Please show a photo of your pilot bearing (behind the clutch disc) ..
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