# VW Beetle adapter plate



## illuminateddan (Dec 19, 2009)

Does anyone know of a good source for an old school vw beetle to ADC L91-4003 adapter plate and couple for a non clutched system?


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## DavidDymaxion (Dec 1, 2008)

http://www.e-volks.com/ has them for a good price.


illuminateddan said:


> Does anyone know of a good source for an old school vw beetle to ADC L91-4003 adapter plate and couple for a non clutched system?


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## Guest (Sep 9, 2010)

Good prices but not so hot in the quality department. Spend the money on a good quality adaptor and by all means go with a clutch. I guarantee you will wish you had if you setup without a clutch. Your vehicle will respond much better if you use your transmission and shifting smoothly and quickly will be required if you drive in any type of traffic. 

Pete 

Rebirth Auto has a good one but not sure if they have the bolt pattern for your motor. Call them. 

Don't skimp on the adaptor.


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## DavidDymaxion (Dec 1, 2008)

Disclaimer: I do not stand to profit from the success or failure of e-volks / Wilderness EV.

Certainly e-volks aims for low cost. I have seen a couple of their adapters, they looked OK, and haven't heard of any failures, but I have little direct knowledge. Have you encountered any specific problems with their adapters?


gottdi said:


> Good prices but not so hot in the quality department. Spend the money on a good quality adaptor and by all means go with a clutch. I guarantee you will wish you had if you setup without a clutch. Your vehicle will respond much better if you use your transmission and shifting smoothly and quickly will be required if you drive in any type of traffic.
> 
> Pete
> 
> ...


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## Guest (Sep 9, 2010)

Hard to get the motors properly positioned for good balance. They don't break but the fit is not so hot. If you have slop then you have to futz with things rather than just bolt on and go. 

Pete 

For low speed driving I guess it would be fine. If it is not using a clutch then the fit issues are compounded. Broken shafts anyone!


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## bart_dood (Sep 2, 2010)

Does anyone have accurate dimensions for these adapter plates? I am designing a custom setup and have a transmission for reference dims but no gasoline motor.
I'll be using the clutch and flywheel on my setup, my blog link is in my sig.


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## EVfun (Mar 14, 2010)

The aircooled VW Beetle bell housing is a simple design. The motor is located with a centering ring that is 11.100 inches in diameter around the motor shaft. The outside diameter should be at least 12.400 inches but could be larger without interfering with anything. The motor shaft location can be used as the center for everything. 

The top 2 bolt holes are located 4.328 inches above the horizontal centerline and 3.897 inches to either side of the vertical centerline (42 degrees to either side of the vertical centerline.) The bottom 2 bolt holes are located 4.117 inches below the horizontal centerline and 4.117 inches to either side of the vertical centerline. The 4 holes should be 7/16 inch in diameter.

You get to set the holes and locating ring for the motor based on what you have chosen. I used a Prestolite MTC-4001 so mine is a step cut with a 8.5 inch diameter to fit the motor locating ring. Most motors have a locating ring diameter smaller than the bolt pattern so the plate can have a through hole in the locating ring diameter. 

My shaft coupler is machined from a VW Bus input to mainshaft coupler turned down to 1.125 inches (for the hardened splines that fit the input shaft) and a Ruland shaft coupler is used to connect the splined coupler and motor shaft. The clutch pilot shaft is cut off the input shaft. Here is a picture of the motor installed. I don't have any pictures of the motor and adapter out of the car.


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## bart_dood (Sep 2, 2010)

EVfun said:


> The aircooled VW Beetle bell housing is a simple design. The motor is located with a centering ring that is 11.100 inches in diameter around the motor shaft. The outside diameter should be at least 12.400 inches but could be larger without interfering with anything. The motor shaft location can be used as the center for everything.
> 
> The top 2 bolt holes are located 4.328 inches above the horizontal centerline and 3.897 inches to either side of the vertical centerline (42 degrees to either side of the vertical centerline.) The bottom 2 bolt holes are located 4.117 inches below the horizontal centerline and 4.117 inches to either side of the vertical centerline. The 4 holes should be 7/16 inch in diameter.
> 
> ...


Thanks a lot EVfun, just to confirm these are the exact reference dimensions? I'll be doing all my CAD design around them so I just need to make such I have exact references before I get parts made or $$$ down the drain.
My parts are custom for a custom motor, so I'm designing everything myself from scratch.

Thanks again!


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## EVfun (Mar 14, 2010)

I double checked my typing and verified they where posted without error. I think the bolt holes are a few thou off, but the bolts fit without issue. I suspect the correct dimensions would be 11mm holes and the holes located on radius 148mm from center with the top 2 located 42 degrees on each side of the vertical center line and the lower ones located at 45 degrees from either side of the vertical center line. I bet the locating ring is actually 282 mm instead of 11.100 inches too. You will notice how that would move things just a few thou, and would make more sense since the old VW Beetle is metric. The locating ring should be about 3mm deep.

I want to point out that if you choose to go without a clutch you will want the shaft coupler to be as small in diameter and light as practical. The inertia of the armature and everything attached to it are what the syncros have to bring to speed when shifting (diameter kills shifting speed.) It will not shift race car fast, but the old Beetle transaxle seems to be quite up to the task of going clutchless and I wouldn't put one back in if someone else volunteered to do it for free. I've been running my adapter without issue since 1999.


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## bart_dood (Sep 2, 2010)

EVfun said:


> I double checked my typing and verified they where posted without error. I think the bolt holes are a few thou off, but the bolts fit without issue. I suspect the correct dimensions would be 11mm holes and the holes located on radius 148mm from center with the top 2 located 42 degrees on each side of the vertical center line and the lower ones located at 45 degrees from either side of the vertical center line. I bet the locating ring is actually 282 mm instead of 11.100 inches too. You will notice how that would move things just a few thou, and would make more sense since the old VW Beetle is metric. The locating ring should be about 3mm deep.
> 
> I want to point out that if you choose to go without a clutch you will want the shaft coupler to be as small in diameter and light as practical. The inertia of the armature and everything attached to it are what the syncros have to bring to speed when shifting (diameter kills shifting speed.) It will not shift race car fast, but the old Beetle transaxle seems to be quite up to the task of going clutchless and I wouldn't put one back in if someone else volunteered to do it for free. I've been running my adapter without issue since 1999.


Yeah I was working on the assumption that everything would be metric and the designers used rounded off numbers. I checked the little counterbore step and I got 282mm off my transmission. I also re-checked my other numbers and got very close figures to the ones you mentioned. Here's an image of what I have.


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## DavidDymaxion (Dec 1, 2008)

I got 11.100 inches for the centering ring for my Porsche tranny. I didn't carefully measure the mounting holes, rather I used big C-clamps to temporarily hold the adapter to the tranny. I then used center punches to mark the center of each hole. You can see how I made my adapter at these links:

http://explodingdinosaurs.com/9electric/adapter/

http://www.explodingdinosaurs.com/9electric/adapter2/


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## EVfun (Mar 14, 2010)

bart_dood said:


> Yeah I was working on the assumption that everything would be metric and the designers used rounded off numbers. I checked the little counterbore step and I got 282mm off my transmission. I also re-checked my other numbers and got very close figures to the ones you mentioned. Here's an image of what I have.


That comes out very close to my numbers. The total difference between my numbers, your numbers, and my assumptions on what the actual numbers most likely are fall within a few thousandths of an inch. I'm confident that the differences wouldn't be noticed when installing a plate made to any one of those numbers. For the most part the differences would fall within reasonable drawing tolerances.


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## bart_dood (Sep 2, 2010)

Can someone out there check the flywheel offset value? I currently have it at 36.6mm (1.441 inches). Is the measurement between the adapter plate surface (or gasoline motor if its an ICE) and the face of the flywheel right near the starter motor teeth.
I've attached a side view showing the dimension I need to double check.

Thanks everyone!


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## bart_dood (Sep 2, 2010)

Here's an ISO shot so you can see the plate and flywheel at an angle.


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## bart_dood (Sep 2, 2010)

Guess nobody has this dim huh?


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## EVfun (Mar 14, 2010)

I went clutchless, so I don't have that information.


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## jefsmk (Dec 12, 2019)

Did these dimensions work out for you on your build? I'm a little confused as my VW trans seems to be opposite -- the larger spaced holes (the 209.304) are on the top, and the smaller are on the bottom (198.063). Other than that, the numbers seem to jive. Did you just have the drawing flipped maybe? Or do I have a bastard tranny??

Edit: never mind - my brain was flipped when typing this I suppose. I'm about to get my adapter machined using these dims as a basis of my design (along with verifying physically best I could). I'll report back with how all worked out.




bart_dood said:


> Yeah I was working on the assumption that everything would be metric and the designers used rounded off numbers. I checked the little counterbore step and I got 282mm off my transmission. I also re-checked my other numbers and got very close figures to the ones you mentioned. Here's an image of what I have.


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