 Purpose Of Hole In Edge Of Flywheel, What is it for? |
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| Osnabruck914 |
 Apr 24 2025, 04:36 PM
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#1
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Member  Group: Members Posts: 123 Joined: 19-December 22 From: United States Member No.: 27,038 Region Association: South East States  |
914-4 2.0 Liter Engine
In the engine compartment looking backwards towards the rear of the car, there is a view port at about the eleven o'clock position of the bell housing through which you can see about an inch or so of the outer extremity of the flywheel. There is a perfectly machined dime-sized hole in that area of the flywheel that passes by that port as you spin the flywheel. When at TDC for Cylinder #1 that hole just starts to appear at the edge of the view port. It is not centered to it. What is it for? Is it another TDC reference, which I doubt, as it is a relatively large hole and does not center to that view port. Is it where material was removed to balance the flywheel? When I adjust my valves I use the factory scribe mark on the circumference edge of the flywheel, plus another mark I painted 180 degrees opposite, plus a 0 degree mark I have on the fan to determine TDC points. So I am puzzled by this hole in the flywheel. Probably a stupid question, but I sure want know. Osnabruck914 |
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| brant |
Apr 24 2025, 04:38 PM
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#2
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914 Wizard Group: Members Posts: 11,949 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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It should be a area where they removed a little bit of weight for the balancing of the flywheel
Nothing to do with TDC |
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| fixer34 |
Apr 24 2025, 04:50 PM
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#3
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Senior Member Group: Members Posts: 1,268 Joined: 16-September 14 From: Chicago area Member No.: 17,908 Region Association: Upper MidWest
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Yep, balance. Think of it the same way as when the shop balances your tires. Instead of adding weights, they remove it from the opposite side,
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| Osnabruck914 |
Apr 24 2025, 04:57 PM
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#4
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Member Group: Members Posts: 123 Joined: 19-December 22 From: United States Member No.: 27,038 Region Association: South East States |
Thanks all. I kinda figured it was that. I was always worried that it was related to TDC and it was supposed to line up with that port perfectly. Very relieved.
Osnabruck914 |
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| JamesM |
Apr 24 2025, 10:13 PM
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#5
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Advanced Member Group: Members Posts: 2,082 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
There is a plastic plug that covers that hole.
Missing on 99% of motors I see. |
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| ClayPerrine |
Apr 25 2025, 05:22 AM
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#6
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Life's been good to me so far..... Group: Admin Posts: 16,316 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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The hole is there to access the bolts for the torque converter in a VW automatic stick shift VW 411/412. The 914 used the same base casting of the engine cases. It's the same reason we have the mounting pads for a mechanical fuel pump, but they have never been machined.
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| ctc911ctc |
Apr 25 2025, 06:42 AM
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#7
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Senior Member Group: Members Posts: 1,124 Joined: 9-June 18 From: boston Member No.: 22,206 Region Association: North East States
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QUOTE(JamesM @ Apr 24 2025, 10:13 PM)  There is a plastic plug that covers that hole. Missing on 99% of motors I see. My most coveted part - so easy to set aside, forget to put back in after a successful test drive and then........GONE (IMG:style_emoticons/default/huh.gif) |
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