NLA-102-201-03 200 mm flywheel brittle gear

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Van Miller
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NLA-102-201-03 200 mm flywheel brittle gear

#1 Post by Van Miller » Fri Jan 04, 2019 11:02 pm

I have 57 Speedster converted to 12V decades ago with but with only 10000 miles on 1883 cc engine with NLA-102-201-03 200 mm flywheel lightened to 14 lbs. The mileage was accrued over about 5 years, car is not raced, always garaged, etc., etc. The engine had to come out in order to fix dent in left rear fender and I noted that flywheel teeth looked quite ragged, the way ring gear teeth looked when people would leave 6V starter in place with 12 V system. The starter motor has black casing on motor shell and 'US.PAT.5163335, (I believe it is from WR and is 1.9kW). Other ID stuff on unit; "Made in Mexico, 6 004 AAO 021 12V, 02-27-15 08:32" and "SR 15N 904 28.26".
I am suspicious of the metallurgy of the beautiful new flywheel. I am planning to take engine out, flywheel off and to have my favorite machine shop put a hardened steel 6V 109 tooth ring gear on the flywheel. Has anyone else encountered early wear of flywheel teeth with these replacement flywheels? Could there be any problems putting hardened steel 109 tooth ring gear on flywheel made of different material, different expansion rate and all that jazz?
BTW: I am always appreciative of our vendors that take the time and trouble to give us our replacement parts so we can keep these old cars on the road, so no complaint about the flywheel.
I would welcome any input on this situation.
Van Miller

Geoff Fleming
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#2 Post by Geoff Fleming » Sat Jan 05, 2019 11:14 am

I owned a factory 12v 356 which came to me with a 6v starter installed. The flywheel /starter combo would often clash. I later replaced the solenoid on the 6v starter motor with a 12v unit and this was the best of both worlds...smooth engagement of the bendix gear with the flywheel and extremely rapid turning of the motor. Never had a problem again, even though the car was a daily driver and in all weather conditions.

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Steve Swift
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#3 Post by Steve Swift » Sat Jan 05, 2019 12:13 pm

Many years ago I built an engine with a Chinese crank, big bore kit, and a non lightened flywheel to see what would happen. At 3K miles a failed wrist pin destroyed the experiment. I had all the parts tested and found the wrist pins lighter, thinner, and way to brittle. The flywheel was softer than the German version and the machinist said it appeared the ring gear was only flame hardened. I no longer have the data but have never used any Chinese parts in an engine since.

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#4 Post by Martin Benade » Sat Jan 05, 2019 6:14 pm

I thought a Chinese crank was only recently available. How long ago was that?

Van Miller
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#5 Post by Van Miller » Sat Jan 05, 2019 8:49 pm

Who makes our 'NOS flywheels', I thought I they were reported as made in Germany. Wilhoit's are noted to be 'super tough 4340 chromoly', they looked subjectively more industrial when I admired than at last year's open house then the bright and shiny replacement flywheels offered by a number of our favorite venders. I liked Geoff's response and I knew that was a solution but I never embarked on it and I thought the replacement flywheels with 12 V starters with 6V pinion gear would make the past solution moot.

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#6 Post by Dick Weiss » Sat Jan 05, 2019 11:00 pm

Van,

Flywheel & teeth aren't brittle, just standard material w/o any treatment. However you SHOULDN'T use a 12V stater
w/o changing it's pinion/Bendix drive; The smaller 12V pinion will really ruin the teeth in a short time!

As mentioned by others, the 6V starter's solenoid should be changed to a 12V so the "pull-in" will be a little softer.
Yes, a slight difference will be heard during a faster engine turn-over, but no matter, the change will last a long time.

Dick

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Steve Swift
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#7 Post by Steve Swift » Sat Jan 05, 2019 11:18 pm

I built the Chinese experiment about 7 years ago to answer your question. I am out of the hobby now. After the destroyed engine I only used real NOS or used Porsche parts. There are no reproduction NOS parts, only Chinese junk or OEM ( read Chinese junk ) repop parts flogged as OEM.

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Harlan Halsey
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#8 Post by Harlan Halsey » Sat Jan 05, 2019 11:40 pm

I Intend to complete the restoration of my '56 with a 12v system and I intend to get one of the aftermarket geared starters. But from what I read here, the 6v stater with a 12v solenoid will work fine. Is my interpretation correct?

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#9 Post by Martin Benade » Sun Jan 06, 2019 12:47 am

I have a modern geared starter and it works fine, but I find the sound unsatisfying after so many years with a stock starter.

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#10 Post by Martin Bruechle » Sun Jan 06, 2019 1:25 am

Harlan, read Geoffs post above.

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#11 Post by Geoff Fleming » Sun Jan 06, 2019 5:33 pm

Harlan,

Here is a more complete history...In 1984, I bought a '63 B coupe to use as a daily driver in the New York Metro area. I knew it was a factory 12v car but didn't understand the signfiicance of the 'Carrera 2' emblem on the rear.
It had a C engine with oil that had a tar-like consistency, so I replaced it with my own 912/S-90 engine. When starting up, it would occasionally 'gronk' as the Bendix gear of the 6v statrter was mis-matched to the flywheel teeth. After I had an engine re-build, with a lightened flywheel, the same occasional , ( not too often), crunching would occur. After driving the car for about seven or eight years,I did find the flywheel teeth badly chipped. I replaced the flywheel with one more 'streetable', ( heavier), and switched the solenoid from 6v to a VW 12v unit. After that, there was never a problem with the engagement.
As I previously mentioned...the best of all worlds, fast turnover of a 6v motor on 12v and smooth engagement of the Bendix gear. ( Car is now being returned to C-2 status...but not by me!)

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Al Zim
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#12 Post by Al Zim » Mon Jan 07, 2019 7:16 pm

What you need to realize is that everything is probably worn out. 55 years at the least have conjured wear situations that were not considered as the cars were designed. As far as we know there seems to be only one supplier of ring gears. Zim's ring gear instillation costs $250.00 which includes the cost of the ring gear, Stitching to form a contentious weld between the ring gear and the flywheel then resurfacing the two pressure of the flywheel and countersinking the threads on the pressure plate bolt holes. Usually the mating surface to the crank has been distorted. Resurfacing to the proper angle is $75.00. If a speedy sleeve needs to be installed that will add another $125.00 to the cost. Shipping and tax is additional. We have been successfully selling a 12 volt starter with 6 volt teeth which does not need a starter bushing and is substantially lighter than the original starter Cost is $225.00 (you can sell your old starter to help defray the cost). Zim's has just purchased a new large metric lathe in addition to the Bridgeport vertical mill we have two additional drill presses one new small vertical mill and small new drill press. As usual prices are subject to change. al zim 2019/01/07
 

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Harlan Halsey
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#13 Post by Harlan Halsey » Mon Jan 07, 2019 8:09 pm

Al,
I have been replacing the ring gears on English cars off and on for decades. The Coventry Climax and the English Ford use a Bendix style starter where the armature rotation throws the pinion gear into engagement. This means that the pinion may not be fully engaged when the load starts with consequent high wear. The ring gear is a ring, smooth inside with teeth outside. You get them off by drilling and then breaking with a cold chisel. To put a new one on, you simply heat it with a torch till the oil smokes and then drop it on. The installation temperature is too low to affect the heat treating of the the gear.
I'm curious as to why you don't use this simple system to put the new ring gear on after you have machined the porsche flywheel to dimension?
Harlan

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Al Zim
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Re: NLA-102-201-03 200 mm flywheel brittle gear

#14 Post by Al Zim » Tue Jan 08, 2019 9:49 am

It has been a long time possibly over 40 years since I have looked at a flywheel on an English car. The 356 flywheels are made of steel not cast iron. The ring gear is machined on the flywheel. Because the engine usually stops in one place, the teeth of the starter engage the same teeth wearing out that section of the ring gear till there is nothing left. It is important to machine the flywheel so there is an interference fit similar to the English cars then to weld the ring gear to the flywheel so it does not slip off. al zim 2019/01/08
 

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Re: NLA-102-201-03 200 mm flywheel brittle gear

#15 Post by Dick Weiss » Tue Jan 08, 2019 11:03 am

Al,

A slight correction; The engine stops in 2-places--180 degrees apart.
Also, I've refinished teeth-edges on several F/wheels during re-finishing of the sealing hub diameter on my special tool grinder.

Dick

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