Gear for ATD - Material and Dealer?

Sebastian Huber

Well Known and Active Forum User
VOC Member
Hello,

ask for advice.
Have to replace the Novotex gear in my Shadow. Had some phone calls last week but didn`t find it ready for shipping.
Was told that it is only available in plastic material, POM ?

Where to find a dealer who has it in stock?
Was it ever made in aluminium?
What are the points breaking down the ATD?

Thanks for help in advance!

Sebastian,
the Bavarian
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Taking the ATD apart is not hard. The unit is held together by a punch-locked ring on the inner side of the gear. Take a note of where everything is before taking it apart. My advice is to do it inside an ice cream 4 litre tub or similar as there are small washers that can fly away. You will need four new rivets, part no. 1115, and a new pair of springs, part no. PR22 A/D. Gears were originally made of "Tufnol", a layered resin product. Some earlier nylon products were tried, but enlarged in service. I believe the current Spares Co. ones are o.k. Before disassembly, check for range of movement, about 16 degrees is good (32 degrees crankshaft) and check that the stop "ears" are not deformed. If this gets too complicated, order a new one from Price Products (in MPH) they are beautifully made. Never use a metal gear, it overloads the magneto bearings and can track current.
 

Sebastian Huber

Well Known and Active Forum User
VOC Member
Hello chankly bore,

thanks a lot for hints.
Have already had special experiences when starting work which seams to be easily done (changed oil seal in Mag. and was told later that the new one are to thin what guides me to an inner oil coled Mad during last season with missfire on Cyl.2., it sticks on the shaft and turned in housing).

But some questions in this post comes out of a slightly dark hour I had together with a friend. He lives in Hamburg I near Munich but it must have been very cloudy on both locations at this time. On a call we run over the pages of VOC Spares and Russel Keps catlogue and searching "gear for Mag drive". In the evening I got a mail from Russel and the question for sources was solved when I realsied that the English expression is pinion.
No Bavarian Beer Bottles had been on my desk think either on my friends one.
I thank good that my skills in workmanship are not so poor as my English is. If fluently English would be a requirement for riding British bikes I think I would be one of those who may have frequently crashes.

But back to my homemade problem.
Russel Kemp told me the name of the plastic material his ones are made of. Have seen on home page of Maugham & Son what they offers.
Certainly I`ll buy one of those and not because of missing cutter in my tool box with the neccessary tooth profile.
But is weight the only reason for using plastic? It won`t be much more heavier in aluminium and would live as long as all axels and pins with their bores in the advance mechanic lives.

Does somebody have experiences with the assortment offeres by VOC-Spares. Is + or -2th a different profile diameter in inch/10?
Expect the pinion I have is of Tufnol, hardly worn in two areas, 180° oposite, the working points.
Acceptable play in ok zones. Feel I`ll start with offered Standard version. ATD does 34°. I adjust timing from 4° to 38° BTDC.


Thanks again,

Sebastian,
the Bavarian
 

bmetcalf

Well Known and Active Forum User
VOC Member
"Have seen on home page of Maugham & Son what they offer."

I tried Google and couldn't find the website. What is their URL?
 

bmetcalf

Well Known and Active Forum User
VOC Member
Thanks, I had that as a bookmark and it came up in my Google search. Unfortunately, I couldn't find their website name in the article.:(
 

davidd

Well Known and Active Forum User
VOC Member
Sebastian,

I prefer the Tufnol and have always had good service with it. My Grey Flash has a steel gear as it is mechanical advance, but I was under the impression that tufnol was used to isolate the mag from grounding through the gears, but I do not know enough about mags to say.

It is not very easy for you, but Coventry Spares here in the US carries parts from many sources, including Maughan, so they often have several choices in stock.

David
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Sebastian, your English beats my High school German by a long way! I assume that when you are talking about + or _ .002" you are referring to ET49, the half-time pinion on the crankshaft. ET 48 was never issued in sizes and always has backlash, presumably to avoid stress on the magneto bearings. There have been some astonishingly good technical articles written about half-time pinion sizes if you want to spend a few long winter nights going insane. What I generally do is get two new 1/8" drill bits and a micrometer to do a comparison on sizes by measuring across two opposite tooth spaces. I never trust what is marked on the pinions. If there was a way to give 4 to 36 degrees advance it might be better if your "Benzin" is as bad as the stuff in Australia. Good Luck and keep at it! Cheers, F5AB/2A/7945 since 1970
 
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