Author Topic: A7 long stroke, new ATD  (Read 424 times)

Offline Johannes

  • Moving Up
  • **
  • Join Date: Aug 2013
  • Posts: 13
  • Karma: 0
A7 long stroke, new ATD
« on: 27.10. 2016 19:27 »
Hello,

I bought a new ATD for my A7 Long stroke. Unfortunately, it doesn't fit. The distance of the new ATD between the end of the shaft and the gear is smaller than the old one. The gear thought the engine housing and the tapered end is not tight. The total length is the same. However, the height of the weights is more.
I consider to repair the old one but the condition is worse and I don't know how to proceed.

Regards
Johannes

Online groily

  • Wise & Enlightened
  • *
  • Join Date: Jul 2007
  • Posts: 1085
  • Karma: 18
    • www.brightsparkmagnetos.com
Re: A7 long stroke, new ATD
« Reply #1 on: 27.10. 2016 22:01 »
Without being able to see all the details from the pix of the new one (the old one is mostly scrap) it looks as if the input and output members aren't correctly assembled, and the position of the gear looks too 'low' as you say.
I think it needs taking apart for checking that the components are in fact the correct ones, and are all there, and that they are assembled in the right order.
Correctly assembled, the tabs on the two parts of the unit (which limit the movement) will close to almost 100% of their depth, not like that one, where there's only partial engagement it seems. Could that be due to the thickness of the linkage parts the springs connect to - can't see enough to be sure, but they look a bit chunky from here? Or is something not seating properly on one of the pins maybe?
For a picture of typical unit, see http://www.brightsparkmagnetos.com/faqs/FAQs%20about%20ATDs/How%20does%20an%20ATD%20work.htm, or the very useful "ATD Repair" document on the site of Priory Magnetos: https://sites.google.com/site/priorymagnetos/atd-units - and follow the link in red type.
Bill

Offline Johannes

  • Moving Up
  • **
  • Join Date: Aug 2013
  • Posts: 13
  • Karma: 0
Re: A7 long stroke, new ATD
« Reply #2 on: 22.01. 2017 16:48 »
Dear all,
I would like to give a feedback of my ATD issue. As Bill mentioned there was something wrong with the ATD. Bill was right! I found a problem with one lever. The pin doesn’t fit proper. I send the ATD back to the dealer with some comments of my investigation. He was friendly and he intend to checked the problem with his supplier. After some weeks, I have got the same ATD back. Everything should be fine. Nothing changed and my problem was still there.
I disassembled the ATD and I did a lot of measurement. At least a hole of one lever were complete out of range (see photo). Without these lever the distance of the gear getting closer to the original but not enough for my A7 long stroke. I shorten the bush of the gear and machined new levers with accurate fit to the pins. Now the ATD is doing well and I do not have any fluctuations in idle speed any more.
My Conclusions:
•   I do not believe that the dealer has not done any investigations.
•   The dimensions and clearances of the aftermarket ATD are not as I expected.
•   The weight of the aftermarket ATD weights are almost 3 Grams different.
•   The aftermarket ATD is a good basis for refurbishment

My thanks to Bill for the fruitful comments and Klaus. He sent me a used ATD immediately for testing.

Online groily

  • Wise & Enlightened
  • *
  • Join Date: Jul 2007
  • Posts: 1085
  • Karma: 18
    • www.brightsparkmagnetos.com
Re: A7 long stroke, new ATD
« Reply #3 on: 22.01. 2017 19:09 »
A happy result Johannes - but not a very good story from the point of view of  the service offered.
I don't imagine it was cheap either.

It's lucky that you had the facilities to do a proper job, and I'm glad it is now functioning correctly.
Bill