Diaphragm spring

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Matchless

Matchless

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Does anyone know when the diaphragm spring centre design changed. Both my Commandos have the original factory fitted type. For the Atlas I am in the process of building I have just received a spring from RGM & the centre is different to my others. Whilst this doesn't matter to me, there is a problem with this sping, in that when fitted the centre boss will not sit square. I have removed the circlip & pulled it apart but cannot see anything wrong. RGM have said they will send me another but I wonder if anyone else has had this problem.

Martyn.
 
I also had issues with the RGM spring and it appears to be there own spring. the one i had would not lift off square and upon inspection the fingers are not staggered like to OE one. IMHO it is only fit for the scrap. order the one from andover.
 
It didn't change 71- 75 . Looking at the 1971 750 and 1975 MK3 parts book both list the same diaphragm, 06-0770.

Now I've had a look at the 68 parts diagram on the Andover site. It's the same part for that first year machine as well, 06-0770


Glen
 
worntorn said:
It didn't change 71- 75 . Looking at the 1971 750 and 1975 MK3 parts book both list the same diaphragm, 06-0770.

Now I've had a look at the 68 parts diagram on the Andover site. It's the same part for that first year machine as well, 06-0770
Click to expand...

The spring strength was supposed to have been increased twice from the original although the part number didn't change, however, it seems the RGM spring centre has been changed.

https://www.rgmnorton.co.uk/buy/clutch-diaphragm-spring-commando_857.htm

Edit: The current AN spring doesn't appear to have the staggered fingers of the original.
https://andover-norton.co.uk/en/shop-details/15410/clutch-diaphragm-spring
 
Last edited:
worntorn said:
06-0770
Click to expand...

???
06-0770 original
superseded by
06-0770 rev 2 edit sorry typo
superseded by
06-0770 rev 3

1. Beside BDM(rip) not caring for me or telling the world about that
2. Being way to long winded in his topics IMO
3. I did believe most of the "facts" he presented
If the factory upped the force twice as he stated, unfortunately I have not measured a notable force difference on the limited diaphragms I had for sampling.
I would have to repeat the setup and source a bigger variety of units.
 
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bill said:
it is hard to tell from the pictures if the one from an is staggered
Click to expand...

It's of no real importance, apparently:


"JM Leadbeater (BDM)"
http://a20b767e.magix.net/#xl_xr_page_5
"..........the ONLY reason for the 40 thou offset to the piercings in the Laycock Eng. (Haussermann) release ring is as follows: The piercings in the release ring require to be larger than the hardened ends of the release ears so as to fit them into the release ring. If the piercings were all in line then the release ring would vibrate on the ears resulting in VERY QUICK WEAR AND FAILURE along with generating MORE noise than any NON totally deaf car owner could stand. (I was told to ask any Hillman Imp owner club member with a few hundred thousand miles use on their original Laycock clutch diaphragm spring and release ring if I did not believe…). So the Haussermann brothers in Germany offset the piercings so the release ears clamped on the release ring eradicating the noise generation and quick wear problems over the ‘normal’ life of a car. They also, so I was told, patented the idea. However just to confirm my thoughts on the subject were something like correct I phoned my friendly retired Chief Clutch Designer and asked him about the effect on lift of the release ears being offset to each other and he said he had never really thought about it but that he would go away and have a think. Overnight he must have had a think because the following morning he phoned saying it was of no real importance as far as he was concerned. Mind you his clutch designs would have had the pressure line in the ‘normal’, ‘standard’, ‘usual’, ‘correct’ position on the Belleville spring and NOT on the release ears. Anyway it is irrelevant now as the NON Laycock spring that has been available from Andover Norton for decades has a different release ring design and all the release ears work together in unison even if they do bend a bit in use!"
 
Thanks for all the replies. I will post it back to RGM in the morning & see what they come up with.
 
My 20 minute basement experiment and write up in july 1997 did not impress BDM.
http://atlanticgreen.com/JML-BDM.htm

L.A.B. said:
It's of no real importance, apparently:
Click to expand...


Finger stagger was to keep a preloaded holding position on the Wasserman made patented diaphragm center to reduce/eliminate a possible noisey rattle when unloaded. It's in his 127 page report

New diaphragm manufacturer probably doesn't care about patented finger stagger design.
 
bill said:
I also had issues with the RGM spring and it appears to be there own spring. the one i had would not lift off square and upon inspection the fingers are not staggered like to OE one. IMHO it is only fit for the scrap. order the one from andover.
Click to expand...
I had the same problem, I didn't use it, waste of money
Terry
 
i also had issues with there fancy stainless cable splitters. the body was aprox. .350 inch to long, I sent them an e mail about this issue and got zero response. so much for customer service!!!

Myford said:
I had the same problem, I didn't use it, waste of money
Terry
Click to expand...
 
L.A.B. said:
It's probably just a simpler (cheaper?) way to do it.
Click to expand...

I would certainly agree.
The Wasserman anti rattle design may have been the original intended outcome. It would seem the staggered finger preload had a benefitial side effect of a strong position retaining force resulting in a more straight lift?
 
The replacement spring arrived from RGM & was just as bad. After a bit of thought it occured to me that the problem was the bore diameter of the spring gets smaller as the spring flattens. This meant the fingers were bottoming out on the slots in the centre & pushing it over at an angle. I put a note in with the spring when I returned it (at my own expense x 2) but haven't heard anything.
I could of course have modified the part to work properly, but why the hell should I pay £40 for a part that is badly made & have to rework, it when I can buy a very good used original one for less!
 
I blame reality shows.
It convinces doofusses there really isn’t any reason to do things in an industry standard manor. They waste time, effort & money doing stupid stuff, and then they are all proud of the accomplishment.
When, if their Mommies hadn’t coddled them, they could focus efforts on improving things, rather than tripping over their own shoe laces. I’m speaking of the spring that bottoms in the holes when compressed. Repeating sophomore metalworking mistakes.
 
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