Joe, Thanks for your reply. It does leave me wondering what is in mine since the supplier did the mod. It would be interesting to know specifics though, effect of reduced thickness of original bore, sleeve movement potential etc. Will have to save or look around for a smaller bore cylinder.
RGM 13mm master cyl upgrade
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Fine. I am a Chartered engineer, have a BSc and PhD in mechanical engineering, was apprentice trained and have designed many things just for interest. Don't take this as meaning anything however about me or anyone else as 'engineer' is used to describe a wide range of individuals from washing machine repair men to rocket designers. Engineer therefore generally means little. I know lots of degree guys who can't put a nut on a bolt and also many trademen who have real expert knowledge in machining tolerances but can't tell you what stress and strain means and would have no idea of how big to design something to minimise failure under load.
My view is that there is absolutely nothing wrong fundamentally with the RGM design. The thread seals on PTFE and should this or the nitrile seal fail then it would be a slow gradual process and it would pump up on the lever to give some breaking effort. I for one am not worried about the scaremongering or I wouldn't have fitted it.
On a different but related note it is amazing that despite all the current worldwide regulations and standards that you can still design a chopper in your garden shed and get it approved without knowing anything about vehicle dynamics, never mind static forces. And modify and hand make half the bits. That present a much bigger risk...
My view is that there is absolutely nothing wrong fundamentally with the RGM design. The thread seals on PTFE and should this or the nitrile seal fail then it would be a slow gradual process and it would pump up on the lever to give some breaking effort. I for one am not worried about the scaremongering or I wouldn't have fitted it.
On a different but related note it is amazing that despite all the current worldwide regulations and standards that you can still design a chopper in your garden shed and get it approved without knowing anything about vehicle dynamics, never mind static forces. And modify and hand make half the bits. That present a much bigger risk...
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JS (ZFD), could you tell us what internal bore your conversion is?
I have one of the "dreaded conversions", and find the brake satisfactory, rather than excellent. If your conversion improves the brake still further, with less leverage at the lever and more feel, I might be interested. The conversion it's definately an improvement over standard, but if I could get one to be near to my *onda brake, then that would be bliss.
I have one of the "dreaded conversions", and find the brake satisfactory, rather than excellent. If your conversion improves the brake still further, with less leverage at the lever and more feel, I might be interested. The conversion it's definately an improvement over standard, but if I could get one to be near to my *onda brake, then that would be bliss.
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Rich_j said:
I had RGM fit the conversion to my Mk3's master cylinder around 5 years ago and the washer/seal has been continuously immersed in DOT4 since that time and no problems to report.
ZFD said:
I'm guessing your friend 'Rudi' would also express the same opinion about various standard Commando parts?
ZFD said:
It's just a shame that the "fully approved master cylinder" is a modern unit which seems to look slightly out of place on a Commando (perhaps the reason for the tiny photos?) and also requires an adaptor to fit the original switch housing instead of a purpose made component that matched the design of the original master cylinder units.
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1. Yes, I would like to stay with the original master cylinder appearance but for reasons given above we can't. From memory I think ours has a bore of 13mm, but decline to swear on it- would have to look at the drawing which I don't have here.
The "tiny photos" have nothing to do with the appearance, but solely with how I downsized the photos months/years ago to get them into our accessories page. I am not ashamed of the appearance which was good enough not to be recognized by a German Classic Motorcycle Mag as non-original. Yes, they are dipsticks, but they were amazed how good the brake was.
2. My friend Rudi works on Norton engines all the time for a living (he is self-employed), and I get most of my feedback on our parts from him. His findings are often identical with those of Mick Hemmings. There seem to be problems only these two gentlemen have on the globe- and they are normally justified. A lot of problems these two gentlemen DON'T have, however, because they insist on genuine parts and shy away from the dubious offerings one tends to find in the marketplace.
The "tiny photos" have nothing to do with the appearance, but solely with how I downsized the photos months/years ago to get them into our accessories page. I am not ashamed of the appearance which was good enough not to be recognized by a German Classic Motorcycle Mag as non-original. Yes, they are dipsticks, but they were amazed how good the brake was.
2. My friend Rudi works on Norton engines all the time for a living (he is self-employed), and I get most of my feedback on our parts from him. His findings are often identical with those of Mick Hemmings. There seem to be problems only these two gentlemen have on the globe- and they are normally justified. A lot of problems these two gentlemen DON'T have, however, because they insist on genuine parts and shy away from the dubious offerings one tends to find in the marketplace.
Having seen the naked sleeve I have no problem with the quality of manufacture. In terms of quality the sleeve is in a completely different league to the both the rubber washer and the adjustable pusher, I think I can guess which bits RGM made. The pusher design is slightly amateurish and the rubber washer looks like it's been punched out with a set of blunt wad punches.
I accept nobody has had a problem so far with the washer material so far but RGM has set themselves up as the manufacturer and design authority for this kit, nobody designing brake system components would select a seal in nitrile, it's a pointless risk to take with what is pretty much the only safety system on a motorcycle. The only reason it could possibly happen is out of ignorance which is quite scary.
I'm also not convinced about the reason why they have to fit an adjustable pusher, there seems no accurate register for setting the insertion depth of the sleeve.
(got one of those mechanical engineering degree thingies as well
)
I accept nobody has had a problem so far with the washer material so far but RGM has set themselves up as the manufacturer and design authority for this kit, nobody designing brake system components would select a seal in nitrile, it's a pointless risk to take with what is pretty much the only safety system on a motorcycle. The only reason it could possibly happen is out of ignorance which is quite scary.
I'm also not convinced about the reason why they have to fit an adjustable pusher, there seems no accurate register for setting the insertion depth of the sleeve.
(got one of those mechanical engineering degree thingies as well
)
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Rich
Good response and I am in general agreement. The RGM washer was quite franlkly crap and wasn't even round on it's outer diameter but it's sat in compression (if you assemble it under load via torque ). Yes there are questions re design and design authority but I feel able to make those judgements having looked at the kit and understanding it. I did call them (RGM) to clarify the instructions as regards to how deep to drill the bore (the instructions are ambiguous) and the answer was dodgy to say the least. Essentially as long as the brass liner fits deep enought to compress the washer then the ragged O/D doesn't matter as it''s sealing just around the through hole (not on the O/D).
To be fair RGM do offer a pressure testing service for the ones they rebuild...
Good response and I am in general agreement. The RGM washer was quite franlkly crap and wasn't even round on it's outer diameter but it's sat in compression (if you assemble it under load via torque ). Yes there are questions re design and design authority but I feel able to make those judgements having looked at the kit and understanding it. I did call them (RGM) to clarify the instructions as regards to how deep to drill the bore (the instructions are ambiguous) and the answer was dodgy to say the least. Essentially as long as the brass liner fits deep enought to compress the washer then the ragged O/D doesn't matter as it''s sealing just around the through hole (not on the O/D).
To be fair RGM do offer a pressure testing service for the ones they rebuild...
That's stirred things up! I guess the design and installation will be proven one way or another when the first one fails, god forbid. From what I was told more than 400 had been completed when mine was done in 2005. Since I had the supplier bore and install mine I haven't seen the parts and unless there is an issue won't be pulling the MC apart. I didn't know the pusher was adjustable and I suppose that alone could raise eyebrows as to the accuracy of the conversion. Though, to be fair there are older automotive systems which are adjustable for clearance and stroke to allow full return of the piston and maintain minimum play on initial takeup, similar for Mk3 rear cyls? I suffered total brake failure on an old car many years ago and wouldn't want to experience that again so in Rich's or FF's opinion is that even remotely likely with this conversion? Seems not but who knows?
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Keith1069 said:
My own Mk3 kit does not have an adjustable pusher. The adjustable pusher may be a later modification, or the complete assembly could be different now?
Keith1069 said:
The sleeve sealing washer appears to be a fibre type in the photo which also shows the non-adjustable pusher, the same as the one fitted to my Mk3's conversion kit. Although RGM did my conversion, their DIY modificaton instructions that I have, refers to a "fibre washer".
(RGM photo)
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FastFred said:
Synthetic DOT4 and 5.1 is still glycol-based fluid, apparently:
http://www.nielsencdg.co.uk/acatalog/in ... _7190.html
http://www.commaoil.com/productsguide/f ... ea8c3103db
http://en.wikipedia.org/wiki/Brake_fluid
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Nitrile seems to be ok with glycol according to this guy...
http://www.rlhudson.com/material_profiles/nitrile.htm
http://www.rlhudson.com/material_profiles/nitrile.htm
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FastFred said:
However it also says:
"Nitrile does not perform well in:
.
.
.
•Automotive brake fluid"
Some useful O-ring info:
http://www.pspglobal.com/polymers-elastomers.html
FastFred said:
.. I am trying to contact RGM for an order since more than a couple of weeks, but I am still waiting for a response..
this is the email I am using: info@rgmmotors.co.uk .. do any of you know if there's another email address to use? :|
thanX!
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