RGM Front M/C Sleeve Kit

I've had cause to bleed my RGM sleeved master cylinder today. I've done it a couple of times before without any problems, but today I could not get the fluid to move out of the master cylinder. I dismantled it, checked the seals, placed the master cylinder in several positions and the piston in three different positions. If I depressed the lever and then blocked the bleed valve on the caliper, released the lever and then removed my finger I got the sound of a vacuum drawing air in.

I have a pressurised bleeding kit which I bought in the 1990's so I tried to pressurise fluid from the master cylinder into and then the feed pipe and caliper. All that happened was the master cylinder slowly filled and then overflowed from the very slight air leaks where the pressure cap seals. I then tried the lever fully depressed all too no avail.

In the end, I attached the pressurised bleeding kit onto the bleed nipple outlet (without the nipple) and I reverse bled the system from the bleed nipple on the caliper and thankfully it worked. I was minutes from ordering a Brembo master cylinder and all of the other bits you need to get such as new switch gear etc.

I'm not really asking a question but relaying my unusual (for me) experience that I have had today in case it is of any help to somebody but I still don't know why I had so much trouble?

L.A.B., I can't quite visualise the bleeding procedure you describe, surely if you hold the master cylinder vertical (disconnected from the bars and switch gear I presume) how do you stop the brake fluid from draining out of the resevoir? If you leave the cap and rubber diaphragm in place you can't put any more fluid in or observe when the air comes out. I am currently struggling with the same issue on my RGM resleeved cylinder, although the last one I fitted on a bike eventually bled OK after a bit of a struggle. I have actually ordered a new master cylinder from Madass, but I would still like to get this one working.

dave M said:

L.A.B., I can't quite visualise the bleeding procedure you describe, surely if you hold the master cylinder vertical (disconnected from the bars and switch gear I presume) how do you stop the brake fluid from draining out of the resevoir? If you leave the cap and rubber diaphragm in place you can't put any more fluid in or observe when the air comes out.

Click to expand...

It's something you need to do in stages, so bleed in the normal way to start with (and I've never found it was necessary to reverse bleed any system) until the system is mostly filled, with the reservoir about half full, fit the diaphragm and cap and release the master cylinder assembly from the handlebar and then use the procedure, the object of the exercise being to work any remaining air bubbles trapped in the circular sleeve cavity out of the master cylinder vent because the vent drilling/s in the sleeve don't always line up with the bleed vent hole in the master cylinder.

After doing it for about a minute, refit the master cylinder and check the feel of the brake, if the brake still feels spongy then repeat the procedure, topping up as necessary.

Thanks Les, that is clear, I'll give it a go today and report back.

Dear Chaps,

I followed LAB's (many thank's Les) suggested method for getting the air out of the master cylinder sleeve which produced some pressure at the lever but not really enough, I then left it overnight with the brake lever tie wrapped back to the bars and the next morning the brake was acceptable, although it comes back a little further than I would like, but I have a lockheed caliper which has larger pistons than the original Norton item, so I should expect the travel to be a bit more. I am not sure what the recommended master cylinder size is for the Lockheed caliper, although one of my chums tried one with the standard bore Norton Master cylinder and reported that it was terrible.

I also received my Madass master cylinder today and I must say it is very neat and physically smaller in a few key areas like the reservoir size, length of cylinder etc. This will make things much easier for me when I eventually put all of the Dunstall equipment, including fairing, on the bike. The standard Norton master cylinder hits the bottom of the tacho with the reservoir on full left lock and the only option is to lower the clip-ons quite a bit on the forks - this is not ideal ergonomics for old geezers with dodgy backs.

dave M said:

I followed LAB's (many thank's Les) suggested method for getting the air out of the master cylinder sleeve which produced some pressure at the lever but not really enough, I then left it overnight with the brake lever tie wrapped back to the bars and the next morning the brake was acceptable, although it comes back a little further than I would like,

Click to expand...

You could try the Old Britts method as you probably haven't got all the air out, although RGM would ask for the brake lever to be included with the master cylinder when they did the conversion as they would bend the lever so the ball end was about 1/2" further from the handlebar.

https://www.oldbritts.com/14_061939.html

While holding the master cylinder vertically in one hand, slowly begin to inject brake fluid into the caliper with the other hand. As you inject the fluid, rotate the upper end of the master cylinder in a circle. Holding the master cylinder vertically and rotating the upper end in a circle which injecting the brake fluid into the caliper ensures that all air bubble will be forced out of the line and into the reservoir.

Click to expand...

dave M said:

but I have a lockheed caliper which has larger pistons than the original Norton item,
I am not sure what the recommended master cylinder size is for the Lockheed caliper,

Click to expand...

Lockheed motorcycle (Lockheed Triumph, AP Racing) caliper pistons are usually 41 or 38mm (Norton is 44mm).
http://www.vintagebrake.com/mastercylinder.htm

dave M wrote;

I followed LAB's (many thank's Les) suggested method for getting the air out of the master cylinder sleeve which produced some pressure at the lever but not really enough, I then left it overnight with the brake lever tie wrapped back to the bars and the next morning the brake was acceptable, although it comes back a little further than I would likequote

Click to expand...

I found that by lengthening the intermediate adjustable fitting that goes between the lever and the end of the piston that was supplied by RGM with my kit, that I could get a lever that barely came from its resting position to nearly full on brake, whereas prior to this, when the length was reduced to the point where the grub screw was flush with the big flat dish, the lever nearly came back to the bar grip.

Obviously if you have air trapped, that wont solve the problem, but I initially thought I had some residual air in my system, but by altering this fitting my lever (which I had played with trying to get a brake) only comes back a few mm before the brake is "on."

Finding this older thread reminded me that I had begun to fit this kit, and gave up in frustration years ago, so I got out the stuff and started again, looking for a better feel on the otherwise stock (except for a S/S hose) system.
Now I have some questions:
1) Why does RGM instruct us to drill out the full length of the bore if we need only 9mm of thread? The unthreaded portion of the sleeve already falls into the bore.
2) Why does the stock MC bore have a tiny hole (about 0.6mm, near as I can tell) and a another 4 or 5 times as large (about 3mm)?
3) If these hole sizes are appropriate, why does the RGM sleeve have 2 holes the same size (which are even smaller than the little stock one)?
3.5) Shd I consider making one of them larger?
4) Is it important to line up the holes in the sleeve with the holes in the stock bore? This is not easy to do while still compressing the seal at the bottom.
5) I could not figure out how to atttach the brake hose without twirling the MC onto it. I feel foolish doing this, but don't see how to leave it loose at the bottom end, without introducing air into the system near the bottom. Should I just bite the bullet and plan to bleed the whole thing?
6) The madass kit looks a lot easier to implement and has 2 conical pushers, instead of 1 cone and 1 o-ring like RGM. Is either design better? RGM kit is 13mm and madass seems to be 1/2".

And here's an observation that might help someone else: I used teflon tape to seal the threads when I was first fiddling with the kit. Coming back to it much later, I found a mucky mess of strings in the "chamber" between the sleeve and the original bore. Some searching reveals a Permatex product 54540 (not cheap!), that's designed for brake fluid jobs like this. I don't think teflon is a good idea for the RGM kit, especially considering the size of the holes in the sleeve.

Mr. Rick said:

1) Why does RGM instruct us to drill out the full length of the bore if we need only 9mm of thread? The unthreaded portion of the sleeve already falls into the bore.

Click to expand...

Are you sure you haven't already drilled it? For a 13mm bore sleeve to "fall" into the original 5/8" (15.875mm) bore, the wall thickness of the sleeve couldn't be more than about 1.4mm and that wouldn't seem to leave enough depth to cut the two external grooves which link the holes in the sleeve to the original holes in the master cylinder.

http://www.rgmnorton.co.uk/buy/13mm-mas ... e_2532.htm

Mr. Rick said:

2) Why does the stock MC bore have a tiny hole (about 0.6mm, near as I can tell) and a another 4 or 5 times as large (about 3mm)?

Click to expand...

http://www.slideshare.net/shaikusmansha ... -of-brakes

21. MASTER CYLINDER Construction and working
22. Master Cylinder • The Master Cylinder is the heart of the hydraulic brake system. • It consists of two main chambers. • The fluid reservoir which contains the fluid to supply to the brake system, and the compression chamber in which the piston operates. • The reservoir supplies fluid to the brake system through two ports. • The larger port is called the filler or intake port and is connected to the hollow portion of the piston between the primary and secondary cups which act as piston seals. • The smaller port is called the relief, bypass or compensating port which connects the reservoir directly with the cylinder and lines when the piston is in the released position.
23. • When the brake pedal[or lever] is depressed, the master cylinder piston moves forward to force the liquid under pressure into the system. • The relief port is sealed out of the system. • The liquid pressure is conducted to the wheel cylinders, where it forces the wheel cylinder pistons outwards. • These pistons force the brake shoes [or pads] out against the brake drums [or discs]. • When brake pedal[lever] is released, the return spring quickly forces the master cylinder piston back against the piston stop. • Because the fluid in the lines returns rather slowly, a vacuum tends to form in the cylinder in front of the piston. • This causes the primary cup to collapse to allow the liquid to flow from the reservoir through the filler port past the piston to fill the vacuum.

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The master cylinder doesn't begin to pump fluid until the 'bypass'/'relief' port is completely covered by the piston seal so it needs to be a small hole.

Mr. Rick said:

4) Is it important to line up the holes in the sleeve with the holes in the stock bore?

Click to expand...

That would be preferable as it should make the sleeved master cylinder easier to bleed but isn't absolutely necessary as the two outer grooves connect the sleeve holes with the original holes but makes it difficult to get the all the air out of the master cylinder.

Mr. Rick said:

5) I could not figure out how to attach the brake hose without twirling the MC onto it. I feel foolish doing this, but don't see how to leave it loose at the bottom end, without introducing air into the system near the bottom.

Click to expand...

With the standard brake line unless you slacken the lower hose fitting then you have to 'screw the master cylinder onto the hose'.

Thanks, L.A.B.
I appreciate the generosity with which you share your remarkable breadth of expertise.
Just as a point of info, the main body of the sleeve (the non-threaded section) measures 15.5 mm OD, and the diameter where the grooves are cut goes down to 14.97-14.98.
So wall thickness is mostly 1.25, and down to about 1mm at the grooves.
As far as I can see, the grooves are redundant, unless they are being used as reference points for the drilling. Or maybe it's just a little easier to keep from breaking off the tiny drill bits with the reduced wall thickness there? Whatever the reason, the entire sleeve must be surrounded by a small chamber full of fluid. Even if you didn't drill it at all past the threaded portion, there wd still be a gap between the 15.88mm (5/8") ID of the stock pc, and the 15.5 OD of the sleeve. This is what makes it hard for me to visualize what's happening.
MIght just get the madass kit so I can quit worrying about it!

Thanks again--
Rick

Mr. Rick said:

As far as I can see, the grooves are redundant, unless they are being used as reference points for the drilling. Or maybe it's just a little easier to keep from breaking off the tiny drill bits with the reduced wall thickness there?

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The only logical reason I can see for the grooves is to connect the holes in the sleeve with the existing holes in the master cylinder as the two sets of holes are hardly ever going line up when the sleeve is screwed fully home.

Mr. Rick said:

Whatever the reason, the entire sleeve must be surrounded by a small chamber full of fluid. Even if you didn't drill it at all past the threaded portion, there wd still be a gap between the 15.88mm (5/8") ID of the stock pc, and the 15.5 OD of the sleeve. This is what makes it hard for me to visualize what's happening.

Click to expand...

I agree that a gap outside the sleeve does defeat the object of the grooves. If there's even a small space between them then air blown into one reservoir port should escape from the other, and I tried blowing into each port of my RGM sleeved master cylinder (using a piece of plastic tube and lung power) but wasn't able to get air to pass between the ports so the sleeve in my master cylinder at least, seems to be a closer fit.

Thanks again, Les.
Always dangerous to challenge authority, but...
I assembled the RGM kit dry and fashioned a tip which fit closely into the filler/intake port, plugged the outlets to the hose and switch, and very easily passed air (not just gas, I swear !) from the intake port to the bypass port, with smokers lungs. Position of the lever/piston made no difference.

I conclude that there is no need to drill the original bore any more than 9mm which accomodates the tappiing job, and further that he grooves are not doing anything useful. If this is correct, and I'm pretty sure it is, the gap between the bore and sleeve becomes just an extension of the reservoir.

I plan to order the Madass kit (although I don't need the hose) and offer a comparison with the RGM kit. Just a preliminary look gives a BIG advantage to the Madass kit:
Rough materials cost for RGM including a hose similar to the Madass kit and including tools to install plus Permatex to seal the threads: $159 plus a whopping $50 shipping from the UK.
Materials cost for Madass kit (tools included and no thread sealer needed): $100 + carriage. Edit: Shipping is NOT free. $30 to California.

Labor in the RGM: make a jig or fixture to hold the M/C for successful boring (drill press mandatory). Bore and tap. Coat threads w Permatex 54540 and fiddle with the Allen key. Keep adjusting the piston pusher until it works. The instruction sheet http://www.rgmnorton.co.uk/csi/1245184/ ... reline.pdf refers to kit 874 which includes this work. But I cd not find any other reference to "kit 874" on the website. Maybe it's free? Very definitely worth sending in your M/C (and lever) and let them do it.
Labor in the Madass kit: Glue the sleeve in and use a hand drill to punch through the sleeve. Same hand drill used to run a pc of fine abrasive inside to remove burs/swarf.

I know I'm working this thread to death. Can't help myself! :roll:

Mr. Rick said:

I assembled the RGM kit dry and fashioned a tip which fit closely into the filler/intake port, plugged the outlets to the hose and switch, and very easily passed air (not just gas, I swear !) from the intake port to the bypass port, with smokers lungs. Position of the lever/piston made no difference.

I conclude that there is no need to drill the original bore any more than 9mm which accomodates the tappiing job, and further that he grooves are not doing anything useful. If this is correct, and I'm pretty sure it is, the gap between the bore and sleeve becomes just an extension of the reservoir.

Click to expand...

RGM fitted the sleeve kit to my master cylinder so it's all a bit of a mystery, and please don't think I'm arguing as, like you, I'm just trying to make some sense of it.

Mr. Rick said:

Labor in the RGM: make a jig or fixture to hold the M/C for successful boring (drill press mandatory). Bore and tap. Coat threads w Permatex 54540 and fiddle with the Allen key. Keep adjusting the piston pusher until it works. The instruction sheet http://www.rgmnorton.co.uk/csi/1245184/ ... reline.pdf refers to kit 874 which includes this work. But I cd not find any other reference to "kit 874" on the website. Maybe it's free?

Click to expand...

RGM used to supply the tool kit if required on a refundable deposit basis. I think they've stopped doing that, now.

Mr. Rick said:

Very definitely worth sending in your M/C (and lever) and let them do it.

Click to expand...

If I remember correctly, I believe RGM has stopped offering this service.

Interesting reading - no problem working it to death. Too important not to :wink:

RGM do charge for fitting the re-sleeve kit and they do them in batches, so could potentially take a few weeks to get done, but what comes back is a ready-to fit master cylinder.
I've had three done now. the first by RGM and the last two myself. They do need to be drilled out to 18mm using a drill press and mounting block, so as LAB says, yours must have been drilled out previously.
You're spot on about the gap between the bore and sleeve just being an extension of the reservoir, and it doesn't matter where the holes end up.

The RGM website still shows the instructions with this:
"PLEASE NOTE. RE-WORKING MASTER CYLINDERS SHOULD ONLY BE UNDERTAKEN
BY PEOPLE WITH THE APPROPRIATE SKILLS AND EXPERIENCE.
WE AND OTHERS HAVE SUCCESSFULLY RE-LINED SEVERAL HUNDRED
MASTER CYLINDERS, IMPROVING THE PERFORMANCE GREATLY. PLEASE
DON'T BLAME US IF YOU MAKE A MESS OF IT. IF YOU WISH US TO DO THE
JOB PLEASE SEND ONLY THE BARE CLEAN MASTER CYLINDER BODY PLUS
YOUR LEVER AND PIVOT BOLT BUT PLEASE NOTE, THESE ARE DONE IN
BATCHES, APPROXIMATELY EVERY TEN WEEKS."

Worth checking though...

I've read of some folks having issues getting theirs to bleed, but mine have all been very straightforward and bled up as easily as any regular master cylinder once installed.

I can't speak for any other alternatives and can't compare.

Thanks again, Les, for sticking with me.
I have sent a letter to RGM, hoping to clear up some of the mysteries..
Will post up their response if I learn anything new.

I ordered the Madass kit, should arrive in a week or so, will try to post a review and comparison later.

B+ : Thanks for the encouragement.. You may regret it!
Agreed it must be drilled for tapping, but to the bottom of the bore, as instructed? Only 9mm of thread needed. Drilling to the bottom only makes the gap bigger.
I don't think I've made a mess of anything (yet) and I like the adjustability of the RGM kit, might even add that element to my Madass install.
RGM also sends a bleeder for the MC, looks pretty handy.

B+Bogus said:

RGM do charge for fitting the re-sleeve kit and they do them in batches, so could potentially take a few weeks to get done,

Click to expand...

Piero said in a previous post: "I asked to RGM to do the job but they answered not now and didnt know when!" so it seems it may take longer than a few weeks or even the "approximately every ten weeks"?

L.A.B. said:

B+Bogus said:

RGM do charge for fitting the re-sleeve kit and they do them in batches, so could potentially take a few weeks to get done,

Click to expand...

Piero said in a previous post: "I asked to RGM to do the job but they answered not now and didnt know when!" so it seems it may take longer than a few weeks or even the "approximately every ten weeks"?

Click to expand...

Quite :wink: