Although I have a large hand, I battle to get my little finger around the brake lever as it sweeps away from the hand grip, Dupytrens contracture not helping. The brakes are definitely still not a two finger operation. I took the bike for a very pleasant test ride on nearby quiet country roads letting it gently accelerate up to about rpm which must be approaching 90mph and giving it some solid stops. I am now mucking about shimming the contact pad of the brake lever trying to bring it closer to the grips to make it easier to grab in an emergency.
Short of fitting a second disc are there any other improvements I can make to the brakes? I have heard that the Ferodo Platinum brake pads give the best results. Does anyone know if it is true? Joined Feb 27, Messages 3, Which unit do you have?
These are all different approaches to the same end result. I believe Don Pender offers the same option. If you installed the kit yourself, then obviously clearing the bleed holes after boring for the sleeve should be done before the installation of the sleeve. It is possible that the holes became blocked with swarf from the boring process.
The kits should also have been supplied with a new piston. If the piston rusted, this would indicate moisture in the system. I have a Miles cylinder on one bike with the stock disc and caliper with Ferodo Platinum pads. It is an improvement, but I have two other bikes with 13 mm sleeved cylinders, one RGM and one Miles, both with 4 piston Brembo caliper and mm floating discs.
These are an order of magnitude better. I hope this helps. Joined Dec 21, Messages Miles kit doesn't use the second bleed hole. Madass is different, more like the original. I have pics of both but didn't want to post them in fear of pissing someone off. Bought a Andover Norton Master cylinder, no difference. I went thru this months ago! PIA I have bled the break from top, master cylinder , to bottom caliper. Bottom to top. And still have spongy front breaks. The best forum explanation was there is an area in the caliper that will not bleed all the air out.
I have decided to ride the bike and hope the bubble gets moved. Good luck. I have been running a beat up old master cylinder off a Honda CB on my cc Norton now for years and years. It's not too pretty, but I actually like it more than that cludgy giant integrated set up on the Mk. Admittedly, I am not at all concerned with maintaining a 'stock' appearance or any of that - but the real reason it's lived on my Norton for so long is that it works so very well.
Other factors: none, except for no chrome on the disk; otherwise stock caliper, lines and pads with the only drawback being no integrated brake light switch. The bore on the Honda master cylinder is 13mm or thereabouts and is thus smaller: a smaller bore gives higher line pressure for less force exerted and hence better braking. My 'conversion' was this simple Bennett bennett30 earthlink.
Nov Some time ago I started a thread on the list to do with Commando front brakes and subsequently modified mine along the lines suggested by return letters. I acknowledged the success of the project but wondered whether anybody would be interested in the full story. My brakes have been through a few permutations. There was a time when they were just inadequate; that was when you could push the bike forward with the brake hard on. This was followed by the period when the fork seal was leaking all over the pads.
Things improved when I rebuilt the master cylinder and bought a new and shorter brake hose. The brake was a lot better, but still the fastest the bike had ever pulled up was when I was bringing it home on the trailer.
A few months ago I ground 3mm off the actuating end of the lever to bring the lever in closer to the grip. I tapped a small screw into the back of it to adjust free play and this meant I always had a handful of lever in an emergency rather than the tips of my fingers clinging on in desperation.
Somewhere in my trawling through magazines I had come across the notion that the smaller the master cylinder piston in relation to the caliper pistons, the more force could be exerted on the pads. Applying this small bit of knowledge to the Norton brake meant that if the piston were smaller, while it would have to move further to have the same effect: it could place more force on the caliper at the same lever pressure, and maybe produce more braking effect.
I decided to sleeve a Lockheed down and see if it would stop the plot. He made the piston by taking relevant measurements from the Norton and the Kawasaki pistons. There are twin and single disc EXs and this modification needs the single disc kit.
I spent some time looking at the two pistons, the Lockheed and the Kawasaki: they were just so different. In principle I had to take the diameter measurements off the Kawasaki and the lengths off the Norton, but there were complications.
I had to build in the groove for the boot, that was easy; but the primary seal, that's the one that does all the work, is a free floating full cup that sits in front of the piston on the Norton. On the Kawasaki this is a ring cup like the Norton secondary seal. Would this matter? Also, between the primary and secondary seal on the Kawasaki there was a spiral groove. Was this a piece of job justification from a Japanese designer and if not, what did it do? Additionally, at the end of the Norton cylinder is a rubber valve that restricts the flow; the Kawasaki doesn't have it.
What was it supposed to do? In a flash one night I realised the spiral groove was actually a bearing surface, grooved to allow the fluid to pass through. The bearing was necessary as the flange in front of it supporting the primary seal which you would expect to be the bearing surface had to be able to allow fluid to pass over it and past the seal on the exhaust stroke, and consequently could not be a close fit on the cylinder wall.
Another worry was whether there would be enough distance between the two ports in the bottom of the cylinder reservoir to allow the increased travel needed so the smaller piston could still pump the same amount of fluid. The answer meant the piston would have to travel half as far again as it used to. I measured the travel in a standard setup; it was about 9mm - the new setup would therefore need about 14mm.
Comparing the distance between the seals on the Norton piston and the positions of the holes in the reservoir showed there was about 20mm available. In action, the primary cup has to start close behind the primary port, which is small so it doesn't rip the cup as it passes over it.
The hole is there so the fluid in the line and caliper is the same body of fluid as in the reservoir. As soon as you move the lever, the primary seal moves across the hole, closes the system, and then begins to pump fluid down the line. The secondary seal travels behind it and basically scavenges the system, pumping excess fluid back into the reservoir through the secondary and bigger port.
The brake must take up before the secondary seal reaches this port. In the modified brake there is plenty of room but the secondary port could be shifted closer to the primary port if you wanted to use another caliper such as one of the fancy Lockheed ones which probably need more fluid to be pumped than the original. This would only work as long as the primary cup does not reach a travel limit in the bore, such as the compressed spring, before it has pumped enough fluid to put the brakes on.
If anyone ever gets that far please take into account the wear on the pads. Failure to do so could result in an event to be filed under the category sudden frightening experiences at speed with crosslinks to stain removal and the parts list. I produced a drawing of the piston which was duly translated into metal. I was thrilled when the machinist cut it off the lathe and handed it to me. I hurried off home, fitted the seals and installed it on the bike.
The first thing I did was put as much pressure on it as I could, both hands at once in a primitive pressure test.
I then pushed it forward and the instant I touched the brake it stopped dead. There was nothing more I could do without taking it out.
I progressed down the street trying it harder and harder. Satisfied it wasn't about to pop, I rode to a clear area and whacked it on hard. The effect was so dramatic I found myself laughing.
I rode up and down crashing to halt and soon my wrists were aching from the effort of holding on. I found I could make the wheel chirp from about 20 m. The increased lever travel means more feel, so its great on the open road. I used the spring from the Kawasaki kit; it was a little short so I stretched it from 40mm to 55mm.
I have now decided it is not strong enough and intend to wind my own sometime. Without complete confidence in the decision, I left out the flow reduction valve in the end of the bore. This part probably generated more talk than any other aspect of the conversion. I rang Brian Slark who was rumoured to have made this modification at some stage.
When I spoke to him in Alabama he was welcoming and encouraging but had no info. What he did have was insight into the original process of designing the brake. He also said they were worried about young American kids hauling the thing on, losing the front and then sueing Norton. In order to satisfy these worries they cleverly made the brake so it didn't work.
It was clearly enough in the eyes of the sales people to be seen to have a disc. Its a great feeling twenty five years later to experience the brake the Commando could have had, and from the outside no-one can tell the difference. It's now been on the bike for a couple of months, which translates into about miles. So what did it cost?
I now have the piston design as a. BMP file if any one wants to clap eyes on it. Mine is made from aluminium bronze 2, and the cylinder liner is stainless steel, although other materials could be used. Chris Ghent ghent. I run a Mk. On the advice of a Triumph-fan friend, I fitted a stainless Bonnie master cylinder, and greatly improved things.
The only problem I ran into, and it was a serious one, was that the caliper side fork slider wore out. A sturdy fork brace is mandatory if the slider is to have a decent life span. A possible hair-raiser is the small reservoir capacity of the rectangular reservoir Grimeca handlebar master cylinder, which really benefits from filling while level and closing up before mounting to the handlebar.
Whilst I never had any occasion to be scared witless by losing the front brake due to fluid drop compensating for pad wear on the front, it could catch up those who don't check the level once in a while or use one of these on a racer or other bike with soft, rapidly wearing pads. Nowadays, I have one of them on my P11 10" twin disc Brembo front brakes from a Ducati vertical twin and Marzocchi front end and am delighted with it.
Thanks for the input, guys! The Norton Owners Club Limited. Registered in England No. VAT Reg No Norton Owners Club. Search Search. User account menu Log in. RGM master cylinder sleeve down kit! Attachments 5db91bdbeae-bfdea3ac4e-jpeg. Hi Rob, I have recently do… Hi Rob, I have recently done this conversion to both my Commandos and it improved both brakes. Install the app. For a better experience, please enable JavaScript in your browser before proceeding.
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Commando master cylinder re-sleeve. Thread starter mgrant Start date Jul 19, Joined Jul 19, Messages I have a 73 Commando with a Hyde racing front caliper, a 13" Hyde disk and a stock master cylinder that was recently resleeved with a stock 15mm piston.
The braking performance of this setup is pretty bad and requires a huge amount of effort on the brake lever to get adequate stopping. Additionally, the lever has a rock hard feel with very little sensitivity. I have heard that resleeving to a 12 or 13mm piston in the master cylinder will provide more mechanical advantage, which will require less effort to stop and also give better feel. Does anyone out there have experience with this type of a resleeve?
If so, please let me know how it works and where you got it done. I do want to retain the stock master cylinder for looks. I also just read that some racing calipers actually use a smaller diameter piston than the stock unit.
In this case, more lever pressure will be required and by using the Hyde caliper with the 15mm piston, I may have a set up that actually requires more force to stop than the stock set up.
Any thoughts on this? Thanks for any help you can provide. Mike Grant. Joined May 28, Messages 2, Anonymous Guest. Front Brake - Master cylinder What are the symptoms of a worm front brake master cylinder?
I bought my 73 Command with standard front brake master cylinder and a 4 piston front brake caliper. The braking performance is bad. The lever can come back to the bars..
I bled the brakes but the problem remains. I was bleeding the brakes according to the manual but squeezing the lever without the top on the reservoir and the bellows sends fluid squirting out.
I suspect the Master Cylinder is worm or the seals shot. Any comments? Brakes Thanks Dave. I'm off the road until this is sorted. The bike came with the standard caliper in a box Either I return the brakes to original or source another master cylinder. I wil probably do both Thanks for the links. Joined Jul 7, Messages 8. It has new seals, and is easy to do. Use compressed air into the brake fluid hole to blow out the pistons if you cannot pull them out.
This is the most common source of poor front brake performance. You can also rebuild the master cylinder with new seals and a plunger, which is good because the plugers get pitted after 30 years That said, stock caliper and master cyl are pretty weak, even after a rebuild. It will go from "dragging feet on the ground to stop" to "sort of stops, with some effort".
I put a new dual-brake AP Lockheed master cyl onto my stock caliper, and I found that feel was FIRM and much improved from the stock master cylinder, however actual braking performance wasn't hugely improved. Note: I also ground and drilled the stock single front disk Then I upgraded to dual Norvil 12" disks and used the dual-braked AP master cylinder
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