Master cylinder 2 sleave or not 2 sleave

Hi all
Here is a question that I have been getting conflicting reports on. That is the sleeving of the master cylinder bore down to a 1/2" bore size and going to a mod on the piston size to suit. I am trying to get a better stopping feel with the stock Lockheed system on the front disk brake system. I have heard that some units that were replaced with the sleeved modification worked really well… and then there were others that said that they had leakage past the sleeve hmmm????
Right now my Norton front master cylinder feels like I’m squeezing a wooden disk, and I am aiming to rectify this with improvements. I have researched some info… a quick fix by going to a braided line hydraulic hose, which would stop some of the ballooning effect happening with the stock rubber hose.
So if you have made any modifications to your M/C then I would like your input on this subject. Thanks.
Thomas

The answer to your question lies within your own thoughts about sudden impact syndrome . Do you want it to hurt just a little bit or a lot. A braided stainless line will really only help if you do something with the master cylinder. I have resleeved mine and although it made a difference it certainly does not compare with my newer modern bike. I did enjoy the old brake as you could go hard into the corners and apply front brake without ever worrying about spitting out the front wheel. I just figured it was Britians first attempts at ABS . You can resleeve reasonably cheap or buy a new Japanese master cylinder for nearly the same price. The question here would then be , do you want it to still look original. I have not tried one with a Japanese master cylinder so i cannot comment. If the mod on the master cylinder is leaking by then the job was just done wrong. Ask around and get a good listen to what peole are saying about what they have done and are they truly satisfied with the changes.

Thomas
Had my m/cyl sleeved last yr by RGM. I've put 6000 miles on the conversion and with a set of EBC pads and Goodridge hose it really stops......up to the limits of what a 10.7" disc can do anyway. Like others have said before it's the best VFM you can put into the Commando braking system. What else can you do for $90. Only slight downside is a creaking from the contact point of the lever that seems to be the aluminum working against the SS piston. Go for it!
Keith

Hi Thomas,
Here's my (New Zealand) cents' worth!
The 850 is my daily ride to work transport, and, yes, as others have said, the standard brake is not up to modern traffic, especially around town. Some years ago, I switched to a Lockheed racing caliper, soft pads and braided hose. This certainly did not remove the "squeezing a concrete brick" feeling at the lever, and only those with hand strength on par with a Silverback Gorilla could make it stop effectively. I did look at resleeving, but it's a bit pricey on this side of the world. So, I've fitted a Lockheed racing lever - I'm pretty pleased with the improvement for a layout of $60NZ. All that's required is to ream out the mounting bolt hole with a 1/4" drill (as the racing lever has a very slightly smaller bore hole) and it bolts straight on.........the lever is a slightly different shape and the fulcrum point that acts on the standard m/s piston is different, giving more leverage...............highly recommended as a "10 minutes in the garage" improvement. Apparently, the racing lever with a resleeve gives the best results, but I'm now a lot happier blatting around central Wellington with the knowledge I can possibly stop quickly if I have to!
Cheers
Nick

resleeve?

I have a '72 roadster with completely stock disc brake and no complaint about it's stopping ability. I do enjoy the back winding roads, so don't believe I'm a slow rider. My weight is 175lbs and ride solo.

A couple of years ago I sleeved the master cylinder in my '74 John Player since it was leaking and needed a rebuild anyway. There really wasn't much improvement and it was difficult to bleed the air out.

Last month I test rode a 2005 Triumph Sprint ST. The Norton brakes are no comparison to modern.

I put a Magura MC years ago and never looked back!
Philippe

sleeve or not

Nick in NZ,

Curious about the comment that Commando disc brakes aren't up to "modern traffic". I ownedand rode a new '72 combat roadster in southern California in 1973. The roads and conditions haven't really changed. What's happenned in NZ since the early 70s?

Hi David,
Not much, there's just more of it! Specifically, away from the cities NZ is still biking heaven. Around town, like anywhere else, I'm up against cars that can stop and turn on a dime, plus the ones that don't look! The standard Commando brake just isn't good enough for an emergency stop. On the open road, when only the rider is making the decisions, it's less of an issue.
Cheers
Nick

Just finished a rebuild/overhaul on my 75 Interstate, used a Suzuki Katana750 M/C(from ebay 14$) 14mm piston.
It works wonderful, much better response,lower hand pressure.

Bill Edwards

hal20308 said:

Hi David,
Not much, there's just more of it! Specifically, away from the cities NZ is still biking heaven. Around town, like anywhere else, I'm up against cars that can stop and turn on a dime, plus the ones that don't look! The standard Commando brake just isn't good enough for an emergency stop. On the open road, when only the rider is making the decisions, it's less of an issue.
Cheers
Nick

Click to expand...

At least you guys aren't using the '71 drum brakes, which are up to the task as long as you have inhuman grip strength! -- i just gave myself tendonitis of the "right pinky" finger. it is really annoying.

I, like others, replaced my MC w/ a magura and went w/ steel lines - still not great but better than stock by a long shot - the only thing you have to remember is that any replacement besides a resleeved replacement (or new stock MC) requires a different the banjo / nut set up from the stock brake (hench replacing the brakeline - no big deal but a few extra $ - i had a custom one made from old britts for $65)

Thomas. For appearances sake I have retained the original master cylinder, disc and caliper. In standard form it is diabolical, needing far too much effort, as already discussed.
I have resleeved the master cylinder using the RGM kit, fitted a Goodrich stainless brake hose and fitted a Lockheed racing brake lever. This has completely transformed the braking and it is now lighter to pull, more progressive and with vastly superior feel and control. Highly recommended.
It is still nowhere near as good as a modern bike but We have to allow for that. To bring the braking up to modern standards would mean fitting bigger disc(s) and 4 pot calipers. Pricey, but arguably not as expensive as crashing the bike.
However I would strongly recommend resleeving, especially with the hose and lever, if possible.Cheers.Ian

At one of the tech sessions at the national this summer Dyno Dave went through this with us. It seems some RGM conversions work with no problem bleeding or braking. Others have had a time getting the air out and still others getting them to perform right.
It seems that if you are in charge of the machining you can get a very flat bottom that has a good finish. Then when you insert the sheave you don't have to use a washer only bearing lock. This helps get the insert placed so that it does everything better. There is a lot of things that have to line up right to get it working right the first time. We sent out four in one batch Three worked well, one didn't. It's a long way back to RGM from here.

EGAD! And I'm riding around in Phoenix AZ traffic with my stock '71 drum?

Once you've got the front brake working take care as the old TT100 might not be up to the job.