P11 Special... CRS front end and brake

More shiny parts on the way for my P11 Special. I'm waiting for CRS GP35R forks, and a 230mm Ceriani replica drum brake in a 1.85x18 Borrani WM2 wheel to show up.

The bike currently has a Betor front end with the stock P11 7-inch SLS brake and a 19" chrome wheel. Nothing really wrong with it other than it really does not stop all that well with the little brake.

The GP35R forks are externally fully adjustable, and the brake is an 9-inch 4LS brake.

This is the first time I've installed a 4LS brake on a motorcycle. To be honest it is sort of a PITA figuring it all out. Disc brakes are a lot easier find parts for, and are cheaper to put together. Possibly lighter, but then again maybe not. And last but not least, more than likely safer to modulate at pace. A really good drum brake will probably take some getting accustomed to. Disc brakes just kind of work. I went with the drum for nostalgic I'm not sure why reasons.

Once I get the parts on, I'll update this thread with what I thought about it all. For now the images below are what I'll be pulling the front end off of except for the triple clamps. Those will be used with the new forks.

A disc wudda spoiled the bike IMHO. Can’t wait for your updates !

Fast Eddie said:

A disc wudda spoiled the bike IMHO. Can’t wait for your updates !

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Yeah, it would have been a period look leap in a funny direction with the discs. However, I keep saying to myself, "Damn this would have be easier with discs". It's been a head scratcher figuring it all out, and making the control parts I've gotten so far function smoothly, but I'll get there. Thanks for the help on venders from you and Ralph.

I can't wait for my updates either. Got a little delay at the wheel builder due to I'm not sure. Covid supply chain issues is the usual excuse. Probably won't have the big pieces for another week or more.

I fitted a GT 750 Suzuki 4ls to the front of my BSA A10
Had to modify the sliders, make the cables and a balance bar for the lever but the bike is at least usable now in the road conditions we now have
Unlike the SLS that it had before
Strangely the TLS 7" on the front of my Indian Enfield is superb

Oooh baz - GT 750 4LS drool those are the bomb. I am going disc on my N15CS, yeah the look will be a clash with the period correct folks but so what, I'll live with the swords and daggers. It'll be a goer (and a stopper, hopefully), not a shower anyway. We all have to do what we can given our circumstances and I got a nearly free set of front lowers and disc from an early Commando. Anyway, nice bike and nice looking brake Schwany. Giving me ideas as I have a spare vintage NHK steering damper sitting on a shelf off of my Suzuki GS1100 turbo.

baz said:

I fitted a GT 750 Suzuki 4ls to the front of my BSA A10
Had to modify the sliders, make the cables and a balance bar for the lever but the bike is at least usable now in the road conditions we now have
Unlike the SLS that it had before
Strangely the TLS 7" on the front of my Indian Enfield is superb

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Sounds good. I thought about salvage, but did not go that route.

I may have to make one longer cable between brake lever and splitter, and have to make some brackets for the fender and the cable adjuster/stops.

I was originally planning to order a 4LS 180mm (7") Ceriani replica brake, but the vendor said it would not be enough brake on a Norton. The 7" brakes are better suited to motorcycles up to 350cc according to him. I believe that to be accurate, but realize his audience is mostly the historic road race crowd. Anywho, bigger is generally better with brakes.

gpzkat said:

Oooh baz - GT 750 4LS drool those are the bomb. I am going disc on my N15CS, yeah the look will be a clash with the period correct folks but so what, I'll live with the swords and daggers. It'll be a goer (and a stopper, hopefully), not a shower anyway. We all have to do what we can given our circumstances and I got a nearly free set of front lowers and disc from an early Commando. Anyway, nice bike and nice looking brake Schwany. Giving me ideas as I have a spare vintage NHK steering damper sitting on a shelf off of my Suzuki GS1100 turbo.

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I chose the 230mm 4LS brake after a lot of getting up early in the morning to think about it days. I had to remind myself that my bike is supposed to be a sleeper build. It looks tame, old, and slow. Looks are deceiving. Best keep it that way. Lots of people prefer the disc brake look on older bikes. I don't think it's a big deal to break the period correct rules. I was going to do a single disc on a Don Pender disc wheel. In the end I wanted to stick to my original sleeper theme.

The pics in this thread are before install. After install is going to be in a couple of weeks I think. That front brake shown would work nice on a bicycle.

Have fun with the drum to disc conversion. Steering dampers are nice. I never go fast enough these days to get much out of mine. I should have installed it 30 years ago when I bought it. Actually it might have been given to me. Can't remember.

Parts arrived. It's not a bolt on setup using my triple clamps, so it'll be a while before I'm finished.

Lesson learned in this situation is an old one. You can pay a little more up front and save a lot of money (personal labor) on the back end. I paid less on the front end with the CRS solution. Good thing I don't have to pay myself to get everything together and make it all work.

I did get some stickers this time.


Bright and shiny


Just getting started. Many hours of fitting and making one thing or another remain before I get to go for a ride.
This 4ls brake is a stopper. It is not particularly light weight. Probably added some weight, which I don't like to do. Fortunately, most of it is down low.

You might wanna up the horsepower to push that lot around ;-)

EstuaryBoy said:

You might wanna up the horsepower to push that lot around ;-)

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I'll weigh the two wheels complete later to find out how much more weight I added. I doubt it is that much. Huge improvement in braking though.

The old horse makes more power than I need as it is. This brake will level the power to weight ratio playing field.

Wrong I am about the weight increase of this brake being minimal. The big 9" 4LS stopper lump on the front axle is a lot heavier than the 7" stock SLS brake. +5lbs

The brake is installed and functional. Only took me about 15X longer than I thought it would because CRS only supplies the major components. I had to chase down and or make parts to finish the job.

The 9" 4LS brake doesn't look that big with the fender in place and the bike on the ground.

I haven't had a chance to take it out for a spin to bed in the shoes and see how the forks work. I only ride in good weather, and it is raining here.



More info later after I get a chance to ride the bike and take a pic of the bike in the sun.

Schwany said:

The brake is installed and functional. Only took me about 15X longer than I thought it would because CRS only supplies the major components. I had to chase down and or make parts to finish the job.

The 9" 4LS brake doesn't look that big with the fender in place and the bike on the ground.

I haven't had a chance to take it out for a spin to bed in the shoes and see how the forks work. I only ride in good weather, and it is raining here.

More info later after I get a chance to ride the bike and take a pic of the bike in the sun.

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That setup looks the nuts

Looking good.

FYI, I have a disk and therefor only use the mudguard stay for the mudguard (Fender?), halfway through my first season with the forks, I noticed the mudguard was out of line with the wheel. It turned out the collar had moved, it is asking a lot of the very small grub screw. I can't remember who told me but somebody in the paddock said I should locktite the collar to the legs, it hasn't moved since.

I know you have a triangulation going on between the drum mount bolt and the mudguard stay collar bolts but I am guessing that you are going to mount the cable on the plate at the back of the forks, I think this will try and pull the collar down when you brake.

I see there are plenty of photos on László's website doing it the same way, so it is obviously a valid way of doing it, even Minnovation do it (it may have been Martin that told me to use locktite, but I cannot be sure) but It wouldn't hurt to clarify with László re the Locktite.

storm42 said:

Looking good.

FYI, I have a disk and therefor only use the mudguard stay for the mudguard (Fender?), halfway through my first season with the forks, I noticed the mudguard was out of line with the wheel. It turned out the collar had moved, it is asking a lot of the very small grub screw. I can't remember who told me but somebody in the paddock said I should locktite the collar to the legs, it hasn't moved since.

I know you have a triangulation going on between the drum mount bolt and the mudguard stay collar bolts but I am guessing that you are going to mount the cable on the plate at the back of the forks, I think this will try and pull the collar down when you brake.

I see there are plenty of photos on László's website doing it the same way, so it is obviously a valid way of doing it, even Minnovation do it (it may have been Martin that told me to use locktite, but I cannot be sure) but It wouldn't hurt to clarify with László re the Locktite.

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I definitely have some things I want to work on later. I eventually plan to cut a set of heftier brake stays out of .25" sheet aluminum and incorporate threaded mudguard mounting holes up higher for a mudguard made for an 18" wheel, as well as drill a hole for access to the grub screw. The thicker brake stay would help with the feel at the bar lever and be a stronger mount for the brake cable stop/adjuster. That is my theory anyway.

I wondered about that grub screw setup on the collar. It is locked down with a translucent blue version of thread locker. I wanted to move the collar up .125" but was concerned that the grub screw goes into a shallow hole. It wouldn't unscrew without some serious force, so I left it alone. If I move the collar up it would give better clearance between the top brake lever and slider, because it would rotate the brake back a little which would clear the first bend in the lever entirely.

Reason for all the clearance BS is my Betor triple clamps have 179.3875mm sanction tube centers, which is narrower than 180mm center triple clamps CRS sells for their brake. The Betor triple clamps are cutting things so close I had to modify the shape of the upper brake lever to clear the sides of the fork slider. If I wasn't such as cheap ass, I would have bought the CRS triple clamps and saved myself a lot of extra work. However, it would have been some work to get the CRS triple clamps to function on my Betor stem. Probably would have had to get a stem made. As you probably know, CRS does not supply anything but the basics pieces. They are not in the business of making bolt-on kits for every bike out there. They are selling race parts for builders.

Side note: The brake would have bolted right up to my Betor forks without the brake lever clearance issue. The Betor forks have the same mount spacing for the brake stay, and don't have a bulge in the slider at the bottom. I almost used the Betor forks to make the install simple, but they are nowhere near as nice a set of suspenders as the CRS GP35R forks.

Thanks for the heads up regarding the collars.

Schwany said:

Wrong I am about the weight increase of this brake being minimal. The big 9" 4LS stopper lump on the front axle is a lot heavier than the 7" stock SLS brake. +5lbs

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Hence the popularity of Magnesium for things like this.

I decided to go with an early 1970's disc. For now I plan to use a japanese caliper, but I might switch to a Lockheed repop or something like that later. I am sure I will draw criticism, but hey, my avatar is what I started with...

Fast Eddie said:

Hence the popularity of Magnesium for things like this.

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I thought about getting the version with magnesium plates but right or wrong listened to the comments about magnesium getting brittle with time. The magnesium version would have been +2.6lbs rather than +5lbs. I don't think I'll notice it that much, but then I have not ridden it with the brake yet either.

With the change from the Koni shocks to the CRS shocks the total weight gain with this wheel and brake is around 2.5lbs. If I had gone with the magnesium brake, it would be zero gain. If I had gone discs, I would have saved some weight.

I had to clean the plates with lemon juice and baking soda. Grimy fingerprints and some shop chemicals stained them. If the magnesium plates would have looked like that, I would not have enjoyed dealing with it. I have other complaints about the wheel brake combo, but I'm holding back until I get out on the road and up to speed to find out if my niggles matter much.

Junglebiker said:

I decided to go with an early 1970's disc. For now I plan to use a japanese caliper, but I might switch to a Lockheed repop or something like that later. I am sure I will draw criticism, but hey, my avatar is what I started with...

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A disc is a good option in my opinion.

If I installed a disc setup on my P11, I would go later model rotor and caliper, and skip the 70's entirely. That's just me though. The only critic I listen to is myself.

Magnesium brake plates are, as you rightly point out, only a minimal saving.

Full magnesium hubs are a different kettle of fish… very light.

You’re right tho, magnesium does degrade faster than aluminium. The guys racing 60+ year old Manx’s are getting concerned about that now.

If being able to still use the same drum in 60+ years is a concern, magnesium might be best avoided…