MK II Brake Upgrades on a Budget

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Dan1950

1974 MK II Roadster
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The OEM brakes on my '74 MK II left a lot to be desired.

The rear brake was not responsive and even with a lot of foot pressure and pedal travel, it did not seem to be able to lock the rear wheel.. I replaced the OEM rear brake shoes with RGM MZ Gold high friction shoes and had the drum turned to provide an even surface to bed in the new linings. The radius of the linings was not the same as the I D of the drum and there was not room for the steel slippers for the brake cam. At first there didn't seem to be much improvement but I figured that would improve as the lining wore to provide better contact with the I D of the drum. I rode a few hundred miles using the rear brake for 90% of my stopping. Eventually the linings bedded to the point that I could re-fit the steel slippers.

The front brake was rather dismal for a disc brake. The lever was hard and provided little feel. Even with significant grip pressure on the lever, there was not a lot of response as far as stopping.

I rebuilt the caliper with new SS pistons and seals. I replaced the OEM pads with FERODO Platinum. A new 13mm master cylinder with mirror mount was installed and a new braided SS hose was used to connect the components. Since the entire system was new with the caliper thoroughly flushed and cleaned, I opted to use DOT 5 silicone brake fluid. Even after repeatedly bleeding the system, the lever seemed a bit soft over the first bit of travel but was firm after about 1/2 of the travel. I discovered this to be an asset once I rode the bike.

MK II Brake Upgrades on a Budget



The performance of the brakes was transformed dramatically.

The rear pedal now seemed to be firmer due to the fact that it took much less foot pressure to initiate rear wheel braking. The rear wheel can now be locked up if enough foot pressure was applied.

It was the front brake however that showed the most dramatic improvement. The seemingly "soft" lever provided (now) much needed "feel" as it took little pressure to get effective brake response. Even with a few semi-quick stopping efforts, I never had to apply more than moderate pressure on the front brake lever.

I now feel that I have brakes that are more than adequate for my riding style. In fact, at normal (legal) highway speeds it would seem like maximum pressure on the lever/pedal might result in putting the bike down if I am not careful. I now feel that I must treat the the brakes with respect as they have reserve capabilities for most of my riding habits.

Now, before everyone starts pointing out that my new found brake performance will not compare to modern standards nor would it compare to the more high $$$ upgrades available, I have to say that I am very pleased. I do not feel like I need more "improvements" over the OEM system.
 
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The radius of the linings was not the same as the I D of the drum and there was not room for the steel slippers for the brake cam.

Eventually the linings bedded to the point that I could re-fit the steel slippers.


"PLEASE NOTE
EXPANDER PLATES (SLIPPERS) SHOULD NOT BE REQUIRED WITH THESE BRAKE SHOES"
 
I know they are not "required" but I feel better having a steel wear surface for the cam over the alloy surface of the shoe.

I would have thought the RGM shoes had the slippers already attached as other replacement shoes do?
 
I would have thought the RGM shoes had the slippers already attached as other replacement shoes do?
There were no steel slippers present that I could see. Maybe they are cast into the alloy? Perhaps I should have tested with a magnet.

Never the less, I do not see a downside to having the slippers present now that the radius of the linings has bedded to the I D of the drum allowing enough clearance for the slippers.
 
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Now, before everyone starts pointing out that my new found brake performance will not compare to modern standard nor would it compare to the more high $$$ upgraded available, I have to say that I am very pleased. I do not feel like I need more "improvements" over the OEM system.
That has been my experience as well. A 13 mm m/c and stock caliper with braided hose has been adequate for me for about 20 years now. Better brake pads (Ferodo?) helped too.
 
Do you really ever want to lock the rear brake while riding the bike ? It is usually only ever used to steady the bike. If you lock the rear brake the rear tyre loses traction, which is not good when you are on a lean. The front brake is critical. It needs to be super-strong but progressive with plenty of feel. The front brake on my Seeley is one-finger operation, but it can stop the bike like hitting a wall. I keep three fingers and a thumb around the throttle and my fore-finger on the brake. That way I have instantaneous go when needed and I never hit anyone.
A single chrome-plated disc is not enough for racing. I use two Japanese high-speed steel discs with asbestos pads and a master cylinder which is intended for use with one disc.
 
Dan,

What you need is to find a steep down hill with a sharp off camber right hand hairpin at the bottom. Enter the turn at 70mph. Then you'll know how well that front brake works, or just crap your pants. ;)

I definitely agree with the before statement. I had a early 70's something Commando in the mid-1980's, and the stock front disc was just like what you described. Stiff feel, but didn't work worth a darn. Sounds like you got that under control though. Good on ya.
 
Do you really ever want to lock the rear brake while riding the bike ?
I don't want to lock the rear brake, but being able to approach that limit if needed is reassuring.
The front brake is critical. It needs to be super-strong but progressive with plenty of feel.
I now have that feel and enough brake for my type of riding.
A single chrome-plated disc is not enough for racing.
I don't intend to race. I just want to be able to stop. I don't plan on pushing any envelopes.
 
Dan,

What you need is to find a steep down hill with a sharp off camber right hand hairpin at the bottom. Enter the turn at 70mph. Then you'll know how well that front brake works, or just crap your pants. ;)

I definitely agree with the before statement. I had a early 70's something Commando in the mid-1980's, and the stock front disc was just like what you described. Stiff feel, but didn't work worth a darn. Sounds like you got that under control though. Good on ya.
Wow !!! Brings back memories . Aug 4 2005 .. A last second decision by the group leader to take the highway exit heading back into Lee , New Hampshire .. 70 MPH , off camber and a significant decreasing radius .. I was definitely not anticipating or ready for this . I remember coming out of the turn white knuckled and pale in the face .. Thankfully i had extra underware because brakes would have been a disaster.

Cheers
 
Let's not forget that Norton detuned the front brake back in the day for fear of people locking the front wheel up and claiming off them
 
They did a good job then. :)
Yep they did
Their biggest market was America and blame culture was already taking hold out there so they detuned the front brake so as not to end up with a claim
Or so it was said at the time,I don't know for certain
 
The OEM brakes on my '74 MK II left a lot to be desired.

The rear brake was not responsive and even with a lot of foot pressure and pedal travel, it did not seem to be able to lock the rear wheel.. I replaced the OEM rear brake shoes shoes with RGM MZ Gold high friction shoes and had the drum turned to provide an even surface to bed in the new linings. The radius of the linings was not the same as the I D of the drum and there was not room for the steel slippers for the brake cam. At first there didn't seem to be much improvement but I figured that would improve as the lining wore to provide better contact with the I D of the drum. I rode a few hundred miles using the rear brake for 90% of my stopping. Eventually the linings bedded to the point that I could re-fit the steel slippers.

The front brake was rather dismal for a disc brake. The lever was hard and provided little feel. Even with significant grip pressure on the lever, there was not a lot of response as far as stopping.

I rebuilt the caliper with new SS pistons and seals. I replaced the OEM pads with FERODO Platinum. A new 13mm master cylinder with mirror mount was installed and a new braided SS hose was used to connect the components. Since the entire system was new with the caliper thoroughly flushed and cleaned, I opted to use DOT 5 silicone brake fluid. Even after repeatedly bleeding the system, the lever seemed a bit soft over the first bit of travel but was firm after about 1/2 of the travel. I discovered this to be an asset once I rode the bike.

MK II Brake Upgrades on a Budget



The performance of the brakes was transformed dramatically.

The rear pedal now seemed to be firmer due to the fact that it took much less foot pressure to initiate rear wheel braking. The rear wheel can now be locked up if enough foot pressure was applied.

It was the front brake however that showed the most dramatic improvement. The seemingly "soft" lever provided (now) much needed "feel" as it took little pressure to get effective brake response. Even with a few semi-quick stopping efforts, I never had to apply more than moderate pressure on the front brake lever.

I now feel that I have brakes that are more than adequate for my riding style. In fact, at normal (legal) highway speeds it would seem like maximum pressure on the lever/pedal might result in putting the bike down if I am not careful. I now feel that I must treat the the brakes with respect as they have reserve capabilities for most of my riding habits.

Now, before everyone starts pointing out that my new found brake performance will not compare to modern standards nor would it compare to the more high $$$ upgrades available, I have to say that I am very pleased. I do not feel like I need more "improvements" over the OEM system.
What I did was fit two strips of 80 grit sandpaper inside the drum with masking tape. Reassemble the drum with no lube. Back on the bike and run in first gear on the stand pressing the brake pedal for a while. Pull and inspect. Repeat until you see full contact. Remove, clean thoroughly, lube and reinstall and you are all good to go.
 
Two switchbacks after this is where my Norton disc brake gave up the ghost and I nearly went over an 800' high cliff.
Strangely, a 47 Vincent just ahead that was setting the very fast pace had no problem.
I've done the ride since with the Madass brake fitted. Two finger braking and no fade, what an improvement!

Glen

 
Two switchbacks after this is where my Norton disc brake gave up the ghost and I nearly went over an 800' high cliff.
Strangely, a 47 Vincent just ahead that was setting the very fast pace had no problem.
I've done the ride since with the Madass brake fitted. Two finger braking and no fade, what an improvement!

Glen


Vincent pilot using more engine braking?
 
I don't think so. We were pretty much in lockstep, hitting brakes and throttle at the same points. He and I have ridden about 25,000 miles together.
When you look at the brake swept area ( there's a Wayback term from Popular Mechanics!) I'll bet the Vincent has ten times the friction area, with its dual brakes fore and aft.
I've never been able to overheat the Vincent brakes on any of these mountain roads, even two up and really pushing it.
The old Norton just has those two 50 cent piece sized discs, how could anyone have expected that to work well?
I'm amazed that the stock Norton disc works at as well it does.

Glen
 
The soft brake lever feel is indicative of micro bubbles trapped within system the stock caliper and MC are commonly hard to bleed fully. Mine was same after full rebuild, sleeving to 13mm MC. After much, much effort, reverse bleedings, overnight waits with lever tied fully held in, etc etc, after several days of no joy, what finally solved it was my rapid flicking the lever in much frustration, like 50+ times, while watching the fluid in the MC from above. Eventually saw two or three micro bubbles float up out the tiny holes in the reservoir bottom. Lever was then nice and firm, has remained so for three season with regular fluid changes.
 
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