Master cylinder 'hot nail' upgrade...

I did a search for the 'hot nail' upgrade to what I understand is the trap valve.
I have not seen any photos of the parts involved so I thought I'd ask the specific question again.

I see reference to using a red hot 6 penny (6d) nail. A 6d nail is 0.12" diameter. How was this hole size the determined?
Should the hole be enlarged on both the plastic trap valve and the rubber secondary cup?

I normally don't do critical brake work modifications just because somebody said so on the internet, but I have some extra parts and there is 15" of snow on the ground outside.

Thanks for any specific comments you may have.

The problem with the stock master cylinder is that it is too big. No manner of hot nails is going to change that.

Not something I'd do to my bike.

JimC said:

The problem with the stock master cylinder is that it is too big. No manner of hot nails is going to change that.

Click to expand...

Pretty much sums it up. Enlarging the opening will increase the FLOW, but not PRESSURE. The brake may bite a split second quicker when applied, due to faster flow, but cannot possibly do any more than that.

First off its a hobot mod so will definitely kill you like it did me, ask anyone. If ya try any other way the hole just closes back up or becomes a ragged mess.
Bob the red hot nail is to destroy the tiny orifice in the biggest softest boot like trap valve thingy. Nail needs to be big enough it leaves a nice big hole that can not offer any Restriction or Resistance to flow or pressure pulse of a panic grip. I left the trap valve in as seems its part of the return spring tension spacing and we do want the piston to retract promptly on let offs. No re-sleeve kits have any restrictor at all so it not dangerous at all.

If will not change the ratio but by golly it will squeal or lock up the tire afterwards if serious enough while prior even white knuckled panic adrenalized grip only dragged speed down and was unable to over tax front traction on pavement.

i get a grin each time I first grip brake a little bit for the definite right now sure slowing action. W/o the dang hole I am not ever fitting a 100 size front again as only lasting about 2 rear tires, getting a flat center instead of triangle slab side wear first 3 or 4 rears later. Only one other fella tired this and told me, he complained to me it was not that great a help as only made his stopping about 1/3rd shorter and he no longer had to plan ahead on turns but still had to grip hard to do so, not two finger action like his moderns. Try it if ya dare.

I have done hobots hot nail upgrade. You can read about it here: hobot-brake-mod-apraisal-t14482.html
(sorry don't know how to make a link here)
I had intended to write a follow up after I had more time on the bike, but have only done a few hundred miles since then. I am getting a little more used to the new braking but it was so bad before for so long that I am still in the habit of leaving lots of space and breaking early so I don't use the now better breaking as much as I could. I probably exagerated how hard you have to pull somewhat, you do have to pull harder than a modern but don't need a death grip to get good breaking.
When I cleaned up my master cylinder I ordered the rubber tipped part also just in case hobots upgrade didn't work, so I could go back to stock. I still have it, you could do the same. It is definatly worth a try.

when I first got my bike on the road it was box stock, all original, including the MC. It was low miles (4200) and the rotor still was mostly chrome plated. I've noticed since the chrome has worn off and down to copper now, braking has iproved significantly. To the point that I don't really see a need to change anything right now. why the hell did they ever chrome that rotor?

I've had a stock master cylinder, SS brake line, stock caliper and a ground, drilled rotor. I now have a 11mm Grimeca master cylinder a Grimeca 2P, I think its 41mm, caliper and a 12" floating rotor. Let me tell you, there is a world of difference.

I sleeved mine to 1/2" and put a Harley seal kit and piston in. I left the hot nail part completely out. Don't miss it.l
Jaydee

mightydaj, appreciate your bravery to -thrust & test me and then actually admit it in public. Glad you survived it so far.
If ya want to stick with Norton part numbered items then hobot hot nail stabbing - HNS- procedure will make the brake front *tire traction* limited at hi speed - not white knuckle teeth gritting force limited at even low speed. If you want similar *tire limited* braking with less lever effort then neck the m/c down but get one w/o any restrictor 'valve' in there, hehe like every other m/c out there but factory Norton-Lockheed. Personally after trying 12 mm m/c with SS hose and RMG race lever on Peel with 1.5 lb of rotor flywheel mass removed by Hienz K, vs just the hot nail treatment on Trixie, I now think the main benefit of replacing the Lockheed m/c is the removal of the 'valve' not the moderately increased leverage. Factory m/c ratio is ~17:1, elite moderns ~ < 25:1, 13mm ~ 19:1, 12 mm ~21:1. My SV650 is ~24:1 and must be careful on the non DOT race tire not to skip front out in panic pull downs or practice from 100+ mph - but on Peel and Trixie could nail brake as hard as I could w/o thought or skill over the ton to get ABS like action of squealing I could control, till slowing enough I had to use skill to ease off lever to remain squealing as speed bled down to upper 60's or lock up loosing deceleration time and stability on let offs after a short instant to let tire re grip and bike get settled back in line. Lightened tri-linked Peel could out brake any cycle I've tested so far and stable enough to ride the locked front many bike lengths trying and trying to ease on for a stoppie and not fly right over the bars > if not increasing brake effort some to fully lock up slide or let off in time not to get run over by Peel. Factory Trixie is not able to tolerate these race level loads [d/t floppy eared untamed isolastics jiggles into end swapping antics] but is still as good or better a stopper than my SV650 or other moderns I've tested, that tend to stoppie in stead of just slide or slow down like Trixie. I think the 'valve' was put in so drum brake imprinted users would not be suddenly falling down right and left with a surprise panic grip. I have scared a few folks and me pulling UN-intended stoppies at gas pump stops on my SV650 after ridding Peel who I had to be set like a dog dragged into the Vet or end up in front on the ground.