Brake Pedal Ratios
- Thread starter Danno66
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My $.02
US cars tend to use a 6:1 Brake peddle ratio.
They also use Brake master cylinders with sizes of 11/16", 7/8", 1" and 1 1/8"
AND, they tend to have BOOSTERS, more often than not.
British cars seem to use a peddle ratio of around 4:1
They also use master cylinders from 5/8" to 7/8".
Seems to me it's 6 of one and half a dozen of the other...
OR, what master size range do you want to use?
DW
US cars tend to use a 6:1 Brake peddle ratio.
They also use Brake master cylinders with sizes of 11/16", 7/8", 1" and 1 1/8"
AND, they tend to have BOOSTERS, more often than not.
British cars seem to use a peddle ratio of around 4:1
They also use master cylinders from 5/8" to 7/8".
Seems to me it's 6 of one and half a dozen of the other...
OR, what master size range do you want to use?
DW
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- 367
Without changing the master (15/16), going to a higher ratio (6:1) will reduce the peddle pressure needed.
Using the same ratio (4:1) peddle, Reducing the Master bore size does the same thing.
15/16 is a very large master size with a 4:1 ratio, it should give a FIRM peddle.
Using the same ratio (4:1) peddle, Reducing the Master bore size does the same thing.
15/16 is a very large master size with a 4:1 ratio, it should give a FIRM peddle.
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I was planning on using the stock pedal with the 15/16 master as it would need no change, but the shop( whom I trust ) and the Wilwood tech keep calling for the 6:1. I’ll be checking in with them in the AM.
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With standard Sunbeam peddles (4:1), I like a soft peddle and use a 3/4" master.
Some like a firmer peddle and use a bigger master size.
a 7/8" master size, with no booster, makes for a VERY Firm peddle.
With bigger diameter Brake rotors, the peddle pressure should be less,
for the same braking as a smaller Dia rotor.
Changing JUST the peddle ratio up, 4:1 to 6;1 will reduce the peddle pressure.
Big questions.... what do you have now ...and what do you want?
BTW, the Tom H MODTIGER 6:1 peddle moves the peddle down, lower than the Clutch peddle.
Some like a firmer peddle and use a bigger master size.
a 7/8" master size, with no booster, makes for a VERY Firm peddle.
With bigger diameter Brake rotors, the peddle pressure should be less,
for the same braking as a smaller Dia rotor.
Changing JUST the peddle ratio up, 4:1 to 6;1 will reduce the peddle pressure.
Big questions.... what do you have now ...and what do you want?
BTW, the Tom H MODTIGER 6:1 peddle moves the peddle down, lower than the Clutch peddle.
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- 118
Thanks for the info, at this point a stock master and pedal. I had ordered a 7/8 master to work with the stock ratio. I’ll pass the 3/4 option on to the workers and go from there. I’d prefer not to modify the pedal if I can. What sucks is the “Kit that fits Tigers” from Wilwood had a master that in no way would have fit. Therefore the scramble to figure out a cure.
Is the problem that Wilwood do not offer a Tiger appropriate master cylinder? MC choice depends on what you are trying to achieve, individual preference, and the combination of components. The individual brake system components are all interrelated, and must be viewed as a total system, rather than as isolated factors. I have settled on a .75 bore MC, no booster, standard pedal ratio, and proportioning valve; with the Wilwood Tiger kit on the front and 54mm single piston callipers on 11" rear rotors.
I have the pedal force design calculation somewhere in my notes, but knee dyno feedback is reasonable. You will need a new dual circuit MC anyway, so why not just pick a .75 one that gives the desired leg force and "feel" rather than fiddling with expensive pedal mods? Not as sophisticated as a ratio to match the system components, but works well. Not surprisingly, most Owners have settled on the .75" MC bore size.
I have a new dual circuit .875 bore MC you can have for the cost of shipping, but I would bet that you will not like the leg effort and feel.
As an aside, my motorcycles all have adjustable ratio Brembo master cylinders, and on a bike one can also vary the inter-axial ratio; or finger to fulcrum distance. This allows fine tuning of ratio in relation to the MC bore size.
I have the pedal force design calculation somewhere in my notes, but knee dyno feedback is reasonable. You will need a new dual circuit MC anyway, so why not just pick a .75 one that gives the desired leg force and "feel" rather than fiddling with expensive pedal mods? Not as sophisticated as a ratio to match the system components, but works well. Not surprisingly, most Owners have settled on the .75" MC bore size.
I have a new dual circuit .875 bore MC you can have for the cost of shipping, but I would bet that you will not like the leg effort and feel.
As an aside, my motorcycles all have adjustable ratio Brembo master cylinders, and on a bike one can also vary the inter-axial ratio; or finger to fulcrum distance. This allows fine tuning of ratio in relation to the MC bore size.
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- 333
I'm going with a very similar setup with Wilwoods all around, Courier M/C, proportioning valve and stock pedal. I hope to have it on the road in a few months and will get real world experience then.
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Latest update…The shop and I agree on the 3/4 master and stock pedal. Looking at the Wilwood catalog, hoping to get refund, I don’t find a remote master with the double outlets and up and down mounting holes. So, back to catalogs to find a winner. I’ll keep you all informed and save whatever part numbers used for later referenc.
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As stated elsewhere, There is a potential for fluid starvation as the available master volume tries to keep up with the larger slave demand in the Wilwood's. Highly suggest a 3/4" tandem master like the Courier, etc. It mounts vertical in the same Rootes holes.
IvaTiger
Gold forum user
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I am not using Wilwood cylinders
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I played the on-line search game and found a few good options. There is a Carquest warehouse in town, and I have a connection. Should be no problem to find a vintage master to use. Thanks for all the help.
I just replaced the entire brake system on my 65 MK1, less the brake lines. The rear cylinders have this ridiculous 3 clip retaining system with the two U clips being pot metal, and broke easily! I replaced them with the Triumph Spitfire all steel 2-clip system. FYI, the pedal attachment to the master cylinder push rod is cumbersome due to the pedal return spring retaining setup. The EASY way to do this is use two zip-ties to hold compression on the spring during install then clip them off.
British engineering from the 1960s is fun~!~!
British engineering from the 1960s is fun~!~!