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Dual master cylinders on a Mk2 Golf?

Posted by Mr. K 
phlat65
Sean Medcroft
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Re: Dual master cylinders on a Mk2 Golf?
November 19, 2010 02:46PM
some people just enjoy working on their cars, are motivated to finish them, and dont lolygag about and do a bunch of extra unnecessary shit. then we go play in the woods.

I can easily make $100+ an hour doing side work at home. I would rather build my own shit instead.
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NoCoast
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Re: Dual master cylinders on a Mk2 Golf?
November 19, 2010 04:34PM
I still remember when one Canadian rally guy that I was talking to was telling me how he actually enjoyed everything up to the actual driving part. Now he just builds rally cars and works service.

There are aspects of filming rallying that I like more than driving.

Everyone has their strengths. It's maximizing those that's important. I'm not rushing out to build a new rear beam or control arm, not because I could not, but because I know someone else already is.
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BJosephD
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Re: Dual master cylinders on a Mk2 Golf?
November 19, 2010 07:49PM
Quote
NoCoast
The wage I put on my free time is around $75 per hour.

i dont get out of bed for any less the $8.75 per hour, thats good money here in maine.
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Dazed_Driver
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Re: Dual master cylinders on a Mk2 Golf?
November 19, 2010 11:18PM
Well, technically, you could be paying someone else to clean house, lol..

I really only meant this in the "buy vs build" argument. Sure, technically you can make it applicable for everything, but certain things are worth doing yourself, IE, cleaning and mowing.

I like this example. I can build a roll cage. I've done it. It took me forever. If I did it again, I'm sure it would take MONTHS less time, however, its not worth my time. I would rather pay someone and get a much nicer cage, quicker.

Stuff like that makes sense to farm out. I see building a pedal box in the same light. I could build one (I actually did, and while it didn't take that long, at all) I would rather buy one if I did it again.

I would NOT pay for someone to stitch weld a car, or do paint prep, or clean off undercoating, or assembly. I wouldnt pay some one to fabricate the brackets for the rear end for the 4 link, etc. Small jobs are quick, they're easy. I can do them efficiently and not waste my time. But something I'm just not that good at, I would rather pay someone who is then spend time learning to build something I realistically wont build a lot of times. The investment is not worth the return, as John stated.
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Greasecar
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Re: Dual master cylinders on a Mk2 Golf?
November 20, 2010 06:00PM
My MK1 has dual a master setup with stock pedals. The whole assembly is mounted to the fire-wall and the balance beam is external (unlike Chad's). I don't know why the photo is so big.





Edited 1 time(s). Last edit at 11/20/2010 06:02PM by Greasecar.
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Mr. K
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Re: Dual master cylinders on a Mk2 Golf?
November 22, 2010 01:52PM
Thanks for the photo Justin! Looks simple yet effective. Interesting how you used the side mounted M/Cs rather than the flange mount like the off-the-shelf versions.

Another noob question related to this: how does the rod from the brake pedal connect to the balance bar? Was too busy at Tall Pines to take a look at different setups this past weekend...

Now to decide if this component is the sort of thing to use my limited fab skills on ;-)
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Tom B
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Re: Dual master cylinders on a Mk2 Golf?
November 22, 2010 03:13PM
Cosworth
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Re: Dual master cylinders on a Mk2 Golf?
November 24, 2010 02:26PM
The problem with making your own pedal assembly by cuting and welding is then the geometry of the system. Its not just expenssive for the materials in it. Its in fact the engineering time put into it. A badly designed/made pedal setup will have you chase hell with brake problems that will never be resolved and you'll end up changing suspension setups, brake bias, pad compounds etc etc just because the pivot points were made wrong.

Everything is easy to make if you're just slapping parts together, if the balance bar tube is not perfectly square then the car will have everything from bias migration mid braking point to brake drag, also the mc rods not being perfectly parallel will create hysteresis and bias migration with pedal travel. Also having the bar centerline go past the pivot will give you mushy feel due to the loss of leverage.

And for those that dont know, the typical bias migration on a good push type pedal box with the rods tuned perfect is 2-3% in line pressure bias, if it has rear pivot mc's then its about 1%. A pull type box will have less than 1%. Now this is ON ENGINEERED Tilton/AP pedal boxes and with the rods setup right, now if its one of those clubman type boxes the migration is even more on order of 7-11%, and then if its something home made with fence pipe type engineering then all that you're doing is wasting time, money, and performance. Because the OE system works pretty good as it is.
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Greasecar
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Re: Dual master cylinders on a Mk2 Golf?
November 25, 2010 09:23AM
I'm pretty sure my box was also made by Cascade since this was Pete VanBogardt's old car. Here is another photo where you can see the top of the box.


The same design could be done using the flange mounts (like in Tom's photo). The shaft from the pedal uses a clevis joint on either end and a threaded extension rod. The aluminum pivot you see the top of in the photo holds the balance bar. I'll have to see if I have any more detailed photos on my other computer.
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john vanlandingham
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Re: Dual master cylinders on a Mk2 Golf?
November 25, 2010 12:16PM
Quote
Cosworth
The problem with making your own pedal assembly by cuting and welding is then the geometry of the system. Its not just expenssive for the materials in it. Its in fact the engineering time put into it. A badly designed/made pedal setup will have you chase hell with brake problems that will never be resolved and you'll end up changing suspension setups, brake bias, pad compounds etc etc just because the pivot points were made wrong.

Everything is easy to make if you're just slapping parts together, if the balance bar tube is not perfectly square then the car will have everything from bias migration mid braking point to brake drag, also the mc rods not being perfectly parallel will create hysteresis and bias migration with pedal travel. Also having the bar centerline go past the pivot will give you mushy feel due to the loss of leverage.

And for those that dont know, the typical bias migration on a good push type pedal box with the rods tuned perfect is 2-3% in line pressure bias, if it has rear pivot mc's then its about 1%. A pull type box will have less than 1%. Now this is ON ENGINEERED Tilton/AP pedal boxes and with the rods setup right, now if its one of those clubman type boxes the migration is even more on order of 7-11%, and then if its something home made with fence pipe type engineering then all that you're doing is wasting time, money, and performance. Because the OE system works pretty good as it is.

Well people gotta try if they are ever to learn.
Somebody made the first pedal box.
Then they learned to make it better.
And better..

The logical conclusion to what you suggest is for people to become good obedient consumers.

And to simply shug when somebody says "we don't have something for____" and say "Like,.............whatever, I guess"
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KTurner
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Re: Dual master cylinders on a Mk2 Golf?
April 29, 2011 08:54AM
bringing the thread back with some picts of the pedals we put together for my impreza. its pretty much a copy of tiltons pedal box measurements applied to a stock subie pedal box:


installed;


The numbers I got from using "mikes brakes" worksheet if anyone wants to double check. I haven't had a lot of time to run around with the car but everything seems pretty good so far. Testing at Summit Point in a couple weeks.

Vehicle weight 2550 lbs
Front weight split 60 %
Wheelbase 98 "
CoG height 14 " (a little low??)
Max deceleration 0.80 g
Brake pedal input force 75 lbs
Brake pedal ratio 6.00 :1
Number of masters 2 cyl
Pad coeff of friction 0.50

Front Rear
Wheel rolling radius 11.8 11.8
Effective braking radius 5 5.2
Brake calliper type 2 2
# of pistons 1 1
diameter ("winking smiley 2.12 1.5
effective piston area 7.060 3.534

Maximum Conditions Front Rear
weight per tire 911 364
friction force per tire 729 291
ideal force balance (%) 71.4 28.6
brake torque per wheel 8597 3439
hydraulic pressure needed 487 374
master cylinder area 0.462 0.601
brake torque ratio 6.476 2.590
Ideal master diameter 0.767 0.875
Ideal Balance 71.4 28.6

Choose closest match 0.750 0.625
master cylinder area 0.442 0.307
resulting brake torque ratio 6.771 5.077
Resulting balance 57.2 42.8
movement / wheel / 1/64" 0.250 0.180
pedal force 35.9 19.1



Edited 2 time(s). Last edit at 04/29/2011 08:56AM by KTurner.
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biknman
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Re: Dual master cylinders on a Mk2 Golf?
November 06, 2011 10:50AM
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john vanlandingham
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Re: Dual master cylinders on a Mk2 Golf?
November 06, 2011 11:49AM
2.12 and 1.5'' was is der los???

Oh formatting.

And ''closest match to rear .875 is .625'' noch ein mal was sägst du junge?

Und weiter: is there really just 364 lbs on the rear tires?? werklich?



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Edited 1 time(s). Last edit at 11/06/2011 02:45PM by john vanlandingham.
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KTurner
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Re: Dual master cylinders on a Mk2 Golf?
November 06, 2011 02:27PM
Quote
john vanlandingham
2.12 and 1.5'' was is der los???

Oh formatting.

And ''closest match to rear .875 is .625'' noch ein mal was sägst du junge?

Ung weiter: is there really just 364 lbs on the rear tires?? werklich?

yeah, I screwed the "rear closet match" field up. we did run a front .75 and rear .625 this year and it was ok but I am going to switch to a .75 for the rear and balance it out.

the low rear weight is under max braking w/ weight transfer. might be a little exaggerated.

either way the brake upgrade was the biggest improvement we made this year so that we were slowing faster, later and with more confidence.
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