flyingbrick Posted October 19, 2012 Share Posted October 19, 2012 hi all. iv just bought a brake pedal box which mounts 2x master cylinders with an adjustable balance bar above the footwell. there are a number of different sized master cylinders available to fit to this unit but I'm at a loss as to how to choose which is best. what's the potential issues by going too large? increased pedal effort and what? does everyone run a brake boosters these days? iv never driven a car without one - do they exist for comfort reasons or are they actually required? car will be approx 1000kg and have v8 vt holden brakes front and rear Quote Link to comment Share on other sites More sharing options...
Raizer Posted October 19, 2012 Share Posted October 19, 2012 Booster is for comfort/weak legged people. Quote Link to comment Share on other sites More sharing options...
SOHC Posted October 19, 2012 Share Posted October 19, 2012 Its better to have the master cylinder bore on the smaller side, the peddle is rock hard and like standing on a brick otherwise, Quote Link to comment Share on other sites More sharing options...
kpr Posted October 19, 2012 Share Posted October 19, 2012 ^ this, go on the smaller side. bought 3/4's for the starlet, then swapped one out for a 5/8.(smallest they sell) as pedal was super heavy and there was bugger all travel. sole of your shoe squashing into your foot, was the pedal feel. but all depends on your pedal ratio's and caliper piston sizes Quote Link to comment Share on other sites More sharing options...
SOHC Posted October 19, 2012 Share Posted October 19, 2012 I don't run a booster because I couldn't be arsed, and I made the peddel box to be under the floor Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 20, 2012 Author Share Posted October 20, 2012 basically- the suggestion is 1" master because with the factory master you run out if fluid to supply the slaves before they are all the way clamped ( does not make sense to me since the pads sit so close to the disk). I guess masters are cheap enough that I can buy a few to try out if needed. Quote Link to comment Share on other sites More sharing options...
SOHC Posted October 20, 2012 Share Posted October 20, 2012 I think fitting a 2 pound residual pressure valve in the line can keep the pistons close to the disk to fix that problem Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 20, 2012 Author Share Posted October 20, 2012 that's great advice, thanks!! Quote Link to comment Share on other sites More sharing options...
SOHC Posted October 20, 2012 Share Posted October 20, 2012 Could you use the VT holden master cylinder and adapt it to fit your peddles? it would take out alot of the gess work Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 20, 2012 Author Share Posted October 20, 2012 new pedal assembly is from Coleman racing- takes two cylinders with a balance bar ( so bias is adjustable) it's made to put the cylinders up above your feet. be near impossible to fit factory cyl to it- and impossible to fit its booster unit. also I have to use remote resiviors Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted October 20, 2012 Author Share Posted October 20, 2012 http://www.colemanracing.com/Brake-Pedal-Assembly-Hanging-Single-Pedal-P4503.aspx this is the assembly iv got coming ( I got mind off ebay for 45usd Quote Link to comment Share on other sites More sharing options...
Simon Posted October 20, 2012 Share Posted October 20, 2012 Thats sweet. I need something like that. I never thought about ditching the booster, but that will make things sooo much easier with my motor because the RH head is touching it. that colman pedal box looks like it has way more leverage so you don't need to run a booster. Quote Link to comment Share on other sites More sharing options...
japawagons Posted October 21, 2012 Share Posted October 21, 2012 You can also remote boost a brake circuit if you find you need more assistance. You can also say boost the front circuit only with a remote booster set up. But probably isn't ideal for a car using balance bar adjustable brake bias. More a suggestion aimed at Simon if you need space for an engine conversion... Quote Link to comment Share on other sites More sharing options...
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