69volunteer 84 Report post Posted January 23, 2017 This is not for a mustang but thought I would post here to get some other responses. What would be the benefit (if any) or detriment of going from a 3/4" bore wheel cylinder to a smaller 5/8" bore? Forgetting about bias and assuming that the front and rear are on two SEPARATE circuits. Any reason someone would have done this? I have a vintage racer and stock on the rear is 3/4". Went to replace a seal over the weekend and noticed that they are 5/8. There is not much 'stock' on this car but I have the original 3/4" with all new seals and would rather just replace instead of search for a rebuild kit. 4 Haroldbiabe, Selmadox, Bryqanfrerm and 1 other reacted to this Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted January 23, 2017 It will reduce the braking efficiency slightly which will require slightly more effort on the pedal to equal the same stopping performance it previously had and will shorten the pedal travel/operating range slightly. Quote Share this post Link to post Share on other sites
69volunteer 84 Report post Posted January 23, 2017 I follow more effort on the pedal--smaller bore size, more restrictive. Not sure I follow the shortened range in the pedal. Thank you though. This car is a momentum car so I try to use the brakes sparingly but they are all up front. I dont think I have ever locked up the rears. I may order another 5/8 to have and then swap to the original 3/4. What I really dont want to deal with is troubleshooting two wheel cylinders which is why I may just swap out the one with the bad seal. Why not order a seal/rebuild kit? I have one but the OD is correct for the piston but the ID is way too small. In the day of the internet, no telling what you will receive when ordering online. Quote Share this post Link to post Share on other sites
RPM 1,190 Report post Posted January 23, 2017 Derek Derek Derek, you can't post a question about a vintage racer, and then leave us hanging without ANY pictures! C'mon man! We need pics. Quote Share this post Link to post Share on other sites
69volunteer 84 Report post Posted January 23, 2017 Red 64 Triumph Spitfire Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted January 23, 2017 Not sure I follow the shortened range in the pedal. the range is shorter because the smaller cylinders hold less fluid. Quote Share this post Link to post Share on other sites
69volunteer 84 Report post Posted January 23, 2017 the range is shorter because the smaller cylinders hold less fluid. ok, that makes sense now. Thanks. Ordered a new 5/8....I'll see what it looks like when it comes in and then go from there. Thanks for the info. Quote Share this post Link to post Share on other sites
shaun071 62 Report post Posted January 24, 2017 It also helps prevent rear wheel lock up. It's a common mod for circuit racers. Quote Share this post Link to post Share on other sites
