Thanks Bill your reply certainly does help. I have fitted braided braided lines but the linkage could do with a bit work. So all i need to do now is find a servo + mastercylinder the same dimensions or as close to the Fiesta items as possible, there is plenty of room and fabrication of the servo tower/bracket if it needs changing should not be problematic. That is of course unless someone has a mk2 servo they want to sell.
On Monday, July 27, 2020 at 8:36:46 AM UTC+1, Bill Allison wrote: > > Hi Russ > > I hope these comments will be useful: > > Your standard setup: Caliper piston area > 2 x 1810mm2 = 3620mm2 > > Hi-Spec setup: Pair of twin piston calipers (a pair of opposing pistons > exerts the same clamping force as a sliding caliper with a single piston) > 4 x 765mm2 = 3060mm2 > > Difference = (3620-3060)/3620 = 85% > > So on the face of it you need a 15% smaller (area-wise) than standard > master cylinder to get the same braking effort, BUT, you need also to take > account of the increase in leverage due to the larger discs: 265/225 (the > effective diameters) implies a 17.5% increase (area-wise) in m/cyl size. > > The two as near as dammit cancel out, so you actually need to not change > master cylinder size! > > I have not incorporated rear slave cylinder size in the calcs because the > rear pressure limiting valve takes them out of the equation at quite low > pedal pressures. > > I hope that helps. > > Regarding pedal feel, it's pretty much essential to replace the rubber > flexible hoses front and rear with braided teflon lines, I found also that > pedal feel can be further transformed by removing play at every point in > the longish route from your foot to the master cylinder, including setting > the m/cyl pushrod clearance. > > > Best regards > Bill > > Bill Allison > Borders Group of Advanced Motorists > National Observer (Cars) > 07702 739474 > 01750 22550 (before 21:00 please) > www.bgam.org.uk and www.bgam.org.uk/ydi > www.iamroadsmart.com > www.facebook.com/BordersAdvancedMotorists > > > > The contents of this message, and any attachments, may include information > that is private and confidential and should not be read by persons other > than the intended addressee(s). IAM RoadSmart nor the sender accepts any > responsibility for viruses and it is your responsibility to check the email > and any attachments. If you have received this email in error, please > inform the sender and delete the message from your computer. IAM RoadSmart > is a trading name. IAM RoadSmart is a trademark. Charity number: 249002 > (England and Wales) SC041201 (Scotland). Registered Address: 1 Albany > Place, Hyde Way, Welwyn Garden City AL7 3BT. > > > > On Sunday, 26 July 2020, 10:54:37 BST, russ price <[email protected] > <javascript:>> wrote: > > > After fitting Hispec 4 pot calipers and 280mm discs i thought i should do > something about a probable leak from the master cylinder, the clue being > rust and bubling paint on the servo. The trouble began when i sheared off a > stud holding the m'cylinder to the servo, no problem i thought i have a > Mondeo m'cylinder/servo which i have heard is used as an upgrade and a > bigger m'cylinder is probably a good idea after going from 2 to 8 pistons > on the front. This i now believe was an olympic standard jump to the wrong > conclusion. > If i have done the maths right, ( I would be grateful if someone checked > my results) i need to go down in m'cylinder bore size. Now i know > calculations of braking forces are really complex but this just about the > "feel" of the brakes. > Here are the figures i used, original calpers single 48mm piston, new > calipers four 31.2 mm pistons, rear slave cylinder 17.5mm, original > m,cylinder 20.6mm, mondeo m'cylinder 25.4 > Which give an original set up m'cylinder/caliper ratio ~ 1:23, original > m'cylinder + new calipers ~ 1:20, mondeo m'cylinder + new caliper ~ 1:13 > So given Fiesta mk2 servo's are not exactly thick on the ground i thought > about a set up similar to that recently used on 003, ie. landrover servo + > Mk1 19mm m'cylinder which should give me a ratio ~ 1:23 > I would really appreciate it if anyone can say to me " Your are talking > nonsense and here's why......" or " Yes that should work but be aware of > ......." > > -- > -- > You received this message because you are subscribed to the Google Groups > "Quantum Owners Group" group. > To post to this group, send email to [email protected] > <javascript:> > To unsubscribe from this group, send email to > [email protected] <javascript:> > For more options, visit this group at > http://groups.google.com/group/quantumowners?hl=en > > IMPORTANT NOTE: All information presented herewith is provided on an "As > Is" basis, without warranty or the implication thereof. Neither the Quantum > Owners Club nor the individuals associated with the Quantum Owners Club or > in the preparation of the above information shall have any liability to any > person or entity with respect to liability, loss, or damage caused or > alleged to be caused directly or indirectly by the instructions contained > within this or related message(s). > --- > You received this message because you are subscribed to the Google Groups > "Quantum Owners Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/quantumowners/5e0fda55-6bbe-41f8-9fb4-400ad2881832o%40googlegroups.com > > <https://groups.google.com/d/msgid/quantumowners/5e0fda55-6bbe-41f8-9fb4-400ad2881832o%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s). --- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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