How much bigger is the surface area of the ST150 calipers compared to the originals ? I wonder if you are getting a similar problem to the one i had when i fitted Willwood 4 pot calipers to mine.
The bigger area of the calipers means the same sized master cylinder and pedal actually puts less force onto the pads. I think that a bigger master cylinder will increase the pedal pressure but only if you press harder, it probably only helps with the matching bigger servo. Was your pedal box from a XR2 ?, the XR2's have the take off for the brake push rod closer to the pivot on the pedal, this means the same pedal pressure gives more pressure at the wheels but at the expense of more travel. On mine even this wasn't enough and i drilled another pivot hole even further up the pedal, this improved the brakes but at the expense of even more travel. I did have a lot of trouble getting all the air out of mine though. i tried a pressure bleeder but that seemed to upset the master cylinder so i ended up with a vacuum bleeder that attaches to an air line and sucks the fluid out of the bleed nipples. This seemed to work best. One test you can do is to clamp both the front flexible brake lines and then try the pedal, it was this test on mine (the pedal went rock solid) that made me realise it was just the increased area of the new calipers that was causing the problem. Another issue can be clearance between end of the pushrod on the servo and the end of the piston in the master cylinder, this wants to be as little as possible without putting any pressure on cylinder when you aren't touching the brakes. It can only really be checked by careful measuring with some digital calipers. The pushrod in the servo can be screwed in/out to adjust it. If the clearance is less than zero you will find you brakes will lock on when they get hot, not good. Jim Jim Turner wrote: > If you mean the long (6") one, yes. The ST150 calipers are single > piston. At the moment, no question or suggestion is silly! > Jim T > > On 9 Aug, 08:11, Jim Hearne <[email protected]> wrote: > >> Silly question, you have got the spring clip fitted to the front of the >> caliper ? (i assuming the ST150 are still single piston). >> >> Jim >> >> >> >> [email protected] wrote: >> >>> Thanks Stuart & Jim. I have now replaced the master cylinder with an >>> S1 unit, checked that there are no leaks, bled the master cylinder,& >>> the rest of the system several times, both starting with the front & >>> back nipples but the brakes still feel soft & don't lock the front >>> wheels. I am using Ford +4 fluid.(About 3 litres to date). The only >>> difference between Stuarts H4 & mine seems to be that his has abs & >>> mine doesn't. Do the ST150 calipers have an abs valve that would cause >>> this problem or am I bleeding the brakes incorrectly. Any help would >>> be appreciated. >>> Jim T- Hide quoted text - >>> >> - Show quoted text - >> > > > > --~--~---------~--~----~------------~-------~--~----~ 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). -~----------~----~----~----~------~----~------~--~---
