Mick Foster Posted July 19, 2019 Report Share Posted July 19, 2019 About three years ago the clutch hydraulics developed a leak. The bulkhead was a bit of a mess so I decided to clean up, paint and replace both brake and clutch master cylinders. As the car was off the road I didn't road test the brakes at the time. I have now just started using it again and I found the brakes were terrible to the point of being dangerous. I then thought a complete brake refurb would be a good idea. I replaced all flexible hoses, rear shoes, front discs, front pads and the offside caliper (as the bleed nipple had snapped off). I then thoroughly bled the system (I have always used silicon fluid) and adjusted the rear drums (with the handbrake disconnected). All the caliper pistons and rear cylinders are free moving and not jammed in any way. I would have thought the brakes would now be good, they are better but still disappointing to the point the wife still won't drive it. Rather spongy and really needs a lot of pressure to stop quickly. On a dry surface it is impossible to lock the wheels. I have the following questions and would be grateful for any advice. 1) Could I have been sold the wrong master cylinder (I got it from Rimmers)? How can I tell? 2) The new front pads came with a strange thick rippled paint on their backs (purchased from the club shop). Is this making them spongy and should I scape it off back down to the metal? 3) Do I need to give the new pads/shoes time to bed in? 4) Is there anything else I need to look at? Thanks in advance for your help. Link to comment Share on other sites More sharing options...
johny Posted July 19, 2019 Report Share Posted July 19, 2019 Pads do take a while to bed in and can give poor braking and spongy peddle in the meantime. Check the discs to see if the complete surface on both sides of each is being used yet.... Link to comment Share on other sites More sharing options...
Mick Foster Posted July 19, 2019 Author Report Share Posted July 19, 2019 Many thanks. I am hoping this is the case as it is the easiest fix. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 19, 2019 Report Share Posted July 19, 2019 Is your 1500 twin line or single line hydraulic circuits Eg, does it have Pdwa valve ??? On the baulkhed What front hub end float have you got.???? The grotty pad backing is hopeless , clean off and fit steel shim anti squeal shims The cyl size is marked in the body casting there are two 0.625 and 0.7" Without checking type 14 calipers had the 0.625 ???? Bedding in 60 to 20 do 3 hard pull ups do not stop, & let cool down Pete Link to comment Share on other sites More sharing options...
Mick Foster Posted July 19, 2019 Author Report Share Posted July 19, 2019 Thanks Pete It's a single line circuit I set up the bearing end float when I replaced the discs. I didn't measure it but I am sure it is right. No play and no binding. I already have shims fitted to the pads, I think I will scrape the stuff off. The master cylinder is marked PT 5/8 (which I think equates to 0.625). The new brakes have done 60 miles of "gentle" driving. Link to comment Share on other sites More sharing options...
NonMember Posted July 19, 2019 Report Share Posted July 19, 2019 27 minutes ago, Mick Foster said: The new brakes have done 60 miles of "gentle" driving. So still too new to work properly. Bed them in as Pete suggested and see if the feel improves. Link to comment Share on other sites More sharing options...
johny Posted July 19, 2019 Report Share Posted July 19, 2019 yes I reckon mine (or my bedding procedure) are particularly slow but I think more like 1000 miles before I can see full contact over the complete discs..... Link to comment Share on other sites More sharing options...
Mick Foster Posted July 19, 2019 Author Report Share Posted July 19, 2019 We only do a few hundred miles at most a year, it could take years to bed them in !!! Link to comment Share on other sites More sharing options...
johny Posted July 20, 2019 Report Share Posted July 20, 2019 Mine are particularly bad as I think there must be some misalignment in the calliper carriers and Im also very restrained on braking so yes it does take a while . However you need to look at yours to see if that is whats happening..... Link to comment Share on other sites More sharing options...
Clive Posted July 20, 2019 Report Share Posted July 20, 2019 What are the discs like? If they are worn/uneven it can make the pedal feel odd, especially worse when new pads first fitted. Have the rear brakes been correctly adjusted. is undo the cable, adjust the shoes then reattach the cable? (If not that give much free play in the pedal) Link to comment Share on other sites More sharing options...
Mick Foster Posted July 20, 2019 Author Report Share Posted July 20, 2019 Thanks Clive I replaced both the pads and discs together so the discs are fine. I did adjust the rear drums with the handbrake cable removed. Then slackened the cable, reattached and adjusted. Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 20, 2019 Report Share Posted July 20, 2019 Mike, You mention changing EVERYTHING, Except the rear cylinders? Free moving isn't really the most important test. (Not leaking perhaps?!! ) Silicon fluid is great but I found it does need re-bleeding several days after the first (and second) attempt. Mintex 11/44 brake pads make an astonishing improvement, expensive but well worth it. Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 20, 2019 Report Share Posted July 20, 2019 Shims and the plastic stuff is too much yes ditch the bungy coating Dont compare with a modern ,a few extra shreaded wheat but the base brake on spits is normally very good So is this a brake friction problem or weany knee syndrome !! You can fit a servo to lighten pedal loads So give it some serious hard braking and get used to more pedal loads see what changes Pete Link to comment Share on other sites More sharing options...
johny Posted July 20, 2019 Report Share Posted July 20, 2019 Mick another test you can do is clamp off brake hoses, for example do this to the two front calliper hoses and see how your pedal feel changes. If theres a great improvement its almost certainly down to the pads not fully bedded.... Also do remember that our brakes are not going to feel like modern ones especially without a servo - Ive had to go to a larger bore master cylinder and NOS asbestos pads to get what I consider an acceptable feel. Link to comment Share on other sites More sharing options...
Mick Foster Posted July 20, 2019 Author Report Share Posted July 20, 2019 Thanks Doug The rear cylinders seem fine. Not sticking on the back plate and no leaks. Another bleed is a good idea. I will certainly consider Mintex pads if things don't improve. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 20, 2019 Report Share Posted July 20, 2019 A larger bore mcyl would increase pedal loads for the same system pressure but reduce travel Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 20, 2019 Report Share Posted July 20, 2019 If you go for mintex 1144 you really must follow a bedding proceedure I will load it when off this silly tablet and back on laptop but trying to configure anew desktop So miracle required Pete Link to comment Share on other sites More sharing options...
Mick Foster Posted July 20, 2019 Author Report Share Posted July 20, 2019 I do appreciate the difference with modern brakes. We have had the Spitfire for 35 years and always had confidence in the brakes but at the moment that confidence is lacking. Whilst I can cope with it, the poor wife won't eat her shredded wheat and desperately needs to do a few squats first. Link to comment Share on other sites More sharing options...
johny Posted July 20, 2019 Report Share Posted July 20, 2019 3 minutes ago, Pete Lewis said: A larger bore mcyl would increase pedal loads for the same system pressure but reduce travel Pete yes I have to have my weetabix every morning but maybe in Micks case a larger m/c with servo (a servo on its own tends to increase pedal travel even more) would work well..... Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 20, 2019 Report Share Posted July 20, 2019 Mick, I replaced the original Girling servo on my GT6 with a Lockheed type and it works very well, it takes the OMG!!! surprise/panic out of braking when you've just been driving the modern. The diehards will tell you a servo doesn't make braking any better, just easier, but I wouldn't be without it. The Lockheed was easy enough to install however there is a connection for it on the GT6 manifold which I'm not sure is there on a Spitfire. You may have to drill and tap a hole in the manifold. Doug Link to comment Share on other sites More sharing options...
Mick Foster Posted July 20, 2019 Author Report Share Posted July 20, 2019 Thanks. Fitting a servo maybe the way to go in the future, especially to help out the wife. Link to comment Share on other sites More sharing options...
NonMember Posted July 20, 2019 Report Share Posted July 20, 2019 12 minutes ago, dougbgt6 said: I replaced the original Girling servo on my GT6 with a Lockheed type and it works very well, it takes the OMG!!! surprise/panic out of braking when you've just been driving the modern. My modern - a Ford Mondeo - was in for repair this week and I had a courtesy car. Horrible thing with feather-light everything and no feel at all. When I picked up the Mondeo I had a couple of minutes of "woooaaaahhhhh" at the pedal effort needed. For some weird reason I don't get that when I swap into a Triumph. Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 20, 2019 Report Share Posted July 20, 2019 Yes, they can go too far with feather-light brakes, I didn't buy a Peugeot 307 because of that. I bought another 306 instead. Current modern is a Jaguar with VERY good brakes, so the Triumph has a lot to live up to brakewise. db Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 20, 2019 Report Share Posted July 20, 2019 Well you certainly know the car , so this is still looking a bedding or pad problem There are not green stuff pads per chance, awfull cardboard things (my view) Did you test both caliper pistons move out ok with pads out and will lightly lever back in to refit the pads Fitting a servo still has to have the foundation braking in a working order Its quite common to up the mcyl size with a servo to maintain a feel balance , Pete Link to comment Share on other sites More sharing options...
JohnD Posted July 20, 2019 Report Share Posted July 20, 2019 10 hours ago, Mick Foster said: We only do a few hundred miles at most a year, it could take years to bed them in !!! "Bedding in" is not just wearing the pads to fit the discs, it's a process to condition them for use. Takes 20 mins to half an hour. Choose your road carefully, other users may not appreciate your intentions! Start by braking from 30-40mph to a walking pace, then from higher and higher speeds until you are going as fast as you ever drive. The idea is to heat the pads, calipes and discs as hot as they ever will get, and keep them there for a while. Nver stop doing the process, then drive normally for a few miles to let them cool down. Done. Some misconceptions above. A larger master cylinder will mean a shorter stroke, but LESS pressure on the brakes. It's hydraulics! A given foot pressure, spread across a wider cylinder, will produce LESS pressure in lb/in^2. That is transmitted to the piston as LESS pressure on the pad. A smaller M/c will need more pedal movement, but more pressure. I'm tempted to say that you ad your wife are too used to a modern ("only a few hunded miles a year in the Spitfire") with the servo boosted brakes they all have. But you also say that " On a dry surface it is impossible to lock the wheels." You should be able to, and no amount of new parts is going to solve this, as you have now replaced most. You also say that the brakes feel spongy, which menas air bubbles, which means that brake pressure will not be optimum. Concentrate on bleeding, thoroughly. Start with slave furthest from master (Right rear), and go through them all, repeatedly if necessary! Good luck! JOhn Link to comment Share on other sites More sharing options...
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