Grubbster Posted July 16, 2013 Share Posted July 16, 2013 I have a 2013 Academy car and from new I've struggled to get a firm brake pedal. CC have bled the brakes several times as have I. We have to run with the standard brake system the only change permitted is Mintex front pads which I've had fitted from the outset. The pedal is a bit soft then gets worse with use. I have tried using higher spec race fluid with no noticeable improvement. 2 weeks ago CC replaced the master cylinder and at the Donington test day last Friday I went 2.5 seconds quicker than my best previous time and most of this was down to confidence in the brakes, but by the afternoon session I was pretty much back where I started - with a long pedal and poor lap times. This was the same in qualifying on Saturday. CC bled the brakes for me before the race but it made little difference. There are no leaks. Looking at my vbox data it is clear that most of the time I am losing is in the braking zones (it looks like I am braking earlier and gentler rather than hard and late) and the spongy pedal also doesn't inspire confidence to follow people closely when approaching corners. So I need to do something. I've heard anecdotally that the master cylinders and rear calipers currently being supplied through CC are recon units and 'known to be problematic' and I've read a few threads here that seem to support this. I thiink my plan is to start replacing components, trying to source reliable items rather than buying them from CC (in case their items are less reliable). The new MC certainly made a big difference for an hour or so - so maybe I'll try replacing this first? Then move to the rear calipers if I don't get an improvement? Looking for ideas, tips and inspiration really, any advice would be greatly received Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted July 16, 2013 Share Posted July 16, 2013 I had a shocking brake pedal feel for years (2208 car). CC said TADTS, it's fine, it was bled to death. It started getting worse, with all the symptoms of a dead MC with no leaking. Replaced with an older MC from someone on here who had upgraded to twins, and my God it's now like it should always have been. See if you can get hold of an earlier model that is known to be good. I wonder if the bores aren't cleaned properly and following the pedal pumping bleeding procedure just ruins the seals. I have my old MC and keep meaning to dismantle it, but the old MC fixed all Have you had a look inside the old MC? Nothing else is weeping? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 16, 2013 Share Posted July 16, 2013 Make sure your rear callipers are sliding properly on their pins. If they're a bit sticky the calliper can't fully squeeze the disk which makes them feel spongy. It does sound more like a master cylinder issue though. Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted July 16, 2013 Share Posted July 16, 2013 After the afternoon session, did the long pedal stay when the car had cooled or did the pedal firm up again as this will be a clue..... Link to comment Share on other sites More sharing options...
makingff Posted July 16, 2013 Share Posted July 16, 2013 Quoting myothercarsa2cv: I had a shocking brake pedal feel for years (2208 car). 2208 car! What engine do they use? Simon Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted July 16, 2013 Share Posted July 16, 2013 Fusion 😬 Link to comment Share on other sites More sharing options...
makingff Posted July 16, 2013 Share Posted July 16, 2013 😬 Link to comment Share on other sites More sharing options...
Grubbster Posted July 16, 2013 Author Share Posted July 16, 2013 Quoting Mackei23b: After the afternoon session, did the long pedal stay when the car had cooled or did the pedal firm up again as this will be a clue..... Good question - after the Friday pm session I left the car until qualifying (the next day) without trying to fix anything as I know that sometimes a brake pedal can firm up again. In this instance it didn't, it was still spongy for qualifying. I wonder where I can source a new MC that is 'good', I don't really want to take the one off my other 7 (which has been fine for 10 years!). Paul - I'll check the rears to see if they slide OK. I'll also fit new rear pads as apparantly once they are 50% worn they take-up can be a bit slow. Link to comment Share on other sites More sharing options...
Z3MCJez Posted July 16, 2013 Share Posted July 16, 2013 Steve, If you push the brake pedal hard, does it keep pushing (I.e. does it feel like pressure is being lost, allowing you to continue to depress the brake further). I drove a friend's Academy car that did that and it was terrifying. That was a master cylinder issue. The other problem I've come across is leaking in the rear calipers. The leak is tiny and would never be noticed in the rubbish that is picked up on circuit. One of the things that was manifested with this most obvious problem was a leak if the handbrake was left on tight. That can be done in the garage, obviously, and is worth testing. I had replacement calipers under warranty for this. I'm told this was a batch issue, but you never know. Can you leave an Easibleed connected overnight in a clean garage at 10-12PSI (with only air in the refill bottle) to see if any leaks come through under a bit of pressure. That should rule out calipers leaking, although not MC. Jez Edited by - Z3MCJez on 16 Jul 2013 11:45:21 Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted July 16, 2013 Share Posted July 16, 2013 Just to add to the quandary.... I've had an airlock in the master cylinder before, which gave the symptoms of blown master cylinder seals, but once the lock was cured a firm pedal was back. As Jez said, it is worth checking all your brakes seals, I'd remove some of the dust seals to check....they can hold quite a bit of fluid before they will weep! One other suggestion...I've always taken a couple of times to bleed the brakes to get a really firm pedal. As said before I've used the easybleed at about 10PSI to get a constant flow of fluid when bleeding. I do an initial bleed and leave it overnight and let any air settle and then do a second bleed after 24hrs and always got a little more air out. So if there are no leaks I'd try another bleed using an easybleed and look for any more air in the fluid, if more air is present and there are no leaks my conclusion would be that there was still some air in the lines.... Good luck! Cheers Ian Link to comment Share on other sites More sharing options...
swsambler Posted July 16, 2013 Share Posted July 16, 2013 When I built my 2010 SV 175 Roadsport, I had a spongy pedal. This was cured by bleeding and persistently tapping the rear calipers with a soft head hammer. It took many bleed sessions to remove all of the air. I would pressurise with Eazibleed and tap then release and then repeat the procedure. Tiny air bubbles came out for a long time. My pedal has been rock hard since then even when sprinting and hillclimbing. Apparently it is due to the orientation of the rear Sierra caliper on the Caterham. Link to comment Share on other sites More sharing options...
shn7 Posted July 16, 2013 Share Posted July 16, 2013 Steve, It may be a pain but as you have a known good m/c on the snot I would swap them. If the problem also swaps cars you're certain to have found the problem (good bleeding assumed). I reckon that's you're quickest/best next diagnostic step. Link to comment Share on other sites More sharing options...
charlie_pank Posted July 16, 2013 Share Posted July 16, 2013 There's no magic to brakes. If the pedal is spongy there is one or more of a number of things happening: 1. Fluid has air in it somewhere and the air is compressing 2. Fluid is boiling 3. Fluid is being lost 4. One or more of the seals in the system are allowing fluid past them Cures/tests: 1. Bleed, bleed and bleed again. Bleed with the rear calipers off the wheels so that the bleed nipple is uppermost. 2. You might have a sticky piston. Check the temp of each hub (carefully) with your hand after a session. If one's much hotter than the others, there's a clue. If this is your problem proper feel should return after it has cooled down 3. Find the leak, it must be coming out somewhere. Most likely candidates are the piston seals or any pipe unions. 4. If it's none of the above, then the only seal that can allow fluid past without causing a leak is the master cylinder. Replace it and try again. I had persistent problems with a clutch master cylinder in a rally car a while ago. I replaced the seals on the master piston a couple of times but it kept failing. Only cured by replacing the whole cylinder assembly. When I took apart the failing M/C I couldn't see anything wrong with it at all. I concluded that you only needed a tiny tiny tiny bit of scoring to allow enough fluid past the seal to cause a problem... Link to comment Share on other sites More sharing options...
elie boone Posted July 16, 2013 Share Posted July 16, 2013 I always use a compressor to bleed the brakes, it's a 5 min job and far better in removing air from the system. All you need is a reservoir cap from an old Escort MK2 with a 5mm hole in it. And it's a one mans job this way. Link to comment Share on other sites More sharing options...
Birkin S3 ZA. Posted July 16, 2013 Share Posted July 16, 2013 Just to be different you have been given all the thing to do and check. I know its a new car but if you have play in the front wheel bearings it can also give more travel to the brake pedal. Chris. Link to comment Share on other sites More sharing options...
Grubbster Posted July 16, 2013 Author Share Posted July 16, 2013 Yes, I'm been told about that, pad knock-back I think. No play in the bearings though. I suspect I'm going to source a new mc and rear pads and get them changed to see how that is Link to comment Share on other sites More sharing options...
OliverSedlacek Posted July 16, 2013 Share Posted July 16, 2013 If the brake pedal starts firm and then gets softer you must be starting with the system bled properly. It's also unlikely to be a leaking slave or caliper as in that case the level goes down and the pedal goes down if you keep some pressure on it. As far as I know, your problem must be an MC problem or stuck rear calipers. Link to comment Share on other sites More sharing options...
david nelson Posted July 17, 2013 Share Posted July 17, 2013 I tried 3 standard mc and found they all felt diffrent. I realise you are limited in whatyou can do. So you changed the fluid no difrrence, changed MC, no long term change. It is there for more likly to be in the system. I think i would start with a run up the road check hub temps. If ok then do the presure test using easybleed, if all ok remove calipers front and back check, reasemble and see what its like. Good luck please post what you find and how you resolve it. David Link to comment Share on other sites More sharing options...
Grubbster Posted July 20, 2013 Author Share Posted July 20, 2013 I've dropped the car off at PGM, it certainly seems like another duff master cylinder - if I press the pedal down firmly and maintain pressure I can push it another 4 inches or so ! No visible leaks (but Andy will check everything just in case). I don't fancy another master cylinder from CC, it does seem a bit hit and miss as to whether you get a good one or not ☹️ So I need to source the correct part from elsewhere. Link to comment Share on other sites More sharing options...
RedCat7 Posted February 9, 2014 Share Posted February 9, 2014 Hi Grubbster Did a new Master Cylinder solve this issue? I have similar symptoms ☹️ Link to comment Share on other sites More sharing options...
Grubbster Posted February 9, 2014 Author Share Posted February 9, 2014 YHM Link to comment Share on other sites More sharing options...
Guest Posted February 9, 2014 Share Posted February 9, 2014 Quoting Grubbster: YHM Awww, I was looking forward an update on this ☹️ Link to comment Share on other sites More sharing options...
Grubbster Posted February 9, 2014 Author Share Posted February 9, 2014 Essentially the issue was that fluid was getting back past the seal in the master cylinder, so a replacement was needed again. The current standard cylinder seems to be pretty poor and it is hard to get a decent pedal when the car is used on track a lot, the old Girling cylinder (no longer in production I believe) was better than the current one supplied. A lot of people in the paddock seem to have problems and spend much of their time bleeding brakes in an attempt to improve them - with limited success. Some people appear to have no problem (or possibly don't realise there is a problem if they haven't ever felt better and believe TADTS). Link to comment Share on other sites More sharing options...
Guest Posted February 9, 2014 Share Posted February 9, 2014 Thanks, so as I guess the Academy cars are restricted to standard cylinders, the options are to keep on replacing them until a good one is found, or take one to an engineer and see if it can be made good? I'm considering the Academy in '15 and my pedalling style demands a robust and study brake pedal, hence my interest :) Link to comment Share on other sites More sharing options...
7 wonders of the world Posted February 9, 2014 Share Posted February 9, 2014 So on a new standard car the probability is you are likely to suffer from one or more of the following: Problems with poor quality master cylinder, leaks from both front and rear remanufactured calipers problems bleeding the rear brakes / potential line failure due to floating calipers being fitted to a rigid brake line, and or squashed brakes lines on the DD. Considering the price tag, and the fact were in 2014 these issues really ought not to be appearing on a car with serious performance. None of these require significant re engineering, off the shelf solutions could be sort from known OE component suppliers - hopefully with a weight reduction too Link to comment Share on other sites More sharing options...
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