Trigger Posted July 19, 2009 Share Posted July 19, 2009 I'm hoping someone can shed some light on this for me... (I've done a search on here, ask a few people and bleed the brakes HEAPS of times but still got a spongy brake pedal?) Note: brakes were working fine (well not noticably spongy) when car was standard, also havent machined the discs or replaced the front pads, just running them as I got them (lots of pad left) If I had to say the brakes "seem" to work a bit better with no vacumm (eg when being towed and engine not running) still not great by any means, but takes at least x3 pumps to try to stop when under vacumm Car: Mitzy Ex Lancer ('82 1200cc) Orginal brake setup: Disc (front) Drum (rear) twin/split resorvour master cylinder Brakes changed to: Starion disc/calipers (front) factory standard drums (rear) Sigma master cylinder and booster Ex m.c: Sigma m.c: (Sigma m.c / booster "bolts in" and all brake lines match up no worries) Have tried bleeding the system (manually and vacumm) and also bled the m.c with no change to the pedal? Even swapped around the x1 way valve with a brand new 1, with no luck? So I swapped the Sigma m.c and booster back with the "orginal" Ex m.c / booster and bleed it all up and still no difference? So the only thing that is different from "orginal" (standard) setup is the Starion front disc / calipers Be keen to hear from anyone else who has done this swap before, but I think most guys are running disc rear end (not drum) and maybe using another model m.c / booster? cheers for any help Quote Link to comment Share on other sites More sharing options...
Dell'orto Posted July 19, 2009 Share Posted July 19, 2009 Starion calipers dont have a massive piston vs Sigma ones do they? Quote Link to comment Share on other sites More sharing options...
cletus Posted July 19, 2009 Share Posted July 19, 2009 another thing, check bleeders are at the top of the calipers?? ie calipers on correct side. Quote Link to comment Share on other sites More sharing options...
Trigger Posted July 19, 2009 Author Share Posted July 19, 2009 Starion calipers dont have a massive piston vs Sigma ones do they? Na, dont think theres much diff (I'll check it out) and yea bleeder nipples are pointing "up" maybe skim the rotors and put some new pads in? Quote Link to comment Share on other sites More sharing options...
thegreatestben Posted July 19, 2009 Share Posted July 19, 2009 I don't think you're problem lies in pads and rotors. What methods have you used to bleed? What fluid? I'd recommend trying a compressor powered bleeder, they rule. Quote Link to comment Share on other sites More sharing options...
Trigger Posted July 19, 2009 Author Share Posted July 19, 2009 I don't think you're problem lies in pads and rotors.What methods have you used to bleed? What fluid? I'd recommend trying a compressor powered bleeder, they rule. True, but was thinking IF I did the pads/rotors that would rule them out? Have vacumm bleed from each point (note: only x1 bleeder for the rear, on the R/R) and have also got someone to pump the pedal manually as I bled from each bleeder under pressure (both for quite a number of times) Been using DOT4 B/F I think its just air in the system still... Havent heard of a "compressor powered bleeder" ? sounds good Quote Link to comment Share on other sites More sharing options...
thegreatestben Posted July 19, 2009 Share Posted July 19, 2009 I have used Uncle jakes one and we have them at tech, If you put a completely new system on you might have air in the system. Quote Link to comment Share on other sites More sharing options...
dirty_leppa Posted July 19, 2009 Share Posted July 19, 2009 its possible the pushrod from the pedal to the M/C is not adjusted properly. i had this same problem at work. i changed the M/C and no pedal pressure. bled all brakes numerous times, changed the fluid and bled again. still nothing. tried back bleeding the system and still nothing. removed M/C, stripped and found seals etc all good. refitted M/C and still nothing. spoke to one of the old timers at work and he said make sure there is a little freeplay between pedal pushrod and M/C. if there is insufficient freeplay, the M/C piston wont move back fully which results in your spongy pedal. just a thought i had. be worth a try i suppose. let us know how you get on Quote Link to comment Share on other sites More sharing options...
filthy one Posted July 19, 2009 Share Posted July 19, 2009 agreed with leppa I just had issues on my Pontiac when changing th MC i never checked on the pushrod end etc . The factory one was hollow meaning half the length of the pushrod went inside the end of the MC piston .. But new MC did not have the hole so when i bolted it up i only had half my pedal stroke & only front brakes due to the pushrod pushing the MC piston in as I bolted it up.. I know its not the same problem your experiancing but it points out that MC can cause issues Quote Link to comment Share on other sites More sharing options...
treggo Posted July 20, 2009 Share Posted July 20, 2009 Are all your rubber brake hoses new? Not shot old ones bulging out? Judging by the work you do I would think they are new though lol Quote Link to comment Share on other sites More sharing options...
Unclejake Posted July 20, 2009 Share Posted July 20, 2009 I can just about guarantee you have a mismatched M/C bore to wheel cylinder/piston ratio. Your pedal is possibly very 'long' rather than spongy. Does the system you are running have a residual presure valve to look after the rear shoes? I say: Hook up the old calipers (they don't have to be mouted to the car but will need pads and a rotor like thing betwen the pads) and try again. If the 'spongy' feel is gone you know you have a mismatch in the fluid displacment ability of the M/C vs. the front calipers. If the problem does not go away clamp off the rear flexible brake line and see what happens I know I sound like a broken record but when you start messing with front calipers you often need to change rear brakes AND the M/C as well.No one listens and they spend three days trying to bleed the brakes and then buy new everything and the problem never goes away until they put back on their old 'inferior' brakes and suddenly have a car that stops Quote Link to comment Share on other sites More sharing options...
Hemi Posted July 20, 2009 Share Posted July 20, 2009 and another thing , did you bleed the master cylinder ?? , as in bench bled it beforehand ? this can cause massive hassles . Quote Link to comment Share on other sites More sharing options...
Ke36 Posted July 20, 2009 Share Posted July 20, 2009 my brakes arent spongy and i have starion fronts with s14 rears and still running off only the 1200cc ex lancer m/c are your pads not new all round? i will say tho after having been to a track day recently and smashed the shit out of the pads they are feeling different for sure, i.e much more travel in the pedal Quote Link to comment Share on other sites More sharing options...
Truenotch Posted July 20, 2009 Share Posted July 20, 2009 my brakes arent spongy and i have starion fronts with s14 rears and still running off only the 1200cc ex lancer m/care your pads not new all round? i will say tho after having been to a track day recently and smashed the shit out of the pads they are feeling different for sure, i.e much more travel in the pedal Your fluid will have boiled or taken on air at the trackday. Always bleed them again after hitting the track. Quote Link to comment Share on other sites More sharing options...
Ke36 Posted July 20, 2009 Share Posted July 20, 2009 my brakes arent spongy and i have starion fronts with s14 rears and still running off only the 1200cc ex lancer m/care your pads not new all round? i will say tho after having been to a track day recently and smashed the shit out of the pads they are feeling different for sure, i.e much more travel in the pedal Your fluid will have boiled or taken on air at the trackday. Always bleed them again after hitting the track. have actually rebuilt the rear brakes (unrelated issue) so rebleed the rears havent touched the front though, so might give that a try, will post up here trigger so you can rule out a mismatch if it all comes up sweet Quote Link to comment Share on other sites More sharing options...
ProZac Posted July 20, 2009 Share Posted July 20, 2009 When i swapped boosters and m/c in my old Sapporo i fucked up the adjustment from the booster to pedal linkage, had it too long or too short, cant remember which... Had the opposite to your problem, no feeling to the brake pedal at all really, but it only needed the slightest movement and the wheels would pretty much lock up. Look at this adjustment, especially as it looks like you've had it all apart to get cleaned and plated? Best of luck man, love the car. Quote Link to comment Share on other sites More sharing options...
Trigger Posted July 20, 2009 Author Share Posted July 20, 2009 cheers HEAPS for all the help and things to try out, Lots of good info, unfortantly I probably wont be able to work on the car until the weekend... Yea, was thinking could be something to do with the Sigma m.c being mis-matched with rest of the brakes? I've re-fitted the standard 1200 m.c and booster now, so will try swapping the calipers over and see if that works, at least then it'll be back to completely "standard" braking system again Wondering if anyone else has changed there m.c on their Ex and what m.c they are now running? (and still using drum rear end) I didnt think it would make sence to use a Starion m.c, because they are disc rear (at least Sigma is drum rear) simlar to Ex, but Starion calipers must be a bit bigger than Sigma/Ex? I'll try find out ALL (Starion, Sigma, Ex) m.c and brake componnet sizes and I'll try "adjusting" the push rod aswell Quote Link to comment Share on other sites More sharing options...
Unclejake Posted July 20, 2009 Share Posted July 20, 2009 ^ An excellent approach IMHO. Good luck dude Quote Link to comment Share on other sites More sharing options...
RT Posted July 20, 2009 Share Posted July 20, 2009 not mitsi but I had a bitch of a problem bleeding the brakes on my capri when I upgraded to vented discs.. no matter how many time I bled them still spongy. Then I noticed a couple of extra nipples that I'd forgotton about. Thought that must have been it.. but no.. turns out my master cyl was shafted. Even though it seemed fine before I started. Got it machined and rebuilt and bingo. Quote Link to comment Share on other sites More sharing options...
mx_freak69 Posted July 21, 2009 Share Posted July 21, 2009 and another thing , did you bleed the master cylinder ?? , as in bench bled it beforehand ? this can cause massive hassles . ^^ True that. Definitely worth taking it off and bench bleeding then refitting to veh. Quote Link to comment Share on other sites More sharing options...
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