Toad 0 Posted May 18, 2007 Afternoon all... I've got 1.8 16 valve with 280mm front disks, and front Goodridge hoses, (I've not gotten around to fitting the rears hoses yet), but have noticed strange behaviour from the brake pedal. When I fitted the brakes I noticed I had comparatively (to the 256mm brakes) a lot of pedal travel before the brakes worked, once I had passed this initial distance, the brakes are solid and worked well. I assumed that there was a bit of air in the system, and rebled them, but to no avail. I still have this random crappy travel at the top of the pedal. However recently I have noticed that if I brake hard (such as avoiding a loon in a discovery), for the next 500 yards, the pedal travel has gone, the brakes work from almost the top of the pedal, just like they used to be. I have also replaced rear brake pads and refurbed one of the rear calipers recently. Has anyone else noticed behaviour like this or know what it might be? I have suspected it's probably the master cylinder, or one of the calipers sticking slightly, but none of them are binding, and the master cylinder doesn't creep or feel spongey at all... Cheers everyone... Tom Quote Share this post Link to post Share on other sites
marc c 0 Posted May 19, 2007 Did you use the 280mm calipers or modify the slider bolts and use your 16v calipers, as the piston in the 280mm calipers is bigger i think so will require more force (travel) to work HTH Marc Quote Share this post Link to post Share on other sites
Supercharged 2 Posted May 19, 2007 Toad, what order are you bleeding?? (just asking becuase the order in the Bentley manual is wrong for UK cars...) Quote Share this post Link to post Share on other sites
Toad 0 Posted May 19, 2007 It's a full 280mm set up with carriers. Supercharged, Rear right, Rear left, front left (no ABS so it's further than ...) front right. I'm sure it's bled properly, plently of fresh fluid came through each nipple. The bias valve is cable tied open, as it's a bit wonky anyway. Quote Share this post Link to post Share on other sites
Toad 0 Posted May 28, 2007 Any ideas anyone?? Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted May 31, 2007 The 'random' dead intial bite might not be so random. For instance, as the car's weight changes (shopping, full tank of petrol), then so does the amount of pedal pressure required to give the same braking effort as the car being lighter. Sounds daft but I have had the same thing for years and never really got to the bottom of it, other than noticing the weight difference thing and how cr@p the design of the pedal leverage is. Fluid and pad temperature also affects initial bite, especially if the pads cool down a lot between braking. This is all assuming low speed, low pedal pressures? Standing hard on the brakes should be consistent. A bigger MC and a relocated pedal fulcrum would do wonders for the Corrado's pedal feel. Quote Share this post Link to post Share on other sites
Toad 0 Posted May 31, 2007 The 'random' dead intial bite might not be so random. For instance, as the car's weight changes (shopping, full tank of petrol), then so does the amount of pedal pressure required to give the same braking effort as the car being lighter. Sounds daft but I have had the same thing for years and never really got to the bottom of it, other than noticing the weight difference thing and how cr@p the design of the pedal leverage is. Fluid and pad temperature also affects initial bite, especially if the pads cool down a lot between braking. This is all assuming low speed, low pedal pressures? Standing hard on the brakes should be consistent. A bigger MC and a relocated pedal fulcrum would do wonders for the Corrado's pedal feel. Yeah, when I get on the pedal hard it is solid and I stop in a good straight line, but the inconsitent pedal travel varies over fairly short distances on single journeys. Lots of travel to start with, followed by little pedal travel after braking very hard, then going back to a lot of pedal travel. It makes me sad :( I think I'll look at replacing the master cylinder seals around the time of the MOT, as it will need new solid brakelines then anyhow. Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted May 31, 2007 Mine is exactly the same, and has been with all manner of different size brakes! I did run replacing the MC past Vince and he said it's not worth it unless it is totally and obviously knackered. Doesn't sound like yours is tbh and mine is OK too. It could be a sticky caliper, that's only sticking intermittantly? Not really sure, I've just lived with it as the braking is always 'acceptable' when it's like that! Quote Share this post Link to post Share on other sites
Toad 0 Posted May 31, 2007 Mine is exactly the same, and has been with all manner of different size brakes! I did run replacing the MC past Vince and he said it's not worth it unless it is totally and obviously knackered. Doesn't sound like yours is tbh and mine is OK too. It could be a sticky caliper, that's only sticking intermittantly? Not really sure, I've just lived with it as the braking is always 'acceptable' when it's like that! I have wondered if it is a claiper playing up. The fronts are 2 year old ex Vr6 calipers which looked pretty good, I re-built one rear completely and have changed the rear pads, so all the calipers have all been off and the sliper pins cleaned and re-greased in the last 2-3 months, so it shouldn't be, but I wonder if a bit of crap got on one of the pins, or perhaps they're over greased and don't slide properly? I replaced the handbrake cables too, so I know the handbrake isn't sticking at all. I'm learning to live with the brakes, but it's a bit frustrating when you don't quite know where the pedal is going to start to work. Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted May 31, 2007 I'm wondering if it's related to the rear calipers? Everytime I replace the rear pads and do as you do, clean up the pins etc, the brakes feel superb, firm and bites at the top of the pedal. And then a month later it goes back to being intermittantly pants again. Those are MK4 calipers I'm not sure what state my bias valve is in though. I did look at Wilwood's 4 pot rear caliper with inbuilt handbrake as an alternative, but never got round to trying it out. It's got to be more reliable than VW's!! Quote Share this post Link to post Share on other sites
Toad 0 Posted May 31, 2007 Yeah... I'm thinking that it could be them as it was a less apparent problem with thte 256's on the front, but still occured to an extent. My Bias valve wouldn't let the rear brakes play until I cable tied it part way open. Other than that, I believe it works as there is a noticable pulse from the piston when you kick the brakes on hard and off again, which I'm led to believe is a test to check they are ok. Maybe I'll get a chance to get the other 4 goodridge hoses fitted and have a good look round them soon. Cheers Kev! Quote Share this post Link to post Share on other sites
dinkus 10 Posted May 31, 2007 How's about an Audi 200 MC? Quote Share this post Link to post Share on other sites
adamukcorrado 0 Posted May 31, 2007 I've replaced all of my system trying to sort out the long pedal travel problem, full goodridge braided lines, brand new VAG MC and vacum servo, 312 discs & calipers with less than 1000miles from new, etc etc. as mentioned above brakes stop perfectly but travel really doesn't inspire confidence!! i've realised that it's something i'm going to have to live with :( Quote Share this post Link to post Share on other sites
Toad 0 Posted May 31, 2007 How's about an Audi 200 MC? Hmmmm. Interesting. Got a feeling it'll be rather like and on/off switch with single piston calipers though... Quote Share this post Link to post Share on other sites
dinkus 10 Posted May 31, 2007 How's about an Audi 200 MC? Hmmmm. Interesting. Got a feeling it'll be rather like and on/off switch with single piston calipers though... Mebbe... I've got 312s tho :norty: Quote Share this post Link to post Share on other sites
