Making unboosted adjustable pedal box brakes work.
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    Default Making unboosted adjustable pedal box brakes work.

    I ran the 309 in a rally over the weekend, it went pretty well, heaps of performance, although there was a misfire at times, still not sorted. Many favourable comments from the road closure officials and spectators re the induction noise.
    We had a major problem with the brakes though, virtually no stopping unless they were right up to temp, just standard Valeo pads. Even a 1km fast stretch would require rewarming the brakes before slowing for the corner!I have upgraded to 206 GTi fronts and 306 GTi 6 rears to get bigger piston areas but still not enough. The master cylinders are as supplied in the adjustable pedal box bulk deal that was organised a year or two back, don't know what they are but can check. Has anyone else used this set up?
    If I can find a pad with 50% greater friction and that works when cold then it will be OK. I don't want to go back to a boosted system as the present set up is very neat and gives clearance to the cam cover.

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    Graham, does the pedal box allow for different mechanical leverage ratios and might this help? I know this would be obvious if it did, but still...


    2003 PEUGEOT 206 GTi

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    1000+ Posts Gamma's Avatar
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    Works hot or cold...

    Making unboosted adjustable pedal box brakes work.-boat-anchor-736693_960_720.jpg

    http://www.demon-tweeks.co.uk/perfor...endix-calipers

    or...Ferodo Racing compound DS3000
    Last edited by Gamma; 6th June 2017 at 02:00 PM.
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    Quote Originally Posted by Gamma View Post
    Works hot or cold...

    Click image for larger version. 

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    great in the wet!!

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    Thanks for the link, I have Bosch calipered 206 GTi brakes which I see are available in Yellow stuff. Unless other better suggestions are made I will give them a try, other brands have been recommended but would require getting the pads custom built.

    Quote Originally Posted by Gamma View Post
    Works hot or cold...

    Click image for larger version. 

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    EBC Brakes Yellowstuff Performance Rear Brake Pad Set | Demon Tweeks

    or...Ferodo Racing compound DS3000

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    Fellow Frogger! Brett's Avatar
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    I have four pots on both 206's one with a booster, one without.
    I'm thinking of putting booster back on.
    Pedal travel will become longer, but currently the non-boosted callipers retard the car rather than brake.
    Which is fine for racing.
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    1000+ Posts PeterT's Avatar
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    If it helps, I'm currently using a 0.7" master cylinder with GTi6 calipers , ie 57mm. Brake pads cost twice as much however. ie Endless.

    '92 205 Mi16
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    I wonder if Holden HK calipers would fit? I remember a 403 with those calipers and no boost worked really well. Also a Datsun 1600 was fine unboosted as was a Renault 12, so it can be done.
    I also remember that E49 Chargers were unboosted and were notorious for not stopping.
    Not worried about the cost, if Endless have more friction hot and cold than the Yellowstuff I will fit them.

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    Endless have a wide range of friction materials. You need to match it to the weight of the car. I can look on the old box, but I think ours is ME20 from memory.

    '92 205 Mi16
    '90 Mi16x4

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    Also, have you got the balance bar adjusted correctly? It needs to be set up so the rear brakes barely work. Set it up 99% front.

    '92 205 Mi16
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    Who knows? Neither front or rear lock up on gravel no matter how hard you push. The floor is flexing by the way, and it has been reinforced around the pedal box mounting. If I get some stopping happening I will be able to adjust the balance. I'm beginning to think this has all been a waste of time and money and should go back to using a booster.
    The Demon Tweeks catalogue has the Bendix and Bosch pads swapped I'm pretty sure. I will double check tomorrow before ordering Bendix pads for my Bosch calipers!

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    The DS3000 take forever to warm up, they are useless on gravel. The EBC yellow work great on the 309.
    I am 40/60 regarding a pedal box vs a booster, our stages are super long and the pedal box can be tricky. I catch myself applying less pressure near the end of the stage on left foot braking and I have to adjust. In general, unless the cam has too much overlap for a booster, I don't install a pedal box. Since you already have one, it is important to adjust the front to rear balance. The way I do that is to use worn gravel tires on tarmac, panic stops from 60 km/h. Measure the tire marks left from all four wheels, stop adjusting when front and rear are equal. On downhill stages I give a little more pressure on the back so I can place the tail with braking.

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    Thanks Thanos, pleased to hear that the yellow stuff are good. I remember your Makinen Coupe didn't stop at all well, have you changed anything on that? I don't left foot brake, backing off is enough to get the car to turn into the corner, handbrake for THR and THL. Locking up wheels on tarmac or bitumen is a dream at the moment!

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    Quote Originally Posted by GRAHAM WALLIS View Post
    I remember your Makinen Coupe didn't stop at all well, have you changed anything on that?
    It took a lot of fiddling with different diameters and balancing and it is much better now. Still a bit scary on the fast tarmac stages, I had to flick it a few times when the braking was not good enough to point it through the turn. A few deep breaths for me, but the spectators seemed to like it.

    Quote Originally Posted by GRAHAM WALLIS View Post
    ...Locking up wheels on tarmac or bitumen is a dream at the moment!
    I would go back to the booster then, you should be able to do this easily if the pedal box worked correctly

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    Need to get clearance for the master cylinder from the cam cover, the only reason I decided to go for the pedal box in the first place, I don't see any other advantage. I will try the yellowstuff pads before giving up as it is all nicely installed now.

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    How much pedal travel do you have?

    If the pedal travel is small you could go to a smaller diameter master cylinder, the pedal travel will be more but you will get more pressure to the calipers.
    Regards Col

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    A fair bit, more than a boosted system so I don't think there is anything to gain there.

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    I think you have 0.625" now? With 52mm Pistons, that's approx the same ratio as my 0.7" and 57mm set up.

    '92 205 Mi16
    '90 Mi16x4

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    Quote Originally Posted by GRAHAM WALLIS View Post
    Neither front or rear lock up on gravel no matter how hard you push.
    It's a cylinder issue. Graham, you have 0.625" and 0.75" cylinders. Post which end you have which cylinder operating.

    Peter, can you post up your cylinder sizes front & rear for Graham's reference pls?

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    Thanks, I'll take a look tomorrow.

    Quote Originally Posted by Bluey View Post
    It's a cylinder issue. Graham, you have 0.625" and 0.75" cylinders. Post which end you have which cylinder operating.

    Peter, can you post up your cylinder sizes front & rear for Graham's reference pls?

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    Front 0.7"
    Rear 0.75"

    '92 205 Mi16
    '90 Mi16x4

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    Front 5/8th rear 3/4 inch.
    I priced some PMU Club Racer pads, $600 for the fronts! The Yellowstuff come in below $200 and are on their way.
    Checking out the car today I found the RHS tie rod end threaded section had bent, it is screwed out further due to the wider 309 track, so think of cutting a piece off an old tie rod and screwing it up against the end of the tie road to reinforce the tie road end. 309 tie rods are a little bit longer but they don't appear to be sold anymore.
    Changing the crank angle sensor may have solved the misfiring problem we had on the event (tacho reading dropped as it happened so had to be either the CAS or the ECU) so the car is gradually being sorted.
    By the way you can fit a 205 Si tacho to the earlier Jetronic car dashes in order to get it working with aftermarket management.

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    Quote Originally Posted by GRAHAM WALLIS View Post
    I priced some PMU Club Racer pads, $600 for the fronts! The Yellowstuff come in below $200 and are on their way.
    Are Yellowstuff pads designed to work without a booster?

    '92 205 Mi16
    '90 Mi16x4

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    Graham, don't be dodgy. Go and get 306 rack arms and add them to the rack. You can then trim them to the length needed and utilise thread into the arm same as standard
    Adrian Wuillemin

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    You have a .625" front master cylinder. You need a .7"
    Adrian Wuillemin

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