Brake Problem?

[evojay71 0]

I seem to have a problem with the brakes on my 205 GTI6 rally car. The set up is DS 3000 rear pads, DS 2500 front pads and ATE Super Blue fluid standard front Brembo discs although the standard discs that were previously on the car never caused any problem. I can't seem to get the front wheels to lock no matter how had I push the brake peddle it travels so far then goes hard.

I've got the bias valve wound right out as far as it will go and the backs will still lock very mildly. Don't get me wrong the car will pull up and stop but it's not as good as it once was.

I'm doing a road rally tonight so to late in the day to change anything now but any ideas to cure my problem would be gratefully accepted.

 

Thanks in advance

Jay

[dcc 855]

is this running with a standard MC?

 

I have gone for a 23mm item to make pedal travel a little better. Should still be able to lock the front with your setup tho

[evojay71 0]

Yes, it's still running the standard master cylinder. I'm thinking it could be the servo or master cylinder?? I did whip the pipe off the vac pump and there was a noticeable difference in peddle feel so would this be more probable the MC is on it's way out??

[welshpug 1,655]

Iirc you want the valve wound right in not out.

[evojay71 0]

If the valve is wound right in then just the rear wheels lock up, the only way I can stop the rears locking is by winding fully out anti clock wise.

[harryskid 193]

Did you say you have a servo with a bias set up?

[evojay71 0]

Did you say you have a servo with a bias set up?

 

Yes I do, I did buy a bias valve from Compbrake when I built the car a number of years and ended up binning it as it was crap. I then bought a Wilwood valve which works fine. I ended up changing the master cylinder on Saturday afternoon with a s/h spare I had here but made little difference.

 

The brakes were good enough on Saturday night and really had no problems but not how they should be.

[welshpug 1,655]

so what was changed or has this issue got progressively worse on existing parts?

 

I would dismantle the front brakes, check the flexis aren't kinked, I guess you had no issues when bleeding the new MC though.

[evojay71 0]

What's changed is the new brake parts I've listed in the first post. I've always run DS2500 pads before and worked fine, but I've dropped a GTI6 in it so this is just a thought? Would the extra weight of the engine along with super soft AO35s on hot road not help the situation??

 

I'm considering a pair of uprated front discs and a brand new 32mm M/C to see if that will improve things? Possibly a case of trial and error until I get the brakes to my liking??

Edited July 16, 2013 by evojay71

[harryskid 193]

Are you using gti6 brakes or are you on 1900 ones as i found on my rally gti6 they were next to usless. Also i have put gti 6 calipers on the rear!

[evojay71 0]

Are you using gti6 brakes or are you on 1900 ones as i found on my rally gti6 they were next to usless. Also i have put gti 6 calipers on the rear!

 

No, because I'm using 14" gravel tyres. I did have GTI6 fronts when I built the car but had clearance issues on the rear so sold them on. Are the GTI6 rear callipers a lot better??

[rallyeash 155]

If you have rear discs already gti6 rears won't make any difference.

 

You can go from 247mm 1.9 brakes upto 266mm discs and calipers from a 306 S16 which is a nice upgrade and fits under 14' wheels.

[welshpug 1,655]

Gti6 rears will make a difference, the pistons are bigger by 2mm, iirc 14% or so more surface area.

[rallyeash 155]

But the rears do fek all anyway!

[welshpug 1,655]

depends how your bias is setup...

 

many hillclimbers and racers have issues with rears locking up with the stock calipers as the rear goes pretty light under big braking over bumps with sticky tyres, whereas the rallyists often want more as they use it to unsettle the rear, and for the handbrake.

Edited July 18, 2013 by welshpug

[Crescent205 11 1 Cars]

out of interest have you still got the rear brake compensator fitted?