I have put a full gti6 brake setup on my 306td. It has new flexi's, new master cylinder etc.
Anyway when the engine is off the brakes are pretty much solid as you ould expect but as soon as the engine is running the brake pedal travels almost to the floor. I have bled it several times using a pressurised kit and theres definatley no leaks or air in the system.
Is it possible the master cylinder needs to be the same as the gti6 master cylinder to displace more fluid or something?
If it does then will the gti6 cylinder fit onto the same servo or is the servo different as well?
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Did you change the calipers? Could be a connection. But for braking problems you need some expert advice.
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ok, little bit more info asmaybe the above isnt clear enough. The gti6 conversion means larger front calipers to go round larger discs, the rear has calipers and sics in place of drums. There are no leaks at all.
I have found out the current cylinder uses an 19mm piston and the gti6 p[ston uses a 22.2mm piston. Big difference in terms of fluid displacement so I think this is where the issue lies.
I now need to know if the larger cylinder will fit onto the existing servo.
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Have you tested the vacuum pump?
If thats fine you could try asking at www.pug306.net. Just try their forum.
tinyurl.com/5lm63
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Actually, the GTi6 uses a 24mm piston, the XSi setup uses a 22.2mm piston :-)
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You mentioned New master cylinder..Is it a new one?. Have you also checked to see whether fluid level drops when foot on pedal.Would need someone else to check this..No expert on pug.but once system full of fluid.And unless their is a fault with master cylinder.See no reason why it wont work.Unless reservoir isnt man enough ie doesnt hold enough fluid.I would think.And may be wrong its faulty master cylinder?
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Steve
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Master cylinder is brand new and definatley not leaking. The problem is definatley the piston size.Been speaking with others using gti6 setup. They have opted for the 23.8mm cylinder off a 406 2litre car. Direct fit to the servo.
Mention of gti6 using a 24mm. Not found a 24mm listed anywhere. Wonder if its the 23.8 ?
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Yes sorry, 24mm = 23.8mm, its a bad habit I have of rounding things, lol.
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Actually just thought of something! On 306's with ABS, the pushrod which comes out of the servo and into the master cylinder is in a different position to those without ABS. (It is slightly longer afaik) All 306's with ABS (apart from the GTi setup) used a 22.2mm master cylinder, which you have fitted. The rest point on the piston on these is positioned slightly differently to compensate for the differing position of the servo ---> master cylinder rod. Thus, if your car does not have ABS, you will have increased pedal travel with whatever master cylinder you fit! So, does your car have ABS?? If not, I think this could be your problem.
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At the moment its still has the non abs 19mm cyliner. The 22.8 came on the 406 2 litre without abs. I didnt know the piston placement was different on the abs versions, very handy to know, thanks.
I'm going to source a 23.8 non abs if I can. If not it will have to be the 22.2 non abs.
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