4 Pot Conversion

[Guest rene]

uprated the brakes of my 205 with 4 pot ap lockheed calipers , brembo grooved standard size discs and ebc green stuff pads , works better but you have to press the pedal pretty hard to get it working , not harder than standard thou , and it brakes harder but not as hard as i hoped , is this because of the standard size discs or wil it help to change the mastercilinder to a 406 item ?

don't now what to expect when changing this as it is standard now .

it's hard to explain , it's progressive up to a point and then it stops , when you brake harder there is no difference and then it locks .

does this make sense ?

[C_W 3 1 Cars]

It doesn't sound like a larger master cylinder will help from that description. I briefly ran a larger master cylinder on mine but with standard calipers; the pedal was firm and moved less but that meant you had to press it harder; with larger calipers it would have worked better.

 

If you experience a firm pedal and it's hard to press then a larger master cylinder may make this worse.

[jackherer 543]

master cylinder size depends entirely on the size of the pistons in the calipers, maybe you need a smaller master cylinder to match these calipers?

[Guest rene]

when reading your replies i don't think a bigger mastercilinder wil help as the pedal is firm and maybe i have to push it a little deeper but not much .

think it has to do with the pads then , bought these from a guy who had them on a 106 rally/race car and they came with worn race pads , tried them for a week but it was mental ! when cold they were ok but while braking they heated up and when you touchd the pedal at any speed they lock up very fast , just not enough grip has anyone has good or bad expirience with green stuf pads ?

not that its not braking hard now , just in the dry there is more grip than stopping power . make any sense ?

[red 0]

If you fit 4 pot calipers to replace 2 pot calipers and the calipers internal volume on the piston side is larger on the 4 pot then you'll need a bigger Master cylinder , as this will give the spongey feel you get on the initial press on the brake pedal

and you'll loose pressure on the system as the volume is larger, if you do the opposite as CW has mentioned fitting a bigger MC to the OE set upthen you'll get a firmer pedal and less movment which can be harder to use, the volumes within the hydraulic systems on brakes will be set with the hole system as standard, and any changes in volume will cause changes in other things to get the ballance back.

 

Rene with respect to the grooved discs, did you clean them with turpintine/white spirits before fitting? as all new discs have an oil coating on them for storage protection which must be washed off before you fit them, or this stuff ends up in the pads and can take an age before the brakes bed in. I found this out to my cost years ago when fitting 4 pots and discs it didn't mention this in the literature with the kit.

 

Regards Russ.....

[Sam 4]

Is it worth fitting a GTI-6 MC with 306 diesel turbo calipers? is pretty much new and only £20 for mc and reservoir might even be able to get the servo cheap too

[Guest rene]

thanks for the advice russ , but i have been a mechanic for 10 years in a pug garage now and have changed some discs before , but you didn't now that of course , so thanks for the advice , i only have no experience with upgrading brakes as we always work on standard cars , i now how it works in theorie but don't want to change things that make no difference . if changing the mc only meens that it wil feel better and don't change performance i wil not bother to do so . thats why i like this forum so much , everything that you can think of someone has tried it before , and has experience with

[C_W 3 1 Cars]

It sounds like it might be the pads are possibly too hard?? If the travel feels ok then the master cylinder should be fine.

 

Perhaps the pads are glazed, being race pads. They can go off and the pedal is firm but very hard to press with not much braking performance.

[Guest rene]

the race pads where old and i used them on the old discs for a few days , then replaced them for brembo groved discs and EBC greenstuf pads and where very gentle for 500 k , and then tried to push them a bit , the car brakes harder then the standard system and doesn't fade , but just not as hard as i hoped