xNORMSKIx

cheers for the replies guys.
not handbrake is off. ive been trying to sort this for a while so didnt want to seize the rears.
I will re-trace the pipes and double check which ones are which. some of the pipes have been replaced before i had the car so they may have been replaced incorrectly?

With regards to the mondeo servo/master is this a direct fit? apart from the piping?

thanks again for the input

DazC

iTrader: (1)

If you check that it has been piped up correctly, correct it if it's not and then make sure that you bleed the rear calipers with the nipple pointing to the sky then you won't need the Mondeo servo and master cylinder.

If the pipes have been replaced then you may not have noticed any issues before hand if they were put back incorrectly. You're only filling small front calipers with fluid with the standard setup so wouldn't have noticed as much until you fitted much larger calipers. This may have emphasised the issue that wasn't as apparent, or wasn't an issue before hand.

Like I said, my car is a S1 Turbo with standard pipe work and a standard master cylinder with AP CP5200 4 pots on the front and 2wd Cossie rears and the pedal is bang on. The 2 drivers side pipes go to 2 load compensator valves on the drivers inner wing then from there to the rear. The other 2 pipes go directly to each front wheel. My issue which was the same symptoms as you're having was just a small amount of air trapped in the rear calipers which only came out when I swung the caliper to point the nipple upwards.

rsturbonutter

Mate he will defo need the master cylinder servo set up. You say that you are running four pots and that is why its fine on your car because you are only moving four small pistons as opposed to one large piston. The mondeo wouldn't have a bigger master/servo if a smaller would be sufficent would it. The size difference in the mondeo gear is quite apparent as they're a lot bigger than the xr3i standard piston. Its not rocket science to work out that if you need more fluid to move the piston then the pedal will travel further to acheive this. Then you got the fact he got discs on rear which again need more fluid than what is required to move the rear wheel cylinders. The mondeo gear is pretty straight forward to fit but a slight opening up of the area where it goes through the bulk head is required. Don't be put off by this as its only slightly. Hope this helps mate

luke19790_3

had the same setup as this guy with no issues on a standard rs turbo master cylinder

rsturbonutter

And you're pedal was the same as before the conversion?
I find that very hard to believe

xNORMSKIx

im going to have a look at the way its been piped first if no difference then ill get my ass down the scrappy! any preference as to which mondeo? ive read a few people have used mk1/2 and a few mk3? or are they the same?

thanks

rsturbonutter

you will be wating a mk1 mate

DazC

iTrader: (1)

I have had single piston 4x4 Cossie calipers on the front of my car too with a perfect pedal. The pedal was as good as it was previously with standard calipers.

How have you worked out that a set of large 4 pots will have need less fluid to move all the pistons than a large single pot caliper? My maths works it out as a smaller surface area for the fluid to work against and therefore requires less fluid to fill on a large single pot caliper than the known measurements for my AP 4 pots.

The pistons in my calipers are 41.3mm of which I have 4 of, and 38.1mm of which I also have 4 of.

The area of the 38mm pistons is 1140.09 x4 = 4560.36
The area of the 43mm pistons is 1452.20 x4 = 5808.8

Total surface area that the fluid has to work against = 10369.16.

The surface area of the single large piston caliper estimated at 80mm diameter piston works out as follows...

80mm piston area - 5026.54 x 2 = 10053.08.

I haven't bothered working out the rear calipers as both Normski and I are using the same calipers so would be a pointless exercise.

DazC

iTrader: (1)

After some scratching around on the net is seems the ST170 piston diameter is 53.9 which means a surface area of 2290.22 x 2 = 4580.44.

If the Mondeo pistons are the same then it needs less than half the fluid displacement required for AP 4 pots...

I maintain 100% that Normski does not need a larger diameter master cylinder.

AstoN_B

iTrader: (1)

Seems definitive. And promising for me too, providing the rebuild of my 25mm M/C is ok.

Have some cossie front calipers to go on front at some point to match the rear conversion already done. Good to know I shouldn't have too much trouble.

ro33

got solution? I have a standard rapier s2 RST front and back disk conversion, probe several master cylinder and the pedal goes way down then roll with it. that could be? lines are new, to remove the splitter, and the nipples are looking up

89barto89

Sorry mate, i have the same fuel pump (i think). It works well both vertical and orizzontal?