Wilwood 4-pots - spongy pedal

G

GTI-R Kid

Guest
Recently fitted a Wilwood 4-pot front brake kit with 310mm discs, but have been left slightly dissappointed in the way they work. When first fitted we dreained the entire brake system of fluid, and refilled it with the stuff Rally Designs supplied us with. We bled the system 3 times to ensure that any trace of air was gone from the system too, but now that they've been tried I can't say I'm overwhelmed by the performance.

When the brakes are first applied the pedal moves a good 2 inches before any proper braking force can be felt. If I let off again and press the pedal straight away the response is totally different and much better. Its like the first push of the pedal primes the lines with fluid, and then they work on the second press.

Is this a common thing after fitting 4-pots and retaining the standard brake master cylinder? There are no leaks in the system, not by the calipers or back at the master cylinder. Is it possible that even after bleeding the brakes 3 times that there's still air somewhere in the system?

Oh and the car is fitted with the Poly Q pads in case it makes any difference. I'll be replacing the rear discs and pads next week (no point having brand new up front and 4 year old stuff on the rear (though only 3000km use - car been stored for years). Think this might help things, or will I just have to bleed another few times.:sad:
 
abyss

abyss

Member
you have to run the brakes in and its a race pad, so you have to give them a bit of stick to heat them up
 
G

GTI-R Kid

Guest
Brakes have been on the car for over 1000km now, should be well run in surely? Also went with the Poly Q as they were supposed to work from 0-900 degrees.

Don't get me wrong, the brakes are brilliant on the second push. But even in slow driving and light braking (say city for example) its the same double pump thing. I'm sure an initial pump at less than 30mph isn't going to generate much heat.
 
abyss

abyss

Member
hmmm do you have the master cylinder support brakes think someone on here sells them might be useful.
 
Mr GTiR

Mr GTiR

New Member
Sounds like you still have standard brake lines. Have you not though to change to the s/s braided lines to reduce brake line flex?
 
CruiseGTi-R

CruiseGTi-R

Member
Don't worry fella, i'm pretty sure its just that they're not bled fully yet. I had the exact same deal with mine.

Once having bled them the first few times I still had a soft pedal, with the second pump much harder.

I then re-bled each nipple a lot, every tiny little bubble makes a difference. One trick some people forget is to bleed as normal, then shut the nipple off, press the pedal down hard (this forces bubbles to the end), then re-bleed again.

It takes ages and is a right hassle. Also do the rears and do them all in the right order.
 
Y

youngsyp

New Member
Best thing to do to make sure it's not got air in the system is find a garage with(or buy They're about £45) a vacuum bleeder. Don't forget, the master cylinders on these cars are at least 12 years old now. Continuous full extension of the master cylinder piston may damage the old piston seal !

If you don't have stainless braided hoses all round, this could also lead to spongyness. The age of the fluid you use can also have an effect ! If you drained the system down fully, you may have dragged in an air bubble that is now hard to shift. If you do intend to bleed them again manually, give them a good fast stamp when you apply the first down stroke on each corner !
 
G

GTI-R Kid

Guest
Fitted the braided lines that came with the kit on the front, haven't changed the lines on the rear .... yet!

Cruise - did you bleed all 4 nipples on each front caliper - or just the top 2?

After searching online before fitting we came up with bleeding in the following way going on posts found, does this sound right?

Rear passenger side
Front drivers side inside nipple
Front drivers side outside nipple
Rear drivers side
Front passenger side inside nipple
Front passenger side outside nipple

Will try bleed them again, and if thats no better might get a garage to do it properly.
 
Y

youngsyp

New Member
GTI-R Kid said:
Fitted the braided lines that came with the kit on the front, haven't changed the lines on the rear .... yet!
Click to expand...
There's your problem ! Change these to braided items and I bet you get the pedal feel you're looking for !

Your bleed order looks good though although, you may want to make a 'Y' hose so that you can bleed each bank on a calliper in one go !
 
D

danmo

Guest
Also braking system on the car is designed to fill the standard 1 pot (or whatever it was) caliper and now you need to fill up 4 pots, so there's always gonna be more travel on the first pust unless you upgrade the master cylinder.
 
Y

youngsyp

New Member
danmo said:
Also braking system on the car is designed to fill the standard 1 pot (or whatever it was) caliper and now you need to fill up 4 pots, so there's always gonna be more travel on the first pust unless you upgrade the master cylinder.
Click to expand...
The 4 pistons on the new caliper will be quite a bit smaller than the single large piston on the old caliper. So, the actual volume of the chamber/s the fluid needs to fill will hardly change at all. You shouldn't notice it in brake application anyway !
 
P

pulsarboby

Guest
just out of curiosity, you have got the calipers on the right way round i take it?
seen this done before where calipers have been put on the wrong side which will leave the bleed nipple at the bottom rather than the top!
this means that the caliper will always retain air 'as air rises' this will play havoc with trying to bleed them.
double check to make sure!!
 
G

GTI-R Kid

Guest
youngsyp - must root out the rear lines and get them fitted so. Every little helps I suppose.

Boby - calipers are universal. 2 nipples on each end so can be mounted either side.

Cruise - cheers for that. Will have to try it.
 
You must log in or register to reply here.
Top