R32 Spongey Brake Pedal

[daninchainz]

Hi, have an r32 with r33 big brakes/5 stud all round and gktech braided lines. Have bled it up, pedal is still very soft, no obvious leaks either but will give it a full flush on the weekend and post results. I was just wondering if people have had issues with the master cylinder/brake booster when doing this conversion or is there a proportionate valve that could make the pedal feel crap? Or is it just how the pedal feels with this conversion. Car is going through cert so needs to be firm 

[niZmO_Man]

Bled the ABS module?

[daninchainz]

Has been deleted 

[KiwiRS4T]

What do you mean by "soft"? Does the pedal go down a long way? Is it easy to depress? or does it continue to sink after first applying it?

[daninchainz]

Goes down 1/2-3/4 of the way with no pressure, pump it up a bit gets firmer but still goes down about 1/2

[GTSBoy]

R33 calipers are hydraulically identical to R32 calipers, and in fact should feel firmer because they physically flex a little less, being iron instead of alloy. So, no, it should not be spongey and it is not a feature of this combo.

The brakes are simply not properly bled, or there is a hydraulic problem.

How are you bleeding them? Manual pump the pedal? You may have stuffed your master cylinder's piston seals by pushing them past the end of the normal travel into caked on crap on the cylinder wall. That can tear the seals. It happens. Power bleeding is much more effective.

Also, have you made sure that you've put the calipers on the correct sides?

[Duncan]

It really does sound like a bleeding issue. 

A mismatched master cylinder creates a long but consistent pedal. 

[daninchainz]

I have upgraded from the 4 stud small brakes to big. I had bled them by my self with a bottle and hose making sure the bottom of the hose was fully submerged so air wouldn’t get sucked back up and pumped the fluid through, the callipers are L and R but not sure about rears as I couldn’t see a mark, will get a mate to help bleed and if that fails will look in to master cylinder thanks !

[Ben C34]

Then it is definitely a bleeding issue.

[blind_elk]

On 2/20/2020 at 7:04 PM, daninchainz said:

the callipers are L and R but not sure about rears as I couldn’t see a mark,

Shouldn't need marks or anything. All you need to do is make sure the bleed nipple is at the top / highest point.

[daninchainz]

Callipers were on wrong side ? swapped them around, bleed nipple on top and bled up fine! Here’s to good braking ?