Brake Issue

[scotiamr2t]

Recently renewed the complete braking system on my race car (used to run ABS but deleted it all). Car now runs hard lines through the inside of the car via a bias valve, all new calipers and flexis front and rear, new discs and pads all round. Also now run a 4 port CUP master cylinder with 1 port blocked off, 1 port to each front caliper and then 1 port to the bias valve and it T's off to the rear calipers after that.

Brakes have been bled so there is no air in the system and the pedal feels great

The issue i am having is the front left locks up rather easily, i have double checked all calipers, sliders, hoses, re-bled the brakes and still the front left locks up

Anyone any ideas?

 

[White16valver]

Is your wheel alignment all good?

I would imagine that if you accidently were running loads more camber on one side than the other (so reducing the amount of rubber on the road in a straight line) it would mean it was easier to lock up.

 

[scotiamr2t]

Alignment an corner weights are there or thereabouts but not perfect as not been set up with a Hunter or similar yet. Been set with string for now and i am usually pretty close, having some mapping tweaks tomorrow then i will get it booked in for a proper alignement

 

[vroomtshh]

How do the ports work? You'e not accidentally got one front to the front brake, a rear to the other front and a rear to the two rears? Or are they split 25% each?

 

[scotiamr2t]

Standard cup master cylinder so split evenly between the 4 ports. Its all as per this diagram

 

[JB21]

Never heard of blocking one of the ports off, most just tee it instead. Saying that I had the same issue for ages with my track 182, after rebuilding the callipers, countless flushes and alignments I gave up and put it down to bad weight distribution (lighter on the NSF).

 

[scotiamr2t]

@JB21 I am leany towards the same thought as you with the front left being a fair bit lighter. Hopefully some more people with track/race cars chime in with further thoughts as its a PITA

 

[JB21]

@JB21 I am leany towards the same thought as you with the front left being a fair bit lighter. Hopefully some more people with track/race cars chime in with further thoughts as its a PITA

Try lowering the NSF an inch or so to see if it makes a difference.

 

[scotiamr2t]

I shall get it in for proper corner weighting and alignment before the next outing. Will reassess after that.

 

[1985michael182]

could it be due to the blanking off of one port ? Is it putting 50% through your front left and then 25% to front right and 25% to the rears pipe. I would have plumbed both rear ports into a T-peice and then run a single line through the car

 

[1985michael182]

Also how are you running the Speedo now with abs deleted?

 

[steviekyle13793]

The above sounds plausible, definitely worth checking!

 

[1985michael182]

And it wouldn't take long to put a little peice of pipe in

 

[scotiamr2t]

No need for a T peice. The brakes are plumbed up as per renaultsport themselves do it, diagram below.

Car is away tomorrow to go on a brake tester, then have alignment and corner weights done.

 

[White16valver]

No need for a T peice. The brakes are plumbed up as per renaultsport themselves do it, diagram below.

Car is away tomorrow to go on a brake tester, then have alignment and corner weights done.

View attachment 1363633

May I ask where you got the diagrams from?

It looks like it comes from a useful manual! lol