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Help Wanted: Odd Braking Problem

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#1 James M

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Posted 30 March 2017 - 01:20 PM

This is for a Turbo, with everything standard except Mintex 1144 pads.

 

The problem I have is with braking on track.  Much (but not all) of the time I get about 50% of what I expect brake-wise when pushing the pedal fairly hard.  After a short time (or perhaps with greater pressure) the pedal then 'gives' (it feels something has unstuck and the pedal depresses another centimetre or so), at which point I get excellent braking.  Note that sometimes I get good braking from the start.  I figure this can't be related to the pads or the lines, or even to one of the calipers sticking (the car isn't unbalanced side-to-side either before or after the pedal 'gives').  It's not obviously related to brake temperature either (and happens with fresh DOT5.1 fluid).  Could it be the master cylinder? 

 

I wondered if anyone has experienced the same problem, or otherwise has any advice on what might be causing it.  I'm also interested in recommendations for Lotus / track specialists not too far from Cambridge who might be able to assist. 

 

On a related note, is there much value in fitting braided lines?

 

Thanks in advance.

 

James



#2 siztenboots

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Posted 30 March 2017 - 01:23 PM

rear compensator valve , it line locks the rear pressure in the abs



#3 gaffer1986

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Posted 30 March 2017 - 01:24 PM

Hi James, I've had this problem before, scared me silly at over 110mph. Then I remembered that I had left the ABS connected for the MOT I did the week before. Disconnected the ABS again and the brakes were spot on for the rest of the day. VX220s have something called dysfunction electronic braking system that needs removing altogether or upgrading to a 4 channel ABS elise unit.

#4 gaffer1986

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Posted 30 March 2017 - 01:25 PM

rear compensator valve , it line locks the rear pressure in the abs

That's what I meant by dysfunctional braking system.

#5 gaffer1986

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Posted 30 March 2017 - 01:28 PM

Disconnect the front and rear off side ABS sensors or cut the wire and install a switch will resolve your issue.

#6 James M

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Posted 30 March 2017 - 01:30 PM

Superb - and thank you both.  Someone at Bedford on Monday mentioned fitting an ABS switch, but that was in another context and I didn't make the connection.

 

Is the Elise unit a worthwhile investment, perhaps with some braided lines while I'm at it, or is the advice to scrap ABS altogether on track?

 

James



#7 gaffer1986

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Posted 30 March 2017 - 01:32 PM

Depends if you want ABS or not. I prefer no electronic intervention so I'm happy to scrap it. Would be good if I could get rid of the light.

#8 fiveoclock

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Posted 30 March 2017 - 05:03 PM

If you intend to do quite a few track days this summer 1144s arent good enough. You'll be on the brakes too long and your brakes will overheat. 







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