Unpredictable under braking

  1. Established Member Joined: May 2010 Posts: 1434
    #1
    EDIT: UPDATE FURTHER DOWN
    I recently let off my bias valve a bit as it seemed when i braked hard so the wheels locked up the car would slide to the left, basically I did it so that when the car was jacked off the ground and the brakes were pressed....i could turn the wheel by hand if i really pushed hard, my mechanic told me to do this as basically the theory was that once on the ground the brakes would be a bit stronger and should be about right.

    Well once id first done it i went up a country road to test it and when I locked up it didnt slide to the left.....but recently ive noticed it is doing it.

    What happens is if i slam on hard so that the wheels lock up(no ABS) the car slides sideways to the left, it doesn't get fully sideways obviously just feels as though im driving on ice and its slid to the left instead of braking in a straight line.

    Do i need to let the valve off a bit more?

    Cheers
  2. Saxperience Post Whore Joined: Dec 2004 Grimsby United Kingdom (England) Posts: 5489 SUPERCHARGED saxo vts
    #2
    That or u have one caliper working better than the other.
  3. Established Member Joined: May 2010 Posts: 1434
    #3
    How would i tell mate and what would cause that?

    Cheers
  4. Established Member Joined: May 2010 Posts: 1434
    #4
    Also is there a way to tell how much to adjust it? Im lowered 60mm
  5. Established Member Joined: Jul 2009 N.wales! Posts: 1024 slammed VTS
    #5
    could be ware and tare, ie, one disk more perished than the other, bits of stones getting in grided bits of pads and disks away, i had this problem, changed all pads and disks, bled brakes and game them a bloody good clean and they felt 100x better... just an idea
  6. Established Member Joined: May 2010 Posts: 1434
    #6
    Ah I see mate, well that doesn't sound too had if that is the case, but is there a way of checking what is the problem before i go shelling out? Im gonna go slacken the bias valve off a bit more now, but dont want to slacken it off too much?
  7. Established Member Joined: May 2010 Posts: 1434
    #7
    Also, on the bias valve, which spring is needed to adjust the strength of the back brakes? I originally thought it was the big spring attached to the trailing arm but i have now slackened thaqt a bit more and the little spring connecting the moving arm and valve, although it still doesn't appear to have made much difference, i only gave each spring a couple of turns, and now the arm has about 5mm or totally free play, 10 or 15mm whils moving that little spring, and the big spring has about 10mm slackness on it before it tensions when the car is jacked up.
  8. Established Member Joined: May 2010 Posts: 1434
    #8
    After letting the spring off more it is still doing it, could it be that the rear brakes arent working enough and causing the car to slide when locked up?

    If not is there a way to quickly disconnect the valve so i can tell if that is the problem or not?
  9. Established Member Joined: May 2010 Posts: 1434
    #9
    After letting the spring off more it is still doing it, could it be that the rear brakes arent working enough and causing the car to slide when locked up?

    If not is there a way to quickly disconnect the valve so i can tell if that is the problem or not?
  10. Established Member Joined: May 2010 Posts: 1434
    #10
    UPDATE
    I took the car to my mechanic and he sent me down to the MOT tester who put it on the brake tester for me....he showed me that both front brakes were braking equally and so were both rear brakes....

    My mechanic then had a play with the bias valve and readjusted it to how he thought was right.

    I have been testing it and it seems sometimes when I brake the car will swing to the left, occasionally to the right and sometimes not at all it will just feel light/squirelly as i believe clarkson calls it lol.

    This only happens when the brakes lock up...apart from that it brakes perfectly straight until sometimes when I lock up.
    Is this just cos its a light car with no ABS locking up from a high speed...plus I have no spare wheel or cage in?


    Cheers
  11. Saxperience Forum Bum Joined: May 2009 Birmingham Posts: 4289 02 VTR'd Furio, 07 Audi A4 Avant S Line
    #11
    Just take it off lol

    When i put a vtr axle on my furio, i didnt use the bias valve, just ran it straight from front to the caliper.

    Havnt had no problems ever, no locking up even in the wet.
  12. Saxperience Post Whore Joined: Apr 2007 Posts: 6640 Integra DC5R & VTS
    #12
    A floaty rear end under hard braking is totally normal in these cars imo - mainly due to bugger all weight in the back.

    As for the bias valve, it's just trial and error. If you're still locking the rears, all you can really do is keep backing the bolt off until you're happy.

    I'm assuming you've seen this thread?
  13. Established Member Joined: May 2010 Posts: 1434
    #13
    [quote=saxo_singh;5478048]Just take it off lol

    When i put a vtr axle on my furio, i didnt use the bias valve, just ran it straight from front to the caliper.

    Havnt had no problems ever, no locking up even in the wet.[/QUOTE

    How do I go about disconnecting it? Do I have to swap brake pipes around etc?

    Quote:
    Originally Posted by LeeumH View Post
    A floaty rear end under hard braking is totally normal in these cars imo - mainly due to bugger all weight in the back.

    As for the bias valve, it's just trial and error. If you're still locking the rears, all you can really do is keep backing the bolt off until you're happy.

    I'm assuming you've seen this thread?
    That was what I was assuming after all this messing about....its quite scary but i suppose if i learn to expect it and lock the wheels the opposite way it seems to stop dead...and my mechanic did say it brakes better than a lot of cars hes seen with ABS lol, although it wasnt sliding for him.
    I've got a feeling my lack of spare wheel may be influencing it...although with my sub I thought it would counterbalance it?

    Im really unsure if thats the case as like I say it doesn't always do it and not always the same direction when it does whip out...

    I hadn't seen that thread mate despite searching i'll check it out now, thanks
  14. Established Member Joined: May 2010 Posts: 1434
    #14
    Ive read that thread now, could somebody clarify a few things to me...
    where it says:
    Quote:
    There is no real measurement for how much you loosen the bolt, as it depends on the lowness of the chassis. Its a good idea to loosen it so bout 15mm of screw thread is visible
    Does this mean i Should have about 15mm visible here...bearing in mind im lowered 60mm? And when the car is jacked off the ground:



    It also says:
    Quote:
    Originally Posted by Ethro View Post
    just to add, the haynes says that when on its wheels so the weight is on it, the spring should have 3mm of play...

    but getting at it while a wheel is on, its a NIGHTMARE!

    Does this mean so when the car is on the ground the spring should be able to be moved left and right about 3mm and have no tension?

    Which of these is best to use with me being down 60mm.

    Cheers
  15. Established Member Joined: May 2010 Posts: 1434
    #15
    Bump .
  16. Saxperience Post Whore Joined: Mar 2003 United Kingdom (England) Posts: 7064
    #16
    Have you got matching tyres on each axle? or tyre pressures?
    Different grip levels could cause the pulling?
  17. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #17
    Out of interest have you tried bleeding the brakes?Air in the brake lines can cause uneven braking mate.

    Steve.
  18. Established Member Joined: May 2010 Posts: 1434
    #18
    Quote:
    Originally Posted by Quick View Post
    Have you got matching tyres on each axle? or tyre pressures?
    Different grip levels could cause the pulling?

    Yeah i've got yoko S drives all round mate, and i use 33 psi front and 30 psi(29 standard + 1 for my sub)

    Quote:
    Originally Posted by stevo67 View Post
    Out of interest have you tried bleeding the brakes?Air in the brake lines can cause uneven braking mate.

    Steve.
    I haven't actually mate, it only does it when locked up though is this still the case? And is it just a case of bleeding from each nipple i remember doing this on and old car with drubs and the nipple shearing off lol
  19. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #19
    Quote:
    Originally Posted by AL3X_ View Post
    Yeah i've got yoko S drives all round mate, and i use 33 psi front and 30 psi(29 standard + 1 for my sub)



    I haven't actually mate, it only does it when locked up though is this still the case? And is it just a case of bleeding from each nipple i remember doing this on and old car with drubs and the nipple shearing off lol
    Put it this way it won`t do any harm,as air does build up after a time.


    Steve.
  20. Established Member Joined: May 2010 Posts: 1434
    #20
    Ahhh fair enough....is there a guide to doing it all? if not i dunno what it could be except the bias valve?
  21. Saxperience Post Whore Joined: Mar 2003 United Kingdom (England) Posts: 7064
    #21
    Also get the tracking checked!
  22. Established Member Joined: May 2010 Posts: 1434
    #22
    I think it may have been the bias valve after all...got my mate to watch me slam on...he said the rears locked up almost straight away...and fronts didn't until i was almost stopped...so i loosened the spring even more to like the guide says of 15mm thread showing...took it for a spin and he then said that after a quick slam on from 30 the fronts locked and rears didnt that time...it stopped a lot straighter anyway so well see.