sentra Posted February 20, 2015 Share Posted February 20, 2015 Hey there, after some rookie dave style opinions here on this can of worms. Ive got an odd thing going on, go through the trap at 180kph and back off. Untill this point everything appears to feel fine. mabey a little twitchy but nothjng major. As soon as start coasting down,the car starts trying to steer to the walls, it definatly feels like its coming from the rear. its a bit hard to tell if it gets worse or better under braking as im a bit preoccupied trying to go straight. the car has every applibile factor i could find online relating to it going on. It has loads of rear spring preload to gain ride height which apprantly can cause it, however at the os dragday it had none and was the same. alignment is good and to oem, the bushes are new urethane and in good condition. The car runs no rear swaybar due to not fitting past diff, which is torsen type toyota unit it is mazda bfmr oem macpherson + irs setup otherwise in the rear. Thoughts, feelings and opinions welcome. Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted February 20, 2015 Share Posted February 20, 2015 Does it make a difference whether you're still in gear or neutral? Does it always start swaying one way first? Quote Link to comment Share on other sites More sharing options...
sentra Posted February 20, 2015 Author Share Posted February 20, 2015 ^ good idea, will check. (not today as i dont want to loose my licence - hence wanting a bunch stuff to check at once) Quote Link to comment Share on other sites More sharing options...
Mof Posted February 20, 2015 Share Posted February 20, 2015 Is it lsd? Quote Link to comment Share on other sites More sharing options...
sentra Posted February 20, 2015 Author Share Posted February 20, 2015 yes but torsen type. im considering welding this week it for unrelated reasons/dohnuts. 6 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted February 20, 2015 Share Posted February 20, 2015 Its not engine braking hardout and causing the rear wheels to skid slightly? Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 21, 2015 Share Posted February 21, 2015 is your brake bias adjustable? Wind some into rear if not might be the proportional valve Quote Link to comment Share on other sites More sharing options...
Unclejake Posted February 21, 2015 Share Posted February 21, 2015 If it isn't the rear end I'd measure your static caster on the front struts and then have a think about how (if) the apparent caster could be effected by a change in stance as you came off the throttle. i.e. it sounds like it's fine when the arse is squatted down, but not when the arse is raised up.... it does sound more like a rear end issue though, or possibly aerodynamics. EDIT: What actual car is this happening in? I Googled a Mazda BMFR and I can't tell if that's always an AWD or not Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted February 21, 2015 Share Posted February 21, 2015 Pretty sure they are, yes. Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 21, 2015 Share Posted February 21, 2015 Uep thet are full time 4wd Quote Link to comment Share on other sites More sharing options...
Styles Posted February 21, 2015 Share Posted February 21, 2015 Are your tyres/rims wider than factory? Could that be exacerbating toe out on deceleration? I have no idea how one could calculate that likelihood. Also, are you able to run in FWD to eliminate rear drivetrain being an issue (I assume not.) Quote Link to comment Share on other sites More sharing options...
V8Pete Posted February 21, 2015 Share Posted February 21, 2015 My 205 used to always try to fuck me over under brakes. Turned out the rear torsion bars were a bit cocked up, which effectively resulted in uneven spring rate/preload in the rear, which, when unloaded under braking, tried to slam the rear sideways. It was more of a turn in a certain direction (left) than a 'sway' though. Are your springs and preload dead even side to side? The difference in mine was noticeable with the car in the air and trying to move the back wheels up and down by hand. Quote Link to comment Share on other sites More sharing options...
Testament Posted February 21, 2015 Share Posted February 21, 2015 The car might have a wheel alignment but is it actually square? The suspension pickups esp. You should put a centerline/centrepoint down the car and triangulate all the point suspension mounts and to the ball joints or a fixed point on each hub. Also has something potentially moved since wheel alignment? This said preload issue sounds plausible, if you set it up to get the ride height square using preload its unlikely the preload is perfectly even/car is a twistie probably Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 21, 2015 Share Posted February 21, 2015 Id be looking at brakes may have a seised slider or incorrect ballence Quote Link to comment Share on other sites More sharing options...
tim13 Posted February 22, 2015 Share Posted February 22, 2015 it could be excessive toe out on decel at either end (toe out can encourage turn in , so too much can be twitchy) if you have non factory springs bushes etc running factory alignment may not be as good as custom settings to match custom components . good luck ..... sounds scary . also if you have new components it might be worth spanner checking too Quote Link to comment Share on other sites More sharing options...
sentra Posted February 22, 2015 Author Share Posted February 22, 2015 cheers for the replys, have made a "special-service tool" to check bushes as a starting point and found some crappyness, will sort that, balance preload (with a tape measure i guess?) and try again. will see if i can somehow get it on aa's brake balance roller later in the week. Quote Link to comment Share on other sites More sharing options...
cletus Posted February 22, 2015 Share Posted February 22, 2015 does it always try to kill you with the same wall? or does it try to kill you with both sides of the track. 1 Quote Link to comment Share on other sites More sharing options...
cletus Posted February 22, 2015 Share Posted February 22, 2015 might be worthwhile checking to see how much bump steer it has as well. from memory they are a bit terrible when slammed Quote Link to comment Share on other sites More sharing options...
sheepers Posted February 22, 2015 Share Posted February 22, 2015 are your diff ratios the same? sounds stupid but I've seen it happen before. Quote Link to comment Share on other sites More sharing options...
sentra Posted February 22, 2015 Author Share Posted February 22, 2015 yup they both came from an oem standard gt4, its allmost back at factory suspension angles now, but ill put it on the list if this round isnt the cure/ cant test easily Quote Link to comment Share on other sites More sharing options...
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