Rear end unstable under brakes

[STiR]

Hi guys,

Under very hard braking, the rear of my car can begin to feel very unsettled and can actually kick out violently. Car is EG civic and chassis is set up very well. Car is running TODA fightex DA with 9k f 7k rear springs (measured), all ITR swaybars, control arms, trailing arms etc, with all new bushings. Brake set up is ITR 5lug 282 mm front and rear, ITR booster+master cylinder. Pads are project mu max 500.

The rear always throws itelf out to the right...

The only thing I can think of is when the calipers were off, it was found that the LEFT rear caliper was 'sticking', I.e the piston wasn't springing back fully. I've just noticed the rear left wheel has quite a bit less brake dust than the right wheel.

I'm inclined towards getting the rear calipers serviced/rebuilt.

Please give your opinion if you are familiar with such things.

Shiraz

[BlitZ]

alignement is 100% i presume..

yeah. check if disc is warped
or could be the piston, but not likily.

Same pads allround?

[bennjamin]

stupid question what brake proportioner are you running ?

[STiR]

alignment has just been done, camber is mild all round. Rear has a little toe out. I'm not sure which brake bias valve is in there? Maybe stock (eg3 breeze?) not sure.

When I put my foot on brakes at low speed sometimes I hear a clunk sound from rear.

[STiR]

Same pads all round

[nd55]

checked trailing arm bushes?

> eg3 breeze

EG3 was drum brakes IIRC.
Probably should grab a '4040' proportioning valve for an ITR conversion.

Nick.

[STiR]

Every single bush has been changed. I don't know if the proportioning valve was changed to be honest

[bennjamin]

change the proportional valve to a proper one off a 4w disc car or better yet a integra type R.

[STiR]

It might have been changed however I can't confrm... How can I tell? Do they look different? Still I don't understand how the rear tries to kill me... The fronts will lock before the rears...could it be something else?

[nd55]

> The fronts will lock before the rears.

That's supposed to happen.
Rears locking first is a safety issue.

> The rear always throws itelf out to the right...
But not like that.

Nick.

[STiR]

I know saying fronts lock first is to suggest bias might be ok? I'll get it checked out

[STiR]

I just booked in the car with racebrakes (melbourne). Next week they'll get it up, check brake line pressures front and rear and check to see what brake proportioning valve is in there. If necessary, we'll probably fit an adjustable brake bias valve in there which will be useful without ABS.

[night_wolf]

(CORRECT ME IF IM WRONG) well two things might be influencing this shiraz, propotional value is stock and the upgraded brake booster and MC arnt able to perform to its ful extend. but this would cause less braking power with the ITR set up you are running.

my second guess would actually be the rear brakes, one of the pins may be stuck/broken OR inner pad wear is uneven. thus causing less braking force on the one side, hence the lack of brake dust on on side in comparision to the other and also the lack of braking force on one wheel is causeing the rear too side a tad.

i personally dont belive it could be your propotional valve since the theory does not apply to the situation...but thats my opinion.

[nd55]

> check brake line pressures front and rear

Any chance you can post the results of the pressure tests?

I'm curious to know what sort of pressure is in the lines under real braking conditions.

Nick.

[JohnL]

If you suspect one of the calipers is siezed (or partially seized), then I think you need to varify this and and if so fix it before trying anything else.