Jamz_

iTrader: (12)

We were on track last week in the scooby (first time its been out on track) and have noted a few problems...

One of the major ones is that the rear end seems to lock up under heavy braking and the front doesnt lockup at all!

Now the front has brembo's fitted, and i would have expected them to lockup but the rear (standard brakes) just lock (i think its one side) and causes the car to loose control.

Its a 93 import

Anyone else had this problem? Is there such thing as a brake bias kit for the impreza?

cheers

James

dunx

iTrader: (3)

You may need a New-Age master cylinder, how's the pedal feel ?

dunx

JDM_Stig

iTrader: (3)

strip the rears down and make sure its all free, i had a issue when i 1st got my wrx and it had a sticking rear caliper, was evil in the rain.

Jamz_

iTrader: (12)

Tell me about it! Saved it the first time, but it fooled me later in the day when i hit a puddle on a corner and the whole back end started trying to get infront of me... was soon ditched on the grass with yellow flags out!

Will take the whole thing appart this weekend (gotta get the gearbox off too, so may as well do it as ill be dirty)

Jamz_

iTrader: (12)

The pedal feels a bit strange... there is nothing for the first bit of the pedal, then starts to bite, but it feels like the rear end bites more then the brembo's on the front :S

Jay m A

iTrader: (2)

Which sounds like you need to rebleed the brakes. The fronts will be working hardest, if theres any air in there they won't be as effective since all the pedal effort goes into compressing the gas rather than the pads on the disks!

Jamz_

iTrader: (12)

Trust me, they've been bled and bled... there is no air in there what so ever!

Fronts aint working their hardest as the rear end is the bit that locks up

ALi-B

iTrader: (1)

Last time I had this was happen; After much poking and prodding the problem was eventually traced to crappy fast road pads on the front that had glazed (EBC).

Turned the car into a death trap - ABS just removed all braking effort (MY97 with teh old 3 channel ABS). With ABS disabled the rears would lock.


Fitted new pads on the front and it solved the problem.

This was with standard calipers though.

Elude

The brakes were bled thoroughly before track. I drove it round for a week and although they do brake well you have to press quite hard before much happens. The pedal is and always has been very soft (compared to my FRS which is rock hard - but I'm running on EBC Redstuff pads which won't help) since we got the car.

It's running Brembo 4 pots on the front which I'm not sure whether is doing the OEM servo/cylinder any favours. I have had the ABS light come on once in the past and then proceeded to give it a test, as you do, and sure enough it locked up at the front.

But as James says it feels like one of the rears is locking up, it's quite a strange feeling. Luckily when it locked up for me there was enough track to get the back end wide and power out but where James was there wasn't as much track. I was never fully on the brakes in the heavy braking zones of the track as it does feel like the car can snap at any time.

dunx

iTrader: (3)

Is the car diving heavily under braking leaving little weight on the rear ?

I'd really look at the brake system, on 22B they suggested a New-Age master cylinder with Brembo's.... as the fluid needed to "move" the four pots in the Brembo's will be far greater than the fluid needed for the standard brakes.

Thus you stamp on the pedal, fronts don't fill as well, rear's do, so lock....

HTH

dunx

Elude

It doesn't feel like it's diving as such. But it does feel like the braking system is tired even after it's full bleed.

Any idea how much a New-Age master cylinder is?

Cheers

scoobyc

iTrader: (2)

eeeeeeeeeebay.

I had my rear right lock up at 120mph into paddock. Now that was fun. Twas snowing too

Ive also heard people run race pads on the front and road pads on the rear, as the race pads on the rear may not get up to temperature to be useful.

Perhaps the opposite is happening? You have red stuff on the front, perhaps they were too cold and if you ahve normal on the rear, the rear will be biting more from cold.

Just a theory...

Jamz_

iTrader: (12)

Im not sure whats on the car actually, will be stripping them down at the weekend to take a look...

The front have drilled and grooved disks on, and the rear are grooved disks... look like EBC's

Elude

I'm not sure what the Impreza is running, they look like the EBC slotted disks on the front. I have RedStuff on the Focus, that might have added some confusion to the mix!

scoobyc

iTrader: (2)

Just a theory. Im not sure if the cold race n cold normal pads would provide enough of a difference in brake bit to shift enough brake bias to the rear to lock it first.

Especially as i assume you did a few warmup laps first to put some temp into them?

Jamz_

iTrader: (12)

Kinda hard to do warmup laps when each session is only 15min... Can warm the oil up from a standing start, but cant warm brakes up

Will probbaly strip the brakes down this weekend and take a closer look

dunx

iTrader: (3)

May be cheaper to go for an in-line bias valve for the rear's to calm them down, but you would need to plumb them into a single brake line from the front end.

HTH

dunx