Brakes/Braking

[JohnBu]

Not 100% happy with my brakes. I'm wondering which is the weak link my current Braking system.

When I brake hard, it locks up the wheels, then ABS kicks in very early, but it doesn't seem to slow down as hard as my MkV GTI.

Front wheels/tyres are 10,000km Goodyear Eagle F1 215/40R17s , RDA or DBA slotted 308mm discs, EBC Greenstuff pads.

Certainly, it doesn't feel unsafe, especially compared to other cars, but I have a feeling, that if the ABS didn't kick in so early, it could stop a tad earlier. Having said that, I've not had an issue with brake fade.

So which is it
- tyres (maybe 225 would help)
- discs,
- pads
or ABS

On the pads, which I've never liked, it seems to be like all or nothing type of braking / less progressive compared than the OEM pads.

[Calibrated]

Not 100% happy with my brakes. I'm wondering which is the weak link my current Braking system.

When I brake hard, it locks up the wheels, then ABS kicks in very early, but it doesn't seem to slow down as hard as my MkV GTI.

Front wheels/tyres are 10,000km Goodyear Eagle F1 215/40R17s , RDA or DBA slotted 308mm discs, EBC Greenstuff pads.

Certainly, it doesn't feel unsafe, especially compared to other cars, but I have a feeling, that if the ABS didn't kick in so early, it could stop a tad earlier. Having said that, I've not had an issue with brake fade.

So which is it
- tyres (maybe 225 would help)
- discs,
- pads
or ABS

On the pads, which I've never liked, it seems to be like all or nothing type of braking / less progressive compared than the OEM pads.
i've noticed that with my greenstuff's too.

dunno what to point out on your setup, because
a) 215's should be perfectly fine (225's would be better though)
b) discs are big enough
c) pads, well, as mentioned above
d) ABS sounds like its doing it's job.

maybe go back to OEM pads? i've found my greenstuff's turn the car into a bit of a pig in traffic. but with hard braking in the twisties they are great.

[nuggz]

On the pads, which I've never liked, it seems to be like all or nothing type of braking / less progressive compared than the OEM pads.

i think thats the answer
afaik the main 2 factors are excessive bite on the brakes, or lack of grip on the front tyres

[JohnBu]

The greenstuff does seem to pull up hard when you want it to, it's just not as progressive as I would like.

Is the fact it's not as progressive making the wheels lock up earlier because when the pads bite, it bites hard, compared to the the OEM pads.

Tyres, same results with the Bridgestone Adrenalins (of the same size).

Maybe, I'll try 225/45R17s on the stock rims. I wonder if the will fit.

I didn't have too much complaints until I began switching driving the GTI. GTI has fantastic brakes, progressive and bites hard, can't recall ABS kicking in either.

[sadavidsriturbo]

Maybe pull the abs fuse and see whats happening ???

[mania]

But it's not ABS's fault it's kicking it - it's kicking in because the wheels are locked. Need to solve that problem to get more progressive/better acting brakes.

Quality rubber + pads I think would be your best bet.. guessing the Golf also $2000 a set tyres?

[gman]

The Greenstuff pads will be 75% of your problem...That and the tyres...A set of 225's or better/gripper rubber will be the other 25%...The Greens are an all or nothing affair...When they come on due to temp, they lock...They suck IMHO and aren't progressive in the way they feel or the way they act on the disc...

I've tried Ferodo 2500's, Pagid Blues, Greenstuff, Redstuff and Yellowstuff pads (red's & yellows were free).

On the EBC pads, the Green were terrible!!!! Red's were OK for the road and average for the track (I have a set with 60% -70% material sitting at home)...Yellow's were marginal for the track, don't use on the road!!!

If you want to improve your brakes, get the A1RM or road spec pads from GSLRALLYSPORT and you will notice a huge difference!!! I have these and they are the best pads I have used, HANDS DOWN!!! I am even going to get some for my HK car and bring them back. They are that good.

Good fluid & braided lines will help. But tyres and pads will make all the difference.

[gslrallysport]

The greenstuff does seem to pull up hard when you want it to, it's just not as progressive as I would like.
Without this becoming an EBC bashing post, I think you've hit the nail on the head with regards to the EBC Green...

EBC Green have very low cold friction level (mid 0.3's I think from memory), but jump up to around the mid 0.4's when hot, so as you say, this confuses the ABS as to the braking threshold during normal driving. So they don't bite as hard as OEM when they're cold, but bite harder when they're hot. Normal pads will sit around 0.40-0.43 mark hot to cold.

So with EBC Green (and Red's are the same) you've got two variables, brake pressure, and brake temp. On the track the later doesn't change that much, but on the road, it goes from both extremes, and that's what gives you that lack of progression with respect to brake pressure, and subsequently the ability of ABS to feather the adhesion limit of the tyres...

Just to be fair, QFM A1RM are the same, going from 0.40-0.48, but it's less of an issue because at 0.40 cold, they're still more normalized in their performance.

I'd other go back to something like a TRW Lucas, or Remsa (which are virtually the same pad), or QFM HPX, which is a 0.41-0.42 cold to hot pad.

[coyotte]

I've recently put new Bendix pads on front, braking is good & brake dust has all but dissappeared. (gotta love that)

[JohnBu]

Lucky for me, I have a set of QFM HPX pads somewhere, just don't have the time to fit them due to renovations.

anybody fitted wider tyres to the stock SRiT wheel, or know what's the widest tyre you can mount on them?

GTI runs 225/45R17s, cheaper/more popular than the SRiT 215/40R17s. Bridgestone Adrenalins are around $230 in 225/45R17 and $250 in 215/40R17s

So there you go, don't go Greenstuff people.

[gman]

225/45/17 will fit on the TS SRi-T. I use them on the track.

Though I am going to 235/40/17's next time...

[hazrd]

my TRWs are like that on the front... if u push the brake pedal ever too slightly hard, she bites HARD, but not to the extent that yours are John, i thought this was normal?????

[JohnBu]

my TRWs are like that on the front... if u push the brake pedal ever too slightly hard, she bites HARD, but not to the extent that yours are John, i thought this was normal?????

naaah doesn't seem to be normal.

biting hard is good, but not if it locks up the Wheels too suddenly.

I'll go 225/45/17 or 235/40/17 next time, depending on what tyre is available in those sizes.

but it will be a while, as front and rear have done less than 20,000km.

excuse me for being slack, how wide are the rims on the SRiT? i can't believe i've nevered checked in the time i've owned the car.. lol

[nuggz]

a bit off topic...
but how hard do you brake@!? i can only recall one time i've hit abs in the past year
(and to try keep it relevant. 225/40/18 tyres, braided lines, 308 slotted and drilled + HPX pads)

[JohnBu]

i don't brake that hard normally, but have had to a couple of times due to emergencies and scaring the GF once or twice.

to give you an indication of how I use the brakes. original rear pads lasted 80,000km, fronts 90,000km.

so i'm pretty light on the brakes, also saves fuel and cleaning the wheels of brake dust.

I'll try to change the pads.. will retain the Greenstuffs, just in case I need a RWC later on when I sell the car.

[MatsHolden]

Do the G SRi-T's have Emergency Brake Assist?
Because the Barina has it and mine had a glitch in the system which was causing the system to kick in early, so under moderate braking I was coming to a screeching stop, fronts locked... quite embarrasing.

[GreyRex]

Funnily enough, this is the issue i've had with my car too

It just feels like the brakes don't 'grab' hard enough, and the pedal's a bit soft

Am hopefully doing something about it in a few weeks

[CNBLU]

braided lines will get rid of the spongy/soft feeling of the brakes

[gman]

Exactly...Braided lines and good fluid will make a huge difference. But the QFM A1RM pads were a huge step up in pedal feel and controlability...No more dead pedal, locking, ABS interference etc. The HPX pads I know nothing about but heard good things.

IMHO, if your ever doing a track day or maybe just hard driving, they are the way to go...

[jim7777777]

I've recently put a set of QFM HPX pads on my Srit. I'm REALLY impressed. They bite hard from cold and I haven't had any issues with the fronts locking early. They are a nice progressive pad.

The only issue I had was that they were EXTREMELY noisy at first. As in when I pulled up at the lights heads turned all around (that was with gentle braking). I got them nice and hot and now they're fine.

[gslrallysport]

A lot of that is the fact that they've got a higher metallic to organic ratio in their compound than most other pads. Which means they work really well, don't dust, but can require a good bit of heat to get the to bed in properly...

[JR]

225/45/17 will fit on the TS SRi-T. I use them on the track.

Though I am going to 235/40/17's next time...

there was a discussion about this last year or something - the general consensus was that "225" would scrub at the back, especially if the car is lowered. the bit where the rear bumper bar joins with the bodywork, above the rear wheel. its a lip on the inside wall, at that location.

also "225/45/17" is not the correct rolling diameter for the ts astra. its too "big"

Specification_Sidewall_Radius__Diameter_Circumfere nce_Revs/km_Difference
215/40-17____86mm__302mm__604mm__1897mm______527_____0.0%
225/45-17____101mm_317mm__634mm__1993mm______502_____5.1%

as u can c above, that's gonna make a significant difference in ur speedo calibration.
also the reason why the dude at tyre shop said no to me when i asked for 225/45/17s.
hence the reason why the turbos come with 215/40/17s as factory stock.


235/40/17s on the otherhand, is a close match. but it would b wider. unless ofcourse u roll the lips.
Specification_Sidewall_Radius__Diameter_Circumfere nce_Revs/km_Difference
215/40-17___86mm___302mm__604mm___1897mm______527_____0.0 %
235/40-17___94mm___310mm__620mm___1947mm______514_____2.6 %

[gman]

My 225/45's which are the Kumho V70A Semi Slicks only ever touched on the front passenger guard once at the track and that was a very exceptional circumstance (read moderately serious, very high speed off circuit excursion).

Never had the rears rub at all and my car is lowered on Bilstein coilovers...Then again if its too low it will always rub...

The 235's are marginally wider overall, but it also depends on the actual tyre too as to how much wider and taller the tyre is...Every manufacturer's interpretation of sizing is a little different...

Currently the Falken Azenis RT-615's in a 215 are great for the road and never rub.