My vote for the worst ABS system goes to?
 

This car! I will start by saying I don't know if something is wrong with my ABS system in particular or this is a problem others have also.

I was running a Brembo STi front brake setup with OEM rears and for awhile I seemed to get away with it while running a Hawk DTC 60 up front and XP12s in the back (at the time it was my only choice). Sometimes I would get ICE mode but can't say it was ever a really big deal.

Now at Lime Rock I had DTC70s and frankly the car setup was somewhat different with more spring rate, more tire, and more aero but I was getting the front wheels to lock up. Now normally I would try to brake hard enough to get some ABS and then back off but I never got ABS, just front lock up. So after pulling about 4 Rosbergs into T1 runoff I just had to brake very early and very softly.

So my gut was telling me I had way to much front bias due to the increase brake torque from the larger rotor and pad compound. This isn't an uncommon issue for me with race cars but instead of getting a big rear brake kit I just decided to go back to the OEM front brakes with race pads thinking it would reduce my front brake torque and balance things out. $2k in ruined tires later this was not the fix either and the same issue is happening with the ABS just turning off. To make matters worse I was also getting "ICE" mode also and with the OEM brakes it's really hard to stop at the speeds we are going!

Turning the ABS off results in ridiculous front bias and it's almost unraceable. It's as if the OEM system is setup with massive front bias and then shuffles brake fluid pressure rearward when need but it's much too slow acting. Whichever engineer thought it would be best to just shut the ABS off is a dumb ass! :lol:

What's the deal, is it just me as usual?

In any event still broke the track record at VIR for TT2 braking like a rookie ;)

In car video:
[ame="https://www.youtube.com/watch?v=7hS2dsVVglQ"]Element Tuning Time Attack FRS VIR Lap Record - YouTube[/ame]

https://fbcdn-sphotos-g-a.akamaihd.n...44608674_o.jpg

have you driven OTHER cars?


lol


my old impreza had ABS feel like the Hulk was ripping my wheels away from the chassis and throwing them into random directions

I posted in your Engine Oil thread, but I'll post again here.

A lot of us track guys have had great success with the AP Racing Sprint/Endurance kits from Essex. While I'm not running nearly as much power, tire, or downforce as you, I didn't have any issues with my Sprint Kit this weekend at VIR with Hawk DTC-60's all around. I know it would be an expensive waste of time if you bought them and it didn't help, but I do know they were specifically designed to work with the stock rear brakes and not mess up the braking balance.

Ha ha....well the 02 WRX was pretty bad but at least it didn't shut off

Right so if you don't change the rotor diameter and you don't change the piston diameter you shouldn't change the braking balance. If you change the rotor diameter you do change front brake torque no matter what you're told if you keep the piston diameter the same.

This is why I went back to my stock brakes to eliminate the issue of me altering the front brake torque with a larger diameter rotor. I'm back to OEM and I'm still having this issue.

I am pretty sure ABS on my WRX is worse or borked completely.

That said I fucking hate ABS in anything other than a panic maneuver when I really need it.

Is anyone else feeling "ABS" pulse before locking up or maybe going into "ice" mode? That's my main concerns is why am I not getting some ABS pulse first before total shut down?

A good ABS system is amazing and a bad one is just that. I normally tend to brake until I get an ABS pulse and then I pull back (similar to threshold braking).

On this car you can't just turn off ABS with good results, you'll have to gut it because something is causing too little rear brake force without ABS on. I guess I could always reduce front force bias driver adjustable Tilton valves.

Maybe the DTC70s are too much and the XP12s suck, I don't know. I feel like it was Ok with the Brembo DTC60 and OEM rear with XP12. I'm stiffer now however so I'm not getting as much weight transfer over the front end as I used to under braking.

I might need to get my steering angle and roll center sensors tested as I did have to replace both after the fire and the airbag deploying.

I have complained about this for awhile and gotten a lot of "its not that bad" or "ICE mode was caused by inability to drive"? Even with track pads and 200TW street tires I have had a few sketchy moments on the brakes on track due to the ABS system. Its the same as you describe, looking for that limit and backing off.. but instead there is no "limit" the next lap you push harder and you don't get a pulse, just ineffective brakes.

Not exactly the same, but ever since I switched from 215/45/17 Sumitomo HTR ZIII --> shorter 235/40/17 Nitto NT05, I always get slight front tire lockup (quick chirps) before ABS engages at the track.

I'm wondering if it has to do with the reduction in tire size and ABS speed sensors.

The Sprint kit that I have only increased the diameter by 4mm (299 vs 295 stock). It really increased the width of the rotor (32mm vs 24mm), allowing for more cooling and heat capacity. The endurance kit is bigger at 325mm diameter and I don't have any experience to comment on it.

As for why you are having issues on stock calipers, I really don't know. I've only run into ice mode a few times, but only on autocross for me, where I'm coming into the stop box sideways and slamming on the brakes while still sliding around. Can definitely be scary, but like I said, I have yet to have any issues with it on track in theorey because I'm not usually sliding into a corner and then braking.

I drove a 2003 Camry without any stability or traction aids in a Michigan winter. Abs on that car consisted of "Oh hey it looks like the wheels locked.......... Let me know how that goes buddy!" and sometimes it would pulse just to spite me as I slowly slid forwards (often with a nice, slow turn in place) through a stop sign at <5 mph while onlookers smirked and I attempted to regain traction.
I called it always-lock braking system.

Sent from my HTC One_M8 using Tapatalk

Normal. It's a Subaru.

Honda's can be pretty bad too. Not as intrusive though.

The problem is more with VSC when doing anything lateral in my experience. Hope the DIY TC defeat posted on the forum will fix this eventually.

You're probably not going 150 mph into your braking zone either. LOL!

The Subaru STi ABS is exceptional! I think Toyota had a hand in this one.

I would be OK with that and it's what I'm used to. I think the key is to keep the front and rear tires square since they come square OEM. This would prevent the wheels speed differential.

In our early testing of the Hydra EMS we did note the OEM CAN wheel speed sensor data is all over the place!

@Element Tuning: Phil, do you know what your brake pad and rotor temps look like after 1 hot lap? We've found that some compounds mix well, and others just don't due to their friction ramp vs force vs temp.

VSC yes. ABS no. Feels just like my other Subarus, non STIs. Slow, clunky and rough. I've had 5 Toyotas, none of them feel like the FRS or my Subarus. Toyota ABS is more refined feeling in my experiences. Historically Toyota usually has done well with brakes up and down the lineup compared to other Japanese car companies. The shitty stopping distance and crap brake pedal feel on the FRS is all Subaru again.

I got some advice from the Nissan guys at the track who also have the "ice" mode issue and it's to get off the brake and back on it. I almost ran off at T1 and at the end of the back straight and lifting and getting back on is the only thing that will restore normal brake force. Unfortunately this means you need to leave some safety room in your braking zones.

I think there is significantly too much front bias and it's easy to "freak" out the ABS. Having fun out there in HPDE and I'm sure people aren't pushing it as hard as I am for a win or a track record. I'm just really curious if anyone else is getting the "ABS OFF" and brake lock up more than the "ICE" mode. Ice mode with a big brake kit isn't as scary but going 150 mph and loosing brake pressure with the OEM brakes had me pushing the brake pedal to the bumper without any improvement. LOL!

I don't even thought I suspected the friction/temp was an issue. I just thought going back to the OEM calipers and rotors would at least satisfy my front to rear bias theory.

I just want to state again I changed the steering angle and yaw sensors without checking calibrations but there are no "faults" showing. I really hope its something like that otherwise I'll be running a 355mm rear brake kit and OEM front. LOL!

Which compounds were you using on the OEM calipers?

Mike, DTC70 front and XP12 rear

well i was just about to make a thread about this because we went and tested our new track car for the first time today and the braking is horrible, front lock up everytime. I have removed a lot of the wiring and for some reason, the ABS doesn't work anymore, no biggie, we were going to remove it in the future anyway. BUT, i thought the bias would still be there but the front locks up everytime and we are running cheap pads. My friend tried a completly stock FRS and it was braking way better he says (even if our car has better tires, brakes and 400 lbs lighter)

We are running on street tires, cheap one also, BF Goodrich Sport Comp2 but we have been running this tire for 2 seasons now with our RSX race car and the car brakes 100 time better than the FRS. We have the Ap racing kit in front and only running Hawk hp+ on all corners and we would light up the front just too easily.

So i was about to order some HPS to put in front but you seem to have the same problem as we have, bias way off. I guess removing the system is going to be inevitable. Also, i tried the car briefly (i am not the driver) and felt like there was absolutly no feeling in the pedal, seems like the brake booster is way too strong, we are going to rip that out also for sure.

edit: can't say how it compares with the ABS running because we never tried that, i would need to search why it is not working but i doubt this is the way we want it to work.

Puma, no it isn't raceable with the ABS disabled. It's going to need the module removed and plumbed directly. I think the booster is OK when the pads get up to temperature the pedal will firm up.

As crazy as it sounds I may have someone put together a kit with smaller front brake pistons to force more rear bias but then again it might just be easy enough to plumb in some front driver adjustable valves so I can pull some pressure out that way.

It hit me at 130 on the front straight of Texas World into turn one! Quite the pucker moment!

Could this be a result of the down force you're running putting more force on the rear tires?

It's definitely "normal" to need more rear brake force when increasing rear downforce and also increased suspension stiffness for optimal braking. Think of it like if you put a 355mm front brake kit on, you better also put close to a 355mm rear brake kit on if you have a "Pro" level car otherwise you're giving up to much in the rear.

Now my car isn't hugely different than it was a couple seasons ago in terms of downforce.

Having more rear downforce etc. shouldn't cause the ABS to stop working. As Jeremy Clarkson would say, "it's stupid, stupid, stupid" LOL!

I am running the sprint brakes, tried multiple compounds and hate the brakes as well. Horrible to modulate and at the extreme limit its either completely unstable feeling or ice mode. As mentioned you always have to leave some safety gap on the table.

I don't have not had this issue with my other sports cars. You could threshold brake easy and know that ABS point.

Ah, the DTC70's torque ramps MUCH quicker with pedal pressure than the XP12. Also, the DTC conducts heat through the pad, whereas the Carbotech tends to hold it on the surface. Third, the Carbotech is a compressible pad, whereas the DTC is not.

I'd make an educated guess that the DTC's larger bite caused it to heat up faster relative to the rear, further increasing front brake bias, causing the fronts to be functioning far more than the rear.

Can you do like 2-3 80-20 stops, and then run out of the car and take laser temps of the brake rotors? I'd bet the fronts will be a lot hotter than the rears. We try to keep the temperatures approximately equal between the axles to maintain brake balance.

Try square compounds or similar staggered compounds...

Yeah I only wrote half of that thought. I was wondering about the bias not the ice mode. Ice mode sounds terrifying.

The lng and lat sensors are in the ABS pump under the hood you might try mounting the pump in rubber to slow down the noise from the higher spring rate or take out every other tooth on the ABS rings to slow the speed rate but either way you need to log it to see why then you can fix what.
DougW

Mike, I agree but really given I've gone back to oem brakes it shouldn't cause an ABS shutdown.

Doug, we do know from our previous wheel speed data it's all over the place but what we don't know is like you said, how is the oem system dealing with the noise.

My brakes used to be very good, let's remember this. I have a suspicion my problems and others could be related to yaw/pitch and pedal pressure and how the ABS system uses this data. With race pads and or larger rotors you end up with more brake torque so less pedal pressure is needed. Now you add into the mix stiffer suspension and more rear aero and all of a sudden you have less brake dive/pitch. I could totally see how that data could be used by the ABS to think the car is on ice because there is little pedal pressure, there is no pitch, front ABS cycles, and voila "ICE Mode!"

I think the brakes are mechanically way too biased to the front. Turn off your ABS and you'll know what I mean! I've already sacrificed $2k in tires so I really am not looking forward to figuring this out but I'm goimg to plumb in the driver adjustable bias valves to reduce front brake force. If it balances the brakes we should be able to figure out what front brake piston diameter will help.

Like Mike said you can to some degree balance the brakes with pad compounds and I do run more friction in the rear of our STi vs the front but temperature imbalance can be tricky.

I'm not sure why your wheel speeds are all over the place mine have always been very consistent when logging them off CAN. The ABS can't work if the wheel speed is erratic that is it's first input then pressure then G slip/rates. Anybody every looked at hacking the stock ABS?
DougW

I'm talking about the raw data and not what you would see via your CAN data logger.

I actually haven't experienced ICE mode on track yet, but since I don't use the BRZ for competition I've already left that extra margin just in case.


The ABS system is this car isn't even as good as the system Honda put in the ITR though 15 years earlier.

A data point that might be useful... pfc 08 in the front and dtc 60 in the rear gave definite rear bias to the brakes. Not fun. It did seem to get worse as the sessions each wore on.

And as a result what was happening? ABS fail, tail happy, ABS rear?

Rear would slow more than the front and start dancing a little when threshhold or abs braking from 100 plus. The abs definitely came on in the rear first. I don't remember it ever engaging in the front. It seemed fine on slower corners. I'm not fast. Switching to stock pads eliminated the dancing but the bite is weak. I have not been back to the track yet to try pfc 08 all around. I have a mostly stock car and never exceeded 114. Definite oh shit moments with the rear dancing. Made me slow down a lot on straights.

Ok thanks. Typically I'm having this issue when speeds are in excess of 140 mph. Ya know when you need your brakes the most Toytoa/Subaru! LOL!

Maybe my XP12 are glazed over in the rear? I'm going to put all OEM pads on and the Prius tires for testing. LOL!

The comedic effect of that much power and down force on those stock tires will make video an absolute requirement for that test session. :paddle: