TKOGTO

Had Hawk HP+ pads and Ti shims from Hard Brakes installed last week. When I went to bed the new pads, the ABS kicked in during stops from as low as 35mph. ABS activation was consistent, i.e, it occurred each time I applied semi-hard to hard pressure to the pedal at all speeds (35, 40, 50 and 60mph). Road surface was clean, no sand, rocks, etc. ABS does not kick in during normal braking. New pads do grab like a SOB. Little to very little pressure needed to stop. Don't remember getting anywhere close to this after I added Hawk HP+ pads to my BMW 5 - 6 years ago.

Any ideas on why this might occur? I am thinking it was the combo of the new pads with the shims and wearing the pads down a little might solve it but am wondering if anyone has had a similar experience.

Thanks

AU N EGL

ABS is your Friend.

if you are not getting into the ABS when bedding your pads, your not braking hard enough

BEZ06

Maybe you need more tire.

If your tires are smooth, not heated up, not a grippy enough compound, then they may be losing traction too early and letting you get into the ABS prematurely.

HP+ isn't a real aggressive pad (but you will get a lot of squeal and dust!!!), but like Tom says, you want to be braking hard enough when bedding to heat the pads/rotors enough to transfer a nice layer of pad material the rotors.

Bob

diddiyo

yup ABS also kicked in when I was bedding my carbotech AX6 pads a few weeks ago.

TKOGTO

Tom - normally I would agree, ABS is your friend but it does not feel like that in this instance. For one, I rarely get into the ABS while stopping from 125 - 130mph before turn 1 @ LRP. To have it start @ 1/3rd the speed suggests something is not right. Second, the car feels unstable now under hard braking, a condition that never existed before. The front end twitches like the brakes are locking up and the rear does the same but to a smaller degree. Not exactly confidence inspiring.

Bob - the Kumho Ecsta XS tires were not really warmed up to start but they were before I was done. About 10 stops then 15 minutes of driving @ highway speeds to cool them down should have taken care of tire temp. Also, they have less than 1,000 miles on them so a lack of grip likely was not a factor.

VetteDrmr

Tires that have aged a bit, plus dirty/dusty street = marginal grip.

TKOGTO

How long did the ABS intervention last?
Do you auto-x or HPDE?

diddiyo

my friend who was in the passenger seat told me it came on since i was focussed on the road so I'm not sure for how long it came on.

so far i've been to a 2-day HPDE and I'm going to a 1-day event next week.

geerookie

I have a BMW 328 and a C5 Corvette (not street legal any more)
From the factory BMW's have MUCH better brakes than a Corvette. I also went to HPS+ pads for the Corvette. Same experience, so nothing is wrong, that is just how bad the brakes were. The BMW were so much better to begin with you didn't notice that big a difference.

AU N EGL

mm if ABS kicks in with the carbotechs - May want to take the calipers off and clean them. Piston rebuild kits are not that expensive.

I guess I take my calipers apart so much and toss them each winter that I am use to ABS coming on.

Plus braking late is a bad habit with me

TKOGTO

Understood. I may have had it kick in on the track w/o feeling it as well. The intervention I was getting while bedding however, you would have to be dead not to feel. Pedal pulsated, front end dipped and darted back and forth. Very unstable all around.

Olitho

That is all very common when the brakes and tires are cold and generally more noticable at lower speeds when you are not focused on modulating pressure like on the track.

TKOGTO

I am not talking about ABS kicking in and you barely notice it like post #4. I am talking about making the whole front unstable, like it's going to brake loose unstable. Sort of feels like the pads grip too hard. The way it is right now, I do not trust the brakes to take them on the track. I have braked too aggressively for corners before learning to modulate and didn't feel anywhere near the instability front end. This can't be normal.

Olitho

I understand your consternation with that, but it is not a big deal. I work on the car all the time before going to races. One of the last things I do before putting the car back into the trailer, especially if I have worked on the brakes, is to do a couple quick laps around the business circle at moderate speeds and then standing on the brakes to make sure ABS is working.

When I do that the car always wiggles some from side to side, especially the front. I can feel the individual tires and pads getting varying grip on their respective surfaces as the wheels start to lock momentarily and then release a bit. The tires are cold, the pads are cold and the speeds relatively slow so it is all very noticeable.

Go drive the **** out of it. It will be fine.


Oli

froggy47

Could be your tires are not up to it. Also those speeds seem a little slow to bed pads, you need some heat in the pads to transfer material. Try again? I run hp+ with street tires 300 wear and with a6's they are fine when properly bedded, dirty but fine stopping.

Here is a procedure

http://www.stoptech.com/tech_info/wp_bedinstock.shtml

Personally I like to start at about 80mph.

If you have glazed then you need to remove the glaze & start over.

Go from high speed stops to lower speed, you should smell "brake pad" if you do it right, no complete stops. If pads catch fire you did it wrong.

jlutherva

TKOGTO,
I ran HP Plus pads for a while with the OEM F1 GYs. It was always a challenge to stay out of the ABS with that combo, especially when the track got a little hot and greasy.

I agree, it's any uncomfortable feeling, especially if your turning slightly. The car gets pretty unsettled.

On the upside, your will learn to modulate the brakes.

Jim

fatbillybob

My car is a racecar with Oli. I don't have the time or energy or the industrial park to bed brakes. I have done it before but never found any compelling reason to do it. In 1970 yes. At the top of the game in motorsports OK maybe you can prove it a benefit with good data aq.. Sure I could be missing something but I don't think so.

If the initial bite of the pad is significantly more than you are used to you will get what you describe. This problem happens at the low speeds especially and even more with the aftermarket BBK's. Even the lame OEM brakes with chinese rotors will stop the car from 150mph in a hurry. At 40-60 with high initial bite pads and stabbing the brakes yes you will get abs and chassis wander. I would expect it. I bet you will not have that at 120 and I hope you work your way up to your braking zones while you learn your new brake modulation.

TKOGTO

Thanks Oli. Sure not trying to be difficult, it's just that ABS @ 35mph feels so foreign to me that I think something's got to be wrong i.e., the shims should not be in with new pads or the ABS sensors are malfunctioning or something else. It feels like it would be impossible to stay out of the ABS from 125mph and still stop the car in time for a turn. The hard application necessary to stop would set the ABS off while a more moderate application, at least feels, like it would not slow the car sufficiently.

Froggy: Tires are Kumhos XS, wear rating 180, with less than 1,000 miles so I think they should be sufficient.
Agreed on the speeds for bedding, they seemed low to me too. However they are what Hawk has as recommended for the HP+ pads.
Got that rancid smell of material transfer after about five 35-40mph stops (released @ ~ 10mph). Did a few more from 45 then a few from ~ 65.

Fatbillybob: Man I hope you're right. The initial bite w/ the HP+s and the shims is a quantum increase over OEM. Perhaps that's the "problem", I am just wholly unaccustomed to real brakes. Funny, at least for me, is I never thought the OEM brakes were weak. During my 1st few track days, I hacked @ them like a rank amateur but soon learned not to slam them. In both cases, the brakes worked quite well, stopping me in a distance and time frame that seemed perfectly reasonable for the effort I applied. With them now, it seems I would need 50, 60, 70% less brake effort, which is a bit unnerving. Will definitely take your advice to get comfortable with new modulation before I work my way into the brake zones.

Thanks

froggy47

You will not get abs at higher speeds, it's a lot easier to stop a wheel at slow speed than high. Think of a spinning bike wheel (upside down bicycle). Crank it to highest speed & hit brake, then crank it much slower & hit brake.

TKOGTO

Yes getting it @ high speeds is what I'm worried about. I will test that on an open stretch after I get the car back. Brought it in this morning to have the ABS sensors checked and to remove the shims. Overkill, perhaps but at least I'll be able to sleep before next track day.