Alcon BBK via Bimmerworld or AP Racing Pro 5000R?

[slcook54]

I'm pretty annoyed at the severity of the rear pad taper on the 9449 kit running DS1.11. I'm switching to DS3.12, and wondering if that will change the taper. I know 'some' taper is expected, but this seems extreme. The fronts do taper as well, but not nearly as aggressively. I guess I'll start flipping the rears if I have to.

[///Mobbin]

That's quite bad, I agree.

[slcook54]

Originally Posted by ///Mobbin

That's quite bad, I agree.

I realized that this my be exacerbated since I'm running Euro MDM. Will hold off final judgment until I turn it off.

[MaX PL]

mdm uses the rear brakes but why would increased use of rear brakes be related to pad taper?

[tsk94]

Originally Posted by MaX PL

mdm uses the rear brakes but why would increased use of rear brakes be related to pad taper?

I believe dogbone and rhyary have both shown (via data) that MDM primarily uses the front brakes - but someone can correct me if I'm mistaken.

Yes MDM would use the brakes more, but it wouldn't affect how the pads taper. That's just a nature of the caliper & piston design.

[MaX PL]

funny thing I noticed while driving to the track last month...

I had full traction on, not mdm, while driving there thru some curvy roads without realizing it. I was taking some turns somewhat quickly and began to get random brake squeal mid turn through these turns. I quickly realized it was traction control applying the rear brakes. It's something you wouldn't normally notice, but with squeaky pads it was very obvious and only happened mid turn.

[roastbeef]

mdm uses the front brakes most of the time. it can use all of the brakes simultaneously or individually. mdm can also cut engine power if necessary. its probably safe to say traction control is just a more intrusive version of mdm.

that being said, traction control probably doesn't contribute to pad taper. pad taper on the inside of the rotor face is probably due to a combination of the inside rotor face being hotter, and the anti-knockback springs keeping the pad slightly pressed against the rotor face without brake activation.

your taper is on the inside passenger side pad, which gets the hottest for laguna seca. i had a professional driver tell me this will be the most worn pad at laguna seca because the most intense braking you'll do at laguna is for turn one downhill, then you're turning left for a decent amount of time, which turns the inside pad/rotor face out of the airflow. once i started paying attention to this, i have noticed consistent personal experiences with results to this theory.

you just have to flip and manage pads apropriately regarding taper. if you run one set of pads for three track days and never touch them for those three days, you're going to have at least one pad with far more wear than the others. just like you wouldn't NOT rotate tires, you should be looking at the wear levels of your pads and rotating them as well.

[sc_tr0jan_m3]

Yep. Problem solved by swapping pads inside/out.

I've tried both the 1.11 and 3.12 and my CCW track always ends up with taper.

[rhyary]

Originally Posted by tsk94

I believe dogbone and rhyary have both shown (via data) that MDM primarily uses the front brakes - but someone can correct me if I'm mistaken.

Yes MDM would use the brakes more, but it wouldn't affect how the pads taper. That's just a nature of the caliper & piston design.

Correct.
MDM uses the front brakes, typically 50-80 PSI to balance the under/oversteer. in addition to cutting power

[rhyary]

Originally Posted by MaX PL

funny thing I noticed while driving to the track last month...

I had full traction on, not mdm, while driving there thru some curvy roads without realizing it. I was taking some turns somewhat quickly and began to get random brake squeal mid turn through these turns. I quickly realized it was traction control applying the rear brakes. It's something you wouldn't normally notice, but with squeaky pads it was very obvious and only happened mid turn.

Data doesn't show MDM apply rear brakes, but I suppose nothing prevents it from applying rear brakes.

[omgzirra_exe]

i got the Alcons installed, and i am in love.

[SYT_Shadow]

Originally Posted by slcook54

I'm pretty annoyed at the severity of the rear pad taper on the 9449 kit running DS1.11. I'm switching to DS3.12, and wondering if that will change the taper. I know 'some' taper is expected, but this seems extreme. The fronts do taper as well, but not nearly as aggressively. I guess I'll start flipping the rears if I have to.

Yup, ridiculous levels of taper. I suffered through that with my AP Radicals as well. I used PFC pads, but the outcome was the same.

I am not flipping pads around. The whole point of a BBK is 'set and forget'. To flip a pad you have to remove the wheel, remove the bridge/bolts and then press the pistons in (as the are not evenly spaced out due to taper), that is just ridiculous.

[slcook54]

Originally Posted by SYT_Shadow

Yup, ridiculous levels of taper. I suffered through that with my AP Radicals as well. I used PFC pads, but the outcome was the same.

I am not flipping pads around. The whole point of a BBK is 'set and forget'. To flip a pad you have to remove the wheel, remove the bridge/bolts and then press the pistons in (as the are not evenly spaced out due to taper), that is just ridiculous.

I hear that, my whole approach is set it and forget it. I'm a finance guy, not a race engineer or even that technical from a mechanical perspective, I just want it to work.

I've been in chats with Phil at Bimmerworld and he also observed that my suspension is way too soft for my use case (450/800). I set it up that way when the car was still doing double duty. As a result the car is pitching forward on heavy braking and likely overloading the fronts, I don't know what, if anything, that's doing to the rears in terms of wear or taper. Regardless, I'm going to move to a stiffer spring setup and new pad compound and see how that effects the overall system. I ordered fresh DS3.12's all around earlier this week from Essex. I'll also look into different compounds in the future if I don't like how these perform.

[SYT_Shadow]

Originally Posted by slcook54

I hear that, my whole approach is set it and forget it. I'm a finance guy, not a race engineer or even that technical from a mechanical perspective, I just want it to work.

I've been in chats with Phil at Bimmerworld and he also observed that my suspension is way too soft for my use case (450/800). I set it up that way when the car was still doing double duty. As a result the car is pitching forward on heavy braking and likely overloading the fronts, I don't know what, if anything, that's doing to the rears in terms of wear or taper. Regardless, I'm going to move to a stiffer spring setup and new pad compound and see how that effects the overall system. I ordered fresh DS3.12's all around earlier this week from Essex. I'll also look into different compounds in the future if I don't like how these perform.

I work in finance now, but am an engineer! Maybe due to that, I have subzero levels of patience for marketing speak or some someone who has lightened a piece to the point the caliper is bending and tapering pads. Zero patience for that crap.

I ran the AP Radicals with the same suspension setup as the PFCs and Alcons: MCS 3WR 800 front 700 rear full coilover. So it's not the soft suspension that's causing the taper. Especially when swapping the caliper to another brand will magically fix that taper wear.

Edit: you're in the right hands with Phil!

[tsk94]

Got my Alcon kit on the car this past weekend - I'll post some pics later. It's on an F82, but my understanding is the kit is pretty much identical between the E9X and F8X. Excited to try it out with the new suspension as well next week

[SYT_Shadow]

Originally Posted by tsk94

Got my Alcon kit on the car this past weekend - I'll post some pics later. It's on an F82, but my understanding is the kit is pretty much identical between the E9X and F8X. Excited to try it out with the new suspension as well next week

looking forward to your feedback!

[DRLane]

Was patiently waiting for the pad taper frustration

I think "set it and forget it" is the wrong mentality for race car. But to each their own.

[omgzirra_exe]

Originally Posted by tsk94

Got my Alcon kit on the car this past weekend - I'll post some pics later. It's on an F82, but my understanding is the kit is pretty much identical between the E9X and F8X. Excited to try it out with the new suspension as well next week

can't wait to hear your thoughts, I'm going to take the car up my local canyon road and see how the braking has changed.

so far for street driving it's been wonderful, chatters a lot but it's not a street BBK.

def will get the anti-rattle for the rotor rings when the time comes.

[SYT_Shadow]

Originally Posted by omgzirra_exe

can't wait to hear your thoughts, I'm going to take the car up my local canyon road and see how the braking has changed.

so far for street driving it's been wonderful, chatters a lot but it's not a street BBK.

def will get the anti-rattle for the rotor rings when the time comes.

Definitely get the antirattle kit! That would drive anyone crazy

[omgzirra_exe]

Originally Posted by SYT_Shadow

Definitely get the antirattle kit! That would drive anyone crazy

I literally backed up my car and thought I hit something

[SYT_Shadow]

Originally Posted by omgzirra_exe

I literally backed up my car and thought I hit something

I've tried running without antirattle clips in every bbk I've had, it's just not possible. Even in a dedicated track-only car scenario, at 160mph it'll rattle a wheel hub straight off!!

[VictorH]

Originally Posted by DRLane

Was patiently waiting for the pad taper frustration

I think "set it and forget it" is the wrong mentality for race car. But to each their own.

For most parts yes, but a properly engineered braking system generally needs pad, rotor and fluid replacement as indicated. No moving and flipping brake pads. SYT-Shadow and I as well as others have run the PFC Z-54 brake kit for literally years with no abnormal pad wear whatsoever regardless of suspension, pad type or use. It's an engineering/design problem which track drivers like us should not have to tolerate.