Brake and Suspension Changes for 2012 AX Season

[dcstep]

I've got a 2009 E92 M3 6MT with Dinan springs, camber plates, 4.10 final drive. Wheels are 10x18" APEX ARC-8s, with Dunlop Direzza 275/35-18s, square setup. The car EDC and I'd like to keep it very streetable.

In this year's club AX championship I came in 2d by .3-seconds cummulative for the year. I'd like to gain a few tenths per lap to keep me in the hunt against turbo E46 M3 that have coil-overs and lightening.

The minimum changes I'm planning are as follows:

• Replace the rear sway bar with the E93 bar in hope of stiffening the rear slightly to get a little more rotation.
  
• Replace the brake lines with steel and try some street/performance pads. For AX I need pads that perform well cold.

I've considered a BBK, but I doubting that AX braking will improve enough to justify the expenditure of over 6-grand. I think that it'd be a mistake to only do the fronts, because the back might be underbraked and I could lose performance. Ideally, I might do the back only, but then the back might be overbraked and I couldn't do much about that without a brake bias valve, which I don't see offered for our cars.

I guess my question to the AXers is, have any of you tried a BBK and how did it improve your competitiveness at AX? I don't do HPDE or track in this car, so a BBK would have to earn its stripes in AX solely. Is there a street/performance pad on the stock calipers that anyone would recommend for AX (has to work well cold)? Anyone done just the steel lines and pads and was that an improvement?

My problem is this is a dual purpose DD/AX car. I once had a competitive ESP 5.0 Mustang that was great at AX, but a pain on the street. I don't want to go there again; otherwise I'd do coil-overs, more radical AX-only tires

Dave

[stega]

Originally Posted by dcstep

I've got a 2009 E92 M3 6MT with Dinan springs, camber plates, 4.10 final drive. Wheels are 10x18" APEX ARC-8s, with Dunlop Direzza 275/35-18s, square setup. The car EDC and I'd like to keep it very streetable.

In this year's club AX championship I came in 2d by .3-seconds cummulative for the year. I'd like to gain a few tenths per lap to keep me in the hunt against turbo E46 M3 that have coil-overs and lightening.

The minimum changes I'm planning are as follows:

• Replace the rear sway bar with the E93 bar in hope of stiffening the rear slightly to get a little more rotation.
  
• Replace the brake lines with steel and try some street/performance pads. For AX I need pads that perform well cold.

I've considered a BBK, but I doubting that AX braking will improve enough to justify the expenditure of over 6-grand. I think that it'd be a mistake to only do the fronts, because the back might be underbraked and I could lose performance. Ideally, I might do the back only, but then the back might be overbraked and I couldn't do much about that without a brake bias valve, which I don't see offered for our cars.

I guess my question to the AXers is, have any of you tried a BBK and how did it improve your competitiveness at AX? I don't do HPDE or track in this car, so a BBK would have to earn its stripes in AX solely. Is there a street/performance pad on the stock calipers that anyone would recommend for AX (has to work well cold)? Anyone done just the steel lines and pads and was that an improvement?

My problem is this is a dual purpose DD/AX car. I once had a competitive ESP 5.0 Mustang that was great at AX, but a pain on the street. I don't want to go there again; otherwise I'd do coil-overs, more radical AX-only tires

Dave

I have the Brembo 380mm kit on my car and I auto-x just about every 2 weeks. Honestly you should just to pads, lines, and fluid w/ the oem brakes. BBK's help with stopping distance but not nearly as much as some may think, they help much more with heat soak/fade issues. I got the kit for the track and for show really not for auto-x but I am sure it helps a bit.

[dcstep]

Originally Posted by stega

I have the Brembo 380mm kit on my car and I auto-x just about every 2 weeks. Honestly you should just to pads, lines, and fluid w/ the oem brakes. BBK's help with stopping distance but not nearly as much as some may think, they help much more with heat soak/fade issues. I got the kit for the track and for show really not for auto-x but I am sure it helps a bit.

Thanks for confirming that.

[HP Autosport]

You may not see the benefits of a BBK in an AX other than some reduction of unsprung weight.

Try Stoptech Street Performance or Porterfield RS4's and SS lines to start. Properly bedded in should give you improve performance over oem at a wide temperature ranges.

One thing to lookout for with a slightly larger rear bar is getting the power down coming out of the turns. You may be giving up a bit of speed...you will have to experiment with it.

What is your alignment settings?

[dcstep]

Originally Posted by HP Autowerks

You may not see the benefits of a BBK in an AX other than some reduction of unsprung weight.

Try Stoptech Street Performance or Porterfield RS4's and SS lines to start. Properly bedded in should give you improve performance over oem at a wide temperature ranges.

One thing to lookout for with a slightly larger rear bar is getting the power down coming out of the turns. You may be giving up a bit of speed...you will have to experiment with it.

What is your alignment settings?

Thanks for the response. Stoptech's Street/Performance is at the top of my list.

Unfortunately it's hard to experiment with rear bars on the E92 M3 because the subframe needs to be dropped. I'm big on trail-braking and want the car to rotate more easily in the really tight corners and turn-arounds. I'm pretty good at controlling wheel spin, but your concern for traction is on my mind.

Another change that I'm planning and failed to mention is to reduce rear camber down below -1 degree. Right now it's at 1.8-degree, which is too much. Front camber is -1.9 degree. I'm not sure how far to go. I was once very serious in ESP with a live-axle 5.0 Mustang, so I might go down pretty close to zero, but I'm thinking -.5 degree.

[HP Autosport]

Originally Posted by dcstep

Thanks for the response. Stoptech's Street/Performance is at the top of my list.

Unfortunately it's hard to experiment with rear bars on the E92 M3 because the subframe needs to be dropped. I'm big on trail-braking and want the car to rotate more easily in the really tight corners and turn-arounds. I'm pretty good at controlling wheel spin, but your concern for traction is on my mind.

Another change that I'm planning and failed to mention is to reduce rear camber down below -1 degree. Right now it's at 1.8-degree, which is too much. Front camber is -1.9 degree. I'm not sure how far to go. I was once very serious in ESP with a live-axle 5.0 Mustang, so I might go down pretty close to zero, but I'm thinking -.5 degree.

Reducing the rear camber may help the rear to rotate a bit better at entry at the expense of getting the power down right after the apex on exit(roll induced camber changes also affect rear traction), but once wheels are straight you will can really get the power down with less rear camber.

[bigjae1976]

I just don't think an auto-x course will be long enough where you'll need the increased heat capacity of a BBK. If you put some upgraded pads on I think your stopping distances will be about the same as a BBK.

Even if you upgrade to R-Comps I don't think you'll ever overheat the OEM brakes...with upgraded pads and fresh fluid.

[dcstep]

Originally Posted by HP Autowerks

Reducing the rear camber may help the rear to rotate a bit better at entry at the expense of getting the power down right after the apex on exit(roll induced camber changes also affect rear traction), but once wheels are straight you will can really get the power down with less rear camber.

That's what I was thinking. I'm pretty patient at the end of corners (unlike most of my students that just can't wait). I'm going to give it a try. Understanding what's likely to happen and driving to optimize it should give me a slight gain.

Anyone here tried the 'vert swaybar on an E92?

Dave

[dcstep]

Originally Posted by bigjae1976

I just don't think an auto-x course will be long enough where you'll need the increased heat capacity of a BBK. If you put some upgraded pads on I think your stopping distances will be about the same as a BBK.

Even if you upgrade to R-Comps I don't think you'll ever overheat the OEM brakes...with upgraded pads and fresh fluid.

Thanks. Yeah, I'm likely to stay in a street-tire class.

I'll get off cheap with these mods.

Dave