charlox5

Car: 2006 AP2, 71K miles. Track / Street use. I've owned for 2 years (I've put 6k miles on the car).

Issue: At the track, I noticed that my car was diving right under heavy braking. Also, I had about 50% rear pads when I got to the track, and left the track with my pass rear brake pad completely worn down to the backing plate. I thought maybe driver's rear is seized. Anyway, I replaced rotors and pads on both sides, when I was returning the driver's rear piston, I confirmed that it was seized. It eventually returned with enough force and leverage, but as a precaution I replaced the caliper with a reman. After installing the new caliper, I went to bleed the driver's rear line and discovered that even with the bleeder screw on the new caliper wide open, the system was holding rock solid pressure. Not just initial pressure and a slow leak, but I could stand on the pedal for hours and it wouldn't move fluid. I undid the flare nut at the hard line soft line transition, stood on the pedal--no fluid.

This led me to think that maybe the prop valve had failed in a position to block flow to driver's rear, but apparently AP2V2 doesn't have a prop valve. If I'm understanding it correctly, the fluid path is MC > VSA modulator > Caliper. I'll inspect the hard line itself, but at first glance, the brake lines look perfectly fine, nary a scratch. And even if it were dented or kinked, would it still keep the pedal firm for an extended period of time? There'd have to be some amount of fluid passing through an imperfect obstruction, I would think. I know the master cylinder is functional because the other 3 corners work (and I would have died on my outlap in T2 at buttonwillow if they didn't). Which leaves the VSA modulator.

I don't know much, if anything about VSA mods, I never ran into them in my years of honda wrenching before this car. Does it make sense that it would have failed in a position that gives me hydraulic pressure to 3 corners, but not a 4th? Do VSA mods fail? And if mine did fail, wouldn't I get a VSA dash light? I have gotten VSA dash lights before, but they were related to the pulser wire and a dirty throttle body. VSA light is not on right now, and I presume that my brake system was in this state when I drove 150 miles to the track, did 8 hours at the track, and drive home--and it didn't light. I'll check my helms and see if there's a stored code. Other than that, I'm going to disconnect the hard line at the VSA mod and see if the line is clogged.

Anyway, what I need to know is (1) how does the VSA modulator work (mechanically)? (2) do VSA mods fail commonly? (3) what are my options aside from bend over and pay $1500 for a new one? can I delete VSA? (4) after replacing can I bleed the system myself or do I need some proprietary scantool mojo from the dealer to do it?

shind3

Read Point 2. Maybe something like that happening with yours?
Tech Center - Trouble Getting Pressure To Brakes'

Also, have you tried to push the pedal with the engine running?

Slowcrash_101

Maybe the abs box has an issue. I'd try to get a used one, they're pretty cheap on ebay.

charlox5

Thanks, I'll check it out. I have pushed the pedal with the engine on, same issue.

When you say ABS box are you talking about the part that's $2300 from honda? If they are cheap on ebay that would be awesome.

Slowcrash_101

Yeah the abs modulator valve. I see them all over.

http://m.ebay.com/sch/i.html?_nkw=S2000+abs+modulator&isNewKw=1&isRefine =true&mfs=GOCLK&acimp=0&_trksid=p2056088.m2428.l13 13.TR0.TRC0.Xs2000+abs+modulator&sqp=s2000+abs+mod ulator

fredsvt

Yes, it is possible, as Honda has had issues with Accord 6mt modulators pulling in air into the rear circuits. Don't ask me how I know this.... ugh.

If you can find someone with a scanner that can talk to the abs/vsa module and activate the solenoids. You may have a chunk of crud in the valving. You can try something, lift all 4 wheels off the ground, run the car, put it in gear and spin the rear tires with the fronts immoblie. The VSA should actuate immediately, leave the bleeder open and see if fluid flows then. If it does, stop, and try conventional bleeding. If there's no flow after vsa operation, yet you had flow during vsa activation, something in the modulator is not working correctly.

shind3

Post in your local forum. Someone has to have a cheapo HDS tool. I have used mine to cycle the ABS, and VSA solenoids individually.