How's ASR defeat work? - PeachParts Mercedes-Benz Forum

pentoman · #1 01-17-2003, 05:50 AM

How do peoples ASR defeat's work?

And has anyone added a simple switch that, say, cuts power to the ABS and therefore the ASR, just for burnouts (!) etc.?

run.exe · #2 01-21-2003, 03:37 PM

The ($1K) ASR defeat switch is merely a simple relay which performs the specified function.

The "poor man's ASR defeat" is simply to open the hood and disconnect the ASR cable... though not advised.

rainmaker · #3 01-21-2003, 04:15 PM

RENNTech's ASR defeat comes with the following:

- the actual switch itself
- a blackbox
- a wire loom that connects to the wires of the ASR module in the computer box to the blackbox
- another wire loom connecting the the switch to the blackbox

Here's a diagram of how it all links up, the green circles indicate where you actually have to cut wires and splice:

Here's a picture of the kit:

yhliem · #4 01-21-2003, 06:01 PM

Rain,

My understanding of how the ASR cutoff is that, in a nutshell, it bypasses the speed setting on the Snow Chain switch. Is this correct?

Daesun · #5 01-21-2003, 06:18 PM

Quote:

Originally posted by yhliem
My understanding of how the ASR cutoff is that, in a nutshell, it bypasses the speed setting on the Snow Chain switch. Is this correct?

Refresh my memory. Up to what speed does the Snow Chain button function normally? ~35 mph? I was under the impression that the Snow Chain button allowed some wheelspin, but did not shut off ASR altogether. If it does indeed disable ASR completely, and it is active up to a speed of at least 25 mph, wouldn't it be as useful as a true ASR defeat when it came to launching the car from a standstill?

yhliem · #6 01-21-2003, 06:46 PM

Daesun,

Although, I'm not too clear on the finer points of the Snow Chain function I believe you are correct in terms of the cutoff speed. Somewhere from ~25-40mph sounds about right.

I don't know if it's a partial disable of ASR or full cutoff and i'm not willing to find out in case it frieds the electronics :p

Does anyone else have a clearer understanding of how it works?

rainmaker · #7 01-21-2003, 08:50 PM

Not too sure on how it works. I tried dissecting the blackbox but RENNTech actually painted over the circuit board to hide what kinda doodads they put in there.

All I know is that it somehow works in conjunction with the snowchain switch. If you look at the diagram, which shows that you tap into the snowchain switch, what it basically does is it keeps it on regardless of speed (the snowchain light is permanently on). If it involved solely that, it doesn't quite explain tapping into the ASR wires in the computer box.

I would surmise though that it somehow blocks the speed differential signals or something from reaching the ASR module so it doesn't kick in above the snowchain cutoff point.

The snowchain switch alone is a bit useless after the initial launch as you'd already be past the cutoff point when you shift into 2nd gear at WOT. The upshift causes wheelspin sometimes as well.

Daesun · #8 01-21-2003, 09:00 PM

Quote:

Originally posted by rainmaker
The snowchain switch alone is a bit useless after the initial launch as you'd already be past the cutoff point when you shift into 2nd gear at WOT. The upshift causes wheelspin sometimes as well.

True, there is some ASR intervention at the 1-2 upshift, esp. on a cool night, but a great deal of wheelspin occurs throughout most of first gear. If the snow chain function served to block ASR for most of first gear (up to 35 mph, tranny shifts at ~40 mph), wouldn't it still aid your launch considerably?

Personally, I think we should all slap 275s on the rear wheels and forget about ASR altogether.

Although I've heard that our beasts will peel a 275 as well.

rainmaker · #9 01-21-2003, 09:12 PM

I guess it depends on your application. For purposes of *****-slapping people from a standing start, you may not need it though there may be occassions when the strategy works against you. ASR intervention isn't too subtle after all...

On the track though, it's a bit of an annoyance when it kicks in powering out of turns (at least trying to...it won't let you). The worst part is when ASR kicks in after the apex, it acts and feels a lot like lift throttle oversteer (which it essentially is) and if you're not quick enough, you'd be pointed at the opposite direction. If you do a search, this actually happens to people exiting an on-ramp/off-ramp. Again, potentially not a pretty sight...

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That's actually not quite accurate because with ASR, there never is a *great* deal of wheelspin. What you actually get is a bit of wheelspin then.....nothing, or next to nothing...power just cuts out and the fun stops for a while.

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That it does. The 18 inch tires I had on when I initially got the car were 235s in front and 265s at the back. I still use them at the track sometimes.

Daesun · #10 01-22-2003, 03:08 PM

Quote:

Originally posted by rainmaker
On the track though, it's a bit of an annoyance when it kicks in powering out of turns (at least trying to...it won't let you). The worst part is when ASR kicks in after the apex, it acts and feels a lot like lift throttle oversteer (which it essentially is) and if you're not quick enough, you'd be pointed at the opposite direction. If you do a search, this actually happens to people exiting an on-ramp/off-ramp. Again, potentially not a pretty sight...

I know what you mean. It's actually very difficult for me to apply throttle coming out of a tight corner without ASR inducing lift-off oversteer like you mentioned. I have to feather it until the car is reasonably straight, and only then can I give it any sort of gas. Also, my tires are really crappy, worse than factory rubber. So was ASR still very intrusive when you were running your 235/265 setup? I'm *hoping* that a 245/275 setup will eliminate most ASR intervention during normal driving.

rainmaker · #11 01-22-2003, 11:56 PM

Although the ASR light comes on, it doesn't quite take over and shut you down. ASR induced lift throttle oversteer only occured when using 235/45 17s at the track, and admittedly, I was driving like an ass trying to tail Mitsu Evo VIs and VIIs around the corners. Their 0-60 times (modded) are around 4.5 so I was trying to get on the power earlier. The long and short of it is that the car first screamed at me (tires and all the blinking lights on the dash) and when I paid it no heed, spun me around then I tried to compensate and ended up compensating and spinning around to the left. At that point I got the picture and backed off a bit...