potent951turbo

I'm having some trouble learning more about option code M224 which I've seen listed as "automatic limited slip differential" and also "active brake differential". Is it true all 993's with LSD option M220 had option M224?

M. Schneider

Hey Colin -
Allow me to inject a wee bit of confusion or clarity depending on which side of the Missisippi you're on..... The 993 chassis has both active brake differential working off the ABS (standard on the 4wd chassis) and a triditional LSD byway of clutches in the differential. I have the nitty gritty details at home ..... later I can explain in detail.

My 2wd MY98 993C2S was ordered with the optional 4 channel (ABS) and the triditional LSD gearbox. (2wd chassis has a 3 channel ABS vacumn system) - ( 4wd chassis has 4 channel hydraulic system)
Gotta zoooom

Bill Verburg

M224is active brake differential(ABD) for Tiptronic, it is a low speed only mechanism that applies one of the rear brakes via the abs pump when differential wheel speeds are detected above a threshold value

M220 is a mechanical 25/65(in normal 993) lsd and ABD for manual transmission

M. Schneider

Hey Colin -
No need for me to chime in any further - Bill provides chapter and verse.

potent951turbo

So if it's a 6-speed car with options M220 and M224, it's got the traditional mechanical LSD but the M224 comes in to play in what sense?

Cemoto

ABD articulates the braking system via ABS

This may help:

saneproductions

Where can I find the rest of this book or article. Love the details!

UDPride

So 224 is standard on the 993 Tips? My gut is telling me yes. I noticed a Tip car with option 224 but not 220 and Im thinking if you are paying extra for it, you gotta have both codes.

Bill Verburg

For 993 M220 includes ABD and LSD, M224 is only ABD

I don't know if it was standard on tips or not. The importer sets the specs so it may or may not and mat also depend on the market for which the car was built.

M220 may not have even been available on tips

UDPride

Ive never seen Limited Slip w/ABD order separately as LSD or just ABD so Im betting Tips got the 224 ABD standard as part of the tranny. Tip cars also got a couple other options standard -- a Tip specific steering wheel (code escapes me) and I think one other.

Cupcar

When looking for a chassis, the only option I wanted was M224, mostly for the 4 channel ABS system instead of usual 3 channel ABS.

The 4 channel ABS is required to individually monitor wheel speed of rear wheels for the ABD function, but that is also useful for braking as each wheel is treated separately.

On the Monroney sticker, the option is described as "Torque Limited Slip with ABD .... $1195"

Also included is a normal clutch pack LSD (as M220 option) as well as differential braking applied to the rear wheels by the ABS system only at speeds less than a speed I can't recall right now, a feature mostly useful for snow and ice.

It was standard not only on C4 but RS cars.

TheOtherEric

And for the record, ABD is completely and utterly useless, despite it soundng like a neat safety feature. In 12 years of owning two 993's, I don't think mine has ever engaged, street or track, dry or rain.

It was probably included just to help journalists record good 0-60 times.