G-LOC Brakes
PrevPrev Go to previous topic
NextNext Go to next topic
Last Post 03 Jan 2001 01:09 PM by  Davard
Excluded Cars
 14 Replies
Sort:
You are not authorized to post a reply.
Author Messages
Paxman
Basic Member
Basic Member
Posts:218


--
28 Dec 2000 04:09 PM
    I see a short list of sample cars on the SCCA website - like Porsches, MGB's (huh?) ;-) , etc.

    Are the BMW M-3's included or excluded? Are any BMW sedans included? Or is this a FWD class?

    Just looking for a little clarification. It appears our Region may try this.

    Thanks!
    dmark101
    New Member
    New Member
    Posts:


    --
    28 Dec 2000 07:48 PM
    no, the m3 should be included. i do believe that it may fall under ESP. i'm not totally sure about this.

    i've personally seen them run at the events i've been to.

    can somebody post this under the rules and regs forum?

    ------------------
    dæmon™
    93pgt - president/scpoc
    member - scca/cal club region
    webmaster - [url="http://www.scpoc.com"]www.scpoc.com[/URL]
    evil administrator™ - [url="http://www.probetalk.com"]www.probetalk.com[/URL]
    rosss
    New Member
    New Member
    Posts:


    --
    29 Dec 2000 07:15 AM
    M3s are excluded because they use Torsen limited slip diffs (at least I think they're torsen). If they used viscous coupled diffs they'd be ok, as long as they meet the displacement limit.

    A well prepped 325 or 328 would probably work nicely though... Especially if you could get rid of some of the pork.

    Sean
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    29 Dec 2000 11:14 PM
    [QUOTE]Originally posted by rosss:
    [b]M3s are excluded because they use Torsen limited slip diffs (at least I think they're torsen). If they used viscous coupled diffs they'd be ok, as long as they meet the displacement limit.

    A well prepped 325 or 328 would probably work nicely though... Especially if you could get rid of some of the pork.

    Sean[/b]
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    29 Dec 2000 11:16 PM
    [QUOTE]Originally posted by Davard:
    [b] [/b]


    Let's try this again.

    The M3 is excluded because it has a clutch-type LSD. The Acura Integra Type-R is the excluded car with a Torsen-type LSD.

    ------------------
    STS '90 Mazda Protege
    LX
    Hondaman
    New Member
    New Member
    Posts:


    --
    30 Dec 2000 12:06 PM
    Yeah, the newer M3s are excluded due to having a clutch type LSD, but the older M3s are not excluded do to having a viscous coupled diff., but I could be wrong about the older M3s.
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    30 Dec 2000 02:33 PM
    The newer M3's ('96 or later) are excluded because their engines, at 3.2+L are too large.

    The '95-'99 M3s do indeed have a clutch type LSD. And no, you can't just put an open diff in an M3 and race in STS.

    The first gen M3 (E30) also has a clutch-type LSD, as do many of the 6-cyl E30s (325i), and so aren't legal in STS either.

    Most E36 3-series came with traction control, rather than a LSD, and are therefore allowed in STS.



    ------------------
    David Avard
    '90 Mazda Protege LX
    Andy 02
    New Member
    New Member
    Posts:


    --
    02 Jan 2001 02:16 PM
    Perhaps a little LSD 101 is in store here... SCCAForums Image

    The rules say. "No limited slip differentials, except for factory viscous coupler type units."

    Originally after reading this, I figured anything, as long as it was okay for stock would be okay in ST, but from what you're saying, that doesn't seem to be true?

    My '72 2002tii in its current trim seems to fit in STS nicely -- (big fat exhaust, 195/60 AVS Sports on 14x6s, really beefy swaybars, bat in the trunk, bilsteins) but I do suffer in wide sweeping turns due to the open diff currently installed. Since the LSD was an original factory option for this car, I figured I could retrofit one, as per stock rules...not the case?

    I guess I'm not sure how a 'viscous coupler type unit' varies from a plain 'ole LSD.

    Thanks for the info, Davard -- btw, as per one of your other posts, referring to ST times, I believe Motaz has an LSD on his 325.

    Thanks!

    Andy -- '72 2002tii
    ColinL
    New Member
    New Member
    Posts:


    --
    02 Jan 2001 03:30 PM
    How it differs is that the SEB put that provision in there expecting a run-of-the-mill, viscous limited slip like the one used in the Sentra SE-R to be allowed because these generally do not respond fast enough to be of major use in autocross (if they did, you have a big wheelspin problem and probably wouldn't win anyway). Older miatae also have a similar differential, and AWD subarus have them in the center, plus newer ones have them at the rear as well.

    A clutch-type mechanical LSD reacts much faster and is generally capable of more bias. Allowing mechanical LSDs also opens the door for torsen, quaife or other automatic biasing differentials, which are of great use to the FWD cars that fill the class.

    There are now active viscous differentials, like what the new e46 M3 uses. These are considerably more useful than the viscous coupler units, but just because they have the word "viscous" in there doesn't mean they would be easily confused with a simple viscous coupler... So even if the M3's differential were offered in a 323 (scoff loudly, I know) it wouldn't be legal. A plain viscous coupler in a 323 would be.
    Rob Lay
    New Member
    New Member
    Posts:


    --
    02 Jan 2001 07:28 PM
    I think my 1993 BMW 325is came standard with LSD. Is it the illegal kind for ST?
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    02 Jan 2001 07:47 PM
    [QUOTE]Originally posted by Andy 02:
    [b]Since the LSD was an original factory option for this car, I figured I could retrofit one, as per stock rules...not the case?

    I guess I'm not sure how a 'viscous coupler type unit' varies from a plain 'ole LSD.

    Thanks for the info, Davard -- btw, as per one of your other posts, referring to ST times, I believe Motaz has an LSD on his 325.

    Andy -- '72 2002tii[/b]


    I would be surprised if the 2002 came with a viscous-coupled LSD, since it was invented by a Brit named Furgeson (sp?) for use in the Jensen Interceptor in the 70's. I don't think it came into common use until the later, with the Eagle wagon (the original sport-utliity wagon) in the late-70's.

    The viscous coupling limited slip is composed of two sets of interlocking plates, one set secured to an inner shaft with the other set secured to an outer cup. Between the plates is a silicon-based fluid that stiffens in response to shearing forces. When the two sets of plates turn at the same speed, there is no shearing force, and hence the fluid stays "thin." As a speed variance between the two sets of plates begins, there is an increasing shearing force, and the fluid begins to thicken, which resists the speed difference between the plates.

    In theory, the fluid could become so thick as to appear solid, but in practice this won't happen, because as the fluid thickens, the plates tend to move at the same rate, which decreases shear force and the fluid becomes thinner. Because of this, they generally don't "lock-up" positively, and the lock-up varies.

    Just wait until cars start coming from the factory with electro-rhealogical shocks. Cadillac in planning on being the first in either the next-gen Seville or the Evoq. Imagine tuning/adjusting your shocks with a laptop. But that's for another thread... SCCAForums Image

    In a different thread, I mentioned that a GS 325 running in Street Tire class had beaten STS by several seconds. My comment was that if someone could figure out how to put down all that power without a LSD (meaning I knew that Peter Mottaz' car had a LSD), then it might be one of the cars to have in STS. (The Neon and Impreza being two of the others.)

    ------------------
    David Avard
    '90 Mazda Protege LX
    ColinL
    New Member
    New Member
    Posts:


    --
    02 Jan 2001 08:40 PM
    Good description of a viscous coupler, Dave. Here's my simple description of the viscous fluid: it's a whole lot like ATF. Just like ATF, you can burn it up with too much slippage.

    ------------------
    -Colin
    99 Impreza 2.5RS SM#22
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    02 Jan 2001 09:29 PM
    [QUOTE]Originally posted by RobBMW:
    [b]I think my 1993 BMW 325is came standard with LSD. Is it the illegal kind for ST?[/b]


    Probably. I don't think BMW uses anything other than clutch-type LSD (one of the illegal types), except in the E46 M3.

    So, if your car has a LSD, it's not STS legal. If the LSD was an option, then you could remove it and put in an open diff and run in STS (but why?).

    ------------------
    David Avard
    '90 Mazda Protege LX

    [This message has been edited by Davard (edited January 02, 2001).]
    Andy 02
    New Member
    New Member
    Posts:


    --
    03 Jan 2001 10:58 AM
    Well, you learn something new every day. If I'm not mistaken, the only BMW that uses a viscous coupler as you've described is the E30 325ix, for its front to rear torque split. Just about every other BMW LSD I can think of is the clutch type.

    Ah well, saves me a few bucks then, if my car's going in to ST! To get into stock, I'd have to go back to a stock rear sway bar, but I could put the LSD in SCCAForums Image ...choices choices...

    Thanks 'tho!

    Andy -- '72 2002tii
    Davard
    Veteran Member
    Veteran Member
    Posts:1249


    --
    03 Jan 2001 01:09 PM
    [QUOTE]Originally posted by Andy 02:
    [B]If I'm not mistaken, the only BMW that uses a viscous coupler as you've described is the E30 325ix, for its front to rear torque split. /B]


    Oops, forgot about that one. Goes to show you, never make sweeping statements. Someone will always find an exception.


    ------------------
    David Avard
    '90 Mazda Protege LX
    You are not authorized to post a reply.


    Vorshlag 88x31 Button G-Loc Button
    Sunoco 88x31 Button
    Woodhouse Motorsports SPS 88x31 Button

    Advertise on SCCAForums.com and reach thousands of visitors per day!

    SafeRacer FREE SHIPPING over $99

    Shop for Pirelli tires at Tire Rack. blank




    Sunoco Bottom 468x60 Banner