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Robbie
Robbie GRM+ Memberand PowerDork
11/16/17 8:29 a.m.

E diff is what I am talking about. And I wouldn't be hacking any programming necessarily (although if I could that would make things easier mechanically). I think you could pull it off with simple circuits even, no computing necessary. And you might be able to trigger the stock ABS pump, or add a second one inline with the first for the two front wheel circuits. With rwd cars with one rear brake line, you would have to add a pump at the end of the single line.

Basically you turn the circuit on via a dash switch, but also trigger it with a brake switch so it will not engage when on the brakes. Finally, give it throttle position so it again only engages past 50% throttle or something. All that is simple circuitry. Then, tap into the existing front wheel speed sensors. Use a chip (LM133?) to translate the frequency into a voltage for each, and then use a voltage divider to bring that voltage down about 30%. Use an op amp voltage comparator circuit to compare the 70% left speed to the 100% right speed. If the left is greater (even with the 30% disadvantage) then fire a relay to shut all the ABS solenoids except the left wheel and the abs motor. Do the same thing with opposite inputs on the right side.

Who's with me? What's the cheapest abs pump that has 9 or 12 solenoids? (I think some abs pumps dont have the ability to block flow backwards toward the master cylinder, but the ones with 3 solenoids per brake line should have the ability)

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
11/16/17 8:34 a.m.

Yeah I think it could be done. You might not even need TPS input, that could be handled by having different activation parameters at different absolute wheel speeds - it could be permissive at low speed so it won't activate on right turns, and much less permissive at high speeds to keep wheelspin in check on high-speed corner exits.

Knurled.
Knurled. GRM+ Memberand MegaDork
11/16/17 4:50 p.m.
TED_fiestaHP said:

  Wheel spin with front drive is reduced by not letting the inside front wheel lift.   One way use stiff front springs and no front sway bar.  The stiff front springs basically provide front sway resistance but don't lift the inside front wheel.   You do want a rear sway bar.  Set up right it will corner on 3 wheels, it should lift the inside rear wheel.

     But without a limited slip diff you can still get some wheel spin.

Roll stiffness is roll stiffness.  You'll still unload a wheel with stiff springs and no bar.  In some respects lifting a wheel is easier because of the increased damping required to control the stiffer springs. 

The trick is to not need so much roll stiffness in the first place.

iceracer
iceracer UltimaDork
11/16/17 5:16 p.m.

Lower the car about one inch.  Stiffer springs and strut/shocks.   0 toe.

When you start out of the corner ,gradually roll on the throttle until the car is showing little lean, then get on the pedal all the way.

I was going to suggest more camber but that won,t help the traction.

malibuguy
malibuguy GRM+ Memberand New Reader
11/16/17 7:13 p.m.

In reply to iceracer :

Car is nearly 1.75 lower then stock and I run toe out already

rslifkin
rslifkin SuperDork
11/16/17 7:48 p.m.
Knurled. said:
TED_fiestaHP said:

  Wheel spin with front drive is reduced by not letting the inside front wheel lift.   One way use stiff front springs and no front sway bar.  The stiff front springs basically provide front sway resistance but don't lift the inside front wheel.   You do want a rear sway bar.  Set up right it will corner on 3 wheels, it should lift the inside rear wheel.

     But without a limited slip diff you can still get some wheel spin.

Roll stiffness is roll stiffness.  You'll still unload a wheel with stiff springs and no bar.  In some respects lifting a wheel is easier because of the increased damping required to control the stiffer springs. 

The trick is to not need so much roll stiffness in the first place.

In theory, that's correct.  But if the bar is limiting suspension droop, getting the same roll stiffness with more spring and no bar can sometimes keep that tire on the ground, even if there's still not a ton of weight on it.  But 100 lbs on a tire is better than 0, so...

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