ABS w/ an LSD?

[ESIRstarion]

I've got a '91 GSX with ABS and no LSD. Would it be possible to swap in an LSD unit without any issues?

Has anyone done this with no ill effects?

Thanks!

 

[knochgoon24]

LSD has nothing to do with ABS.

LSD keeps your wheels from slipping as you give it gas.
ABS keeps your wheels from locking up as you mash the brake.

 

[ESIRstarion]

Obviously it does have something to do with it or Mitsu would of made the LSD an option with ABS in '91. This is the only year where you could not have ABS and LSD on the same car.

 

[DSM_PWR]

No theres no effect...

And they are two totally different systems..

 

[Dragon TalonTsi]

LSD has nothing to do with ABS.

LSD keeps your wheels from slipping as you give it gas.
ABS keeps your wheels from locking up as you mash the brake.

Yes and no. ABS is the electromechanical way of controlling the slip rate of your tires so you can control and stop easier. ANd LSD is strictly mechanical way of doing the same thing, only different. Some ABS/TCS use the same systems. Like my GTP, it has both ABS w/LSD and TCS (Traction Control). DSM's use both to do the same job... Hence this is not the only way they can operate there are many other ways they incorporate these systems into an automobile.

90's have problems all together JK!

But no theres no effect...

And they are two totally different systems..

They are different but they do peform the same tasks, just in a different way.

 

[knochgoon24]

Off wikipedia...

ABS:

A typical ABS is composed of a central electronic control unit (ECU), four wheel speed sensors — one for each wheel — and two or more hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel, and when it detects a wheel rotating significantly slower than the others — a condition indicative of impending wheel lock — it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel. The wheel then turns faster; when the ECU detects it is turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied and the wheel slows. This process is repeated continuously, and can be detected by the driver via brake pedal pulsation. A typical anti-lock system can apply and release braking pressure up to 20 times a second.

ABS

LSD:
Here's the link to LSDs on wikipedia. I don't know which type of rear differential we have, so you can just read about them all. LSDs

As you see, two totally different systems.


The LSD is the differential itself. The ABS is just a toothed ring on the axle that a sensor can count to get the wheel speed.

Yes and no. ABS is the electromechanical way of controlling the slip rate of your tires so you can control and stop easier. ANd LSD is strictly mechanical way of doing the same thing, only different. Some ABS/TCS use the same systems. Like my GTP, it has both ABS w/LSD and TCS (Traction Control). DSM's use both to do the same job... Hence this is not the only way they can operate there are many other ways they incorporate these systems into an automobile.

Then let me rephrase, the systems have nothing to do with each other. Like you said, one is mechanical, the other is electrical. As far as he's conserned, there is no reason they both can't be on the car, that's just the way it was offered that year.

 

[ESIRstarion]

There had to be a reason why Mitsu didn't give ABS cars in '91 LSD's.

Does anyone know why?

 

[Dragon TalonTsi]

Off wikipedia...

ABS:
ABS

LSD:
Here's the link to LSDs on wikipedia. I don't know which type of rear differential we have, so you can just read about them all. LSDs

As you see, two totally different systems.


The LSD is the differential itself. The ABS is just a toothed ring on the axle that a sensor can count to get the wheel speed.




Then let me rephrase, the systems have nothing to do with each other. Like you said, one is mechanical, the other is electrical. As far as he's conserned, there is no reason they both can't be on the car, that's just the way it was offered that year.

Anyone can pull up a wikipedia link, but I work on them on a daily basis. One is electromechanical, meaning it combines electrical sensors and mechanical devices to do one job. The mechanical device is strictly that, it does one thing by means of mechanics to do something. And WSS (wheel speed sensor) is an AC producing sensor, that's how the PCM reads the signals coming from one tire to another, monitoring every tires rotational speed. And LSD (Viscious clutch type) senses when one tire "loses fire" and causes the other one to grip by forcing the viscous clutch do to the work. Just like a viscous fan clutch, same principles, only different objects.

 

[GPTourer]

There had to be a reason why Mitsu didn't give ABS cars in '91 LSD's.

Does anyone know why?

This is key, but people seem more concerned with flexing their knowlege on how ABS and LSDs work. It really doesn't matter how these systems work in general, what matters is how Mitsubishi designed this particular car. The same thing happened years later with the 2004 Evolution RS. You could not have ABS on those cars and they were the only ones with a front LSD that year. Then the next year you could get both.

 

[knochgoon24]

Anyone can pull up a wikipedia link, but I work on them on a daily basis. One is electromechanical, meaning it combines electrical sensors and mechanical devices to do one job. The mechanical device is strictly that, it does one thing by means of mechanics to do something. And WSS (wheel speed sensor) is an AC producing sensor, that's how the PCM reads the signals coming from one tire to another, monitoring every tires rotational speed. And LSD (Viscious clutch type) senses when one tire "loses fire" and causes the other one to grip by forcing the viscous clutch do to the work. Just like a viscous fan clutch, same principles, only different objects.

I wasn't aiming that towards you. You seem to know you stuff (and proved it). That was aimed more towards the OP to get a basic understanding of ABS and LSDs.

 

[->PrOjEcTGS<-]

A little information and you can put it all together.

How our Viscous LSD works:
In the LSD is a cylindrical chamber of fluid filled with a stack of perforated discs that rotates with the normal motion of the output shafts. When one wheel spins faster than the other the heat generated expands the discs apart and locks the diff.

What happens when the rear wheels lock up together? The rear end comes around and you spin out of control. That is why early ABS was only on the rear of the vehicle. To prevent a spin out so the driver can remain in control.

How our ABS works:
The ABS controller senses wheel speeds and determines if a wheel is spinning faster or slower than the others. If it's spinning slower (Locked Up) then the ABS unit reduces hydraulic power to that wheel so until the speeds are the same again.

What happens when braking with an Viscous type LSD:

Now, If you are braking and one of the rear wheels locks up the LSD is going to lock also since the difference in speed is going to heat it up and force it to lock. Now the wheels are going to spin the same speed. In this case one wheel is locked. If the spinning wheel doesn't have enough traction it will lock as well brining the rear end around and leaving the driver without control. Hopefully the other wheel has enough traction and can break the brake's grip on the locked up wheel.

What happens with ABS on an LSD rear:
The wheels will technically hardly ever be activated since the difference in wheel speed will rarely ever be different. And since it's AWD it relays the speed difference to the front of the vehicle as well and the Viscous coupler will lock up and cause the front wheels to turn the same speed. So if you are locking up the rear wheels on an LSD car you are probably locking up all four wheels and ABS will not help you in that situation.

Now you do have to account for the G-meter. It senses any sudden motion and relays that to the ABS unit to engage. So if you are locking up all wheels and going slow enough the G-meter will not engage the unit.

I really think it was Mitsu's way of dodging law suits.

The above is only my theory on how the system works. If you have a better think on things then let's hear it.

 

[Dragon TalonTsi]

I wasn't aiming that towards you. You seem to know you stuff (and proved it). That was aimed more towards the OP to get a basic understanding of ABS and LSDs.

I wasn't trying to have a pissing contest, its just he could've done the links and research himself. People are not ignorant to how the internet and google work.

A little information and you can put it all together.

How our Viscous LSD works:
In the LSD is a cylindrical chamber of fluid filled with a stack of perforated discs that rotates with the normal motion of the output shafts. When one wheel spins faster than the other the heat generated expands the discs apart and locks the diff.

What happens when the rear wheels lock up together? The rear end comes around and you spin out of control. That is why early ABS was only on the rear of the vehicle. To prevent a spin out so the driver can remain in control.

How our ABS works:
The ABS controller senses wheel speeds and determines if a wheel is spinning faster or slower than the others. If it's spinning slower (Locked Up) then the ABS unit reduces hydraulic power to that wheel so until the speeds are the same again.

What happens when braking with an Viscous type LSD:

Now, If you are braking and one of the rear wheels locks up the LSD is going to lock also since the difference in speed is going to heat it up and force it to lock. Now the wheels are going to spin the same speed. In this case one wheel is locked. If the spinning wheel doesn't have enough traction it will lock as well brining the rear end around and leaving the driver without control. Hopefully the other wheel has enough traction and can break the brake's grip on the locked up wheel.

What happens with ABS on an LSD rear:
The wheels will technically hardly ever be activated since the difference in wheel speed will rarely ever be different. And since it's AWD it relays the speed difference to the front of the vehicle as well and the Viscous coupler will lock up and cause the front wheels to turn the same speed. So if you are locking up the rear wheels on an LSD car you are probably locking up all four wheels and ABS will not help you in that situation.

Now you do have to account for the G-meter. It senses any sudden motion and relays that to the ABS unit to engage. So if you are locking up all wheels and going slow enough the G-meter will not engage the unit.

I really think it was Mitsu's way of dodging law suits.

The above is only my theory on how the system works. If you have a better think on things then let's hear it.

I was going to get even more technical, but people won't understand what this is or what that does. Trying to keep it simple enough for everyone to understand. You hit the nail on the head though. And just so everyone understands, ABS is not stronger than LSD. If the systems are separate just like in DSM's, only the situation will dictate wether or not both systems work. In cars with INTEGRAL ABS/TCS/LSD, they will work together, not against like in our DSMs.