Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 11 of 11 Posts

·
Registered
Joined
·
3,618 Posts
Discussion Starter · #1 ·
I know this isn't the correct place for this post.. but I think you guys know about this stuff..This is probably a familiar question...

I don't have TCS, and my car is putting out around 250LB/FT of torque from like 2000 RPM.. how the heck do I get better traction out of bends.. especially in the wet ?

I drove lastnight after a rain storm and was spinning my tyres (Michelin Pilot Sports btw) in first, second and third gears out of almost every corner.....

Will a LSD help?.. will stiffening up the back of the car help? Or will I just have to live with it and not be so quick on the throttle.. (it's just kinda hard since the torque comes in sooo early...)

Also running a Koni/Eibach set up.. (2001 9-3 TiD + Abbott Steering clamp + Abbott Diesel upgrade)
 

·
Registered
Joined
·
3,892 Posts
Fitting a LSD will help, but it won't cure it completely, I've got a Quaife LSD (from Abbott's)in my Aero and it is a drastic improvement but you can still provoke wheelspin, but it's more controllable with the LSD fitted, it also does make car more stable on fast sweeping type roads as well.
 

·
Registered
Joined
·
4,215 Posts
negative effects of lsd..
seeing the wall melt into the floor...
seriosly though
the steering became heavier..more meaty
when really pushing it through more severe bends you can get almost a self steering effect like the wheels are trying to pull more lock..ultimate oversteer ? you really need to have a firm hand on the tiller to compensate ...scary at first but you get use to it
also if you come off the power or go in off boost then it reverts to the old plough on understeer ..
again scary but you do get use to it...
Stability through long sweepers is superb and if you keep the power on and do not go too crazy then it corners like it is on rails
 

·
Registered
Joined
·
4,215 Posts
no such thing as a silly question..
lsd= limited slip differential
limits the slip between the driving wheel..
on a conventional diff when on wheel looses traction it continues to spin ..the lsd limits this ..hance the name The quaife one uses a special fluid that thickens when stirred so transmitting the torque to the other wheel
tcs= traction control system
saab system has two phases
up to 30 mph senses that a wheel is slipping and brakes that wheel ...above that speed it just cuts the power..
this system works very well in the snow ..
so having both theoretically is too much but they do work in different ways and do different things..
clear as mud ?
 

·
Registered
Joined
·
3,618 Posts
Discussion Starter · #8 ·
LSD - Limited Slip Differential
TCS - Traction Control System

Different mechanisims to curb wheelspin and get more grip to the wheel that can best us it.

The conventional differential delivers the same amount of torque to each powered wheel when both wheels have equal traction.

But when one wheel has less traction than the other, for example, when one wheel slips on ice, the other wheel cannot deliver torque. All turning effort goes to the slipping wheel. A limited slip differential can help to provide good traction even though one wheel is slipping. It is very similar to the standard unit but has some means of preventing wheel spin and loss of traction. The standard differential delivers maximum torque to the wheel with minimum traction. The limited slip differential delivers maximum torque to the wheel with maximum traction and LSD manufacturers use various mechanical and hydrodynamic means to deliver the effect - such as viscous coupling etc...

TCS however, relies on electric and electronic means to curb wheelspin.. for example.. the ABS sensors are used to detect a wheel that is spinning faster than the others, and the system then either/both retards the throttle or/and brakes the spinning wheel.

Some TCS systems are also combined with Yaw and pitch sensors to detect how the car is moving and can use the brakes and throttle to help the car corner, such as the DSC systems in BMWs and the active components in Mitsibushi Lancer EVOs..
 

·
Registered
Joined
·
3,892 Posts
LSD = Limited Slip Differential
Generally available in 2 different forms, an clutch type or gear type.
Clutch types, surprise surprise, use a clutch type arrangement that 'locks' the diff up at the determined pre-load, which can be manually set, when installing the diff, depending on likely use, i.e competition or road use. The higher the pre-load the more aggresive the diff action. This was the type of LSD fitted in the Capri 2.8i's back in the '80's. This type of diff when fitted in a FWD car is not recommended for road use..very ...err....interesting..
The gear type as in the Quaife unit sold by Abbott's, is a 'softer' acting form of limited slip diff, and works on a torgue sensing gear system, so, when doing the shopping run to Tesco's you woundnt know a LSD was fitted, but, giving a dose of torque through the transmission causes the gears to progressivly lock up the diff, thereby enhancing the traction. As described by 'ylee' you do have to adjust your driving technique to this, but it ain't rocket science, so not really a problem.
TCS...ahh the dreaded Traction Control System. This works by activating the ABS sensors when the computer detects the wheels spinning and thereby applying small brake imputs the the spinning wheels...this all occuring in milliseconds with accompaning shuting off of the throttle. All clever stuff and great for stopping granny spinning the wheels on a frosty morning, but [expletive deleted] for err, shall we say, enthusiast driving.
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top