[TheChairGuy]

I love improving my driving experience for sane money...I have a '99 (5 speed) SAAB 9-3 hatchback with 68,000 original miles on it.  The first 30K occurred the first 2 years, since then, I haven't driven as much (little commute to anywhere now but by plane) 

I have spent oodles improving the handling of this car - the stock ride was really pathetic for a car that infers sporting intentions.  I bought it for the hatch versatility, relatively roominess, fantastic seats, enviable safety and reliability (Consumer Reports) record, idiosynchratic styling and relatively good gas mileage and power. 

It was $299 month for 48 month lease originally and I had a Honda Accord with 217,000 miles in August 1999...certainly all made sense to me.

Except the handling - which was just slightly better than abysmal in stock form 

So, the first thing that was added was a thicker rear sway bar.  Tightened up the rear nicely....I didn't feel out of control on the highway, in particular.

A steering rack brace was added....to tighten up flex there.  It dialed in a more direct feel with the steering...and greatly helped eradicate torque steer of 185hp driving the front wheels.

The front bushes were replaced with poly jobs.  Tho more noise came up thru the tires, it eliminated most of the rest of torque steer that there was.  Tighter, more responsive handling too.

Lastly, among handling improvements (I have power improvements, too) was new SAAB Sport shocks, springs and struts.  Frankly, overpriced for the gains experienced....next time I'll buy Bilstein or Eibach.

One thing that never left was dreaded understeer - real bad - it drives me nutz to have spent what I've spent and not be satisfied with my driving experience.  No matter what - I couldn't dial it out.  Fighting my wheel hard and not having it make an arc around the twisties without overcorrection was not fun.  I had hoped this SAAB would be a grown up example of my late and beloved 1991 VW GTI, but it fell short of the mark with dreadful understeer, primarily.

Then, I was browsing a SAAB forum a few months ago and someone there suggested running the tires at lower pressures in the back as the fronts.  Aywhere from 2 to 5 lbs difference to dial in the right line on your FWD car (due to differences in weight distribution, how much cargo/people handled, etc).

Well son-of-a-gun, if that guys wasn't a damn sage    I dropped tire pressure from 42 psi in the rear slowly by 1 psi and kept driving until I found the right point at which gentle oversteer was induced...it was about 4 lbs for me.  So, I know run my Bridgestone G-009's at 42 psi front / 38 psi rear and have near perfect, thrilling handling!!

Damn if this isn't the neatest trick going - and cheapest.  To boot, with the rear deflated by 4 lbs, the car runs more compliantly with dips and bumps and there is no notable loss in mileage (as it's only the rears that were slightly deflated).

My car drives more neutrally than my wife's 2004 BMW 325ci now with better steering feel (the BMW weighs 700+ lbs more, so heft has a lot to do with it for sure).  I hope one or more of you is helped by this utterly free tweek for your FWD car...if you love driving as much as I do, and don't much like dreaded understeer built into most FWD vehicles mostly because of their poor weight distribution of 61/39% or so...build a little 'squish' into your rear tires and dial it out. For free 

John

[b5pt9]

I believe you but it seems counter-intuitive.  Usually dropping tire pressure results in more bite at that end of the car, not less.

Have you done a performance alignment?  I've been tuning understeer out of my WRX and going from the stock 0 front / -1.5 rear camber to -1.5 / -1.5 really improved frontend bite and turn-in.  This is a cheap mod as well.

[TheChairGuy]

Nope, I've not futzed around with camber - as the SAAB has a semi-indy rear, I figured there wasn't a whole lot one could do with angles that would change responsiveness.  Nonetheless, it's not something I'd do...I'd leave for my alignment shop.

Reducing the rear tire pressure really does work wonders....tho the tall-ish SAAB is still prone to body lean (I have the stock 15" rims/195/60's...I actually like smaller tires as less patch and I get more steering feel instead vagueness of larger patches)...it now mostly neutral steers instead of understeers with half a tank of gas and my wife in front and 34 lb daughter in back with 4lbs less air in the rears.

Believe it or not, I feel the weight distribution difference now if I am driving solo now instead of stocked with passengers 

As you turn, the front tires bite down (more air pressure) while the rears 'slide' (with less pressure) inducing more neutral steering (in a car that understeers) as a result.  I don't know if the inverse exists...would cars with gross oversteer (like Porsche 911's) respond to less pressure in the fronts and more in the rear

With a WRX, none of this likely applies...as all-wheel drive is inherently better planted and your car has better weight distribution fore and aft from the start 

John

[JLM]

My 1979 Saab 99 was pedestrian at best on the original European Goodyears.  Swapping out to Dunlap SP4 (not sure of model anymore) gave it a much more sporty demeanor.  That experience made me a believer in good tires.

Living in the great white north teaches you of the value of good tires.  Trying to get another winter out of tires versus paying for a tow truck plus damages plus hassles isn't worth it.

[Bob in St. Louis]

Nope, I've not futzed around with camber - as the SAAB has a semi-indy rear, I figured there wasn't a whole lot one could do with angles that would change responsiveness.  Nonetheless, it's not something I'd do...I'd leave for my alignment shop.

Shims are used to adjust rear camber. Too much negative camber will cause excessive tire wear on the inner tread. As long as you're aware of this and keep an eye on it, you'll be fine. I've got a few customers who have tweeked their SAAB's rear camber but they forget to keep an eye on the tread life. By the time we see the car again there's cords showing.  duh.....

Bob

[ltr317]

Nope, I've not futzed around with camber - as the SAAB has a semi-indy rear, I figured there wasn't a whole lot one could do with angles that would change responsiveness.  Nonetheless, it's not something I'd do...I'd leave for my alignment shop.

Reducing the rear tire pressure really does work wonders....tho the tall-ish SAAB is still prone to body lean (I have the stock 15" rims/195/60's...I actually like smaller tires as less patch and I get more steering feel instead vagueness of larger patches)...it now mostly neutral steers instead of understeers with half a tank of gas and my wife in front and 34 lb daughter in back with 4lbs less air in the rears.

Believe it or not, I feel the weight distribution difference now if I am driving solo now instead of stocked with passengers 

As you turn, the front tires bite down (more air pressure) while the rears 'slide' (with less pressure) inducing more neutral steering (in a car that understeers) as a result.  I don't know if the inverse exists...would cars with gross oversteer (like Porsche 911's) respond to less pressure in the fronts and more in the rear

With a WRX, none of this likely applies...as all-wheel drive is inherently better planted and your car has better weight distribution fore and aft from the start 

John

First thing a regular autocrosser or road racer learns is adjusting tire pressures to reduce/increase underteer/oversteer (up to a point!).  When I used to race or do track days, I would come in after the first practice session, and adjust tire pressures immediately while the tires were still warm.  I generally like a little oversteer for most tracks, and would increase the rear tire pressures a little. 

The inverse is also true, and for all cars.  All wheel drive cars will still benefit though less than 2 wheel drive cars.  It's a matter of how much weight is the optimal weight pressing down from the car to the surface, thereby providing more or less traction. This is the coefficient of friction or CF.  There are several factors contributing to CF, some controllable and others not by the driver, but adjusting tire pressure does help for a better CF up to a point. 

As for negative camber, I wouldn't go overboard on a street car.  Bob from St Louis is right, too much nc will wear the tires out much sooner than the estimated life expectancy, and will void any warranty.  I think 1.5 negative camber is the max for a street car, but there are other suspension tricks needed to get the max out of that setting.     

[Bob in St. Louis]

there are other suspension tricks needed to get the max out of that setting.     

Lowering the overall center of gravity of the vehicle and lower aspect ratios on the tires being high on the list.

Bob

[ltr317]

there are other suspension tricks needed to get the max out of that setting.     

Lowering the overall center of gravity of the vehicle and lower aspect ratios on the tires being high on the list.

Bob

Yes, absolutely!  Plus, caster and toe in/out settings in conjunction with the camber settings.   

[Bob in St. Louis]

Yea, that's true. But FRONT caster is a slightly rare adjustment to find on most cars with OE suspension systems.
REAR caster is VERY rare to find OE. The only cars I know of that come with rear caster adjustments are some Porsche's and the Pontiac Solstice / Saturn Sky common platforms. 

Regarding non-O.E. alignment adjustments: Just be careful if the car is driven "normal" 99% of the time. You may find yourself buying high dollar tires more often than than is justifyable to have superb handling for that 1% f the time you're "driving it like you stole it". 

Bob

[ltr317]

Yea, that's true. But FRONT caster is a slightly rare adjustment to find on most cars with OE suspension systems.
REAR caster is VERY rare to find OE. The only cars I know of that come with rear caster adjustments are some Porsche's and the Pontiac Solstice / Saturn Sky common platforms. 

Regarding non-O.E. alignment adjustments: Just be careful if the car is driven "normal" 99% of the time. You may find yourself buying high dollar tires more often than than is justifyable to have superb handling for that 1% f the time you're "driving it like you stole it". 

Bob

Yes, that's right.  I had a few Porsche 911s in my time, though nothing newer than 1980s models.  I especially like the earliest 911s (1966-1969), with the short wheelbase, where you could induce power oversteer very easily as needed around curved entrance and exit ramps.  It scared a lot of Porsche owners when the end came around if they drove beyond their skill level.  The Porsche club set up their driver school partially because of novices not knowing how to drive these rear engined cars correctly.       

[Bob in St. Louis]

Many years ago I did a four wheel alignment on a twin turbo. Jeez man, All three angles on all four wheels. Took me all friggin' day.
Although the test drive afterwards.........  aa
Words can't describe that. So I won't even try. Nothing better than somebody elses car. 

Bob

[ltr317]

Many years ago I did a four wheel alignment on a twin turbo. Jeez man, All three angles on all four wheels. Took me all friggin' day.
Although the test drive afterwards.........  aa
Words can't describe that. So I won't even try. Nothing better than somebody elses car. 

Bob

I've never driven a twin turbo, but did drive a friend's single turbo a long time ago.  Except for a little turbo lag, that car took off like a bat out of hell.  In stock condition, I didn't think it cornered as well as the lighter 911 at the time.  It sure was fast though in a straight line. 

[TheChairGuy]

Lowering the overall center of gravity of the vehicle and lower aspect ratios on the tires being high on the list.

Bob

The SAAB sport shocks/springs/struts (made by Sachs/BOGE) lowered the car by a little less than 1/2"...I like keeping reasonable clearance.  It's got a fairly aggressive, low front air dam on it...any lower than this and it'll scrape too many road dips and or parking 'blocks' in front of the car.

Car is 9yo...no warranty left to concern myself with.

Right now, the ride is still compliant....even tho it's leagues stiffer than stock with the sport shocks/struts/springs and subbing in poly bushes all around the front. The 4lb pressure differential from front to rear is amazingly helpful from twisties to highway to even pulling into a parking spot.  I am now correctly pointing this vehicle and feel in control of it (first time).

It's nearly the equal of my late and beloved 1991 VW GTI in that regard now...with better seats, more room, and more amenities (and airbags) 

I don't like large, low profile tires - in general. With a 3100 lb car and 102" wheelbase...15" tires/60 series of H or V rating is plenty grippy enough.  The 16's and up, especially when you run 50 series or lower, adds additional weight to the 4 corners - exactly where you don't want it for handling.  You might gain G's, but you lose steering feel and mileage.

It's bad enough that today's cars tend towards heavy (with safety gear, a def positive, and aluminum being too costly for many price points, the only way weight can go is up, up, up).  Heavier cars mean larger power steering systems - which zap power, immediacy, and deaden the steering/handling/nimbleness.

When you add in biggie tires and lower profiles to larger cars and oversized power steering systems you get wooden steering response.

The newest BMW 3 series (drove a base auto version with 16/55's for a weekend last month) has good communication somehow despite it's 3300+ lb bulk. Don't know how those guys do it, frankly 

John

[Bob in St. Louis]

Yes. I didn't get stupid at all around the corners. Being a (drastically) different car than I was familiar with, the LAST thing I wanted to do was tell the boss I wrapped a $100,000+ car around a telephone pole.  I assume I might get fired for that little stunt. LOL So I took it easy.
In a straight line though, it was amazingly tolorant of the throttle. I was very suprised at how much thottle it would take without (detectable) tire spin. No tail wag at all. I think I know what it feels like to be shot out of a cannon. 

By the way, since we've highjacked this thread........ ......I'd give my left nut to have a few laps in that car shown in your avatar.  aa

John, true what you've said about the tires. It's been a long time since I was in the hotrodding arena. I've been OE for many years now. Another drawback with <50 series tires is potholes can mash a $500 wheel and tire combo in a split second. Makes for unhappy automobile owners when their butt is on the side of the road with a blown tire and bent wheel.

Bob

[jules]

Some of the suggestions made above would seem to working on the basis of decreasing the grip at the rear of the car to match the loss of grip caused by understeer at the front of the car.

One reasonably cheap option here, that wouldn't cause excessive tyre wear, would be to use a stiffer roll bar on the rear of the car [if such things are available for the SAAB]. This transfers some of the roll load from the outside front tyre to the outside rear tyre with overall better balance and handling. The trade off is slightly less independence between the two sides of the rear suspension.

jules

[TheChairGuy]

Some of the suggestions made above would seem to working on the basis of decreasing the grip at the rear of the car to match the loss of grip caused by understeer at the front of the car.

One reasonably cheap option here, that wouldn't cause excessive tyre wear, would be to use a stiffer roll bar on the rear of the car [if such things are available for the SAAB]. This transfers some of the roll load from the outside front tyre to the outside rear tyre with overall better balance and handling. The trade off is slightly less independence between the two sides of the rear suspension.

jules

Hey Jules! Haven't seen you for a time....

Yes, looking at my overly long first post in this thread I did note that a thicker 22mm roll bar (I think stock was 19mm) was added early on in the cars life.  It helped, particularly on highway I felt, but didn't provide the turn in needed.

The rear is not fully independent as it is, so the car was a good candidate for thicker/stiffer anti-rollbar.

Bleeding off the 4lb did the trick...and some 

Do they have SAAB's in Oz (at least I think that's where you are  )? Didn't know if GM (Holden locally, I think) exported that division down there.

John

[jules]

ah yes,  , you did mention the roll bar!

Plenty of SAABs here and pretty much everything else. We do have some fairly tight laws on modification so there's rather less "creativity" allowed here than apparently happens in some US states.

I drive a WRX and also have a beach buggy. The latter are now very frowned on so I'm lucky that it was registered for road use some 30 years ago and has stayed that way. The WRX understeers. The Buggy oversteers 

jules

[ltr317]

Some of the suggestions made above would seem to working on the basis of decreasing the grip at the rear of the car to match the loss of grip caused by understeer at the front of the car.

One reasonably cheap option here, that wouldn't cause excessive tyre wear, would be to use a stiffer roll bar on the rear of the car [if such things are available for the SAAB]. This transfers some of the roll load from the outside front tyre to the outside rear tyre with overall better balance and handling. The trade off is slightly less independence between the two sides of the rear suspension.

jules

Yes, I only mention tire pressures as a way to adjust handling because John's original thread is about getting rid of his understeer from reducing rear tire pressure.  Actually, the better way to do that is to simultaneously increase the front tire pressure incrementally while reducing rear pressure.  You get a more balance car that way.  Again, this has to do with CF. 

[ltr317]

[/quote]
The newest BMW 3 series (drove a base auto version with 16/55's for a weekend last month) has good communication somehow despite it's 3300+ lb bulk. Don't know how those guys do it, frankly 

John
[/quote]

I drove my nephew's leased BMW E90 325xi (four wheel drive version) last year, and had a lot of fun tossing it around.   
It handles pretty good in stock form, though I should warn him the next time.  He was pretty shaken up after he got out of the car with me.

[ltr317]

Yes. I didn't get stupid at all around the corners. Being a (drastically) different car than I was familiar with, the LAST thing I wanted to do was tell the boss I wrapped a $100,000+ car around a telephone pole.  I assume I might get fired for that little stunt. LOL So I took it easy.
In a straight line though, it was amazingly tolorant of the throttle. I was very suprised at how much thottle it would take without (detectable) tire spin. No tail wag at all. I think I know what it feels like to be shot out of a cannon. 

By the way, since we've highjacked this thread........ ......I'd give my left nut to have a few laps in that car shown in your avatar.  aa

John, true what you've said about the tires. It's been a long time since I was in the hotrodding arena. I've been OE for many years now. Another drawback with <50 series tires is potholes can mash a $500 wheel and tire combo in a split second. Makes for unhappy automobile owners when their butt is on the side of the road with a blown tire and bent wheel.

Bob

Oh, that used to my rental race car.  It's a Sport Renault, precusor to the Spec Racer Ford which is still a popular race class in SCCA.  The only difference is the engine and tranny.  It was an Reliance engine and 4 speed in the Renault, and an Escort engine and 5 speed in the Ford.  I've driven both, and the main differences is about 15 more horsepower and slightly quicker acceleration with the Ford.  Not much total horsepower in either car, so momentum is your friend when you're racing one of these.  Brakes, what brakes?  I don't need no stinkin' brakes.