eliminating understeer
 

I have a bone stock suspension on an 89 Carrera. I find it understeers far to much. What the suspension upgrade to address this. I forget if it's bigger sway bar in the rear or front (or something else).

Thanks,

Chris
89 G50 Carrera

Same tire size all around goes a long way. Adding an adjustable sway on the rear allows you to fine-tune.

Bigger rear sway bar; you can also adjust alignment, tire pressures, tire sizes, etc

You want understeer in a 911! Oversteer ='s death!

My '87 with helper coilovers has massive understeer too, but that's a good thing.

Did you know the front tires on a stock 89 Carrera are bigger than the rears.
Well taller anyway.

I can appreciate understeer but I want more balance. So thicker and adjustable rear sway bar is what I am hearing for a starting point.

Chris

89 Carrera with LSD G50

You have a few options to adjust your cars handling. Ill start from the least to most intrusive:

1. Alignment settings(more camber bias to the front wheels will aid help reduce understeer)
2. Sway bar as others have mentioned, a stiffer rear sway bar will help reduce understeer)
3. Tire sizes as others have mentioned, have more front tread will provide more grip to the turning wheel, aiding in overs) for example if you run 205F/225R currently, stepping up to 215 or 225 in the front will help the car oversteer

You would be surprised how much a correct alignment can transform your car, I would start with that.

Spend a couple more and have it corner balanced.

do you have front and rear bars already
when is it under steering, turn entry, exit
are these fast turns as on a track or slower, like autoX or mountain roads.

how you drive it can also change how it is balanced.
yanking the steering wheel at turn in can cause under steer.
too much gas can cause under steer.

its just unusual for this request.

had the 930 on track a few weeks ago. tons of turn in over steer. back on the gas at turn in to reduce. I had to change how I was driving to get "drivable"
going to mountains this week. I love the over steer on the tight roads.

I also had under steer at the track. too much gas in the middle of turn.


add or increase sway bar at rear to reduce under steer or increase over steer. .
trust me, over steer at 100mph is a bit scary.

The easy answer for changing a car's balance is stiffen the end you want to loosen. Soften the end you want to tighten up.
Obviously adding more tire on an end of the car will tighten it up. Narrower tires loosens up that end.
You can adjust tire pressures. There will be one pressure that produces the best grip at the load your car creates. This pressure can vary wildly with the exact tire you run! Get a smooth section of concrete you can drive in circles on (skidpad) and test it. Any variation from the optimal pressure will loosen that end. (Driving in the wet rewards high pressures so expect the balance to change.)

You can also change alignment. Adding camber on the end of the car you want to tighten until it gets to its optimum for grip. Increasing camber past what gives the best grip will loosen the car but we are talking pretty extreme. The optimum camber for grip will hog out the inside edge of the tire.

One less obvious way of adjusting balance is how you drive. Increasing how much brake you carry into a turn will loosen a car. (And with the natural human tendency to overdo things can take you into a situation you can't get out of.)

Try lifting mid corner. 😉

"I have a bone stock suspension on an 89 Carrera."

Please post a picture of your "bone stock" ride. It may not be as bone stock as you think since most enthusiasts have no idea what bone stock is.


Cheers,

Joe
87 "bone stock" Carrera (that does not understeer!)

Lots of ways to sj=kiun that cat, but look at the t-bars.

http://forums.pelicanparts.com/uploa...1542225612.gif

911s seem to inherently understeer at low speeds. As the speeds increase, that transitions to oversteer. If you dial out the low speed understeer, you might find yourself with unacceptable (:eek:) oversteer at higher speeds.

In my journey to do what you're asking above, I made some of the steps noted to reduce understeer as much as possible while still allowing a nice, neutral slide at speed (think Turn 12 at Road Atlanta).

http://image.motortrend.com/f/motors...g-scion-tc.jpg

Maybe?

Like it's been said, it's all about balance.

If the front is stiff and has a small contact patch, you will lose grip. I think you've got it.

Not sure this holds true for '89 Carrera's geometry... for '79 930, I found playing with rake results in over/under steer tuning. To induce oversteer... lower front end. (Check/adjust alignment after setting height.)

A stock 911 does not understeer or oversteer. The driver, however, can induce one or the other.

Vic Elford - On Balance

How about tires? How old are they? Old tires may negatively affect it as will tire pressures..

Lift or dab the brakes just before turn in. Once it turns in, adjust attitude with right foot.

You got LSD? That will exacerbate understeer in tight turns.
Johan

great chart bill!!
over on the right side, I don't see where it gets the delta F/R and % F/R

got one for sway bars.
I have considered increasing the rear Tbar to reduce squat under acceleration but would be curious as to what sway bar up front to keep the balance the same?
86 930.
not to hi jack BTW.