Heavy steering, bump steer, etc.

prebordao · 10-26-2010, 05:50 AM

About the heavy steering issue...
I thought that my car's height was stock Euro, but it turned out it is slightly lower...

At the front, I measured the distance between wheel center and torsion bar center and came up with 125mm. According to the "good" book it should be 108, so I have a 17mm difference (about 3/4").

Without any spacers inserted below the steering rack, is this difference enough for being felt as a heavier steering in corners ?

I like the car as it is, both in looks and in handling, it's just the steering that I would like to improve. If I insert the spacers below the steering rack, should they have the same height as the difference that I found (about 17mm) ??

Thanks

Trackrash · Trackrash's Garage

Read all about it here. 3.2 Carrera and SC handling

stlrj · 10-26-2010, 06:19 AM

Quote:

Originally Posted by prebordao

I like the car as it is, both in looks and in handling, it's just the steering that I would like to improve.

If you like the way it looks and handles, then you will have to accept the heavy steering as a small price to pay.

ossiblue · 10-26-2010, 07:32 AM

The spacers under the rack are to avoid bump-steer, and their absence should not cause heavy steering. You probably have a toe-out, negative camber, corner balance issue or a combination of all three, unless you've had the car aligned and balanced since the lowering.

Steve@Rennsport · 10-26-2010, 07:40 AM

Excessively heavy steering can be caused by wider wheels & tires, low tire pressures as well as too much front caster.

I'd review your caster settings and if its 6 degrees, take some of that out.

prebordao · 10-26-2010, 09:14 AM

Front tires are 195, so I was thinking of caster. So probably 5.5 would be ok ?

nesslar · 10-26-2010, 11:58 AM

Any pictures? Maybe just raising the front to a reasonable height would fix it up.....a lot of guys like the front way too low (just my opinion) and it ain't meant to be that way without reworking things. I have always liked the look of about 3/4" to 1" "rake" measured along the rocker panels, higher at the rear of course. Some folks don't like that much space above their front tires, but it's a 911! This is all maybe less than $.02 worth...
17mm is quite a bit. How high is the rear? And 5.5 caster probably isn't enough of a change. That's only less than 10% of only 6 degrees, if that is where you're at. Just curious, how is it you like the handling when it's heavy in the corners? I don't understand, so maybe I'll learn even more here.

prebordao · 10-26-2010, 12:21 PM

I don't think is too low, but have a look...

I find the steering heavy in really tight corners... but then again I've never driven another 911... what do I know

nesslar · 10-26-2010, 12:24 PM

Hmmmm..... it doesn't look so low....alignment time? Maybe the rear is even a bit high, but hard to tell.

prebordao · 10-26-2010, 12:29 PM

I might try an alignment... a few months ago I went to a shop for an alignment, but their equipment was acting funny, so they asked me to comeback later. Anyway, I told them my suspicions about caster being to much, and they said they didn't touch caster, that it was "fixed"...
Can you believe this ? Maybe today's cars really don't need a caster alignment ? Anyway got to try another shop...

Flieger · Flieger's Garage

Caster is adjustable, though it may be difficult to do since it will effect other angles. (That is a characteristic of a strut suspension like on the front of a 911) You should re-evaluate your chosen shop.

nesslar · 01:07 PM

Boy, that sounds like sage advice! Get the front end aligned and I bet your troubles go away. Steve must be right; get it set to specs. and I can't believe it will be a waste of time/money. I can get a quality front AND rear alignment for $100 from a guy who works on quite a few Porsches and other (rare) cars........in fact last time it included a bit of rear suspension work. Fine job, too. Try to see if someone on this board knows of someone in your area.

stlrj · 10-26-2010, 04:43 PM

Quote:

Originally Posted by nesslar

Boy, that sounds like sage advice! Get the front end aligned and I bet your troubles go away. Steve must be right; get it set to specs. and I can't believe it will be a waste of time/money. I can get a quality front AND rear alignment for $100 from a guy who works on quite a few Porsches and other (rare) cars........in fact last time it included a bit of rear suspension work. Fine job, too. Try to see if someone on this board knows of someone in your area.

How is it possible to align our cars to specs if we insist on having our cars looking the way we want with the right stance? Seems there will always be compromises to take into consideration that usually results in heavier steering or more understeer.

How can we have our cake and eat it too?

Cheers,

Joe

Trackrash · Trackrash's Garage

I agree, caster will make a difference on how "heavy" the steering feels.

For an alignment go to a shop that SPECIALIZES in Porsches. To say that caster is not adjustable is nonsense.

You may want to jack up the front end and lift the wheels off the ground. Then turn the steering wheel. You should be able to turn it with one finger. Then check to see if there is ANY play in the front suspension by grabbing the tires and trying to move them.

Good luck and let us know what happens.

Steve@Rennsport · 10-26-2010, 05:54 PM

Quote:

Originally Posted by prebordao

Front tires are 195, so I was thinking of caster. So probably 5.5 would be ok ?

That will make a big difference,....

Love that color!!!!!