Jason997.1

Hi all,

I bought an 06 S Cab, with 19x8 ET57 front wheels, and 19x11 ET67 rears. There are no spacers that I can see.

I notice that there is a little bit of steering kickback when I hit little bumps while cornering.

a) would 5mm spacers in the front cure the kickback?
b) did the car come from the factory with these spacers? Or were they some kind of option? (only talking about narrowbody cars)

Thanks in advance!

rickdogg82

5mm spacers were an option I believe and should not affect kickback. You might just be "feeling" the road more than you might have with your previous car.

nwGTS

Any spacer on the 997 will affect the scrub radius. Scrub radius is what will affect bump steer the most or what you are calling kickback. The 997's current front mcpherson setup in tandem with OEM wheel offsets have a bit of positive scrub to increase steering feel and response. It's a feature. Not a problem.

Rikky001

5mm spacers were an option.
How long since your car had the alignment checked?
A 10 year old car might need new bushings, they deteriorate after time.
my 4S is almost 9 years but changed the bushings last year - made a difference.
I run 5mm front and 17mm back, like the stance without the wheels sticking out.

Jason997.1

So the 5 mm spacer will increase, not decrease the feel,response, and kickback?


Was it an option you checked when you buy the car new? Or does it come with certain wheel or suspension options?


I plan to get GT3 LCA's and dial in some front negative camber to reduce understeer.

LexVan

Maybe buy a front strut brace.

nwGTS

Adding a spacer will increase the offset which will in turn increase the scrub radius which will increase bump steer which is what I'll assume you mean by kickback. Feel and response are subjective so I can't comment on that.

Everything I've read and been told says a front strut brace is worthless on a 997 with our chassis. LexVan usually has solid advice so I'd like him to tell me why this would help.

Cheers!

Jason997.1

Thanks.

I thought bump steer was toe change with suspension compression making the car turn, and kickback was the steering wheel trying to move in your hands, but if you held it steady, the car would not change direction.

Is the strut brace useless even in Cabrios?

nwGTS

I didn't think about that for Cabrios. May be a different situation but I don't have any experience there.

This is all relative mind you since we're talking millimeters but the car would be more difficult to steer the greater the scrub radius.

Scrub radius will give you bump steer in one-wheel bumps
For high-speed stability in the presence of road disturbances, zero or slight negative scrub radius is desirable (negative is outside the wheel center plane)
Braking forces introduce steer torques proportional to the scrub radius. (This is actually more important for FWD cars as there are also forces induced by the wheels driving)
There are some good stabilizing effects scrub has on front wheel drive cars.
Negative scrub radius will make the car more difficult to steer (imagine trying to turn the wheel by swinging it at the end of your arm... like turning a Radio Flyer wagon front axle).
And in your definition, yes you would increase input to the tie rod->steering rack->steering column->steering wheel on hard bumps which would increase kickback.
Now, realize that many people run 10mm spacers up front without issue and Porsche even supplies 5mm spacers for some of its cars.
So I'm not trying to spread FUD here or doom and gloom, just want to bring up the physics that can't be circumvented.
Suspension geometries fascinate me and scare the hell out of me at the same time.

And just for example... the scrub radius on go karts is bananas:

Jason997.1

OK so 5 mm here or there won't affect stuff too much.

So is it all about looks then? How come some cars come with it and some without? Was it a $500 check box when new?

OKB

alignment and new tires cure alot of problems, spacers of any kind would be hardly noticable at all

Philster

Steering kickback is about (lack of) dampening. Anything related to the firmness of the suspension, from tire pressures, bushings, shocks, etc.

Most run tire pressures of around 33-34 front and about 38-39 rear. Tires are the first defense, so having them too hard is going to magnify little bumps.

I would like to know the wheel brand/type/material/size and the tires you have and how old they are (tire make and model).

If the suspension is excessively worn and the shocks are loaded over and too much roll is realized, then this can also contribute to kickback. So... how many miles on the car?

.

mrhebert

Get 7's and 15's. 5's do not make much difference.

ksozay

Have 5s on mine from the factory with 11" tires out back. Not able to detect any changes in steering feel. But that's just me.

Jason997.1

Are these 7 mm spacers + bolts decent?:
http://www.ebay.com/bhp/7mm-wheel-spacer
I'm looking to reduce understeer. (Yes I'm going to get an alignment too)

And, would they fit with my front 19x8" ET 57mm wheels with 235/35 tires?

TIA