Do I need a bump steer kit??
 

Have lowered my car to 26"-25,5", if I measure diff between center torsion bar and center wheel I'm about 30mm lower than euro spec. In front the tie rods are almost horizontal(maybe little higher toward wheel)and A-arms are horizontal.
Do I need the bump steer kit at this height??

/Hans
911 3.0 SC -79

Yes, but one of the ~$10 kits that shims the steering rack down is all you need

Interesting.

I have a stock 1983 SC and as I understand the US '83 cars were delivered with euro suspension height. The car sits at almost exactly 26" front 25.5" rear.(measured at the center of the fender lips)

The height of my car may be due to aging shocks, but what exactly is the factory euro height measurement supposed to be and do I need a bump-steer kit?

Yep, and it makes a world of difference. No more "hit a bump and pull an arm out of it's socket".

measuring height at the fender is affected bu the actail height and the tires.

the best way to mesure ride height is the distance in height of the t-bar caenter and axle center.

these #s gradually rose for US cars during the 70s and 80s

the bigger this # the lower the car

for all 911 from '79-83
front
RoW spec is 108+/-5mm
US was from 99+/-5mm to 94+/-5mm

rear
RoW spec is 16+/-5mm
US spec is 37+/-5mm

Zacko - what size wheels and tires are you running on your 79? I have an 80 SC with 205/50/17s on the front - my car, as best I could determine, is at stock US height - 99mm from t bar center to center of wheel and my fender is 25.5" off the ground.

This makes me think that I would need to reduce the diameter of my wheel/tire combo if I wanted to lower the car
. Yes?

Yup, ditto that. Makes a world of difference.

It lowers the car but does not correct suspension geometry. Lo at the tie rods when the csr sits on a level suface if th e tie rod are horizontal then you are good.

This bump steer kits cost about $60 here in Sweden, but that's not a problem. I'm afraid of making this bump steer if I put the steering rack to high.

I'm running on 225/45/17 in front and I think that's the same height as stock.

The height to center wheel is 310mm and to front center torsion bar is 168 mm and it's makes the difference of 142 mm. Compare to euro spec(108mm), it's 34 mm lower.

/Hans
911-3.0 SC -79

Noticed that the spec that Bill listed is for '79 to '83 cars. Any idea whether this is the same spec for an '84 and if not what it is for a US '84 911?

When we dropped my track car to the deck we needed spacers 1.5X longer than the kit. A good race shop (where you want to get it corner balanced anyway) will have a suspension geometry tracker to plot your angles throughout its travel and can properly space the rack at the same time.

Why couldnt it be this easy on a 964!

Is horizontal for the tie rods still the best for a 964?

RT

yep, unfortanately it's a much more costly proposition on 964 & 993


the upper pair of uprights are the 964 steel versions, w/ axial caliper mounts and long steering arm. The lower pair is 993RS(aka GT2 EVO) w/ radial caliper mounts and short steering arm
http://forums.pelicanparts.com/uploa...1201391600.jpg

on left here is the 993RS upright and on right a stock 993 aluminum w/ radial caliper mounts and long arm.
http://forums.pelicanparts.com/uploa...1205424925.jpg

The 993RS tirod also is shaped differently

Stock 993 outer and inner tierod top, RS outer w/ Evo monoball inner bottom
http://forums.pelicanparts.com/uploa...1199803625.jpg

You can also use ERP outer w/ a height adjustment similar to that on the more expensive 911 kits
http://forums.pelicanparts.com/uploa...1205810877.jpg

It's the nuts a low car
My 993 w/ RS uprights
http://forums.pelicanparts.com/uploa...1190984221.jpg
http://forums.pelicanparts.com/uploa...1205868270.jpg

On my C3 I used the $10 steering rack washers(well they were ~$10 back circa 1979) worked great at the extreme low end of RoW height which on my car w/ at that time 16" tires 25.25F & 24.625" r
C3(now w/ 17" tires


http://forums.pelicanparts.com/uploa...1206101686.jpg

Setting bump is not rocket science, but I will say that i like the tie rod end adjusters better, here is the reason, each wheel needs to be set independently of each other(the bump will be slightly different for each wheel), i am sure the spacers will probably do fine for the street, but due to different size tires checking the fender lip is not always an accurate measurement. I am amazed that no one has come up with a rack bolt measurement. Kevin

'84 up Carrera is the same as the SC RoW spec
front
RoW spec is 108+/-5mm

rear
RoW spec is 16+/-5mm

Stock tire front for a '79 was more like 205/55 R16.
Bump steer kit is just two 12-13 mm spacers and longer metric bolts.
With the kit installed, you can always adjust it so the tierods are level.
I have the spacers under the rack and height is 25"F/24.5"R fender lip to ground.