ScottMellor

No I mean because I have full suspension travel now I don't have to wear a mouthguard when driving over a matchbox.

Correct me if I'm wrong, but most cars are lowered by screwing down on the spring perches. This compresses the spring, making the ride harsher and also reduces the amount of suspension travel. The GT2 uprights raise the spindle, in effect lowering the car while maintaining full spring range of motion. That's why the factory did it that way. The other way is a bit of a bodge.
I was amazed at the change is ride compliance in the Guap apres installation of the GT2 uprights.

Bill Verburg

It depends on the design of the perches and struts, You will have full suspension travel no matter what wheel carrier is used and harshness should not be affected either as that is a function of shock valving and spring rate.

All struts have a small range of height adjustment that is used primarily to corner balance the car, you raise the perch compressing the spring a bit and shift the load a bit. But you still have a full range of travel. Some struts adjust the height by screwing the lower leg up into the upper leg, JIC 's are built that way, these totally separate corner balance from ride height.

Most cars change ride height by changing the spring lengths and shock lengths.


An RS or Cup shock is shorter than a stock shock and uses a shorter spring, there is still some adjustment at the perch which is mostly used for corner balance.

Some cars have free standing springs that are not under compression at full droop, there is a wider range of heights available here but again it's mostly used for corner balance adjustment.


The RS wheel carriers provide only 1 function on a lowered car, they return steering geometry to a place where bump steer is minimized.

I'll get out to my car in the next few days and measure the spindle height, perhaps someone can do the same w/ stock wheel carriers. It shouldn't be too difficult to measure the height difference between the axle center line and say the lower bolt, from this pic it appears that the lower bolt appears to line up fairly well w/ the bottom of the well that contains the abs ring


While we are waiting for someone to measure compare to this pic of a stock 993 wheel carrier, note where the lower bolt lines up

ScottMellor

So lots of variables here. I look forward to the answer.
I can say that with PSS9s and only switching to the RS uprights the ride was night and day different.

Bradford

I have always understood that the RS uprights primary function was to allow additional suspension travel on lowered cars to avoid bump steer (duh). How it would change the compliancy of the ride during normal driving, that I can't understand.

Yes, I would like to have this set-up

ScottMellor

Bump steer is a completely separate issue caused by the control arms not being at the optimum angle in a lowered car.
When we switched El Guapo to the RS uprights and control arms, according to Mike Schatz, the spindles are raised thus lowering the car and also allowing the spring length to be set back to whatever the more optimal length is , which made the compliance over bumps waaaay improved.
Ask Mike for the details because I'm sure I'm losing a lot in the translation.

Let's swap cars next time we get together and you can see what I mean.

ACEparts_com

Thanks for all the great replies! I'll be pressing ahead with this tweek very soon.

cavlino

My thanks as well to all the great information being shared here.

Bill Verburg

correct the only difference between RS and and normal wheel carrier is the steering arm, normal has a long arm w/ the tie rod on top, RS has a short arm w/ the tie rod below, the difference in length and location restores the tie rod geometry when the car is lowered byy moving the outer end of the tie rod wrt the inner end, there are a range of heights where the geometry is w/i a reasonable range, it is not a discreet change, at the ideal height bump steer is minimized but can never be eliminated, it would be as bad to use RS wheel carriers at normal ride height as it would be to use normal wheel carriers at lowered ride height.

I am sure what he said was lost in translation. It is the outer end of the tierod that is raised to return it to the original geometry at stock ride height. geometry meaning the height of the outer and inner tie rod ends wrt to each other

the spring perches can be put any where you want independent of the wheel carrier, moving the spring perches moves the chassis which moves the inner tie rod pivot, stock struts have a very limited range of motion for the perches in front and none in back where they use shims instead, aftermarket struts usually have a greater range of perch location and are of often shorter as well both change chassis height wrt the wheel carrier axle height. ie they change the height of the inner end of the tierod wrt the outer end

after inspecting the wheel carriers the spindle height(aka axle height) is the same, it's easiest to see when the arms are on a bench but you can line up the lower shock bolt w/ the abs wheel well, it is the same on both.

ACEparts_com

Well, uprights, wheel bearings (i'm assuming the RS items are the same as the TT items?), ABS sensors and screws are all ordered. It turns out my car already has the RS track rods on it.

I'm keen to feel the difference!

Mike J

What do the uprights cost these days? (just curious)...

ACEparts_com

Around £400 each so about $600.

I enquired about the COMPLETE TT'S' suspension kit - it's still available and contains over 75 parts including the uprights, shocks, anti roll bars etc... £5,000.

Bill Verburg

tt wheel carriers are the same as the normal aspirated street 993s and have the long arm
993.341.157(8).03 /L(/R)
these use the stock bent outer tierod

RS wheel carriers are the same as ttS, GT2, Cup, RSR and have the short arm
993.341.157(8).81 /L(/R)
these use the straight RS outer tirod

If you already had the RS trackrods(tie rods? ) then you should have the RS wheel carriers already
Just to be sure
993RS wheel carriers and outer tierods


on left RS on right n/a & tt


top n/a & tt tierod, bottom RS tierod

911PERVY

Maybe he just had the middle section of the track rod from the RS?

ACEparts_com

No, I have the whole track rod assembly. It actually works quite well when the car is lowered (the angles). They've been on the car for at least 6 years without trouble.

911PERVY

Its going to be so much better with the correct carriers then!