Grand Am APR cars have Passat OE Aluminum Upright?

[the bruce]

Also, is upright the same as spindles???

spindles = hubs = uprights

S3 = RS3 = Leon Cupra = Passat

From what i've gathered the geometry is the same. It just an unsprung mass reduction mod.

Almost the same. Alignment will stay the same.

Steering ratio is changed though. The Aluminium spindles have a shorter steering arm
which gives a noticable plus.

BTW, don't underestimate the improved cooling of the wheel bearings !!

the cast iron uprights are weak..

the aluminium ones are much stronger

True. That's one more reason why Volkswagen euse them on heavier cars (R36, Sharan).

 

[carsfeverguy]

BTW, don't underestimate the improved cooling of the wheel bearings !!

Is that due to the aluminium acting like a heat sink??

Steering ratio is changed though. The Aluminium spindles have a shorter steering arm
which gives a noticable plus.

Was reading up on steering ratios... Would that quicken the steering ratio or lower it?
Also, would it change the feel of the steering into being harder to turn, which is something I would definitely like more.

 

[the bruce]

Is that due to the aluminium acting like a heat sink??

Was reading up on steering ratios... Would that quicken the steering ratio or lower it?
Also, would it change the feel of the steering into being harder to turn, which is something I would definitely like more.

Yes, aluminium is the prefered material for heatsinks. Much better heat conducter compared to steel.
(copper is even better, but heavy and expensive)

And yes - steering will be slightly quicker. In conjunction with stiffer LCA bushes and top mounts this
is a noticable step forward.

 

[carsfeverguy]

Bruce, sorry to ask again, but by saying the steering will be quicker, does that mean that the steering ratio be slower, making the steering more direct?

 

[the bruce]

Of course more direct. You have to make (slightly) less turns on the (steering) wheel.

Just take some time and think about it. When the steering arm of the upright/knuckle
is short every movement of the rack and pinion causes a large amount of wheel turn.
If this steering arm is waaaaayyyyy longer every input has only few effect.

 

[carsfeverguy]

Thank you for the explanation, as always very helpful and informative.

 

[the bruce]

Of course, quicker. Otherwise it would be a disadvantage.

S4 knuckels have shortest steering arm, TT knuckels have longest
(TTs come with a different steering rack and have shorter wheel base):

Broken steel knuckel after one day at the German GP circuit in Hockenheim:

That's why APR recommend the stringer S3/Passat aluminium replacement !!

 

[carsfeverguy]

I think everyone is going to panic now that you posted that pic. :scared0016:

 

[APRMK6GTi]

I think everyone is going to panic now that you posted that pic. :scared0016:

i agree

 

[SRoads]

Will this work with Apikol brackets for Porsche boxier calipers???

Yes

 

[the bruce]

:23::23::23::23:

Hey, we don't know the exact circumstances. Possibly did he curb it once?
Did he overtorquen the bolt?
It's the first cracked GTI swivel I've seen. I did by far see many more failing
brake rotors, wheels and tires !!

On the other hand - the lighter Passat/S3 hub is stronger. Another point:
If even an OE hub can crack, should I trust an aftermarket hub developed
with less than 1/1000th the engineering capacity Volkswagen has?

 

[carsfeverguy]

Bruce,
may need your input on this one.

As far as ball joints go, should I use the ones already on the car? how about the wheel bearings? Should I get them transferred from my iron uprights to the aluminium ones? or should I go for new ones???

Also, why is the GTI ball joint(1K0407366C & 1K0407365C) as listed on ECS Tuning different than the Passat Ball Joint( 3C0407365A & 3C0407365B)... Is one heavier duty? If the Passat ones are heavier duty, would the FEBI brand be ok (part of bilstein I think)

 

[the bruce]

When I fitted the S3 knuckels I transferred the bearings from the old iron to the
aluminium ones, but with new ball joints as these are cheap. Sadly I missed to
compare them, but both do fit both alloy and steel arms and swivels.
Just TT arms need their own specific ball joints.
If you want new one I'd get Passat ones though. Have them compared to the
old ones and let us know the difference if there is any.

Currently Febi-Bilstein isn't related to Bilstein which is a Thyssen-Krupp company.

http://www.febi.com/febius/home.html

http://www.bilstein.de/en/home/

 

[Talguy]

Hey Bruce, what is your take on milling down the brake mounting points on the passat spindle so that I can transfer my BBK for my GTI to those spindles.

 

[carsfeverguy]

First of , the bracket has to sit in front of the spindle when bolted. If it sits at the back of the spindle, than that BBK design will not work with these spindles, since the spindles attachment points are wider, and it will throw off the fit of the caliper.

Now, if you have a bbk that fits in the front of the spindle, the shaving will depend on the particular bracket used. It would be minimal I believe, and the passat spindles do have a pointy edge, guessing from the forming mold process.

Will let you know when I mount mine.