Originally Posted by
Mirko
I'm not allowed to post URL's. 
Hi Paul,
thank you for the link to the article about the Front End. I really enjoyed reading it. It’s very well written from a passionate racer and gave me some good hints.
Nonetheless, when it comes to the 2 degrees steering knuckles the description of the way they are mounted is a bit confusing.
I don’t understand what's meant by: “leans the kingpin into the car”.
If the top end of the King Pin would be kicked outboard the Rollcentre high increased. This would confirm the described driving experience.
I did some rough measurements and a bit off fooling around with CAD. The basic dimensions are:
Front Tire diameter: 41mm
Ground Clearance: 3,5mm
Camber: 1,5deg
Front Axle Wide: 172mm
Recative Caster Block: 0deg
Reactive Caster Block spaced 2mm inboard (short Asso 5.1 Frontbrace)
The green lines show the basic condition of my Asso R5.2. The pink lines show the top of the King Pin kicked 2 degrees outboard. With 1,5 degree camber the King Pin angle is +0,5 degree to Z. On the contrary the blue lines represent the top of the King Pin been kicked 2 degrees inboard. It leads to a King Pin angle of -3,5 degrees towards Z.
Attachment 1139432
Rollcentre height standard: 8,6mm
Rollcentre height King Pin 2deg outboard (+0,5deg): 12,9mm
Rollcentre height King Pin 2deg inboard (-3,5deg): 4,3mm
The values might not be 100 percent correct because of the rough measuring I did, bit it gives a good impression of what happens. The change in the static Rollcentre height appears to be quite drastic. It might advantageously to get hold of the 1deg and 2deg Steering Knuckle to raise the Rollcentre on high grip Tracks.
There were some more spots in the article I’d like to quote.
Maybe the front holes are intended for 1/12 while the rear holes are fitting the geometry on 1/10 pancars (World GT).
Nice to know, because the whole axle isn't to expensive.
I can confirm that my fella Chris and I also experienced collapsing of the AE front springs after a view races. We measure the length from time to time and they become shorter. A pair of AE 0.022 springs I bought had 2 different lengths just out of the bag. I tried to pull them to the same length but it wasn’t possible. So I did not use them because they would have tweaked the car.
Maybe it’s worth getting the parts #4693 and #4694 of the R5.1 Lipo Kit. Would they fit on the R5.2?
Hi Mirko
Regarding the steering arm inserts, the handling change is more to do with the way the tyre is presented to the track, than the change in roll centres.
If you imagine a theoretical kingpin with 2 degrees negative camber and 2 degrees castor, with the standard steering arm the axle is always at 90 degrees to the kingpin. With the wheels straight you have 2 degrees negative camber at the wheel. Turn the outside wheel through 90 degrees (exaggerated to make a point) and it will give 2 degrees negative camber at the wheel again. The inside wheel turned through 90 degrees will have 2 degreed positive camber.
Now, fit a steering arm with 2 degrees built in postive camber. To have 2 degrees negative at the wheel, the kingpin is now inclined at 4 degrees. Turn the outside wheel as before, and the tyre is flat on the track at zero degrees. Hence loads of mid corner steering from the loaded wheel. The inside wheel is now at 4 degrees postive running lightly on it's outside edge.
As I said its exaggerated to highlight the point. In practice, we run 2 to 2 1/2 degrees negative camber on the wheel to keep them wearing flat. This also makes the car less twitchy as initially you have a smaller contact patch on the track. On turn in, you ramp up onto a fuller contact patch on the loaded wheel than on a standard steering arm, which gives the good mid corner grip.
One extra not for everyone. The front end on my car has stayed perfectly true and slop free through 2 National weekend and nunerous club nights. This includes 3 head on collisons with solid objects that have twice left the pod seperated from the chassis, and once delaminated the chassis. I was unlucky each time to find the only solid bits on the track. Only spent £3 in spares to fix the broken bits though.
