TurnNBurn

Well, I first saw them on Felix Law’s 4X on the front upper arms, where it was explained that it helps support the hood from caving in under the pressure of the air hitting these ultra lightweight bodies at speed up front.

So that was my first thought, as I mentioned above, since maybe the pressure on the rear wing might make it buckle in the rear, but then I saw the rear body post collars on Yugo’s car, and they look like they are well above the reach of those screws, so that’s where I Drew a blank.

Brian10811

iTrader: (4)

Yes those A sponsor guys get Ultra Ultra light bodies. Perhaps that is the case. Some even sand down the thickness to make ultra light. I saw it done for oval racing.

corallyman

iTrader: (101)

Ok, so here is my best and (last) guess to the long screws. Haha. I rewatched the video on my PC and not my phone this time, and those screws are no where near the body to help with deflection when the car is traveling in a straight line, but maybe when the car is moving into a hard sweeper, leaning into it, then maybe it helps at that point.

Car is going super sonic in a straight line and has soft suspension settings, it then turns into a hard left sweeper so the chassis and body lean to the outside which would be the right side. However the right suspension would then lean upward moving that screw in the rear upper arm up towards the body which is leaning downward. The goal would be to keep the light and flexible body off the carpet (digging in) and also off the rear tire, which can cause sudden unpredicted cornering. That's my best guess.

Steve

TurnNBurn

It kind of makes me wonder if any of this stuff will lead to a running change. I know there were quite a few things on the 4X Evo that eventually made its way into the Pro kit. I would be most interested to see if the additional post that Yugo had installed in the mid-rear makes its way into production.

dlruk

He qualified 7th at ETS this weekend which was good considering the field https://www.myrcm.ch/myrcm/report/en/49404/245157

Airwave

iTrader: (1)

What I love in this video is the setup. The roll centers are off this planet... "In the front we have 3mm and in the back 5mm" lol By the way I'm quite reassured because it comes close to the p4x pro setup...

TurnNBurn

What was also interesting (if I understood correctly) is that he put some anti-dive into the front end?

Johnny Wishbone

iTrader: (6)

I think I figured out the screws in the upper arms.

They are for supports to float the body, BUT, he was running front upper arms in the rear......so he was probably just using a set that he had previously installed in the front.

Mystery solved.

Johnny Wishbone

iTrader: (6)

Interesting shock settings for Micro Thalheimer from the ETS race.

Drilled the shock pistons to 4 X 1.1mm and reduced the overall shock length to 55mm rear and 53mm front. Also drilled the shock cap 1.1mm to get 0 rebound.

Take note that's overall shock length which seems to be easier to get consistent settings over trying to set gap from shock body to spring perch.

TurnNBurn

Which is interesting, considering that the front and rear upper arms are different part numbers... I was originally under the impression that they were all the same, similar to the pre 3-point rear armed 4X, but apparently not.

Is there REALLY a difference between the upper front/rear arms?

BigRon

iTrader: (22)

The fronts have more threading space for the pillow ball.

Airwave

iTrader: (1)

I don't have the impression that the rear upper arms are longer than in the box... Are you sure?

Yes they are different:

Johnny Wishbone

iTrader: (6)

If you look at the video you can see that the length from the roll bar mount to the end of the arm is longer than on the stock rear arm. That and I am pretty sure I either read or heard them say that they have been running the front upper arms in the rear of the car, just never put that information together. Not sure why other than more material for the ball stud to thread in? But I'm just guessing on that.

Airwave

iTrader: (1)

That's just that we can also see a lot of the ball stud thread... And the rear width was not excessive also... Honestly, I don't understand why they produce difference parts for front and rear, especially if drivers are using the front in the rear...

miller tyme

iTrader: (5)

Just to clear up and provide a little confirmation. A lot of us in the US are running front upper arms in the rear upper position. That is in everything from USGT thru Modified. There is no difference in them other than the length at the end to provide more support for the pivot ball threads when running a wider track width. As to why they just don't make them both the same, remember the US is the ONLY market on black carpet, the rest of the world runs a lot lower traction, and the narrower car rotates better when traction is low.