RTA bushed OEM vs Harder placements.?!

[jesse888]

Reviving this thread as I'm about to start building an EK9 track car and I'm considering what to do with the suspesnsion setup, I had been swaying toward the idea of a complete hardrace pillow ball setup incorporating adjustable camber and toe arms to make the most balls out hardcore setup I can, allowing a precise geometry setup and adjustability.. Then I read this thread! Would the toe in effect you get under braking with OEM RTA bushes be as beneficial on an EK9 with significant downforce? I'm thinking downforce would increase braking stability quite a lot in itself and could mean this toe in effect is less beneficial/necessary?

Can anyone with track car experience comment?

Before my current ek9 I would have said always use oem for the rta, now I've got one with the hardrace rubber bush in and I can't tell any difference tbh. I'm also considering the pillow ball set up on my track car. Hoping the solid bearings are going to help the "feel" I get through the suspension as to what each tyre is doing.
You can always add some toe in on the rear to compensate if you really don't like it?

 

[Trondelond]

I used a pillow ball RTA setup on my Del Sol, and it caused all sorts of oversteer. In addition, the rear end wanted to race the front end during braking from 60+mph. Not sure how much aerodynamics would help though. But I'd at least go for some poly units, to let the rear have a tiny bit of toe-in. Even if it's a track car, doesn't HAVE tro try to kill you all the time! Besides, it would let you focus on other things than not dying during brake-in.

 

[Kozy]

I used Energy Suspension RTA bushes in my EK4. Initially I thought what I think everyone probably does. "Wow, the rear end feels so tight!"

After a few autotest events though, I began to realise it was actually harder to enter corners hard on the brakes as the back end wanted to step out more. This was further exacerbated when I fitted front 282s without upgrading the rears. The increased front bias meant the rears were doing less work, less work meant less pull on the RTA, which reduced the toe in even more.

On top of that, the reduced rear brake effort also reduced the anti-lift effect from the rear suspension (see how it squats down if you try to pull away with the handbrake on, that's the anti-lift effect in action), which then increased the camber loss as the rear end lifted more under braking.

The combined effect was then more toe out and less camber at the rear than I had as stock when trailbraking. It's not a good set up, at all. You can try and tune it out with the dampers, but it's putting a sticking plaster on a bullet wound.

For once that's not just me spouting rhetoric either, I did it and it really was crap.

 

[NLek]

I can hit my brakes as hard as I want at 200km/h with no hands on the steering wheel and the car gives no crimp, also the car feels very confident under trial braking. I'm using the beefier OEM RTA bushings that can be found on MG ZS:

Left Type R (which is just the same as 1.4 city model)/ right MG: