View Full Version : Sworkz S104 Evo High Grip Chassis Tuning

12-11-2015, 04:27 PM
Please note, the following write up is based on my own personal findings. I have done this write up as so if someone else is find the same issues as myself, then this my be of use to you.

After racing the car a good number of times now on high grip tracks, I thought I would do a write up of what my personal findings are as regards to the handling of the car on high grip. The first thing I found was that the car wanted to shift alot of it's weight to the rear when coming out of the corner on power while trying to steer, this would cause the inside front wheel to lift and the weight transfer to the rear outside wheel. This really unsettled the car and made it hard to drive. So after trying everything setup wise 'that would normally stop this happening' it would still do it. I modified a centre drive shaft as so I could use a slipper clutch, while this helped somewhat, the issue was still there. I tried heavy roll bars, Roll centre changes ,shock pistons & oil, anti squat & kick up, slipper clutch/centre diff with light oil and Yatabe heavy purple springs! nothing seemed to work for me. So, I started to look at the suspension geometry and compare it to other 10th off road car, and what I found was that the Sworkz has ultra long arms 'inner to outer hinge pin pivot points' compared to other 10th cars, not only that, but the shock mounting holes on the arms are almost central on the arms. To me, this explains why the weight transfer happens so easily, as there is to much leverage on the arm. So I made some changes, I drilled one more outer hole on both the front and rear arms and took to the track. The car now cornered flatter and the weight transfer happened much later. But the feedback the car was telling me on the track was that the Yatabe Purple springs are still to soft for the 104's suspension geometry! so I looked for even stiffer springs for both the front and rear. For the front I got Durango Purple 4.20lb - light brown 4.52lb - olive green 4.82lb, for the rear TLR Red 2.6 - Orange 2.9 - Silver 3.4.

I put the Durango light brown on the front and the TLR Orange on the rear and went back on the track. WOW! what a difference! The car stayed flatter but most importantly the squatting problem was almost gone! The car now had a better steering feel, and had more on power steering as the weight was now more evenly distributed. Even with the stiffer springs the car was better at jumping and landing, there wasn't much change with bump handing compered to when on softer springs. I then went to lighter roll bars and the grip in the corners felt more constant. I was able to go 1.5 seconds a lap faster now, and I felt like there was still room for more fine tuning.

My next race with the car was on a flat, very high grip, tight track. I changed the rear spring to the TLR Silver and the car was really good. I feel the stiffer springs have 'woken' the car up, given it more overall grip and now I can push the car harder. On the bench the car doesn't feel over sprung but feels right!

Below I have listed photos of mods I have done to the car to gain more stability and balance to the car. I will also be running the car on low grip tracks, but from what the car feels like on track, I don't think I will need to make to many changes to get the car to work on slippy. For me, I truly think the car needs a far higher shock spring setup than what we would normally run on most other 10th buggies.

Video, TQ and win: https://www.youtube.com/watch?v=SVs9lku8__I

Basic set up:
Front 1.4x2 pistons 'glued and re drilled kit piston', Durango light brown spring, 500cst oil, new outer hole on arm.

Rear 1.5x2 piston, TLR orange spring or Silver if really high grip, 350cst oil, new outer hole on arm.

Diffs: Front- 15k Centre- slipper clutch/or 30k Rear- 4k

Roll Bars: front 1.5 Rear 1.6

Front arms have had 2mm removed from the front of them to move them forward. You will need to also put 2mm shim behind the ball stud on the steering rack and 2mm spacers behind the shock stand off.

In the kit you should have the RTR plastic steering plates, trim off the ribbing from them and fit them under the carbon fibre ones, this gives better strength and removes bump steer.

Remove 2mm from the rear of the rear arms, this is to give a longer wheelbase, more stability.

New outer hole on front arm, drilled as so there is no change in droop from middle to outer hole.

New outer hole on rear arm, you will need to unwind the shock end to gain the correct amount of droop. You will need to add an up travel limiter on the shaft to stop the drive shaft from over extension into the drive cups.

Chassis layout. I have found that running the motor forward, with the speedo at the rear, but with shorty battery, gives a better front to rear, side to side weight balance. you can now add weight down the centre of the chassis, to give the desired front to rear weight percentage. You will have the drill two counter sunk hole on the chassis to be able to fit the battery on the left side.

Extra chassis flex by removing the ribbing from the top deck.

servo linkage setup. setting up the steering bell crank on the same side as the servo horn, makes removal of the centre diff much easier.