XRAY - Model racing cars

Me and my friend have been away from RC for over 12yrs, and recently we purchased T2 009 EU and start picking up the hobby again.

We had no experience driving a front spool, and the last weekend, we tested drive our cars at a LRT (about 50mX20m Asphalt) and both of us found out that a front spool is on-power understeer.
This is what happen at the track..............When we ran into the big ramp after the straight way, our cars feel being push away from the corner and ran wide ---> Full throttle on straight, about 3/4 throttle around the BIG ramp. In the in-field, it is more an intermediate course. Basically, we found that front spool: corner entry - understeer, mid-corner - understeer, corner exit - normal.

There are more steering when off-power and initial throttle (corner exit). For me, I don't think it is oversteer when off-power and initial throttle , but just the right amount of steering, maybe just for my driving styles.

After the day, I was checking out solution to fix this on-power (corner entry / mid corner) understeering issue and am confused with this....... on page. 38 of the Setup book v.2, "Front Full-Time Solid Axle"


"Best used when: there is low-medium traction, and the leans towads off-power oversteer and/or the track requies braking for the coners. Using this axle gives less off power steering and efficiency (less runtime). Best suited to an aggressive driving style"

Q1: I am a bit confused with this, so..... solid front axle give MORE off-power steering or LESS off-power steering??

Q2: Do you feel more or less the same with a front spool....this is understeer into turns when on-power where you carry some sort of speed but more steering when off-power or initial throttle"?? Or is it just my driving style?

Q3: I am thinking of getting back to a front diff in order to solve the above. I know that there are 2 diffs, the Multi Diff and a regular Diff (the one on the rear). The Multi Diff requires to run with 52mm driveshaft/wishbone and the Regular Diff runs with 50mm driveshaft/wishbone. Both of these diff will fit the front? Is this correct?

Q4: Any suggestion on how to set it up into more steer-able without changing back to diff?

I want a smooth driving car, which is stable while giving enough edge to turn into corners.

Thank you guys.

I had the same issue. I switched to the front diff and my car feels much better balanced now. I do run on a very small parking lot track though. What is the size of your track?

I too run '009' and im no expert but i feel the spool gives more grip off power and tends to understeer on power the way i got this under control was to use a high front end grip shell and to make changes to my setup. The car will be easier to drive and control with a diff but will be slower, after switching from a diff to a spool my lap was 2 sec's quicker
so answers to your questions...
Q1 Front full time solid axle is a spool so gives you 4wd brake so you have less off power steering (ie Front one way gives maxium off power steering, Front solid one way axle gives good off power steering)

Q2 As above front full time soild axle and spool are the same and yes it will feel the same

Q3 Multi diff will run on 50mm (50mm is what is in the 006) and i guess it will run on 52mm all you need is the c clips to go on the end of the drive shafts..XR305240 or XR305241

Yes I was referring to the Quicksaver. Position is 5 is fully extended, ie less Ackermann. I think the Instruction manual recommends position 3 to start with (sorry I do not have the manual with me.) My plastic cap is set as per the Instruction Manual, which I am sure is with the tip facing to the front. I will check the car tomorrow and if different will let you know. The Setup manual has a good section on Ackermann which you will benefit from reading. Good luck!

Thank you once again, Peter~!!! You are such a great help:D

My car now goes wherever I want it to go, I can drive it comfortably!! Here is what I did, one after one.

1. Play with the weight balance for a while. I have my car balanced at home with balance tools - 10g to the front of the battery and 40g to the back of the battery, it was perfect on the balancing tool. But on the track it can't go straight and I have larger right turns. So I take some of the g off, now, 10g to the front and 20g to the back. It goes straight and left and right turn is pretty much the same (setting in radio is the same), but the car is not balanced on the balancing tools. I assume it only measure the car is in balance in still motion, but can't reflect reality. i.e. motor spinning and drive belt spinning, etc.

2. Changed quick saver position from No.2 to No.4. It feels totally different in cornering, more steering now at corner entry and smooth in mid corner and corner exit, but still not enough, I think there are still room to be improved.

3. Reduced front track width to 1.15mm. Yes, much more steering, but a bit nervous, so I change it to 1.3mm and it feels stable yet more steering. Hence, I have to look elsewhere to increase steering.

4. Reduced wheel base, less stable.

5. Fine tuned ackermann angle on the steer block, I moved it forward. I don't like it, so I moved it back to the original place.

The car was good enough to run for the night. So that's about it for lastnight. Next weekend, I will play around more with the ackermann (ie. No3. hole and forward steer block hole) chasis flex, and roll center links.

Hopefully, I can find myself a comfortable setting and start setup my 1:12 soon, to train my fingers.