XRAY - Model racing cars

hi all i have a kinda strange question. How much difference do you guys think the transmitter makes to the way a car FEELS. I ask because i use a futaba 3vc on an FK and a fellow racer has a KO Esprit 2 on the same car and another racer has a cheaper sanwa on the same car and their cars feel very similar to each other yet mine feels much less responsive with less general grip all round even tho we all run the same setup. Im trying to find the cause of this as at the moment i think the car is not allowing me to be a quick as i could be. Any help would be appreciated with both the transmitter question or any suggestions as to why my car feels this way thanks in advance

Nathan

How do you have your transmitter setup? Is it because your running steering and throttle curves that are different to your friends?

This may sound even stranger, recently i was told that a very well known driver was having problems with his car. He couldn't work out what was wrong. He changed his reciever for another of the same type and the car was good again.
There was nothing wrong with the reciever (interferance etc) but he was much happier with the new reciever.
So maybe different equipment does give a different feel.

i havnt really played around with the curves so cant answer that at the moment but i will look into it. Will KO crystals work in a futaba reciever does anyone know as i will try the ko unit and see it there is any difference.

The transmitter and more importantly the speedo and servo can make a very real difference to the feel of the car. However the problem you describe points more to a setup/build problem as you indicate a lack of grip all round compared to your friends. If your problem only was a lack of responsiveness it could for instance be that your servo is too slow or even malfunctioning. In this case however it doesn't seem to be the cause. Easy check is to try your friends equipment in your car if you want to be sure.

Now assuming you have exactly the same setup, there are three areas I would look into:

1. Do a run with your friend´s tyres and have him/her clean them, apply the additive and dry them as they normally do. If you now have a responsive car with more grip the problem is in the tyres, inserts, wheels and/or cleaner & additive. This is the single most important area with regards to grip!

2. Do a run with your friend´s dampers on the car. Dampers are very important too. It is not just about which oil weight you use and how many holes are open, but also how much rebound you have, shock length and which type of oil (XRay oil or e.g. Orion oil) you use.

3. Make sure your suspension is truly free. When you drive a lot of force is put on the suspension which can result in the suspension binding while driving even if it feels ok when you check it on the workbench. Compare your suspension with that of your friends. For instance, do they have more play on the arms than you do?

I realized that after changing car setup options and finding the right setup of tires, shocks, gearing and weight distribution, I was able to tweak the transmitter settings to settle the car for each track type. The EXP and EPA settings are the most important to me. Here is what I found with my setup using my JR XS3 transmitter and the new RS310 receiver (that comes with the new JR XS3Pro which I did not want to pay for, so I ordered the receiver separately to cut down on weight and chassis mounting size):

1. Set the EXP initially using the long straight portion of the track. Run your car down the straight and make a few course corrections left & right as you go. At first, do this testing while standing at one end of the straight and at 75% throttle to make sure you don't destroy the car on the wall. If the car feels too twitchy, oversteers a lot and you find yourself letting off the gas to avoid hitting the wall or the car is slowing down too much, then you need to reduce your EXP setting to a negative number. Repeat this using incremental steps of -5 points on your EXP until you find a comfortable setting. As you get the setting more comfortable start going full throttle and then move to the drivers stand and tweak it some more if necessary.

2. Second, set the EPA for left and right SEPERATELY. Run your car through all of the tightest curves on the whole track and note what the rear end does mid-corner. If the rear end slides and causes you to oversteer too much, then reduce the EPA setting for the direction of the turn. If it was a left turn, then reduce the left EPA setting by -5 and vice versa for a right turn. One thing to note here is that if you can find a car setup that is near perfect, you should be able to set your EPA to the max for tight agressive steering and still have your rear end planted mid-corner. I've found this type of setup now by using the following rear setup options:
* Switched from 26mm 35 shore rear tires to 30mm 30 shore rear tires
* Switched from light blue rear springs to blue rear springs
* Switched from 30wt rear shock oil to 35wt
* Switched from rear upper shock position #4 to #3
* Switched from rear inner camber link position #1 to position #2 using new camber link studs that attach to rear shock tower (I also use 3mm shims on the outer camber link)
* Switched from 2 degree rear toe-in to 2.5 degrees

3. Fine-tune the EXP last. Go through the larger radius corners (sweepers and mid size corners) and note if you are able to put the car on multiple lines for corner entry curves at will. If you have to turn the transmitter wheel too much during corner entry and the car feels a little lazy to turn in, then increase the EXP setting by +2 and try again until you find a comfortable setting. If the car turns too sharply and you end up clipping the corner dots most of the time, then decrease the EXP setting by -2 and try again until you find a comfortable setting. This new EXP setting may conflict with what you found to be a comfortable EXP setting on the long straight test in #1 above. If it is a slight discomfort, then you should adjust your driving input on the transmitter wheel to compensate. I always tune the EXP for best comfort on the straight if the straight is not in front of the drivers stand and it is hard to gauge the distance from your car to the wall. If the straight is right in front of the stand, then I tune the EXP for best corner entry feel, since I can see the car down the straight and make corrections more easily. If the settings are too far apart to give you enough comfort for the straight AND corner entry, then I would suggest tuning the EXP for corner entry and changing one or more of the following settings on your car to gain stability down the straight:
* Decrease front toe by .5 degrees
* Add rear toe by .5 degrees
* Change body to a more stable neutral steering body
* Do not trim your bodies rear spoiler. Use its full height on the sides and back lip.

Today I set EPA to the max and EXP anywhere from -45 to -90. I use high negative EXP numbers to allow me to change lines more easily during any part of the corner for passing situations.

I always try to remember to repeat these transmitter tuning steps after every car setup change I make. However, I have forgotten to do this a few times and ended up chasing too many other setup changes to compensate before I remembered these steps.

There is a lot more to fine tuning the transmitter for other things, but these were the ones that greatly helped me in consistency and qualifying for the A mains instead of the B mains.

thanks for all the help guys. I have tried using their whells which didnt change the problem. The car is built very well (hey i cant drive em but i can build em ok lol) its the freest of all of them and all suspension is totally free ( i took an awful lot of time when building to make sure it was perfect. I havnt tried changing the shocks but i will try that as it is my least favorite job when building and im not too hot at that part of the build. I have tried 2 servos both very high quality and both new (airtronics 0.07secs and KO 0.06 secs) and also have tried 2 speedos (keyence extreme and lrp quantum 2) so dont think my problem lies there either but will definately try the shocks next time out.
Thanks again for all the help if you guys think of anything else to try it would be great.

Check the torque of the servo's tht your friends are using because if the torque of your servo is less this might be the problem. this sounds like a real puzzle.

Can you ask them if you can have a run with their car and see how you get on?

~Rebound of the shock might be the thing because it does make a bit of difference. just pop there shock bottom off and check how their's feels compared to yours