XRAY - Model racing cars

Hello,

are the T4 shock pistons intended to have about 0.7-0.8mm of play in the shock body? I don't think so. Any explanations? I don't know the diameter of the old alu shock pistons right out of the head but I'am afraid that I got those old alu shock pistons included with my kit.

Hi,

I also noticed quiet some play of the pistons. I thought it might be intentionally to reduce friction?

No, normally shock pistons must not have play at all there. They should run smooth but this without any play. This play could lead to a travel stop of the shock shaft which a) destroys the shock and b) leads i.e. to curious traction rolling where you never would expect it.

Mine also had play, I was thinking that perhaps the pistons swell slightly once installed with the oil etc.

Skiddins

Maybe we'll get the answer here because I'm done with those T series shocks! Really. Since I run Xray, I just got 1 car which has great shocks and that's the XB9 ...

yes hopefully we can get some answers as to why theres a big play in the pistons and the shaft is wobbly.

Guys,

we spent a lot of time testing the shocks. I was testing on many different tracks on both carpet and asphalt and tried over 8 different alternatives of the pistons sizes. The goal was to find the best oil flow in the shocks to get the best balance between traction, stability and steering. What we found that works best, is what you have in hands.

Guys,

What is the reason why you are complaining about play between piston and shock body? do you have any particular problem with that? I am just curious and would like to know the reason why you are complaining and saying that you are "done with these shocks"

Thank you

I think it's just the way the piston seems to be very loose inside the shock body, there is a lot of play side to side when installed on the shaft.

It seems a bit strange that we have pistons with very small differences in hole sizes, yet by comparison a large gap around the outside (certainly a lot more than there used to be on the old alloy and plastic shocks)

Skiddins

P.S. I'm curious about it as well, but still think it's the best car I have ever owned so far

Skiddins,

regarding to play of the shaft, it is made by purpose as the shaft moves more smoothly through the orings and plastic shim and thanks to that it provides more traction.

Hello Martin,

thank you for coming in to this topic. The reason why I wrote "I'm done with these shocks" was that it's just not ok with these pistons IMO. No matter where you looking at, most of the other great companies include fully machined pistons or provide them as an option part. As an engineer you know that pistons have to match the cylinder in a perfect manner. There wouldn't be any reason for producing shock pistons for 10,- for two pieces if there's no need for it to say it different.

The shock parts itself are made in an awesome quality and also I have NO doubt about the Xray molds that really must be one of the best in the industry but this isn't what I'm complaining about. Also I'm not complaining about the bottom end play as this is just better than no or less play but if you would provide a perfect fitting piston, now that would make things better. Even just because the bottom play would lead to much less leaking with pistons without play than it actually does.

And perfect molds for perfect roundness help nothing if the noses are on the side of the pistons, so on their contact surface. And 0.7 to 0.8mm play is extreme.

If you want to stay with your idea of the pistons then please offer optional fully machinde pistons for your kits. There're so much option parts from Xray for several kits already so why not something that important like shock pistons as well? I wrote you the story with my Inferno 777 SP1 shock pistons and there was a huge difference between the fully machined ones and the stock non-SP ones that also were included due to the casting process.

Thank you for your time,

Stefan

well we never considered to make machined pistons as the demand would be not high. The competition provides CNC machined pistons as IMO they are not able to make the roudness with the molded part as we do. We pay attention to every small details on our molds and therefore we have the highest quality molds on the market. Every team driver is happy with the performance of our pistons. When we made prototype shocks and the mold for pistons was not ready, we used machined pistons. Then when the mold was ready, whole team was testing back to back the difference between molded and machined pistons and there was no difference at all. But to make our customers happy and satisfied, we can ask if there is any demand for machined pistons. If yes, we will make them, no problem.

As I explained the play was made by purpose to get optimal traction, steering and stability. If you are traction rolling very easy, than your car is too hard on dampening. Do u use standard shock settings? I drove last two races on super high traction and all other competition cars were traction rolling and I had no problem at all. The only what I changed was the front springs, instead of 2.7, I used 2.5 to make the car steer easier and to avoid traction roll.

I run it pretty much kit setup again, except for the 2000 cSt diff oil. With the ETS tyres I also set 3° of camber front and rear and O-rings (1) on the shocks. Maybe I'll switch the front and rear springs v.v.. The car itself is the fastest in corner speed, in corner steering and at corner exit from what I see together with the ...7. So I'm really very happy with the car itself. Just to point this out.

Maybe 3 degree camber is the problem. This gives you a lot of steering. I always use 1.5 in rear. Normally I use 1.5 also in front but if I want to gain more steering, I use 2 but no more than that. I found that the car has the best stability in high grip conditions and with ETS tires when I use 2.3-2.6 springs in both front and rear. But you can try to switch the springs, that would make the car easier as well.

Ok. Thanks. Actually it became better with the 3° camber around but I'll follow your suggestions next time when I switched the springs. I'll order springs and ARB for the T4 tomorrow (for generell purpose). As for the grip conditions, I mean if you walk over the carpet on our track you would almost get stuck to the driver stand's stairway. Does this maybe extend the usual meaning of super high grip? I don't know any other carpet that sticky I had been to.

wow, that must be really super high traction. I think you need to glue the sides of the front tires to eliminate traction roll. Also to lean down front and rear shocks by one hole compare to basic set up. I would use 2.3-2.6 in both front and rear and harder rear anti roll bar. I found also that when i put some extra weight under front bumper, it would make the car more stable and easier to drive. You can try that, I use 15g .

Martin, Im an xray user and fan. I used to own a T3r and now a T4. Thank you for your reply regarding the shocks that the pistons were intentionally designed to be loose around the body which will make the shaft wobbly but will result to more traction.