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How to cool down electric touring car rubber tires on carpet?

How to cool down electric touring car rubber tires on carpet?

Old 08-09-2010, 04:48 AM
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Default How to cool down electric touring car rubber tires on carpet?

Hi, I race indoors in the UK on a low/medium grip carpet track. My car is an Xray 009 with Sorex 28R tires.

Its summer here and i'm having strange handling issues and i've come to the conclusion that the heat is causing the problem and has been for some time. My car also has a lot of power, even with a 13.5 because of having a SP esc with the latest firmware which also exagerates the problem.

When I take out the front screws from the top deck (which you're not really supposed to do as per Xray manual on carpet) the car has horrendous snap oversteer on entry and mid corner, which is why i'm also sure tire temps have hit the roof, because it's no where near as bad in the winter. Even with all screws in barring the front post, the car is better but the problem is less. General setup changes to the car don't solve it, unless I stick on new tires that last 2 runs and then the snap returns!

My tire temps are - FrLeft 83F - FrRight 86F --- RrLeft 83F - RrRight 83F.
To me this seems too high for Sorex 28R tires. I want to stick with this tire, as a lot use it at my club and at the big events its the tire of choice. What setup changes would drastically cool the tires down, other than changing the tire to a higher temp version like 32Rs?
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Old 08-09-2010, 05:13 AM
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I don't think 80-90 Fahrenheit is at all hot for tyres.

What is your pre-race tyre prep routine? How does the handling develop during the race?

If tyre temperatures were the problem, I would expect the handling to get worse once the tyres get to racing temperature (ie a couple of minutes into the run), and be accompanied with squealing noises.

Your problem sounds more like a fundamental handling fault, probably an excessively soft front end. There is very little you can do with car setup to take temperature off the tyres, it has a lot more to do with the track conditions and the load you are putting through them from your fingers and thumbs.

Also, if you can't get 28R's to work, there is no point avoiding 32Rs. A tyre that works FOR YOU is always going to be faster than a tyre that doesn't work FOR YOU.
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Old 08-09-2010, 05:22 AM
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I think four things have the most effect on tyre temps. 1. Driving style 2. track conditions 3. Car balance 4. Cambers, but overal tyre temp should be the same

Anyway I also think that 86F tyres dont have nothing to do with your problems.
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Old 08-09-2010, 06:53 AM
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Softer springs=hotter tires
Harder springs=cooler tires

Try to use harder springs on all four corners.
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Old 08-09-2010, 07:00 AM
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Originally Posted by tomislav
Softer springs=hotter tires
Harder springs=cooler tires

Try to use harder springs on all four corners.
I think youve made an error there. Its the other way round surely?
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Old 08-09-2010, 07:06 AM
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Lol 85 degrees is not hot for tires on any surface.

I think you have to look at your setup or the track for reasons why your car is ill handling.

Plus I think sorex 28s are good for up to about 110 degrees or something around that.
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Old 08-09-2010, 07:08 AM
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With softer springs you get more weight transfer. With harder you get more slip. I think overal effect should be the same or hotter with harder suspension.
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Old 08-09-2010, 07:09 AM
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Originally Posted by sosidge
I don't think 80-90 Fahrenheit is at all hot for tyres.

What is your pre-race tyre prep routine? How does the handling develop during the race?

If tyre temperatures were the problem, I would expect the handling to get worse once the tyres get to racing temperature (ie a couple of minutes into the run), and be accompanied with squealing noises.

Your problem sounds more like a fundamental handling fault, probably an excessively soft front end. There is very little you can do with car setup to take temperature off the tyres, it has a lot more to do with the track conditions and the load you are putting through them from your fingers and thumbs.

Also, if you can't get 28R's to work, there is no point avoiding 32Rs. A tyre that works FOR YOU is always going to be faster than a tyre that doesn't work FOR YOU.
It does get worse during the run, thats for sure. As i've stated already, the setup is changed back and fourth and there is next to no difference. The front end is as per stock xray setup for carpet. 2.8fr/2.6r. I've tried 3.0 front springs and it seems worse. Probably even more nervous.

The things that I have found that does help are angling the rear camber links and standing up the shocks at the rear 1, as it stabilises the rear on entry, but no where near enough throughout the corner. I run 2 deg camber all over. I don't want to make myself seem arrogant, but I am a regular A finalist in a field of 60-80 drivers in the winter, so I know how to drive smoothly. I have been driving rc cars for almost 20 years on and off. The problem is that I could run 32R but there are events that state I have to run 28R and I really need to get the car dialled on the tire of choice.
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Old 08-09-2010, 07:10 AM
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Originally Posted by L@gger
With softer springs you get more weight transfer. With harder you get more slip. I think overal effect should be the same or hotter with harder suspension.
I agree entirely. I tried 2.6/2.4, instead of 2.8/2.6 and the overall handling was the same.
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Old 08-09-2010, 07:15 AM
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Originally Posted by L.Fairtrace
Lol 85 degrees is not hot for tires on any surface.

I think you have to look at your setup or the track for reasons why your car is ill handling.

Plus I think sorex 28s are good for up to about 110 degrees or something around that.
Ok, so tire temp is not the issue then


I asked the question, thinking temp could be the issue, but it looks like i'll have to reconsider wtf is going on. I can drive it as it is, but I just want the rear end to stay planted, so I can drive with another 50% confidence the car will go exactly where I need it to go. I actually like a slight oversteer handling car, but my problem is not general oversteer, its that dreaded snap that looses a lot of corner speed.
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Old 08-09-2010, 07:39 AM
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Are you using any additve?

When yes, It could be that there's a sticky mess on your tires, or the tires are getting sticky, and pick-up a lot of dust/hears/etc... Try a different one, and try not to let your tires dry up. Keep the tires wet all the time, untill you make them "dry" with a towel to go on the track.

When no... I think something is wrong with the set-up. 85 Deg's voor 28's is not hot, like all others say. It looks to me that you have to much steering. When you start at cold tires the car is "ok" and after a few laps the tires get warmed up, and you get more steering.... But that would not explain te flex setting you made...

Best Regards

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Old 08-09-2010, 07:40 AM
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Originally Posted by maxg123456
It does get worse during the run, thats for sure. As i've stated already, the setup is changed back and fourth and there is next to no difference. The front end is as per stock xray setup for carpet. 2.8fr/2.6r. I've tried 3.0 front springs and it seems worse. Probably even more nervous.

The things that I have found that does help are angling the rear camber links and standing up the shocks at the rear 1, as it stabilises the rear on entry, but no where near enough throughout the corner. I run 2 deg camber all over. I don't want to make myself seem arrogant, but I am a regular A finalist in a field of 60-80 drivers in the winter, so I know how to drive smoothly. I have been driving rc cars for almost 20 years on and off. The problem is that I could run 32R but there are events that state I have to run 28R and I really need to get the car dialled on the tire of choice.
But what are you doing with the tyres pre-race?

As for the snap oversteer, it's a common problem I have seen in the past with XRAYs. I'm going back to early T2s and 007s, when I used to race with a few people that chose them. Back then the cars components were too stiff and didn't generate any rear traction. I don't know if they've resolved that with the cars now.
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Old 08-09-2010, 07:54 AM
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Originally Posted by maxg123456
I think youve made an error there. Its the other way round surely?
You are correct, i'v made mistake, softer spring coller tire, harder spring hotter tire, so advice is to go on softer spring, not harder,
thanks for notice my mistake
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Old 08-09-2010, 08:00 AM
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Originally Posted by maxg123456
Ok, so tire temp is not the issue then


I asked the question, thinking temp could be the issue, but it looks like i'll have to reconsider wtf is going on. I can drive it as it is, but I just want the rear end to stay planted, so I can drive with another 50% confidence the car will go exactly where I need it to go. I actually like a slight oversteer handling car, but my problem is not general oversteer, its that dreaded snap that looses a lot of corner speed.
If you can't find a fix in the chassis, you can glue the front sidewalls with CA, it works, but you will need to reglue it every couple of runs. Many think it's a "hack" but it does work if you can't find another solution. You could also try a less aggressive body.
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Old 08-09-2010, 08:09 AM
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Originally Posted by Robert_K
Are you using any additve?

When yes, It could be that there's a sticky mess on your tires, or the tires are getting sticky, and pick-up a lot of dust/hears/etc... Try a different one, and try not to let your tires dry up. Keep the tires wet all the time, untill you make them "dry" with a towel to go on the track.

When no... I think something is wrong with the set-up. 85 Deg's voor 28's is not hot, like all others say. It looks to me that you have to much steering. When you start at cold tires the car is "ok" and after a few laps the tires get warmed up, and you get more steering.... But that would not explain te flex setting you made...

Best Regards

Robert
Hi,
thanks for the response. I use LRP carpet additive. I apply 15 mins before the race all round. I've also tried 20 mins rear, 5/10 front before the heat started and car was better but I find the cars handling issue is still there. 10% better, rather than a near cure.

The reason I mentioned the flex at the front, is because a few weeks ago, I thought I had the problem cured because before the final I decided to put all the front flex screws back in the front and the car was 10 times better. It had mild understeer believe it or not, instead of snap oversteer it had one heat earlier. This is also why I thought the front tires overheating was causing the strange handling. It seems I was wrong.
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