XRAY - Model racing cars

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 Post subject: Understeer
PostPosted: Tue Feb 03, 2015 22:16:50 
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Joined: Mon Jul 11, 2011 17:29:00
Posts: 11
I'not a very experienced driver and I have the problem that my X12 understeers. Both, at high speed when entering a corner and also on power when exiting a corner. The setup should be ok, as described in many of the published setups. Tires are pink rear and magenta front. Is something wrong with my driving technique? I was in particular wondering, whether people break before a corner or whether they just steer and let the car brake by pushing? Any suggestions?

I was also wondering, what the effect of the main damper and spring is. What happens if I make them harder or softer? on power at the exit of the corner and while braking? There is a lot of information on the side and front springs and damper and people seem to be consistent in their opinions, but for the main damper everybody seems to write something different.


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 Post subject: Re: Understeer
PostPosted: Mon Feb 09, 2015 14:57:59 
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team driver
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Joined: Mon Nov 18, 2013 11:37:46
Posts: 73
Hi,

have you tried one of the set ups from the xray site? Either mine or Alex's will be a good start point.

When you say understeer do you mean a lot or only a small amount?

A stiffer centre spring i find gives more steering on entry to a corner.

What additive do you use? And what coverage do you give front tyre?

cheers
Oj


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 Post subject: Re: Understeer
PostPosted: Tue Feb 10, 2015 19:39:29 
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Joined: Mon Jul 11, 2011 17:29:00
Posts: 11
Hi Olly

I tried CS High Grip and Speedtech RC Foam Liquid. Both are often used around here. I cover half of the front tire (and the entire rear tire). The car understeers a lot when entering the corner. It also pushes on power out of the corner, but not so badly. The motor is 10.5T boosted.

I started from the Basic Setup, tried also some minor changes I have seen in the setups of the Team Drivers. Everything pretty much standard, no weird settings. What I have not done so far is gluing some of the holes in the shock piston.

I might however have found a problem. I set camber with the setup system to 1.5°, but the front tires wear in a conical form quite a bit. When I measure camber at the wheels, it is much less, due to some play in the front suspension. I now set it to 1.5° measured at the wheel and I will try what impact this has. How do you usually measure camber?

I was just wondering about the driving technique of the experts, do you use the brake a lot? Or do you just steer and let the car slow down that way?

Thanks a lot!


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 Post subject: Re: Understeer
PostPosted: Wed Feb 11, 2015 11:22:35 
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team driver
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Joined: Mon Nov 18, 2013 11:37:46
Posts: 73
Hey,

I always set camber so tyre wears flat, i will set camber to 1 or 1.5 and just adjust it by eye rather than using a station. If after a run one tyre isnt flat i will adjust it by small amounts until its flat.

I usually use a camber gauge against wheel for intial setting, with foam tyre and the play in the front end a set up wheel sits differently on the board which is why i don't use it.

I tend to use some brakes to help car turn but you should be able to make car turn without.

do you run inline battery or across chassis?

Cheers
Oj


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 Post subject: Re: Understeer
PostPosted: Sat Feb 14, 2015 01:33:38 
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Joined: Mon Jul 11, 2011 17:29:00
Posts: 11
Hi
The battery is across the Chassis.
I copied one of your Setups and I got the Camber right. That helped, it's much better, but I'm not there yet. Particularly when the car goes fast, at the end of the straight, it doesn't have much steering. It looks to me that the body I'm using has much more downforce at the rear, could that have so much influence?
I also saw, that other cars sometime tip over in a corner. That never happens to me (of course that's a good thing), but that shows that grip at the front is not so brilliant.


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 Post subject: Re: Understeer
PostPosted: Mon Feb 16, 2015 11:15:06 
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team driver
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Joined: Mon Nov 18, 2013 11:37:46
Posts: 73
Hey,

good to hear it was better. :)

what body do you use?

Also what size tyre? Sometimes too small gives less high speed steering as it compresses onto wheel rim.

what make of tyre is it?

Regards
Olly


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 Post subject: Re: Understeer
PostPosted: Thu Apr 02, 2015 19:29:42 
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Joined: Mon Jul 11, 2011 17:29:00
Posts: 11
Hi
Thanks a lot for your all your advice! In the meantime I tried a few things, including another body with less rear downforce, that also helped. When I treated more surface (3/4) of the front tire, I actually got too much grip in the front. It seems very difficult to get every detail right. If not everything is perfect, the car is difficult to drive. I guess I just have to practice, practice and practice...


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 Post subject: Re: Understeer
PostPosted: Fri Aug 07, 2015 23:25:03 
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Joined: Mon Jul 11, 2011 17:29:00
Posts: 11
Hi Olly

One more question... how much maximum steering angle do you have (outside wheel) on a average track (including some tight bends)? Or alternatively, what is the steering cycle (how do you measure, outside wheel to outside wheel, mid car to mid car or inner wheel to inner wheel?)?

Doe anybody know, how much slipping angel a typical foam front tire has at maximum lateral traction?

Carlos


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 Post subject: Re: Understeer
PostPosted: Fri Sep 25, 2015 15:21:40 
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team driver
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Joined: Mon Nov 18, 2013 11:37:46
Posts: 73
Hey,

I don't measure the exact angle but i always run maximum lock on my transmitter. Set your end points so the inside wheel is turning as much as possible without touching the steering link.

Cheers


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