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How to determine the correct amount of rear toe-in?

How to determine the correct amount of rear toe-in?

Old 07-30-2015, 02:59 PM
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Default How to determine the correct amount of rear toe-in?

At this point I've been driving RCs for a couple years, and I have a basic grasp of how to tune the camber on all four wheels and the toe on the front wheels. But what about the rear wheels? I know they should always be toed-in, but how can I tell whether they should be toed-in 1 degree, or 2, or 3, or somewhere in between? What's the handling characteristic that is used to identify incorrect toe-in on the rear wheels?
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Old 07-30-2015, 03:23 PM
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Originally Posted by fyrstormer View Post
At this point I've been driving RCs for a couple years, and I have a basic grasp of how to tune the camber on all four wheels and the toe on the front wheels. But what about the rear wheels? I know they should always be toed-in, but how can I tell whether they should be toed-in 1 degree, or 2, or 3, or somewhere in between? What's the handling characteristic that is used to identify incorrect toe-in on the rear wheels?
More toe will plant the rear end during cornering and tends to square the car up faster on acceleration. You've usually gone too far if the car is is just too planted, you don't have enough if you have severe looseness mainly during exit acceleration.

Adjusting toe is of course balanced with the rest of the possible chassis adjustments. A small toe adjustment can have a large effect.
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Old 07-30-2015, 09:03 PM
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Would different rear toe settings affect handling during braking at all?

Also, what does "too planted" mean?
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Old 07-30-2015, 09:10 PM
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Originally Posted by fyrstormer View Post
Would different rear toe settings affect handling during braking at all?

Also, what does "too planted" mean?
doesn't want to turn/rotate sharply. rear toe really depends on driving style, class your driving in, grip levels etc..
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Old 07-31-2015, 12:50 AM
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It's always a compromise,
But if the grip is high and you get push on power under steer then try reducing rear toe,
If the grip is low and you get on power over steer then try adding toe,but the usual is between 2.5 and 3 dog in the UK,
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Old 07-31-2015, 01:08 AM
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So more rear toe-in biases the vehicle in favor of understeer? Does it add any stability during hard braking or does it make the rear of the vehicle more unstable because the rear wheels are fighting against each other?
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Old 07-31-2015, 01:16 AM
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the least you can go without spinning out...
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Old 07-31-2015, 02:37 AM
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More toe will assist under braking as well, from my experience at least. Reducing rear droop, stiffening the front suspension, and changing your weight distribution to more front bias can each also alleviate it so you don't have as much weight transfer under braking.

When I say too planted, I mean the car is past the point of feeling free in the corner and you end up scrubbing corner speed. It's a fine line between too loose and too tight, finding the point where your car is the fastest.

I said more toe would square the car up faster, that isn't the best description after thinking about it. It's more like the car will track straighter when under acceleration, so too much toe and you will lose the sweeping effect coming out of the corner.
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Old 07-31-2015, 08:46 AM
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Dude, just drive it and tune it to your liking. If your lap times get better, you're on the right track.

More rear toe gives better straight line tracking but takes away some of the speed. As explained above, cornering requires somewhat opposite settings, so you'll have to compromise somewhere. That is where your lap times come into play to hint you.
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Old 07-31-2015, 12:38 PM
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When I ask about precise measurements, people tell me to drive it by feel. When I tell people I drive my car by feel, they tell me I need precise measurements.

The car is nitro-powered, so its weight bias is somewhat towards the rear and there's nothing I can do about it except to add lead ballast to the front -- which is an option, but one I'd rather not take because it's already pretty heavy for such a small vehicle.

Thanks for clarifying what rear toe-in does. I had been compensating for oversteer in corners by toeing-out the front wheels, but that has the obvious problem of causing it to wander when it's supposed to be going straight. So now I know what else I can adjust to improve cornering without affecting straight-line performance as much.
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Old 07-31-2015, 02:03 PM
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Add in more tow out will make the car darty like you mentioned and will increase turn in, which can also cause oversteer.
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Old 08-01-2015, 11:13 AM
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Originally Posted by fyrstormer View Post
When I ask about precise measurements, people tell me to drive it by feel. When I tell people I drive my car by feel, they tell me I need precise measurements.

The car is nitro-powered, so its weight bias is somewhat towards the rear and there's nothing I can do about it except to add lead ballast to the front -- which is an option, but one I'd rather not take because it's already pretty heavy for such a small vehicle.

Thanks for clarifying what rear toe-in does. I had been compensating for oversteer in corners by toeing-out the front wheels, but that has the obvious problem of causing it to wander when it's supposed to be going straight. So now I know what else I can adjust to improve cornering without affecting straight-line performance as much.
Your question wasn't about precise measurements. To measure precisely you need a setup station, but that's not going to tell you what you need but rather what you have.

Your post suggests you might have some other problems though. Toe should be kept at a minimum because of its adverse effect on speed. Personally I run nearly no toe at the front
(maybe half a degree) and very little at the back (1.5 per side) and my cars go arrow straight.

We told you to decide by feel instead of giving you an exact value, because there isn't one good for everything and everybody. To set a certain value and measure it, use a station, there is no other way, but what value to use it's up to you to find out.

Like I said above: keep an eye on lap times.

Last edited by niznai; 08-02-2015 at 04:34 AM.
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Old 08-01-2015, 09:01 PM
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I don't race. The nearest tracks are an hour away in different directions. I suppose I could track speed via GPS runs, but...meh.

I just wanted to know how to decide whether each of my vehicles has enough rear toe-in. Thanks for the info.
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Old 08-02-2015, 05:40 AM
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It doesn't matter then.
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Old 08-02-2015, 06:55 AM
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If you neither race nor do speed runs, you probably just bash around on a parking lot or a street - in both cases setup doesn't mean all that much. As long as the car handles ok for you and you're having fun with it, you got all you need.

Only when you try to get the last bit of extra speed or need to lower your lap times, setup quickly gets really important.

Last edited by DirkW; 08-02-2015 at 07:57 AM.
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