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Old 05-06-2002, 11:17 AM   #16
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also if you have to crank the steering and the car is pushing, you are scrubbing off a lot of speed in the corner, you want to take the corner at a speed that your car will turn with mininal steering input and keep that speed through the turn
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Old 05-06-2002, 09:09 PM   #17
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Quote:
Originally posted by linger


Iso Octane - everyone has a different driving style and I tend to disagree with yours. If your car is understeering and you crank the steering even more, all you do is wear down the front tires faster. That in turn will give you less and less steering over time as the front tires get prematurely worn.
Yeah, that is quite true. I really don't know how to drive with understeer, because imo the point at which the car is exceeding it's limit of adhesion is not quite as pronounced (or dramatic). The change to understeer is too progressive, imo.

And with oversteer, there's the false sense of security that you have more steering if needed, and you can use the application of throttle to balance oversteer, which gives the false sense of more speed.

lol, i'm just dillusional
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Old 05-08-2002, 11:46 AM   #18
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Hi there smash123,

you probaly don't have the set-up book of Martin Crisp?
If you want to go fast get yourself the book it's worth
every dollar.I eas struggling my ass off to get faster
lap times until I got the set-up book and started working
from there I am consistently faster.You won't be dissapointed.
Visit www.mpowered-racing.com

Good luck
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Old 05-08-2002, 12:39 PM   #19
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JacoSA is correct, the mpowered chassis setup guide is very helpful, it will definitely come in handy if you want to get the most out of your car.

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Old 05-08-2002, 05:22 PM   #20
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Thanks for all reply.

I will take a look setup book.

I know less steering throw = faster concer speed. So, this week at Socal, I use 70% steering throw on my xxx-s and shorter rear camber linkage(inner second hole), higher rear ride high and softer front spring(green). harder on rear(purple). Concer speed improved but still can't go as fast as pro guy. Can't still figure out how they can make turn so tigh while carrrying a lot speed. And as usual, before turn I let off throttle or leave some power then turn slow and little steering to prepare get in while holding little power and more through out the turn.
I see my car rotute when turning. That is good, my car can point to the exit of a turn. So, I can shoot out earlier.
I believe this is not my driving skill that don't allow me to make fast tigh turn. It is my car can't do it. Acutally, my car is fairly fast in Socal but still no match with pro guy. And I'm using the cheapest SHM. Welcome any suggestion. Thanks
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Old 05-08-2002, 09:59 PM   #21
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Default Getting more corner speed

Hi Smash123,

I received a few orders for my mPowered-Racing Chassis Setup guide from people that linked to my site from this thread. So I thought I would check out this thread. Thanks by the way for mentioning my book here.

Without knowing your setup it is difficult to know exactly how to get more corner speed out of your car. But having said that here are some general rules of thumb on how to help you get some more corner speed.

If you are not using a front one-way on your car and the "pro guy" is then this is likely the major reason you are not getting the corner speed that "pro guy" is. Front one-ways are difficult to drive as the make the car more loose, but the make a huge difference in the corner speed and corner exit sped of your car.

In addition to a front one-way there are a number of things you can do to give you more corner speed. After reading some of this thread it sounds like you are looking for more "on-power" steering. To achieve this you want to keep more of the car's weight over the front wheels. Chassis setup is all about distributing the right amount of the existing weight of the car to the tires that needs the most grip to achieve the balance you are looking for. So if you need more on-power steering then you need to change the chassis setup so that more of the existing weight of the car is kept over the front wheels while you are corning. This can be achieved by either stiffening the rear end of your car or reducing how much the front of your car lifts up while accelerating. Yes you can also soften the front as well, but since this is an on-power situation changes to the rear stiffness will have a more significant impact on the handling than softening the front. To stiffen the rear you should likely start with stiffer springs or stand up your rear shocks more. You could also raise the rear roll center but I would start with the springs. However if you make the rear of the car too stiff this will create an off-power oversteer situation.

As mentioned above the other way to keep more weight over the front wheels is to reduce the amount the front of the car lifts up while accelerating. You can use the droop screws on the XXXS to do this. The droop screws limit the travel of the lower "A" arms which will in-turn limit the amount the front lifts up under acceleration. Tighten down the droop screws until you have about 1mm of "up-travel" as a starting point. "Up-travel" is the distance the chassis moves up before the wheels come off the ground when you lift the chassis up. I like to use a ride height gauge to measure this. The more front up-travel you have in the front the more your car will push. The less front up-travel you have the less your car will push.

I hope this helps.


Last edited by mcrisp; 05-09-2002 at 02:21 PM.
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Old 05-09-2002, 03:53 AM   #22
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Also be aware that if your rear end isn't properly set-up then limiting front droop will compound your problem. If your rear end is set too soft and then you limit the front up travel the weight will transfer so quickly that the car will actually lift the front tires off the track surface and worsen your understeer problem. you could try 5-10 weight heavier oil in the back shocks, or even small spacers on the rear shock shafts outside the bodies, either one of these options will also help to keep the weight from transfering as quickly, but would be more suttle than front droop.



I know it sounds goofy, but when I am triing to figure out what changes I need to make or what a particular change will do I always think of how it would effect the suspension of a T-Maxx....... really!!!... the big heavy truck has so much suspension travel and reacts so slowly that you actually have time to see what the suspension is doing, so you can actually imagine what is happening. You can actually see how if you brake and turn right at the same time how most of the weight of the car is transferred onto the right front tire, and if you accelerate while turning right then most of the weight is transferred to the left rear tire with the left front and right rear getting about the same amount of weight while the right front actually wants to leave the ground it has so little weight on it. Just think about it!!!!!!!
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Old 05-09-2002, 01:42 PM   #23
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OK Impact and Martin-

Taking what you have said, what would you do if your car is rotating through the turn very well, but still has a slight push on entry and some oversteer on exit? The turn-in isn't quite as responsive as I think it should be and the car will "kick" the rear end as I (smoothly) increase from approx. 40% throttle to full throttle on exit.

The car is drivable as it is, and I might be mistaking a very fast set-up for an exit oversteer, I don't know.... In fact, the car has won every club race I've entered with it so far this year

The car has double oneways and I thought about loosening the rear diff a little to help correct it, but I hate to remove power to adjust a traction problem. I'm a big believer in adjusting to fix the end of the car that has a traction problem, not the end that doesn't to make the car balanced. It's sorta like when a car has waaay to much steering- why take away front traction to fix the problem when what you need is MORE rear traction to match the front?

Does any of this make sense? LOL
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Old 05-09-2002, 02:12 PM   #24
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After running schumacher cars for almost two years ( I now runa tc3),one adjustment can have the most impact...DROOP. Before You change a spring or oil, you should try the droop adjustment. Most racers don't realize that getting more or less steering (or traction for that matter) requires slight tweaking. Barring a whole new venue that you have never raced at before. Droop rocks. My 2 cents--Al
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Old 05-09-2002, 02:17 PM   #25
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Hi BigDogRacing

To help with the corner exit oversteer you could try increasing the front up-travel by 1mm increments until you get the balance you want.

In terms of getting more steering at corner entry you could also increase the rear up-travel by 1mm increments until you get the balance you want. In addition you could reduce the front caster to give you more initial turn-in. This reduction in caster will also give you less steering mid corner and corner exit.

Both of these suggestions will allow you to control the weight transfer more with the throttle.

Assuming your car is well balanced mid corner in general, I would not suggest any spring changes.
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Old 05-09-2002, 04:32 PM   #26
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OR you could try adjusting your front toe.

Toe-in will decrease your steering going into a turn and increase your steering coming out, while toe-out will increase your turn in and decrease your steering coming off the turn. This is all on the front.

I say this because you mention that your car seems to understeer going into the turns and oversteer coming off, so I am assuming you are using toe-in, try going to 0 deg. toe and maybe even try 1-2 deg. toe-out.

Not to step on anyones toes, but once people started having the option of setting droop alot of people jump to droop settings before they try anything else. Remember droop is an important part of the set-up, but I find it way too easy to really mess up the set-up by triing to adjust too much with those 4 little screws.... Many times when you are asking set-up advice people automatically say add/ remove droop, well I have never.... and I do mean NEVER seen a car that either end requires more than 2mm over what the other end uses.

What I am triing to say is hypothetically----

If the front is set at 4mm droop the back should be between 2-6mm. if you are using 1mm or 7mm then your set-up has other problems that need addressed.

Here check this out for set-up info, it is put together for the XXX-S, but is relevent to almost any RC car. Also it is compiled by some of the best tuners in the country, if not the world!!

Losi set-up guide
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Old 05-09-2002, 05:47 PM   #27
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IMPACTPLAYR makes an important point about not going to far on the up-travel/droop. I also don't have more than 2mm difference in up-travel between the front and rear of my car. In fact the majority of the time I don't have more than 1mm difference.

The toe-out idea that IMPACTPLAYR talks about is a good one to a point. Just like IMPACTPLAYR points out that you don't want to go too far with the droop/up-travel, you also don't want to go too far with the toe-out. I would suggest that you not go more than 1 degree of toe-out. Like IMPACTPLAYR, I am not trying to step on any toes here.

If you use toe-out your front tires are going to generate more heat due to the constant slip-angle, and potentially over-heat part way through the race, causing your car to push more as the race goes on. Also given the additional slip-angle created by toe-out you will reduce the speed of your car and put more drain on the battery.

According to a 900 page book full of engeering formulas, called "Racing Car Vehicle Dynamics", "for racing, it is common to use parallel steering". Which means there is no toe-in or toe-out.

The reason why more toe-out will cause less steering mid corner can be explained by looking at tire performance. The lighter the load on a tire, using less slip angle produces higher cornering forces. When cornering, the inside tire has less load on it as the outside tire is taking the majority of the load. Given this reduced load on the inside tire you will actually get more cornering force with less slip angle on that inside tire (i.e. less or no static toe-out).

So, yes toe-out can help your situation, but in my opinion (and yes we all have one ) I think it is better to focus on weight transfer and keep the steering parallel so your tires and thus handling remain more consistent through the race.

Last edited by mcrisp; 05-09-2002 at 05:50 PM.
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Old 05-09-2002, 06:52 PM   #28
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mCrisp:

I have just downloaded your tuning guide, and after a quick read I must commend you on your work, very detailed and precise descriptions of car physics..I can highly recommend this for any serious racer!

Keep up the great work!
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Old 05-09-2002, 07:04 PM   #29
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Thanks King-G!

At the Tamiya worlds I met some really kool folks from Australia! You Australians know how to have fun!

cya,
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Old 05-09-2002, 07:46 PM   #30
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Martin- I see your point. I also agree with your ideas on toe out and have always been against more than a little toe out. Admittedly, I will use some toe in (less than 2 deg. always) to calm a front end down, but I always try to tune with 0 toe. I only use toe in or out for fine tuning or if the track changes mid race to aviod upsetting teh whole setup.

Like I said earlier the condition is NOT extreme and I agree that a slight amout of toe out might help. One really good thing about toe out is that it's a pretty easy adjustment relatively so I can try it and go back to the original setting in between rounds.

Also, I'm running quite a bit of droop both front and rear, so I'm thinking about reducing both. After that I can change the difference from front to back. Right now they are pretty close- like 4/3 front/back which works out to 2.5/1.5 up travel with my current RH setting (5.5 f/r)

At this stage we are fine tuning (which I don't really have anyone here to coach me) so other than reading and help from you guys, I'm flying solo. I should also add that when I say fine tuning, I mean fine tuning because the car is wicked fast.

Thanks guys
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