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Old 06-19-2010, 09:51 AM   #1
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Default Brief (Daft) Tourer handling Question (TA05)

Hi folks,

Recently began running my TA05-IFS car that I recently purchased from a fellow racer. Having set it back to stock I have a strange handling problem; the car tends to under-steer or handle relatively neutrally coming out of right-handers, yet coming out of left-handers as soon as I get on the power the back steps way out and it spins. This is so bad that if from a standing start I go hard right the car turns gradually, yet hard left the car will spin on a sixpence.

I have balanced the car as best as I can in terms of weight (similar setup to my TA05R), replaced the diffs front and rear, and also swapped the CVD assemblies round on the rear in case there was some binding somewhere making the diff give all of the power to the right wheel. None of this seems to have made a difference.

The only thing that I have found that has seemed to make a difference is to adjust my shock collars. On the rear I had my right shock collar all the way up to the top of the shock, and on the left it is down a little. Levelling these out seems to have neutralised the handling a little (it seems someway between spinning out and being controlled now, but at least equal through both types of corner), although I'm not sure why. I always assumed that the collars had no effect other than to adjust the ride height. I now have the problem that the car is sitting slightly higher on the one side.

Also, to improve traction to the rear should I lay the rear shocks down or stand them up more? I'm currently running soft springs on the front (yellow) and super-soft on the rear (red).

Any advice on how to get this thing around the track properly would be much appreciated as I have a big race day tomorrow.

Cheers!
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Old 06-19-2010, 10:56 AM   #2
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Make sure that your steering servo is centered and that you have the same travel in both directions.
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Old 06-19-2010, 11:05 AM   #3
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Thanks, should have mentioned that my EPA is set correctly. The correct setup of the TA05 is not to have the servo horn central on the servo however (as shown in the picture below) - do you think this could be causing the problem?

http://www.rceasy.com/wp-content/upl...ta05-ifs04.jpg

Thanks!
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Old 06-19-2010, 11:24 AM   #4
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Quote:
Originally Posted by Andysan View Post
Thanks, should have mentioned that my EPA is set correctly. The correct setup of the TA05 is not to have the servo horn central on the servo however (as shown in the picture below) - do you think this could be causing the problem?



Thanks!
If you place your car on floor give it full lock and push it so it turns around 180degrees, does it turn within the same radius left to right?
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Old 06-19-2010, 12:15 PM   #5
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If you place your car on floor give it full lock and push it so it turns around 180degrees, does it turn within the same radius left to right?
Hi thanks for your help!

Never thought of trying this and it has certainly put some issues to rest. I tried this and measured the diameter when turning left in a circle on full lock left and right with the throttle trim set to the lowest point where the vehicle will still actually move. The diameter for both is just over 5ft, give or take an inch for each one. This level of error is acceptable enough for me to be happy with.

With the collars now level the car still spins out more when turning left than right, although not quite to the same extent as before - I reckon its probably manageable now. Trouble is the car is quite happy to spin out when I put the power down now in either direction. Not sure if I'm expecting too much, my driveway is smooth asphalt and Im running a 13.5T BL. I dont run asphalt very often aso not sure if this is what to expect or not.

I'm happy to take the car to the track tomorrow like this now, however if once the tyres have been prepped and heated I'm still getting power-on oversteer on the proper racing surface of the circuit what should I adjust to fix this please? I only know of softening the rear springs, adding rear toe in and slackening off the diff. Should I lay the shocks down more etc..?

Cheers!
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Old 06-19-2010, 12:32 PM   #6
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Have you also checked your droop settings on your suspension, make sure one of the front/rear wheels isnt lifting off the floor to early while corning.
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Old 06-19-2010, 12:53 PM   #7
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Yep, it's more than likely your droop settings. It seems you have too much droop on the left rear and it's letting the rear diff unload.

Equalise the droop left to right and start with 2mm droop above ride height. That is say your ride height is at 5mm and it takes 2mm of upward movement (lift from center of chassis with say a tip of a small screwdriver) to just lift the tires off the ground.
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Old 06-19-2010, 01:18 PM   #8
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Hi,

Have measured my droop all around via the following method (all I have in the way of a gauge is a HPI one):



This reads as 3mm all around.

When I attempt to measure the droop by lifting the car as described by FREAKAH I'm getting about 5mm on the rear (although not 100% certain as cant be completely accurate). What I'm confused by is if I had more droop wouldnt the left tyre stay in contact with the ground as the car rolls to the right for longer than if I had too little droop (i.e. the left tyre becomes unloaded when it is off the ground)? I've been trying to understand the concept from the free Hudy tuning manual (available here, hope it helps someone) and it says that priority should be to decrease front droop and not increase the rear for this problem (quick ref table on p54). My brain hurts lol!

Thanks!
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Old 06-19-2010, 01:43 PM   #9
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have you check your shocks? make sure its the same (or almost same) lenght? also build your shocks good, smooth and as even as you can..
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Old 06-19-2010, 01:54 PM   #10
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Quote:
Originally Posted by Andysan View Post
Hi,

Have measured my droop all around via the following method (all I have in the way of a gauge is a HPI one):



This reads as 3mm all around.

When I attempt to measure the droop by lifting the car as described by FREAKAH I'm getting about 5mm on the rear (although not 100% certain as cant be completely accurate). What I'm confused by is if I had more droop wouldnt the left tyre stay in contact with the ground as the car rolls to the right for longer than if I had too little droop (i.e. the left tyre becomes unloaded when it is off the ground)? I've been trying to understand the concept from the free Hudy tuning manual hope it helps someone) and it says that priority should be to decrease front droop and not increase the rear for this problem (quick ref table on p54). My brain hurts lol!

Thanks!
As far as I understood droop is as you describe, the more droop you have the tyre coming off load when cornering will stay in contact the ground longer.

Next thing maybe to look at are your camber angles, toe settings and weight distribtion if you can, also make sure everything moves freely ie wishbones up and down with out shocks connected.
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Old 06-19-2010, 02:33 PM   #11
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Quote:
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have you check your shocks? make sure its the same (or almost same) lenght? also build your shocks good, smooth and as even as you can..
Thanks, as I measure the difference in shock length between the car on its wheels and the car in the air its 2mm all round so par for the course. Yeah, might have a look inside them and check they are OK.


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As far as I understood droop is as you describe, the more droop you have the tyre coming off load when cornering will stay in contact the ground longer.

Next thing maybe to look at are your camber angles, toe settings and weight distribtion if you can, also make sure everything moves freely ie wishbones up and down with out shocks connected.
OK, will try the car at the track as it is now given the minor changes Ive made and make changes from the Hudy Setup Guide as is necessary.

Thanks all for your help, will report back tomorrow night.
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Old 06-19-2010, 02:56 PM   #12
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There is a limit of how much droop you can have which also depends on the rest of your setup like roll centers, springs, shock angles, etc.. While it is true that more droop allows the inside tire to stay in contact with the ground as the chassis rolls, it also may allow the chassis to roll too much and too soon thereby unloading the tire suddenly when the droop limit is reached. Seeing as you have super soft rear springs, this scenario may be the case.

You also have to take your driving style into consideration. If you thow a car into a corner and punch it coming out with the wheels turned, a car with more droop would more than likely break traction easier/faster than a car with less droop. More droop seems to be more suited to a smoother driving style with smoother steering and throttle inputs.
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Last edited by FREAKAH; 06-19-2010 at 03:46 PM.
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Old 06-19-2010, 03:07 PM   #13
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Change your bearings in your hubs and diffs with new good bearings. You could chase every setting and still have a very basic problem. Actually its the first thing I change when problems arise.
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Old 06-19-2010, 03:48 PM   #14
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Also check the hexes on your wheels. A slightly loose wheel nut can allow them to strip.
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Old 06-19-2010, 04:36 PM   #15
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OK, thanks for that. Its too late in the day here to try anything else but I will bear this all in mind at the track tomorrow.

That thought about too soft suspension making me reach the droop limit is particularly interesting as I am a very aggressive driver by nature.
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