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Old 03-25-2014, 05:24 AM   #211
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Hey Martin, thanks for the tips about the bumpy track. I will try that this weekend. Would you consider adding a section on your site about pin sweep? Unless I missed it.

Thanks for all the tips and advice. I heard you were at the Canadian nats, hopefully you make more races this year.
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Old 03-25-2014, 02:19 PM   #212
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Ok so I have tamed the traction rolling some on my car, but still having some issues. I think it is coming from me having to much initial turn in. I have turned the expo down to 80% to help some with it, but it still wants to dig in hard on corner entry. My line of thought is this is throwing all the weight to the font outside tire, then roll-o-rama. I already have a half weight heaver oil in front along with then next heavier spring. In an effort to keep the car balanced, what would be the next step in reducing turn in? As it is now I have plenty of rear traction as well. When the car doesnt roll, it rotates on a dime.
your gonna be stumped when you read through this ,you have actually been making it worse,read on
Traction Rolling - how to solve it
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Old 03-25-2014, 03:58 PM   #213
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Was reading about the shock 'pack' and the difference with piston hole size etc.

Is there any way of calulating what cSt oil, or how much higher the cSt should be if I increase the piston holes from 4x1.1mm to 4hole x1.2mm?

Thanks
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Old 03-25-2014, 05:44 PM   #214
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Ok, so a new path to take, soften the oils up a half weight, go to a lighter spring front and rear, and how bout a wierd one here, go to say -3/3.5 on camber to reduce the chances of the sidewall rolling under? Its a thought. As it is now I am running longest links possible to reduce camber gain.
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Old 03-25-2014, 05:45 PM   #215
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Originally Posted by Skiddins View Post
Was reading about the shock 'pack' and the difference with piston hole size etc.

Is there any way of calulating what cSt oil, or how much higher the cSt should be if I increase the piston holes from 4x1.1mm to 4hole x1.2mm?

Thanks
Skiddins
Go here: http://www.petitrc.com/reglages/xray...etsXRayT4.html

Click "Damper Chart"

Some interesting info there...

-Mike
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Old 03-25-2014, 08:00 PM   #216
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Default Corner exiting traction troubles

Hi there I have the 6.1 world's kit and I am almost happy with my setup. I'm just struggling with a little bit of traction trouble on power exiting a corner. I've tried droop ride height shock position and new tires all around. Any ideas which is the best way to go? More droop lean The shocks in more? Can someone please help.
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Old 03-25-2014, 08:31 PM   #217
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Originally Posted by theproffesor View Post
Ok so I have tamed the traction rolling some on my car, but still having some issues. I think it is coming from me having to much initial turn in. I have turned the expo down to 80% to help some with it, but it still wants to dig in hard on corner entry. My line of thought is this is throwing all the weight to the font outside tire, then roll-o-rama. I already have a half weight heaver oil in front along with then next heavier spring. In an effort to keep the car balanced, what would be the next step in reducing turn in? As it is now I have plenty of rear traction as well. When the car doesnt roll, it rotates on a dime.
Hi,

I have never been a fan of using expo on steering, as I like a linear feel to the steering....but that may be just a personal preference.

Having said that your thinking along the lines of reducing forward weight transfer is sound and certainly one aspect of reducing the problem. In addition to thicker front shock oils and springs you should also look at reducing the amount of droop the car has in the rear and also the front. The rear is more important however.

If you are already one spring up on the front then I don't see this as a spring issue, as I typically run the same springs front and rear and at most one spring up in the front.

There are some other things that can be done to reduce that harsh turn-in as well.

1) ensure you don't have any toe-out in the front.
2) increase your rear toe to 3 degrees is it is already not at 3
3) a stiffer front swaybar
4) Add some front anti dive by raising the rear block in the front of the car by about 0.5mm to 1mm.

Now if you issue is traction rolling and not just an overly sharp turn-in then I would recommend a different approach.

a) lower the front roll center by adding more shims to the inboard upper link on the front.
b) run the same spring rate in the front as you are currently running in the rear, and these spring rates should not be very high.
c) reduce the front camber to 1 degrees and the rear to 1.5 degrees. Add more camber until you traction roll again, and then back off a little.
d) reduce droop to 2mm in the front and rear of the car. also try 1.5mm droop in the front. all droop setings are "above ride height".
e) increase your ackerman to make the car push more in the middle of the corner.


Cheers,
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Old 03-25-2014, 08:45 PM   #218
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Quote:
Originally Posted by Adam B View Post
Hey Martin, thanks for the tips about the bumpy track. I will try that this weekend. Would you consider adding a section on your site about pin sweep? Unless I missed it.

Thanks for all the tips and advice. I heard you were at the Canadian nats, hopefully you make more races this year.
It was a one race deal for the most part, but I think I might end up doing some club racing during the winter months. Nothing to costly as my extra money goes to full size car racing.

Quote:
Originally Posted by theproffesor View Post
Ok, so a new path to take, soften the oils up a half weight, go to a lighter spring front and rear, and how bout a wierd one here, go to say -3/3.5 on camber to reduce the chances of the sidewall rolling under? Its a thought. As it is now I am running longest links possible to reduce camber gain.
Read my post above for a more complete answer. Definitely do not go to -3 camber to reduce the outside sidewall from rolling under. This is something I hear off-road racers will do, but in on road this will make things worse. Instead go to -1 all around or -1 front and -1.5 rear.

Quote:
Originally Posted by grippgoat View Post
Go here: http://www.petitrc.com/reglages/xray...etsXRayT4.html

Click "Damper Chart"

Some interesting info there...

-Mike
Thanks Mike - good chart.

Quote:
Originally Posted by Bgilli26 View Post
Hi there I have the 6.1 world's kit and I am almost happy with my setup. I'm just struggling with a little bit of traction trouble on power exiting a corner. I've tried droop ride height shock position and new tires all around. Any ideas which is the best way to go? More droop lean The shocks in more? Can someone please help.
When you say you have tried droop, ride height and shock position, I am not sure from that what you actually tried? Did you increase or decrease the droop. Did you increase or decrease the ride height? Did you lay down or stand up the shocks?

Also when you say you are struggling with traction, do you mean forward grip? do you mean the rear is loose? the car is tight?

The more I know, the better I can help

Cheers,
Martin.
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Old 03-25-2014, 10:20 PM   #219
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Oops yes I'm sorry I layed the rear shocks down to 2c I went from 6mm all around to 5.5 rear only and the droop I lowered the rear arms. They were touching on the 10mm blocks but now they are 1mm over touching. People do droop so many different ways I can find out the droop using actual arms for you tomorrow if that would definitely make a more precise description. But yes on throttle coming out of corners it gets loose. I can use Throttle control but sometimes when you're defending or fighting for positions I could use just a little more grip almost so it can just hook around the corner. Please let me know of any ideas and I'll get the exact measurement the other way tomorrow morning before work. Also if it's easier to pm me you can do that also. Thank you Martin for all that you do!
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Old 03-26-2014, 03:48 AM   #220
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Quote:
Originally Posted by grippgoat View Post
Go here: http://www.petitrc.com/reglages/xray...etsXRayT4.html

Click "Damper Chart"

Some interesting info there...

-Mike
Interesting

Does anyone know how it's being calculated?
I just just worked out the area of the piston holes I had (4x1.1) used with 350 oil and applied that percentage difference to the oil and came up with an increase in oil to 420cSt (using 4x1.2mm pistons)

However, that chart suggests I need to more than double what I thought the difference was (up to 500 cSt or more)
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Old 03-26-2014, 05:53 AM   #221
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Originally Posted by Skiddins View Post
Interesting

Does anyone know how it's being calculated?
I just just worked out the area of the piston holes I had (4x1.1) used with 350 oil and applied that percentage difference to the oil and came up with an increase in oil to 420cSt (using 4x1.2mm pistons)

However, that chart suggests I need to more than double what I thought the difference was (up to 500 cSt or more)
The way I'm reading it, if you want to just reduce the pack, whilst maintaining static damping rate, then you need to draw a vertical line from your exisiting setup... so that would give just over 500cst. And then to maintain same pack but change damping rate, go with a horizontal line..

I suspect that the values are not calculated, and actually tested instead. Simply converting the percentage area of the piston hole sizes doesn't take into account differences in the types of flow through the piston holes (a small hole is going to be more turbulent vs a bigger hole).

HiH
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Old 03-26-2014, 05:31 PM   #222
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Originally Posted by Bgilli26 View Post
Oops yes I'm sorry I layed the rear shocks down to 2c I went from 6mm all around to 5.5 rear only and the droop I lowered the rear arms. They were touching on the 10mm blocks but now they are 1mm over touching. People do droop so many different ways I can find out the droop using actual arms for you tomorrow if that would definitely make a more precise description. But yes on throttle coming out of corners it gets loose. I can use Throttle control but sometimes when you're defending or fighting for positions I could use just a little more grip almost so it can just hook around the corner. Please let me know of any ideas and I'll get the exact measurement the other way tomorrow morning before work. Also if it's easier to pm me you can do that also. Thank you Martin for all that you do!
The first thing I would do to gain more rear grip is to stand up the rear shocks. This may sound counter intuitive, so let me explain why. Yes it is true that laying down the shocks makes the rear end softer and in many cases having a softer rear spring rate would allow more weight transfer to the rear and in theory give you more grip in the rear. Although it does allow more weight transfer to the rear it also allows for the rear to roll more causing a greater difference in the vertical load between the inside and outside tires at the rear of the car, which looses lateral grip. Its hard to predict if the rearward weight transfer will generate more grip than is being lost by the rear rolling (or leaning). If the rear rolls a lot more than the front however this will almost always lead to an on power over steer situation in my experience.

I can't comment on your droop settings because unfortunately I am not fully sure I understand what you measurements are. The way I like to measure them is to measure the ride height and then lift the car until the tires are about to come off the table, and then measure the ride height again. The different between the two ride height measurements in the droop. I like this method because I don't have to take the wheels off. I also will use a droop guage as it is the most accurate way to doing things and I am not too lazy
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Old 03-26-2014, 06:31 PM   #223
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Default Droop

So I checked my droop the way you explained by checking ride height then lifting until the tires almost come off the ground. With my rear ride height at 5.5 it was lifted and my ride height was about 7.4 in the rear. 6mm ride height up front and the same test I am at 7.8. Maybe you can suggest a good setting just based on the ride height. Also I will stand my shocks up one in the rear and try that also. Thank you very much for taking the time to help me out!
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The first thing I would do to gain more rear grip is to stand up the rear shocks. This may sound counter intuitive, so let me explain why. Yes it is true that laying down the shocks makes the rear end softer and in many cases having a softer rear spring rate would allow more weight transfer to the rear and in theory give you more grip in the rear. Although it does allow more weight transfer to the rear it also allows for the rear to roll more causing a greater difference in the vertical load between the inside and outside tires at the rear of the car, which looses lateral grip. Its hard to predict if the rearward weight transfer will generate more grip that n is being lost by the rear rolling (or leaning). If the rear rolls a lot more than the front however this will almost always lead to an on power over steer situation in my experience.

I can't comment on your droop settings because unfortunately I am not fully sure I understand what you measurements are. The way I like to measure them is to measure the ride height and then lift the car until the tires are about to come off the table, and then measure the ride height again. The different between the two ride height measurements in the droop. I like this method because I don't have to take the wheels off. I also will use a droop guage as it is the most accurate way to doing things and I am not too lazy
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Old 03-26-2014, 09:08 PM   #224
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Hello Martin,

just to throw a confusing log on the fire.

what is your opinion on piston depth at ride height?
ie, how far the piston protrudes at rest.

DJC
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Old 03-27-2014, 04:37 AM   #225
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Hey Martin,

In terms of corner speed, what do you have to do with your rollcenter, both lower arms and turnbuckels?

Regards Robert
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