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Old 04-19-2014, 03:31 AM   #331
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With the tyres having less grip, I thought there maybe more to it than that.
The track I race at is a low grip painted concrete surface.
I'll give it a try at the next track meet when the shell is painted.
Thanks
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Old 04-22-2014, 08:44 PM   #332
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Originally Posted by spencehotbodies View Post
Hello Martin

This maybe has already been asked? I'm getting high front tyre wear, we race on Tarmac, hasn't been treated. What would you try first?
stop turning

this is common on tarmaq for the front tires to wear more than the rears.

Quote:
Originally Posted by Crashmaster View Post
Hi Martin,

I'm running a Yok BD7 with the setup attached on medium grip tarmac track in 13.5 boosted. I'm stuggling with the car understeering and feeling far too safe in slower speed corners, gernally feelng as though the front end is too weak. In high speed generally the car is pretty well balanced.

Could you offer any tips on things to try to give more front end in the slower corners?

Thanks
Dan
When I looked at your setup I don't see any values for the amount of spacers you are running on the inboard position of the upper links. Can you provide that?

I would reduce the rear toe to 2.5 to get some more steering.

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Originally Posted by Fredp1 View Post
Hi Marttin,

What setup recommendations would you suggest for VTA coming from a 21.5 touring car?
Thanks
Fred
P. S just signed up for LearnSetup.com.
Hey Fred. I have never run or setup a VTA car, so I would just start with my touring car setup and go from there.

Quote:
Originally Posted by hyujmn View Post
I personally ran pretty similar setups between 25.5 VTA and 17.5 TC on two identical cars. I think I went just a hair softer all around on the springs/shocks on the TC.
good advice I think.
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Old 04-22-2014, 08:47 PM   #333
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Originally Posted by Fredp1 View Post
With the tyres having less grip, I thought there maybe more to it than that.
The track I race at is a low grip painted concrete surface.
I'll give it a try at the next track meet when the shell is painted.
Thanks
From what I have seen from simply watching the VTA cars, I think given the very low power the key difference will be running very very little rear toe and and fairly low rear roll center to free up the car so that it carries more momemtum in the corners.
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Old 04-24-2014, 02:15 AM   #334
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Quote:
Originally Posted by Martin Crisp View Post
When I looked at your setup I don't see any values for the amount of spacers you are running on the inboard position of the upper links. Can you provide that?

I would reduce the rear toe to 2.5 to get some more steering.
Hi Martin,

Thanks for replying first of all - I'm currently not running any spacers on the inboard links so thy are in the lowest position.

I have run with 2.5 deg rear toe previously however have struggled with corner exit stability in lower grip conditions. Hopefully as grip comes up in the summer this will be ok though!

Thanks
Dan
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Old 04-24-2014, 10:06 AM   #335
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Originally Posted by Crashmaster View Post
Hi Martin,

Thanks for replying first of all - I'm currently not running any spacers on the inboard links so thy are in the lowest position.

I have run with 2.5 deg rear toe previously however have struggled with corner exit stability in lower grip conditions. Hopefully as grip comes up in the summer this will be ok though!

Thanks
Dan
Hi Dan,

Yes, 2.5 rear toe will reduce traction coming off the corner like you experience. But now that I know that you are not running any spacers on the inboard upper links we can get you what you need by playing with those spacers, with you keeping your 3 degrees rear toe in.

Basically the more spacers you add on those inboard upper links the less grip you will get at that end of the car. So to get more steering add a 2mm spacer on the rear inboard upper link. You may find that you will prefer 1.5mm or even 2.5mm, but lests start with 2mm and see.

Cheers.
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Old 04-24-2014, 10:44 AM   #336
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Quote:
Originally Posted by Martin Crisp View Post
Hi Dan,

Yes, 2.5 rear toe will reduce traction coming off the corner like you experience. But now that I know that you are not running any spacers on the inboard upper links we can get you what you need by playing with those spacers, with you keeping your 3 degrees rear toe in.

Basically the more spacers you add on those inboard upper links the less grip you will get at that end of the car. So to get more steering add a 2mm spacer on the rear inboard upper link. You may find that you will prefer 1.5mm or even 2.5mm, but lests start with 2mm and see.

Cheers.
2mm on a Yokomo is a lot of shim
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Old 04-24-2014, 08:16 PM   #337
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2mm on a Yokomo is a lot of shim
could be too much for sure... 1mm might be the right answer. 2mm will for sure make a difference and then you can back off a little.
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Old 04-24-2014, 10:02 PM   #338
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I haven't compared BD7 roll center with other new chassis but compared with my previous car it has a very low roll center.

No shims with short link rear roll center is -7.5mm.

2mm of shims on inboard link short link rear roll center is -9.7mm

My previous car FT TC4 the rear roll center adjustment range was between 0 and -4mm kit setting -3mm.

Last edited by frozenpod; 04-24-2014 at 10:12 PM. Reason: Added FT TC4
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Old 04-24-2014, 11:07 PM   #339
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Default Spring rate and shock oil

Hi Martin,

Got a copy of your setup workbench but want to get more inside from you on how the spring and shock oil combination will effect the car handling especially on touring car. What is the difference if I use harder spring with softer shock oil compare to softer spring with harder shock oil? I am asking on the overall effect to the car handling.

And what condition will those combination be the best to use or try?

FYI, I am running BD7 on a mid size technical track with medium traction and temp can go up to 50 - 60C.

As I am get difference view trom my local track guys on this combination. If you can point me to the right direction on how to go about setting my car with difference combination.

Thx
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Old 04-25-2014, 01:02 AM   #340
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Quote:
Originally Posted by Martin Crisp View Post
Hi Dan,

Yes, 2.5 rear toe will reduce traction coming off the corner like you experience. But now that I know that you are not running any spacers on the inboard upper links we can get you what you need by playing with those spacers, with you keeping your 3 degrees rear toe in.

Basically the more spacers you add on those inboard upper links the less grip you will get at that end of the car. So to get more steering add a 2mm spacer on the rear inboard upper link. You may find that you will prefer 1.5mm or even 2.5mm, but lests start with 2mm and see.

Cheers.
Cheers guys, hoping to get out this weekend if the weather plays ball so will play with it between 1 and 2mm and back it off to feel.

If I go down the 2.5dg rear toe route and want to get back some rear traction would you recomend anything in particular like softer damping or playing with rear squat?

Thanks
Dan
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Old 04-25-2014, 09:51 AM   #341
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Originally Posted by thesaint View Post
Hi Martin,

Got a copy of your setup workbench but want to get more inside from you on how the spring and shock oil combination will effect the car handling especially on touring car. What is the difference if I use harder spring with softer shock oil compare to softer spring with harder shock oil? I am asking on the overall effect to the car handling.

And what condition will those combination be the best to use or try?

FYI, I am running BD7 on a mid size technical track with medium traction and temp can go up to 50 - 60C.

As I am get difference view trom my local track guys on this combination. If you can point me to the right direction on how to go about setting my car with difference combination.

Thx
The hard spring with a soft oil will make the car very bouncy and as a result the tire will not produce as much or consistent grip.

As soft spring with a harder oil would be better than hard spring with a soft oil, but like anything you can go too far with the oil being too hard.

Having said that...

The way I think about shock oils and spring rates is that as the spring rate goes up so must the shock oil cst rating assuming a constant piston setting. In other words the oil needs to match the spring, so that it can better control the spring especially during rebound.

Another aspect of spring / oil / piston settings is that in most cases it is better to have larger piston holes and heavier oil than thinner oil and small holes. This will allow your car to handle the bumps better and also prevent "jacking down".

It handles the bumps better because the larger holes with a heavier oil will have less pack (high speed dampening) allowing the spring to compress quickly when you hit a bump, while at the same time not allowing the low speed dampening to happen too quickly allowing for nice transitions.

Jacking down happens when the rebound is too strong and the spring does not have enough time to extend itself again before the next bump. This will cause the car loose ride height when going over bumps in while cornering to the point where the chassis might hit, or the car just takes too long to transition back to a normal state. This can reduce traction and make handling inconsistent.

So to summarize :
* match your oil to you spring rates
* use larger holes in the pistons.

this will give you a more compliant ride with a lower frequency keeping the tire on the ground producing higher and more consistent grip.


Quote:
Originally Posted by Crashmaster View Post
Cheers guys, hoping to get out this weekend if the weather plays ball so will play with it between 1 and 2mm and back it off to feel.

If I go down the 2.5dg rear toe route and want to get back some rear traction would you recomend anything in particular like softer damping or playing with rear squat?

Thanks
Dan
If the 2.5 rear toe makes the car too loose then I would go back to 3 degrees, or raise the rear roll center by adding spacers to the outboard upper link.
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Old 04-25-2014, 09:24 PM   #342
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Originally Posted by Martin Crisp View Post
The hard spring with a soft oil will make the car very bouncy and as a result the tire will not produce as much or consistent grip.

As soft spring with a harder oil would be better than hard spring with a soft oil, but like anything you can go too far with the oil being too hard.

Having said that...

The way I think about shock oils and spring rates is that as the spring rate goes up so must the shock oil cst rating assuming a constant piston setting. In other words the oil needs to match the spring, so that it can better control the spring especially during rebound.

Another aspect of spring / oil / piston settings is that in most cases it is better to have larger piston holes and heavier oil than thinner oil and small holes. This will allow your car to handle the bumps better and also prevent "jacking down".

It handles the bumps better because the larger holes with a heavier oil will have less pack (high speed dampening) allowing the spring to compress quickly when you hit a bump, while at the same time not allowing the low speed dampening to happen too quickly allowing for nice transitions.

Jacking down happens when the rebound is too strong and the spring does not have enough time to extend itself again before the next bump. This will cause the car loose ride height when going over bumps in while cornering to the point where the chassis might hit, or the car just takes too long to transition back to a normal state. This can reduce traction and make handling inconsistent.

So to summarize :
* match your oil to you spring rates
* use larger holes in the pistons.

this will give you a more compliant ride with a lower frequency keeping the tire on the ground producing higher and more consistent grip.



If the 2.5 rear toe makes the car too loose then I would go back to 3 degrees, or raise the rear roll center by adding spacers to the outboard upper link.

Hi Martin,

Thx for the detail explanation on the effect of spring and shock oil combination. Do you have a guide or table on the matching spring rate and shock oil to start with?

Rgds
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Old 04-27-2014, 05:16 AM   #343
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Martin,

What is the best way to generate more heat in tyres?

Cheers josh
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Old 04-27-2014, 05:35 AM   #344
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Drive harder
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Old 04-27-2014, 06:00 AM   #345
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lol
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