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Old 03-01-2014, 07:50 AM   #16
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Martin, first thanks for sharing all of your knowledge with us. I do subscribe to both you apps and do use them.
I find setting droop on a TC to be a bit challenging. I have tried many ways but have settled on using a set of stepped ride height gauges to set the chassis on. If RH is to be 5 with 3 droop I set the chassis on 8 on the step gauge then use a piece of paper as a go no-go gauge under the wheel while I adjust the droop screw. I set the gauges under the car nearest the axle line that I can. I do one end at a time. I may add .5 if the tire inserts are soft. Is there anything flawed in doing this?
Thanks
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Old 03-01-2014, 10:26 AM   #17
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Originally Posted by Martin Crisp View Post
The link length will affect both the roll center and the camber gain, but the dominant affect is on the camber gain. The shorter the upper link the more camber gain (increase in negative camber) you will get as the suspension is compressed. This increase in camber gain will typically give that end of the car more grip in the corner. If you already have a lot of camber then more camber gain in the corner would actually take away grip because the contact patch becomes smaller, but in reality this wont happen with the amount of camber we typically run on our touring cars (i.e. between 1 to 2.5 degrees.

So if you shorten the front upper links you will get more steering. If you shorten the rear upper links your car will have less steering and more rear grip.

Cheers.
Simple, but excellent answer. Thank you
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Old 03-01-2014, 01:44 PM   #18
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Interested in what tire choices people are using on asphalt?
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Old 03-01-2014, 06:12 PM   #19
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Originally Posted by Josh-n-ya View Post
Interested in what tire choices people are using on asphalt?
Really? read the topic please!

Hey Martin, dont know if you remember the name, but I used to race with ya at Fastcats.. anyway.. I am still having issues with setup.. use the book a lot

Seems like most current cars are focused on roll centre as the big tuning feature. Why is that??

2 - is there a way to learn how to read the car?? I find it difficult to really figure out push into in the middle or on exit.. oversteer is easier.
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Old 03-01-2014, 08:40 PM   #20
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Hey Martin how's it going. I was about to ask you on FB for setup help but I bumped into this topic in the forums. Great job & Thanks for doing this for us.
Here goes my questions:
If you put shims on your front outer link what does that do?
If you put shims on your front inner link what does that do?

If you put shims on your rear outer link what does that do?
If you put shims on your rear inner link what does that do?

If I want to gain high corner speed what needs to be done?
I tend to go into the corner hard & I can't get my BD7 to rotate.
I have 2.5 deg rear toe.
I believe I have 1mm shims all around under my bulkheads. Should I remove it?
I'm running HPI silver springs all around.

Thx-John
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Old 03-01-2014, 09:06 PM   #21
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Originally Posted by dan_vector View Post
It's an interesting discussion regarding the general hardness or softness of the car depending on grip levels. For example above we are talking about a soft car in low grip conditions for valid reasons to the extent of running without ARB's.

At TITC last week the traction was incredibly high. Higher than I've ever seen. Traction roll was a big problem and I went for a stiff car to try to counteract it - I ended up with a very nervous car that was difficult to drive. The best thing I found was maintaining the heavy dampening and rear diff simply going down 3 grades of springs softer all round made a massive difference and almost eliminated the traction roll problem and making the car very easy to drive. Lap times were the same but I was more consistent.

One of the biggest things I've found helps is chassis flex. High flex in low traction and little or zero flex in high grip conditions almost make more influence than shocks/springs.

How does this stack up with theory Martin?? Thanks for all your hard work - I'm signed up to the new website. It's brilliant!
Hey Dan

I wish I had the opportunity to race at TITC...looks like a fantastic event! Plus I have always wanted to visit Thailand.

Basically yes, to your question..."does this stack up with theory". There is another thread on this forum that I had started a couple of weeks ago dealing with how to fix traction rolling you might want to read through.

But in general you wan the car to keep it's center of gravity as low as possible. So if for example you went really stiff on the springs, this will not allow the car to lean into the surface, which will keep the CG high. Also if you have a lot of droop in the car the inside may lift up during cornering, which would raise the CG. So less droop and softer springs will help keep the CG lower. You also wan to lower the roll center so that you don't make the car poll vault over over itself. You also wan to control the speed at which the car leans. You don't want it to be too fast or too slow...this is where your shock oils/pistons can help. If you provide too much dampening then the shocks won't compress fast enough and you might poll vault over the outside tire. If you provide too little dampening then the car will roll so fast that it picks up too much momentum in the roll, making it more tippy or prone to traction rolling.

Cheers
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Old 03-01-2014, 09:19 PM   #22
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Originally Posted by OldLosiRacer View Post
Martin, first thanks for sharing all of your knowledge with us. I do subscribe to both you apps and do use them.
I find setting droop on a TC to be a bit challenging. I have tried many ways but have settled on using a set of stepped ride height gauges to set the chassis on. If RH is to be 5 with 3 droop I set the chassis on 8 on the step gauge then use a piece of paper as a go no-go gauge under the wheel while I adjust the droop screw. I set the gauges under the car nearest the axle line that I can. I do one end at a time. I may add .5 if the tire inserts are soft. Is there anything flawed in doing this?
Thanks
I am not sure I understand what you are doing with the piece of paper to be honest. The droop gages are a good tool, but I hate that you have to take the tires off to use them. Instead I use a very simple method which allows me to keep the tires on the car. First I measure the ride height (e.g 5mm). Then I lift that end of the car up until the tires are just about to come off the ground, Then I measure the ride height at that point. Lets assume it measured at 8mm. This would give me a 3mm above ride height droop measurement.

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Originally Posted by nf_ekt View Post
Simple, but excellent answer. Thank you


Quote:
Originally Posted by Josh-n-ya View Post
Interested in what tire choices people are using on asphalt?
There are a lot of great tires out there. Each asphalt is different and the air/surface temps would play a big roll in choosing the best tire. So in my opinion there really is no "best tire" for asphalt.

Quote:
Originally Posted by Bikerbob View Post

Hey Martin, dont know if you remember the name, but I used to race with ya at Fastcats.. anyway.. I am still having issues with setup.. use the book a lot

Seems like most current cars are focused on roll centre as the big tuning feature. Why is that??

2 - is there a way to learn how to read the car?? I find it difficult to really figure out push into in the middle or on exit.. oversteer is easier.
Not able to remember you from a rctech name like bikerbob sorry

I have long focused on roll centers as one of the most important things I optimize. I don' think it has anything to do with the cars of today or yesterday. I just think it is such a critical aspect of getting a well balanced car.


Quote:
Originally Posted by DJGonzo69 View Post
Hey Martin how's it going. I was about to ask you on FB for setup help but I bumped into this topic in the forums. Great job & Thanks for doing this for us.
Here goes my questions:
If you put shims on your front outer link what does that do?
If you put shims on your front inner link what does that do?

If you put shims on your rear outer link what does that do?
If you put shims on your rear inner link what does that do?

If I want to gain high corner speed what needs to be done?
I tend to go into the corner hard & I can't get my BD7 to rotate.
I have 2.5 deg rear toe.
I believe I have 1mm shims all around under my bulkheads. Should I remove it?
I'm running HPI silver springs all around.

Thx-John

If you put shims on your front outer link what does that do?
-> this will raise the front roll center, making the car have more on powersteering and less off power steering.

If you put shims on your front inner link what does that do?
-> this will lower the front roll center, making the car have feel like it turns in a little better, but will push in the middle and exit of the corner.

If you put shims on your rear outer link what does that do?
->This will raise the rear roll center giving the rear more lateral grip making the car push more.
If you put shims on your rear inner link what does that do?
-> this will lower the rear roll center making the rear of the car roll more, reducing rear grip. It will make the car more loose in the middle and corner exit.
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Old 03-01-2014, 09:25 PM   #23
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martin, thanks for the explanation on the camber link length question. it really helped. i applied this to my car today. the rear was really loose in more than one corner. so i shortened the links in the rear only and it really locked in the rear. so much so i dropped my lap times by 1/2 sec. so i decided to try it on the front since it was still pushing a little. it had alot more steering but the car wasnt consistent on lap times. i had only one lap that was faster than the first group of laps (10 lap runs). the first group of laps was much more consistent. i changed the front camber link back to where it was int he first place and the lap times went back to the same as the first set of laps. it really makes a big difference in how much grip the car has. i have your app and ill read it some more.
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Old 03-01-2014, 09:52 PM   #24
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Quote:
Originally Posted by Bikerbob View Post
Really? read the topic please!

Hey Martin, dont know if you remember the name, but I used to race with ya at Fastcats.. anyway.. I am still having issues with setup.. use the book a lot

Seems like most current cars are focused on roll centre as the big tuning feature. Why is that??

2 - is there a way to learn how to read the car?? I find it difficult to really figure out push into in the middle or on exit.. oversteer is easier.
Uhh, tires play a big role in setup I think!

Thanks for your answer below Martin.
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Old 03-01-2014, 10:22 PM   #25
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Originally Posted by Josh-n-ya View Post
Uhh, tires play a big role in setup I think!

Thanks for your answer below Martin.
Most real races have a spec tire that makes the point moot. Even Hobbytown has a spec tire in three classes now.
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Old 03-01-2014, 10:33 PM   #26
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Most real races have a spec tire that makes the point moot. Even Hobbytown has a spec tire in three classes now.
good point. i run vta/gt. we have to run hpi d compound tires. its all about sauce treatment and heat.
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Old 03-01-2014, 10:36 PM   #27
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Hey Dan

I wish I had the opportunity to race at TITC...looks like a fantastic event! Plus I have always wanted to visit Thailand.

Basically yes, to your question..."does this stack up with theory". There is another thread on this forum that I had started a couple of weeks ago dealing with how to fix traction rolling you might want to read through.

But in general you wan the car to keep it's center of gravity as low as possible. So if for example you went really stiff on the springs, this will not allow the car to lean into the surface, which will keep the CG high. Also if you have a lot of droop in the car the inside may lift up during cornering, which would raise the CG. So less droop and softer springs will help keep the CG lower. You also wan to lower the roll center so that you don't make the car poll vault over over itself. You also wan to control the speed at which the car leans. You don't want it to be too fast or too slow...this is where your shock oils/pistons can help. If you provide too much dampening then the shocks won't compress fast enough and you might poll vault over the outside tire. If you provide too little dampening then the car will roll so fast that it picks up too much momentum in the roll, making it more tippy or prone to traction rolling.

Cheers
Thanks Martin. It really was a brilliant event! There's always next year

Yeah, I had a good read of the traction roll thread and that helped alot but it just seemed that I was having to go in a slightly different direction. For example I found that raisng the rear roll center (removing shims from inner link) actually helped reduce the traction roll tendancy.
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Old 03-02-2014, 12:16 AM   #28
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Subscribed! Just getting back into touring after a 6 year run in offroad. All these adjustments you mention seem to have the same effects in offroad. I understand setup much better now than I ever did during my last TC experiences..

Many thanks for all your great and easy to understand advice!
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Old 03-02-2014, 08:33 AM   #29
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Hi Martin.
Just raced my new Xray first time today, and it seems to have some oversteering. I tried to adjust away from it on the radio, because i thought it was my friving there was causing the problem. But it seems that it is the car setup.

Where do you surgest me to start looking ?

I am not a experince driver yet, but am trying my best.
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Old 03-02-2014, 08:35 AM   #30
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Originally Posted by dragonracing View Post
martin, thanks for the explanation on the camber link length question. it really helped. i applied this to my car today. the rear was really loose in more than one corner. so i shortened the links in the rear only and it really locked in the rear. so much so i dropped my lap times by 1/2 sec. so i decided to try it on the front since it was still pushing a little. it had alot more steering but the car wasnt consistent on lap times. i had only one lap that was faster than the first group of laps (10 lap runs). the first group of laps was much more consistent. i changed the front camber link back to where it was int he first place and the lap times went back to the same as the first set of laps. it really makes a big difference in how much grip the car has. i have your app and ill read it some more.
Excellent. Its good that you are experimenting!

Quote:
Originally Posted by dan_vector View Post
Thanks Martin. It really was a brilliant event! There's always next year

Yeah, I had a good read of the traction roll thread and that helped alot but it just seemed that I was having to go in a slightly different direction. For example I found that raisng the rear roll center (removing shims from inner link) actually helped reduce the traction roll tendancy.
My buddy Keith Yu has often encouraged me to go.

That's the thing about setup...it is the sum of its parts. Meaning that depending on what else you have going on with your setup and how the car is handling, sometimes going the opposite direction can be the right answer as you found out.

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Originally Posted by DekelzMan View Post
Subscribed! Just getting back into touring after a 6 year run in offroad. All these adjustments you mention seem to have the same effects in offroad. I understand setup much better now than I ever did during my last TC experiences..

Many thanks for all your great and easy to understand advice!
Yeah...the setup advice in the app and also in LearnSetup.com will work on offroad vehicles for sure. In fact it will work on full sized real race cars as well.

Glad everyone is liking this forum. It takes a fair amount of time to keep on top of it from my point of view, so I am glad everyone is getting value out of it . It is very rewarding to see racers be able to apply this knowledge and get positive results.

Cheers,
Martin.
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