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Old 03-31-2014, 07:37 AM   #241
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Martin,

This weekend at a race, one of my fellow competitors in TC had an interesting set up in the rear of his car. He used 1/2 deg anti dive in the rear and 1-1.5 deg rear toe. Allegedly, he said with anti-dive, he was able to run less rear toe for better rotation and maintain the forward drive. I drove the car after the main and it was definitely set up in a way that allowed more throttle in the long bid sweeper on a large medium bite asphalt track.

I wondered if you have any thoughts on this concept?

Thanks,
Justin
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Old 03-31-2014, 08:46 AM   #242
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Quote:
Originally Posted by gocoogs View Post
Martin,

This weekend at a race, one of my fellow competitors in TC had an interesting set up in the rear of his car. He used 1/2 deg anti dive in the rear and 1-1.5 deg rear toe. Allegedly, he said with anti-dive, he was able to run less rear toe for better rotation and maintain the forward drive. I drove the car after the main and it was definitely set up in a way that allowed more throttle in the long bid sweeper on a large medium bite asphalt track.

I wondered if you have any thoughts on this concept?

Thanks,
Justin
What do you mean by anti-dive (that's only at the front)
You mean either anti-squat (rear edge of the rear wishbones are lower) or pro squat (front edge of rear wishbones is lower)

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Old 03-31-2014, 08:47 AM   #243
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sorry skiddins... pro squat... u are right!
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Old 03-31-2014, 08:52 AM   #244
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My experience with anti-squat is that it prevents the weight transferring to the rear. That explain the increase high speed steering.
But I found that it caused traction issues out of tighter corners because it wouldn't allow that weight transfer.

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Old 03-31-2014, 12:07 PM   #245
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Yes agree with you skiddins, anti squat does that... Put pro squat would encourage more weight transfer no?
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Old 03-31-2014, 12:12 PM   #246
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Questions?? Help

I have an nitro rc truck and the center gear spins when I pull the truck back but doesn't when I push it forward? What's wrong with it
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Old 03-31-2014, 12:20 PM   #247
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Originally Posted by Aaron7889 View Post
I have an nitro rc truck and the center gear spins when I pull the truck back but doesn't when I push it forward? What's wrong with it
You will be better off putting this into the off-road section as a question, this thread pertains to on-road (TC) car chassis setup.

Interested to see MC's response to gocoogs question regarding pro & anti-squat.
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Old 03-31-2014, 12:52 PM   #248
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Hi Martin,

I'll start off by saying that I love your app! It has helped me understand many if the features I was hazy of, or didn't grasp before. Thank you!

My question is related to caster. What would happen if you were to run caster where the hub leans forward (negative caster?)? Would you have to run more static camber because you would lose camber with dynamic caster?

I'm curious because I once had to run forward leaning caster as I broke and only had left side caster blocks. The wheels were staggered, but the car was decent and I was able to finish the mains before I could grab a replacement! Haha, It was a while ago though, and I wasn't as good of a driver yet to notice the change as much as I would now. Thanks!

Ted
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Old 04-01-2014, 02:01 AM   #249
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Is LearnSetup.com an actual app that can be used without internet connection or more of paid access to a website? It seems like the later. Reason I ask is I don't always have internet connection at the track.
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Old 04-01-2014, 02:41 AM   #250
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Quote:
Originally Posted by gocoogs View Post
Yes agree with you skiddins, anti squat does that... Put pro squat would encourage more weight transfer no?
Yes, but you may find it transfers too much which can cause other issues.
Best to keep the rear pivot pins level if you can so you get a good compromise.
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Old 04-01-2014, 07:02 AM   #251
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Hi Martin, diff question.

What effect does increasing or decreasing the weight of your diff oil have?

I was under the impression that decreasing oil weight (loosening) in the rear diff increases the rear traction on exit because it doesn't allow the outside tire as much spin or slip. It may not be as fast out but it allows it to hook up more.

In my current setup it calls for 2000cst but I find the rear wants to break loose on-power. Assuming I have the rest of the setup correct, would lowering the oil weight in the rear diff allow for more traction on-power, or do I have this wrong?

Cheers,
Tyler
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Old 04-01-2014, 08:20 AM   #252
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Sorry for not being more responsive over the last couple of days. Been busy with my full size race car and work.

Quote:
Originally Posted by Mister-E View Post
Hi Martin,

A question on tire balancing.
Would you recommend to do it on the used rubber tires for 1/10 on road?
I do understand and realize their importance and started to balance the tires for my TC.
However, when I checked after 1 run, the balanced tires are becoming unbalanced again!

Apparently, the inner foam is moving inside the tire.
I don't balance my wheels, but for sure balancing can help when you have a wheel that is really bad. Perhaps the foam is the reason as you suggest. I hate to say it, but the only way to solve the issue is to rebalance the wheels.

Quote:
Originally Posted by nascarkeith View Post
Ok I will admit I haven't read every single post just glanced through so forgive me if this has already been covered.

I am running a TC4 in the USVTA class on a tight, carpet, high grip track. My set up seams very different than most I see online. I have 11.5 lb front springs and 20 lb rear springs. 2 degrees of rear toe in. The smallest shim under all arm mounts. 3 washers under the camber link up front and 2 washers in the rear. The car drives well but sometimes picks up a slight push halfway through a run.

I've noticed most set ups run a stiffer front spring. My fastest lap is a 9.7 and average is 10.0. The fastest lap on the track in VTA is a 8.99. Not sure if my lack of speed is set up or me. The car does seem to really dig into the corner and loose speed. It also traction rolls when the grip comes up.

I will happily accept any advice you can give.
From watching VTA cars, but not actually looking at their setups, they seem to get their steering by making the rear free. Since they are so under powered, you can get away with this and maintaing good corner speed. It looks like the way top VTA cars free up the rear of their car is to allow the rear to roll/lean a lot in the corners. This is perhaps a function of running a fairly low rear roll center, or perhaps laying down the rear shocks.

I gather you are running a stiff rear spring to try and get the car to rotate, but with such a soft front spring at 11.5 lbs you car is likely just hitting the front portion of the chassis on the driving surface a lot, and this is causing the car to push.

Here is what I would suggest to find a better setup.

1) A]Start with the same spring rate front and rear in the 13lb range and mount the upper shocks in their middle hole positions. This is just to set a starting point which can be tuned after we see what your car is doing.
2) You did not mention the height of the washers you use on the upper links, but I will assume they are all the same size and perhaps 1mm in height. Since you have 3 in the front and 2 in the back, I would suggest going to 2 in the front so the front and rear are the same.
3) now if your car needs more steering then try the following
a) reduce rear toe-in to 1.5 degrees
b) add another spacer to the rear inboard upper link.
4) if your car needs less steering then try add another spacer to the front inboard upper link should be enough.

Quote:
Originally Posted by theproffesor View Post
I cant ever think of a situation I ran a softer spring up front than the rear. With being that soft up front, its no wonder it digs in so hard and rolls. Whatvare your other seting at, droop, ride hight, shock oil, ect. If your set-up is different than everyone else's and your lap times are a second slower, why wouldn't you give the other set-up a try? (Im not trying to be condesending, just throwing it out there)


I would also like to say Martin is the man. I took his set-up advise and my car went from looking like a bingo ball tumbler, to being glued to the track. In fact it has so much grip now, and doesn't want to roll, that it scrubs serious speed through the corners. I can watch the rear end bounce as its coming through some of the tighter turns. I have tried to do some of the things I know that free up the rear end, but the front needs to be freed up as well. The whole car is now tight. I am running a very slight anti-dive per instructions, and I think this is what is helping the traction rolling. But since the car now has soooo much grip and fights rolling on its own, would it be ok to remove it? Would going up on shock oil also help? My car is actually fun to drive again.

try lowering the rear roll center to get it to slide more. It really helps the rear come around when exiting those tight corners as well as in general more mid corner and corner exit steering

Thanks for the help
Quote:
Originally Posted by nf_ekt View Post
I haven't read this thread a whole lot since it went past the first 6-7 pages, but I must say I owe some gratitude to MC for his insight. In the past I had been told / taught that sway bars and high RC was more for when you are too hooked up and need to free the car up some... I guess maybe it goes back to carpet & foam tires (?)... at least that is IIRC , I have worked so much on trying to soften the car to fix traction issues! Well anyways I took a long break from RC and it seams that upon getting back in, I spent a lot of time trying what I thought was correct only to have frustrating results. What I have learned here (within the first few pages) in terms of just camber link angle, length, and shock position has helped so very much. And I would have never thought sway bars could have made such a difference (even in VTA)! I have in the course of 2 race meets taken a car I fought with all day and made it to where I am running a fast lap less than a tenth from the guys with a lot more track time and in some cases much better equipment. I get a fraction of the track time compared to some but I am in the mix and enjoying racing again, good stuff.
Having a good handling car is critical imo to enjoying the hobby.

Quote:
Originally Posted by CraigM View Post
I've always wondered this, what exactly does having rake in the ride height do? In what situation would you run a bigger split between front and rear ride height compared to a smaller split or no split at all?
Rake (having the front ride height lower than the rear ride height) produces more steering and also more downforce. The additional downforce is generated not just from the increased angle of the body hood, roof, wing etc. The increased downforce also happens because of the airflow under the chassis helps pull down the car to the track. Next time you watch F1 take a look at the ground clearance at the front of the chassis versus the back of the chassis. There is a huge difference. They do this to generate more downforce. I run rake in my full sized race car for this reason as well.

Quote:
Originally Posted by Brian McGreevy View Post
Miata?
yes Sir!!! Starting to put some cosworth cams in for a little more power. Also working on some aero improvements with a splitter, spoiler and roof.

Quote:
Originally Posted by ASM View Post
I can vouch for the improvement. Your car is right in the hunt now - nice work!
Awesome!!!
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Old 04-01-2014, 08:40 AM   #253
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Quote:
Originally Posted by gocoogs View Post
Martin,

This weekend at a race, one of my fellow competitors in TC had an interesting set up in the rear of his car. He used 1/2 deg anti dive in the rear and 1-1.5 deg rear toe. Allegedly, he said with anti-dive, he was able to run less rear toe for better rotation and maintain the forward drive. I drove the car after the main and it was definitely set up in a way that allowed more throttle in the long bid sweeper on a large medium bite asphalt track.

I wondered if you have any thoughts on this concept?

Thanks,
Justin
Hey Justin

I was going to ask if you meant pro-squat, but that has been clarified in later posts. Yes Pro-squat is similar to running a slightly softer rear spring allowing more reward weight transfer, but also more lateral roll. As you can imagine there are a lot of complex things happening and it is hard to determine if the rearward weight transfer which adds rear grip is going to generate more rear grip than the grip lost due to more lateral roll.

Ironically I have never driven a pro-squat car, so I don't have any real data points of testing to see if pro-squat allows you to less rear toe.

It is for sure something that would need some testing before I could comment with confidence about what to expect.

I don't believe I have seen a full sized race car that runs pro-squat, but perhaps they exist.

Quote:
Originally Posted by Aaron7889 View Post
I have an nitro rc truck and the center gear spins when I pull the truck back but doesn't when I push it forward? What's wrong with it
Do you mean the center differential?

Quote:
Originally Posted by nf_ekt View Post
You will be better off putting this into the off-road section as a question, this thread pertains to on-road (TC) car chassis setup.

Interested to see MC's response to gocoogs question regarding pro & anti-squat.
I really don't mind answering off-road questions as so much is common between the two disciplines. If I get enough off-road questions here, then I will create a similar thread in the offroad forum just to keep things organized.

Quote:
Originally Posted by mschumi101 View Post
Hi Martin,

I'll start off by saying that I love your app! It has helped me understand many if the features I was hazy of, or didn't grasp before. Thank you!

My question is related to caster. What would happen if you were to run caster where the hub leans forward (negative caster?)? Would you have to run more static camber because you would lose camber with dynamic caster?

I'm curious because I once had to run forward leaning caster as I broke and only had left side caster blocks. The wheels were staggered, but the car was decent and I was able to finish the mains before I could grab a replacement! Haha, It was a while ago though, and I wasn't as good of a driver yet to notice the change as much as I would now. Thanks!

Ted
yes...you would need more static camber to compensate.

I have seen a few drivers mistakenly put the front uprights on backwards and loved the handling of their cars, not knowing what they had done. It certainly would take away mid corner steering.

Quote:
Originally Posted by Odin544 View Post
Is LearnSetup.com an actual app that can be used without internet connection or more of paid access to a website? It seems like the later. Reason I ask is I don't always have internet connection at the track.
LearnSetup.com is a web based app, meaning that you need connectivity to access it. I also have the Setupworkbench.com app available as an actual app that is installed on either iPhone, iPad or most Android devices if you want that type of app. The content in LearnSetup.com is more up to date and will continue to evolve, where the setupworkbench.com app will not be evolving beyond its current form.

Quote:
Originally Posted by TurboT View Post
Hi Martin, diff question.

What effect does increasing or decreasing the weight of your diff oil have?

I was under the impression that decreasing oil weight (loosening) in the rear diff increases the rear traction on exit because it doesn't allow the outside tire as much spin or slip. It may not be as fast out but it allows it to hook up more.

In my current setup it calls for 2000cst but I find the rear wants to break loose on-power. Assuming I have the rest of the setup correct, would lowering the oil weight in the rear diff allow for more traction on-power, or do I have this wrong?

Cheers,
Tyler
Hey Tyler,

Yes you have that right. The thicker the oil in both the front and rear diff, the more on power steering you will have, which can lead to a loose condition if you go too far. The rear diff oil thickness will impact this more than the front diff oil thickness however.

So yes, if you have 2k in the rear, going to 1.5k or 1k will make the car less loose when existing corners.

Whew! A lot of questions to answer today! Awesome! All great questions.
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Old 04-01-2014, 08:57 AM   #254
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Thanks for all the replies, Martin! Awesome to continue to have your experience and expertise in setup for everyone to benefit from!
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Old 04-01-2014, 09:40 AM   #255
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Hey Martin.

My car starts neutral and balanced however during the course of the run the car slowly becomes loose to a point of indri ability.

Any ideas?
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