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Universal Starting Setup - How to.

Old 08-10-2015, 01:21 PM
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Default Universal Starting Setup - How to.

Here's a collection of racing wisdom that can be applied with our buggies, don't matter which brand or iteration.

Objective: To have better load distribution between the tires by having the suspension geometry have the job of keeping roll within acceptable range and maximise slip angle management at all possible times.

Step 1:
Let's start with a car that is already built and ready to run. First goal is to have level suspension arms as they help roll centre migration and therefore keeping roll in check. If your car doesn't have roll centre adjustment from lower arm chances are at least the rear arm is level with the axle, if not then axles level or slightly below level (the diff outdrives are lower than wheel centre) is preferred. If the car has roll centre adjustment from lower arm then the setting with the arm farther from the chassis while retaining arms level with the ground is a good start, if car is too skatey then go down one setting and increase ride height same amount. Anti squat can be the same as before but kick up (or pro lift) will be reduced, start by using one degree less.

If the car has such adjustment choose hinge pins high for high traction surfaces (HRC) and low hinge pins to low traction surfaces (LRC). A change in camber link hole is expected so try each change alone. Don't get hung up on certain ride height number, arms level with ground is the best start 99% of the time.

Ride height should be now set. Around 26mm front and rear sounds good.


Step 2:
The next step is setting roll centre height, for a safe to drive car the front upper link inner mounting point should be lower than the rear one. For example, the rear has 3 vertical positions you can choose, the front also has 3 positions so you pick the front lowest one and the middle one in the rear.

Step 3:
Setting camber link length and camber. As you know, more tire contact patch means more grip. Start by having less initial camber, like 1 degree and start with the inner shock tower holes and inner hub holes to have a medium length camber link that can grow or shorten depending of camber curve profile required by track constraints. If the front or rear shock towers don't have enough possibilities then the ones you picked in step 2 remain unchanged.

Step 4:
Let's finalize with anti squat and pro lift. One thing I learned recently is that you want as much anti squat as you can because it keeps the rear wheels from having too much camber during acceleration. Less pro lift mellows out the car.

Step 5:
Bump steer elimination. With the front wheels fully steered to the right side and lock the front right wheel with your hand so it doesn't steer and work your suspension up and down. If when you press down the chassis the left steers more to the right that's bump in and really makes the car twitchy and nervous. If it doesn't noticeably steers or steers less then it's bump out and a preferred steering geometry. Too much either way is bad of course.

Step 6:
Whatever shock package the manual told you to build, if it has larger hole in the rear pistons than the front even better. Use the tires the fast drivers use at your track.


Now with this starting setup the car should be driving quite well and have more load transferred between the front tires (meaning the first tire to lose grip are the fronts because they will reach the to much load first), regarding step 3 sometimes more static camber and less camber gain (longer upper link or arm) works better. Try for yourself without getting lost. The most important objective is to manage slip angles and tire load.

There you go, your car has a general setup that works anywhere and is a good starting point.

Last edited by 30Tooth; 12-18-2016 at 03:52 PM.
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Old 08-10-2015, 07:36 PM
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This is an interesting thread. In step one, you're saying you want to have the rear lower arms parallel to the axles by using the rear inner hinge pin bushings? And I assume parallel with the ground? Can you further explain the benefit of this? Also wouldn't ride height and, if your car is equipped, the rear hub height have a lot to do with the axle being parallel?
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Old 08-11-2015, 06:55 AM
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Originally Posted by My ST-RR EVO
This is an interesting thread. In step one, you're saying you want to have the rear lower arms parallel to the axles by using the rear inner hinge pin bushings? And I assume parallel with the ground? Can you further explain the benefit of this? Also wouldn't ride height and, if your car is equipped, the rear hub height have a lot to do with the axle being parallel?
Thank you.

Yep, if possible both arm and axle parallel to ground. I mentioned inner hinge pin bushings because some cars don't have adjustable rear hub height but it's the same outcome really. Mugen cars have both adjustments for example.
About why it's better to be this way, you gain more control over roll center migration (it doesn't wander as much leading to a much more composed/planted car) and you get rid of most of axle induced behaviour like axle bind where the CVD wants to straighten itself and stiffens the suspension.
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Old 08-13-2015, 09:18 AM
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Objective: Tuning from low to high traction tracks and vice versa.

To further explain ride height by having arms parallel to ground picture this:
Let's say the rear end is at 30mm ride height when it has the rear arms parallel to ground, if you need to lower it now that you are running at a very high grip fast track the procedure would be: change inner hinge pin bushings to high roll centre or whatever setting moves the hinge pins closer to diff outdrives or change hub height to have parallel arms again, move the rear inner camber link up a hole in the shock tower to have roll center height at the same place as before and done. The car is x mm lower and still has parallel arms and the big benefit in this situation of less roll moment because you lowered CG but kept RC height the same (instead of lowering RC and CG and in the end just messing things further). Hope this helps.

Conclusion: Lower CG and less roll couple to make the car roll less and therefore manage camber in a more transparent way.

Last edited by 30Tooth; 12-18-2016 at 03:55 PM.
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Old 08-14-2015, 12:29 AM
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Can u go into some detail and explain how and why axle bind happens?

How many millimeters of ride height lowering would warrant raising the rc at the lower arm and lowering it on the tower to match and then off course raising the hub? Hopefully 1 or 2mm would be negligible. Most pros just adjust the spring collars.
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Old 08-14-2015, 12:51 AM
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Btw, I try a lot of different set ups on my car to try and get more out of it. Starting with my preferred rear suspension geometry, I eyeballed the angles of the rear arms and axles. Inner part of the rear arm was higher than the outer part. The axle sat lower at the diff than it did at the hub. I tried your set up method and re-did the whole rear end. With just making the arms and axle parallel I couldn't get the car to perform right. The rear was way to loose to drive comfortably and led to a lot of mistakes. However, once I raised and extended the rear link, it all came together and I was very satisfied with the new geometry, mostly the car's ability to be punched out of a corner. Now I'm not saying the car was necessarily any faster in the overall race distance than it was in the 3 prior race weeks, but not slower either, just different. However, having said that, I think I'm going to stick with it for a while. Thoughts?
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Old 08-14-2015, 08:52 AM
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Originally Posted by My ST-RR EVO
Can u go into some detail and explain how and why axle bind happens?

How many millimeters of ride height lowering would warrant raising the rc at the lower arm and lowering it on the tower to match and then off course raising the hub? Hopefully 1 or 2mm would be negligible. Most pros just adjust the spring collars.
Not much detail but axle bind happens when there's a variation in axle shaft angle, the pin sides slide in and out of the slot and with more grip at the wheel the more it binds. If the axle shaft was straight the pin sides wouldn't slide and therefore friction would be zero.

Bellow 2mm I wouldn't worry about it, now if your car has bushings that allow increments in 2mm, why not?

Originally Posted by My ST-RR EVO
Btw, I try a lot of different set ups on my car to try and get more out of it. Starting with my preferred rear suspension geometry, I eyeballed the angles of the rear arms and axles. Inner part of the rear arm was higher than the outer part. The axle sat lower at the diff than it did at the hub. I tried your set up method and re-did the whole rear end. With just making the arms and axle parallel I couldn't get the car to perform right. The rear was way to loose to drive comfortably and led to a lot of mistakes. However, once I raised and extended the rear link, it all came together and I was very satisfied with the new geometry, mostly the car's ability to be punched out of a corner. Now I'm not saying the car was necessarily any faster in the overall race distance than it was in the 3 prior race weeks, but not slower either, just different. However, having said that, I think I'm going to stick with it for a while. Thoughts?
Thank you for giving my method a shot! The changes you've made might be "better" for a couple reasons, you mentioned punch out of corners and that's my feelings too (hence I called it starting setup, because it's traction biased), the new rear end geometry might enable you to run different shock package/front end geometry or have less wheelspin or stay planted even in most extreme conditions. Small things that add up.
Now where it gets difficult to explain, changes in roll center height are different depending where they are made. Changing the bottom arm inner bushings or inner camber link position is a bigger change than hub height or outer camber link position. The outer camber link position is the best place to tune camber gain because it almost doesn't mess with RC height, that's why upper hub positions are spaced up and down further than shock tower positions, which overlap. The D815 has 4 different hub heights and 7 inner arm bushings right? That's a lot but you don't need all, pick those that allow arms to be parallel at the ride height you run the most.
In your case, lowering the inner arm bushing or raising the hub lowered RC height and with the upper link changes moved it to where it was before while having parallel arms, roll couple should be less and the rear has less influence in the front end, unlocking some setup possibilities.
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Old 08-15-2015, 01:11 AM
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So the prevention of axle bind translates to more traction?

Step 4- I understand how more anti squat would reduce squat which would reduce camber gain especially if a short link is used, but then the true function of anti squat is eliminated. That doesn't seem right. Maybe a longer link and less initial static camber would be a better idea? Really it's all a balance though isn't it?
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Old 08-15-2015, 04:40 AM
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Originally Posted by My ST-RR EVO
So the prevention of axle bind translates to more traction?

Step 4- I understand how more anti squat would reduce squat which would reduce camber gain especially if a short link is used, but then the true function of anti squat is eliminated. That doesn't seem right. Maybe a longer link and less initial static camber would be a better idea? Really it's all a balance though isn't it?
With less axle bind come a more fluid car, the suspension doesn't fight the inputs received. I've driven cars with dog bones, CVDs, universals and once you drive a car with less axle bind you can feel it.

Objective: Reduce rear camber gain to keep the tires vertical with the track on acceleration.
In your example when the car accelerates with short camber links the wheels gain camber, if you use more anti squat the pitch motion is less but you maintain camber gain in roll because anti squat has negligible influence in roll.
Conclusion: Separating both functions and where they work the best takes days of testing. Balancing all this is very difficult because you can have high and low speed turns with or without bumps, off camber turns and all in the same track, but once you find the happy medium it's just tiny adjustments here and there from track to track.

On my way to the track, going to test some stuff

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Old 08-16-2015, 12:17 AM
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On the front of the car the relationship between the arm, axle and diff is not nearly as adjustable. Hub height is fixed (on my D815 anyway), but the knuckle has a total of 2mm of up or down adjustability with in the c-hub. Is that the right adjustment to make the axle parallel with the arm? There aren't really any other options.
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Old 08-16-2015, 07:25 AM
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Originally Posted by My ST-RR EVO
On the front of the car the relationship between the arm, axle and diff is not nearly as adjustable. Hub height is fixed (on my D815 anyway), but the knuckle has a total of 2mm of up or down adjustability with in the c-hub. Is that the right adjustment to make the axle parallel with the arm? There aren't really any other options.
That's fine and nothing wrong with it. I think the d812 had this geometry in the front. Word of caution, keep an eye in bump steer, yesterday testing showed that adjustment has a big effect in handling.
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Old 08-17-2015, 12:50 AM
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Step 3- as I mentioned, I do a lot of my own testing. I've heard the saying, "shorter tracks, shorter links. Longer tracks, longer links." Have you found this to be true? It seems to me that once you find the right link length it works everywhere, barring something extreme.
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Old 08-17-2015, 05:50 AM
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Originally Posted by My ST-RR EVO
Step 3- as I mentioned, I do a lot of my own testing. I've heard the saying, "shorter tracks, shorter links. Longer tracks, longer links." Have you found this to be true? It seems to me that once you find the right link length it works everywhere, barring something extreme.
Sort of, Ryan Lutz said in a tuning guide that low traction - short links and high traction - long links, which is about the same because we are tuning overall response. My testing also shows that when you found a link length that isn't twitchy or lazy for you it works almost everywhere.

Another thing I've learned in the last testing session, once you found a general ride height, lowering or raising the front 1-2mm is enough to change substantially overall steering.

* 26/8/2015 edit * the more I think about this the more evident is that I struck in equal or almost equal roll couples front and rear, any tiny adjustment changes one way or the other and that's why I can tune so much with a turn in the ride height adjusters.
I didn't mentioned anti-roll bars because I'm still testing these out but start without them and see if one end rolls more than the other. /edit

Last edited by 30Tooth; 08-26-2015 at 07:42 AM.
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Old 11-30-2015, 03:24 PM
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Objective: Showing outdrive wear with a car tuned by me.
One more thing to add now that I've been running my cars like this since a while. Check those outdrives with at least more than 2 gallons. Having less axle bind the drivetrain becomes way more efficient and stuff lasts considerably more time.
Conclusion: Diff oil tuning has a lot to do with it, on the other hand this car has much less wear on the rear diff outdrives than others. Still, less axle angles and plunge provides less wear.
Attached Thumbnails Universal Starting Setup - How to.-img_20151130_143138.jpg   Universal Starting Setup - How to.-img_20151130_143146.jpg  

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Old 11-30-2015, 05:33 PM
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What point are you making with the outdrive photos? They look like they're in really good shape especially for 2 gallons!
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