At track chassis tuning guides

[joedoozer]

I have a feeling that this thread might get out of hand......but here goes, lol.

I am still learning the workings of the 4 link. Finally getting the handle on a good base line to take to the track. I have had a pretty good track record of adjusting the car to changing track conditions. I have 2 "cheat sheets" I use to decide what to change on the car, I don't have the confidence to make a change without confirming it at this point lol.

This one
http://www.larryshaw.com/printablesetupsheet.pdf

and this one (kind of big)
http://www.afabcorp.com/exp/files/re...cle_tuning.pdf

For the most part I use the Afco one, but I like the format of the Shaw one, it's easier to look through and compare changes. But there are differences in both guides. Wedge for example and LLB too. Is the Afco guide more accurate? Should I stop referring to the Shaw one?

On another note. I am just bouncing ideas around in my head here. Generally speaking increased bar angles means increased load to that tire. On Left Side bars the increased angle increases the load on the LR, and also roll steers the LR forward. Is it safe to assume the forward drive added to the LR out weighs the added roll steer? I have made a LUB adjustment before to tighten the car on exit before. That means more load to the LR. And the added roll steer wasn't enough to cause a loose condition.

I keep notes on how the adjustments effect the car. But I like having the guide to turn to when I need it. I am just wondering what one is correct and what one should I take out of my book.

[joedoozer]

Raising the LLB on the frame would add more roll steer than the upper bar, because it's shorter. That would loosen the car. Maybe I answered one of my questions myself haha.

[MasterSbilt_Racer]

Raising the LLB on the frame would add more roll steer than the upper bar, because it's shorter. That would loosen the car. Maybe I answered one of my questions myself haha.

The effect to the spring rate is the bigger deal here. It effectively stiffens a spring behind.

[MasterSbilt_Racer]

None of these guides can always be right. Style of track, style of driver, car's attitude before adjustment, and many other variables come into play. You really have to understand vehicle dynamics to get it right most of the time. I say most, because sometimes a change may cause the car to take an entirely different attitude than expected and you will then be wrong.

[joedoozer]

The effect to the spring rate is the bigger deal here. It effectively stiffens a spring behind.

I thought the more the B/C indexed the more it effectively stiffens the spring. I can't seem to picture a bottom bar doing that if you raised it on the chassis. Not if the spring is behind. Maybe I am seeing it wrong in my head.

[MasterSbilt_Racer]

I thought the more the B/C indexed the more it effectively stiffens the spring. I can't seem to picture a bottom bar doing that if you raised it on the chassis. Not if the spring is behind. Maybe I am seeing it wrong in my head.

When you compress the lr below ride height, a more-angled lr lower will cause the birdcage to rotate more counter-clockwise. This loads the spring more for a given wheel movement. This means the wheel rate will be stiffer.

[MasterSbilt_Racer]

Or if you look at the lr during droop travel, it causes the birdcage to rotate more clockwise. This unloads the rear spring faster. A spring that unloads quickly during a small amount of travel is stiffer than one that takes a lot of movement to unload.

[joedoozer]

When you compress the lr below ride height, a more-angled lr lower will cause the birdcage to rotate more counter-clockwise. This loads the spring more for a given wheel movement. This means the wheel rate will be stiffer.

hmmm going to have to think about this somemore.

[TALON75]

doozie- never forget K.I.S.S. ! I make bar adjustments based on a simple concept that the lower bars=steer bars, upper bars=drive bars. If you need more steer raise either lower bar(conditions will sometimes determine which side it should be), if you need more drive raise the bar on which side you need to drive more, reading tires really helps to determine this, BUT... gotta also understand what the driver is doing to the car, ie. sliding too sideways on entry, spinning them on exit,ect. Also I believe the Shaw guide is all you really need at the track, simple basic ideas for quickly tuning the car, the Afco one is for studying during the week to better understand the complete package of how the car needs to work, but a bit complicated for quick reference . Good Luck !

[joedoozer]

doozie- never forget K.I.S.S. ! I make bar adjustments based on a simple concept that the lower bars=steer bars, upper bars=drive bars. If you need more steer raise either lower bar(conditions will sometimes determine which side it should be), if you need more drive raise the bar on which side you need to drive more, reading tires really helps to determine this, BUT... gotta also understand what the driver is doing to the car, ie. sliding too sideways on entry, spinning them on exit,ect. Also I believe the Shaw guide is all you really need at the track, simple basic ideas for quickly tuning the car, the Afco one is for studying during the week to better understand the complete package of how the car needs to work, but a bit complicated for quick reference . Good Luck !

My main concern was the differences between the 2 guides. Afco says decreasing bite will loosen the car, Shaw says that will tighten entry. Is it because Afco lists it under the "on throttle" sections, and Shaw is assuming you are off throttle on corner entry?

[MasterSbilt_Racer]

My main concern was the differences between the 2 guides. Afco says decreasing bite will loosen the car, Shaw says that will tighten entry. Is it because Afco lists it under the "on throttle" sections, and Shaw is assuming you are off throttle on corner entry?

That is correct. Talon's assertations are also okay as long as you are talking about a traditional setup with lr behind on floater and rr ahead on floater. You wil usually get the correct answer, but sometimes for the wrong reasons. The reason raising the lower and raising the upper are different is because of what they do to the spring rate. They effect the thrust angles the same.

[joedoozer]

That is correct. Talon's assertations are also okay as long as you are talking about a traditional setup with lr behind on floater and rr ahead on floater. You wil usually get the correct answer, but sometimes for the wrong reasons. The reason raising the lower and raising the upper are different is because of what they do to the spring rate. They effect the thrust angles the same.

Traditional set ups right now. Nothing clamped, stacked or bumped. Good to know that the Shaw guide assumes you are off throttle on corner entry. I think that clears up any confusion in the 2 guides.

[sj valley dave]

We learned that after dealing with corner entry! After a few conversations with Skip Arp and Joe Garrison we finally got it figured out that bite and corner entry totally depended if we were on throttle or off throttle...Now the driver is getting in more in an "on throttle" deal so we can adjust accordingly..We are on a traditional setup also, so like Talon posted, bottom bars are "steering" upper bars are "drive" ...

[jedclampit]

One to make you boys think.....use your guides, wisely!
OK, you have a car that is up all the way on bars thru mid corner and off , all lr travel/drop is used, will raising the lr upper bar @ frame make the car tighter or looser off corner,with same drop? Why?
MBR save your reply for later!

[drtrkr244]

One to make you boys think.....use your guides, wisely!
OK, you have a car that is up all the way on bars thru mid corner and off , all lr travel/drop is used, will raising the lr upper bar @ frame make the car tighter or looser off corner,with same drop? Why?
MBR save your reply for later!

Every car that I have worked on inc, Mastersbilt, Rockets, Warriors, Snow Bros., raising the LUB always increased forward bite.

Put your car on scales , raise LUB, and look at the change, and thats in a static state!

[sj valley dave]

We have raced our DLM on pavement and even when we chained down the LR to keep rear steer out, which you do not want on pavement to the degree we do on clay, when we added LUB angle we increased the drive off the LR tire...

[MasterSbilt_Racer]

One to make you boys think.....use your guides, wisely!
OK, you have a car that is up all the way on bars thru mid corner and off , all lr travel/drop is used, will raising the lr upper bar @ frame make the car tighter or looser off corner,with same drop? Why?
MBR save your reply for later!

I will stay out. I see where you are going with this. But I am not sure it would come into play unless I was helping Don O'Neal.

[TALON75]

I say tighter, you are increasing drive angle on the lr even if the drop is staying the same that will increase load on the lr . You will also index more into the spring, but you said it is always on the bars so at that point the spring has little to no effect( at least on the one I work on!) , you also do get a little steer out of it but not as much as raising the lower that is why I say the lowers are for steer and the uppers are for drive, they both do both jobs really but with different affects .

[jason29a]

The Afco guide is written by Mark Bush... And it really gets in to detail. But he will tell you that when adjusting your car you have to think of when, where, and what. On the throttle and off the throttle and braking are two differnent things. LRU bar angle will increase loose roll steer and may require an extra adjustment to counter act it. But your on the right track with your thinking. No matter what adjustment you are making always think of what its doing to the car at the tires and how its affecting the contact patch.

PS... Kevin Shaw and Mark Bush are thinking alike, there just explaining different

[jedclampit]

Handling will be looser, more steer no increase in drive angle. Very useful on fast, momentum tracks.
Increased angle will help get/keep car up, but once up against limiter, more angle adds steer, therefore looser handling.