Theory thread

[95shaw]

In light of recent questions on threads, seems like a worthy discussion.
No need to give secrets, just discussion.

I find by simply talking, I can learn a lot more than being told.
Thoughts?

[95shaw]

By the way,

Thanks to those who always contribute, without being condescending.
I'm sure I am not alone in this.

[Kromulous]

Headed to PRI Saturday, really interested in these position dependent shocks. Also i seen Bilstein is supposed to have some new SLM shocks really interested in seeing them as well. Along with very high compression LRs.

Theory stuff, what about Axles. I see a lot of the Strange Oval axles for sale, various sizes etc. Anyone care to share some experience with these?

Also i wonder what the Sanctioning bodies are going to do on the Rules for 2019, any big changes coming down?

[Krooser]

The guys I know say those Strange axles are great for lightening your wallet...

[billetbirdcage]

Headed to PRI Saturday, really interested in these position dependent shocks. Also i seen Bilstein is supposed to have some new SLM shocks really interested in seeing them as well. Along with very high compression LRs.

Theory stuff, what about Axles. I see a lot of the Strange Oval axles for sale, various sizes etc. Anyone care to share some experience with these?

Also i wonder what the Sanctioning bodies are going to do on the Rules for 2019, any big changes coming down?

It's been fairly quiet on any rules changes as far as Lucas or WoO, so I really don't expect any real changes coming.

Axles: I'll take a stab at this one. Now granted this is opinion and have some guys running different sized axles per recommendation of the chassis manufacturer but I haven't tested back to back actually changing them so. . . .

Now, I don't doubt you can slightly change the car in the middle with different axles sizes (wrap up of the axle) but I'm not buying what is said about them at least one part: More wrap (smaller diameter axle) adds forward drive.

1. If cushioning or allowing more wrap in the axle adds forward drive, then why doesn't a softer 5th coil add forward bite?

2. If that wrap up helps, then what happens when you hit a slick spot. . . .? A guy could argue that when that happens it un-wraps and causes higher wheel spin, think about it. If it wraps up and then loses traction it has to unwrap and then rewrap back up, seems like a vicious cycle to me.

3. If wrap is true, then why aren't we still using the "SHOCKER" rubber drive flanges from the mid 90's still. . . . ? That whole craze was from Bill Frye and mind games, funny story.

Things that make you say hmm

[fastford]

i agree with you billet , but maybe they act sort of like the old leaf spring did , you could get some unreal forward drive with them ....

[Burke1118]

Headed to PRI Saturday, really interested in these position dependent shocks. Also i seen Bilstein is supposed to have some new SLM shocks really interested in seeing them as well. Along with very high compression LRsAny luck with this? I haven’t had any..

[hucktyson]

Those “ wrap up axels “ were the ultimate marketing scheme. Since they came about we have seen more broken axel DNF than ever before ...

[RaceEngineer]

You want a "wrap-up axle"? Try titanium. About half the spring rate. Not sure where you install a shock to control the unwrap though. Lol

[fastford]

that is why i never bought into them RE , its obvious the wrap up could gain traction , but on dirt , the uncontrolled wrap up and wrap down would take away any benefit....JMO....

[Kromulous]

PRI Show was great, new Bilstein Shocks are really nice looking. They have double, triple adjustable, and a IDA style and Canisters. ASI-R i think was the new designation but still looking for the right info on them.

Wrap axles, sounded like snake oil but just thought i would ask. We just run solid axles.

I will say out of all the PRI stuff i talked too the Penske people was the most interesting. Also talked at length to Hyperco about the springs, and stacks.

[billetbirdcage]

Generally the best advice I can give to a struggling team or one that just isn't up to speed is:

1. Stick with the basics. If you have reasonable equipment for where your racing, then work on the basic's like making the right calls on adjustments for the car thru the night, getting good and accurate feed back from the driver (this includes realizing when you are being told the wrong info, more common then you think), and if the problem is driving related. Driving issues could be as simple as running the wrong line, inducing problems, or being to aggressive or not enough, and Etc.

2. Once your able to consistently run upfront, then you can start looking at other areas to find speed but most of the time, guys aren't getting all of the speed out of their equipment they have even with very basic set ups.

3. Crew, this is probably where most are severely lacking and don't realize it. A good crew guy that actually watches the car and not the race is a HUGE plus, especially when it comes to handling problems. Many many times that crew guy can give info that driver can't and can be used to identify when the driver is feeling or misreading the car.

4. Testing, too many people try to solve problems from race to race. You can't tell crap (IMO) from a change to the car when the track is different the next time you on it. This includes from a heat race to the feature, you have no idea how much you actually changed the car or was it mostly the track that made the car different or not. Knowing how much basic changes/adjustments does to the car and if the driver can even feel them during a private test session, will go a long ways on the driver knowing if that is the right change and if it's too much or not enough and more needs to be done. YOU WILL LEARN MORE IN 6 HOURS OF A PRIVATE TEST THEN YOU WILL IN A YEAR OF RACING. Least if you have a good track and make full use of your time.

Just my thoughts

[Jking24]

Generally the best advice I can give to a struggling team or one that just isn't up to speed is:1. Stick with the basics. If you have reasonable equipment for where your racing, then work on the basic's like making the right calls on adjustments for the car thru the night, getting good and accurate feed back from the driver (this includes realizing when you are being told the wrong info, more common then you think), and if the problem is driving related. Driving issues could be as simple as running the wrong line, inducing problems, or being to aggressive or not enough, and Etc.2. Once your able to consistently run upfront, then you can start looking at other areas to find speed but most of the time, guys aren't getting all of the speed out of their equipment they have even with very basic set ups.3. Crew, this is probably where most are severely lacking and don't realize it. A good crew guy that actually watches the car and not the race is a HUGE plus, especially when it comes to handling problems. Many many times that crew guy can give info that driver can't and can be used to identify when the driver is feeling or misreading the car.4. Testing, too many people try to solve problems from race to race. You can't tell crap (IMO) from a change to the car when the track is different the next time you on it. This includes from a heat race to the feature, you have no idea how much you actually changed the car or was it mostly the track that made the car different or not. Knowing how much basic changes/adjustments does to the car and if the driver can even feel them during a private test session, will go a long ways on the driver knowing if that is the right change and if it's too much or not enough and more needs to be done. YOU WILL LEARN MORE IN 6 HOURS OF A PRIVATE TEST THEN YOU WILL IN A YEAR OF RACING. Least if you have a good track and make full use of your time.Just my thoughtsYou hit the nail on the head billet especially in reference to the crew guy what happened with the guy running third is in no way helping you unless your running fourth and you probably already know what happened to him. But now days more so than ever. With the attitude of the race car being so important a good crew guy watching just two or three key things can make all the difference in the world. And most racers are always looking for speed secrets when they struggle with fundamental adjustments. One thing i hear alot is a guy say I'm to tight but everything he tells you he did adjustment wise made him tighter. Yet he does them week in and week out. When asked why he does those things he ays their just keeping up with the race track

[fastford]

billet , your no. 1 & 3 reminded me of a young driver i was trying to help , i could see him turn the wheel left , then right in the turn , he argued with me the car was not tight , he was 100% positive the car was loose , so i put the ole piece of white tape on the steering wheel and guess what , he made three laps , came back in with a big old grin on his face and said " your right , what do we do? " that piece of tape will help a young or inexperienced driver more than any thing . I also told another driver to put the tape on and he never would , 3 years later , he is still making the car loose so it will turn and still running in the back........

[ZERO25]

billet , your no. 1 & 3 reminded me of a young driver i was trying to help , i could see him turn the wheel left , then right in the turn , he argued with me the car was not tight , he was 100% positive the car was loose , so i put the ole piece of white tape on the steering wheel and guess what , he made three laps , came back in with a big old grin on his face and said " your right , what do we do? " that piece of tape will help a young or inexperienced driver more than any thing . I also told another driver to put the tape on and he never would , 3 years later , he is still making the car loose so it will turn and still running in the back........

I liked to use the neon green color, you could see it very well, esp from the infield!

Unlike drivers, the steering wheel NEVER lies! lol

[95shaw]

Was looking at the lr spacer thread.
Curious about the theory of sharter axle tubes and 2 off wheels versus standard wheels and axle tubes?

[billetbirdcage]

Was looking at the lr spacer thread.
Curious about the theory of sharter axle tubes and 2 off wheels versus standard wheels and axle tubes?

Not sure about now, but bloomer used to run a 2" shorter axle RR tube then you would for a 5 off wheel so he could use a 3" off wheel. This kept everything the same but put the caliper and rotor outside the wheel for less heat to RR tire and wheel for 100 lap races. Obviously it also allows to suck the RR in easily with a wheel offset change, I think they do make a 6" off wheel but they aren't stocked at weld (IIRC).

[fastford]

who makes the new "tornado" spring for the left rear that is about 80 lbs and like 16 inches long , its 5 inches at the top and 2 at the bottom . caught a glimpse at one today.......

[Kromulous]

Swift makes that spring, see em a lot on cars now.

We're on to the Testing deal this year, i agree with Billet. Just to hard to gain speed racing, during a race a night. You have to come to the track with your stuff ready to rumble now days. So we're planning a couple Testing nights this year.


I wonder how much that RR wheel flexes over a 5" offset?

[fastford]

TST has been pretty good the last couple years about leaving the track open after the last race for a short practice session , provided its not one of those long , drawn out nights. If you want to bring your car out before you jump strait into a race and make some laps or just finished the feature and want to make a change and go right back out to see what it did , i think its great........Hope they keep it up.....

[95shaw]

Swift makes that spring, see em a lot on cars now.

We're on to the Testing deal this year, i agree with Billet. Just to hard to gain speed racing, during a race a night. You have to come to the track with your stuff ready to rumble now days. So we're planning a couple Testing nights this year.


I wonder how much that RR wheel flexes over a 5" offset?

The wheel flex was the reason for my asking about the theory.
I guess everything is a compromise.

[Kromulous]

Personally i like idea, you have a lot of options at hand with the offsets, and still get the brake cooling, which i never even thought of as a benefit LOL.

[billetbirdcage]

Personally i like idea, you have a lot of options at hand with the offsets, and still get the brake cooling, which i never even thought of as a benefit LOL.

I've done it on some rear ends just to allow more testing (shortening axle tube 2"), however depending on your set up and cages you may not be able to remove 2" and still have the cage the same place from the center section (basically removing the 2" or whatever from between the snout and the cage/brake bracket). Also on RR it's pretty easy to get the tire into the lower part of the 4 link bracket if on a fast track due to tire flex, so you really need to pay attention before trying it. 1" is doable on many chassis with tame on j-bar but 2" rarely works as far as sucking the RR inboard. Also it's hard on some cars to go out on the RR without the body rubbing the RR tire statically

I just used wheel spacers instead of offset on wheels as it just to easy for someone to make a mistake on wheels and where they go.

[CCHIEF]

I recall the days of 3"s and 5"s on Masters cars, what a friggin pain in the azz.

[Kromulous]

Sounds like its a classic saying i use here at work all the time, It sounds good on paper...

Packaging on that RR would be pain.

[95shaw]

The reason for this thread is to dispel some of the monkey see, monkey do, things.

They will always be there.
Knowing what is the actual theory behind the pieces, help to make better choices..

Maybe???
Lol.

[JLyons]

billet , your no. 1 & 3 reminded me of a young driver i was trying to help , i could see him turn the wheel left , then right in the turn , he argued with me the car was not tight , he was 100% positive the car was loose , so i put the ole piece of white tape on the steering wheel and guess what , he made three laps , came back in with a big old grin on his face and said " your right , what do we do? " that piece of tape will help a young or inexperienced driver more than any thing . I also told another driver to put the tape on and he never would , 3 years later , he is still making the car loose so it will turn and still running in the back........Fill me in on the “wheel tape” the rule if thumbs and what you are looking for to be able to do for it to be “on kill”

[Matt49]

On the steering wheel tape:
As a driver, almost everything you do in the car is by the seat of your pants and gross motor skills. There is very little "thought" going into it. The wheel tape paints a picture that you otherwise would not see. Regardless of what I "feel" or what I "recall" doing in the seat, if I'm at the center of the corner and that wheel tape is at 10 o'clock, the car is TIGHT. You can't argue with that. But without the tape, you CAN argue with that and a driver will tell lies to even himself.
The wheel tape and the final location of the brake bias adjuster is the ultimate driver lie detector kit.

[fastford]

thanks for explaining that matt, i could not decipher post 27 very well......

[JLyons]

Haha I just re read my post and couldn’t really decipher it either, sorry guys haha and yea I understand that, I would think it would be though to rely on that because your wheel location in the center depends on your entry and how on the “throttle tight” you are and how much you are on/off the gas.I would like to put some on mine just to see, I know it’s gonna show tight because I like a tighter car, but that’s something I want to work on is getting more comfortable with a car that’s a little looser then what I have preferred.

[Highwayman]

This is a great thread.

[RocketManNINE]

While we are talking about theory. I am having a hard time wrapping my head around the fact that I can give my shock guy my shocks and he can smash them and give them back to me and I can go racing without ever putting my car on scales. Wouldn't there be a difference if one of my drivers is 225 lbs. and the other one is 165 lbs.? I am just having a hard time understanding how this is possible. Please help with the theory.

[fastford]

if you have consistent ride heights with the driver in the car , then it dont matter how much they weigh , when you send the shock man your shock length,s at ride height , he can put you on the numbers on the smasher , or at least mine can , its really about providing your shock guy with accurate info ......

[Kromulous]

I think the key as with all race car set up is to be consistent. Same fuel, same led, same, same, same etc etc. In the shop i even considered having set up tires, same set every time. I have been also looking at replacing the Driver, with led shot, 200 lbs worth just to be more consistent. Ive wondered as well, why even have the Driver weight in there? Same Driver all the time? then why mess with it. I did this for years with Modifieds, but changed with SLMs, not sure why LOL.


Here lately i have been making charts of the 4_link indexing effects on the shock length changes. Since running a limiter chain there is a impact when you move the 4 link rods around on how much shock drop you have. Sometimes upwards of an inch difference. That will make a big impact on the load numbers at full droop. My question now is do i want that increase or do i reset the load after i change bars locations ?

[RocketManNINE]

So let me put this theory into play. I scale the car and give my center to center measurements to my shock guy. Now by theory I do not have to put my car back on the scales the rest of the year. So now I go and run it and my chassis flexes (because by theory the biggest spring on the car is the flex of the chassis) so now how do I know that my bite has not changed? Also with all these steel left rear birdcages what are people doing to get the left side weight back down to a reasonable percentage without getting the overall weight to a high amount?

[Kromulous]

Good point, i think that is why CBR was putting new cars on a shaker and simulating 6 races. The mounting points will change from new i would imagine. Affecting all sorts of measurements.

[billetbirdcage]

So let me put this theory into play. I scale the car and give my center to center measurements to my shock guy. Now by theory I do not have to put my car back on the scales the rest of the year. So now I go and run it and my chassis flexes (because by theory the biggest spring on the car is the flex of the chassis) so now how do I know that my bite has not changed? Also with all these steel left rear birdcages what are people doing to get the left side weight back down to a reasonable percentage without getting the overall weight to a high amount?

You will change the LR bite if you:

1. Change stagger
2. Change stagger on front
3. Move a single bar on car, because most brackets on the LR are not at the right hieght.
4. Add or subtract fuel
5. You get the idea.....

That being said: If the car is moving around/flexing that much, then you have other problems. But putting on scales once in a while with a set of scale tires and everything the same will help you find issues for sure.

However you can just check the pin to pin measurements with the car on the ground (obviously everything has to be the same and on a level or same surface it was all set at. But if something is off then the pin to pin will be off with the correct smash numbers. Meaning if 17.5" on RF is the ride hieght with the smashed coilover on the car, then if it's off or any other corner of the car is off, then you have a problem or something bent.

As far as heavy LR components everyone is gonna be different but years ago when I started doing it, we measured the difference in left %. Meaning if I was 54.5% left and added 40# to LR axle, then the new % was 55.1%. At first we did not lower the %, because the car still see's the 54.5% left as dynamic roll. Some will lower the % and some won't, it's what works for you mostly.

[MasterSbilt_Racer]

While we are talking about theory. I am having a hard time wrapping my head around the fact that I can give my shock guy my shocks and he can smash them and give them back to me and I can go racing without ever putting my car on scales. Wouldn't there be a difference if one of my drivers is 225 lbs. and the other one is 165 lbs.? I am just having a hard time understanding how this is possible. Please help with the theory.

You cant fix left side percent no matter how much you twist on the shocks. The driver difference has to be adjusted with weight placement.

[MasterSbilt_Racer]

So let me put this theory into play. I scale the car and give my center to center measurements to my shock guy. Now by theory I do not have to put my car back on the scales the rest of the year. So now I go and run it and my chassis flexes (because by theory the biggest spring on the car is the flex of the chassis) so now how do I know that my bite has not changed? Also with all these steel left rear birdcages what are people doing to get the left side weight back down to a reasonable percentage without getting the overall weight to a high amount?

Some sanctions increased minimum weight by 50# since learning of the heavy lr trend.

[95shaw]

Was reading the bump steer guage post, and had a related question

Dou you set toe with the rf on the bumpstop? And lf on tether?

[Austin34471]

Was reading the bump steer guage post, and had a related question

Dou you set toe with the rf on the bumpstop? And lf on tether?

Do you race with the car there or at ride height?

[95shaw]

Do you race with the car there or at ride height?

So, can we say the need to check bump steer is effectively eliminated, as long as toe is optimized, on the bump, and near tether?

Maybe offer some insight on benefits of bump steer guage with this setup.

[billetbirdcage]

Lets say a few thing for the sake of discussion:

So if you set toe at .5" out statically like most measure it, then it is what it is at the dymanic. Lets say that this is at the ideal toe out of .75" (making up a number). Does it really matter whether which way you measure it, it's still at the ideal .75" toe out.

How much toe out is perfect? lets just say it's .75". What is or how much does the toe change when you steer? Is it still .75"? How much Ackerman the car has will effect how much this changes.

No matter how you measure it, it's a reference point. Sure knowing the dynamic toe out can be useful if you going to alter stuff to have a different toe's between static and dynamic and anything in between that the car see's. However if your just adjusting the toe without altering anything else that changes the toe curve or Akerman then you can just adjust the toe what ever amount you want from either state and see if it helps the car. But doing it from static is a hell of a lot easier.

Using my first paragraph dimensions which are the exact same thing just measured different ways and both will measure the same in the other state, so what did you gain by making it harder to measure by going to the dynamic state after you did it once just to know that number?

.5" out static wheels straight
.75" out dynamic wheels straight

if you alter either states measurement a 1/4" more out you still end up with this:

.75 static
1.0" dynamic

[Austin34471]

Lets say a few thing for the sake of discussion:

So if you set toe at .5" out statically like most measure it, then it is what it is at the dymanic. Lets say that this is at the ideal toe out of .75" (making up a number). Does it really matter whether which way you measure it, it's still at the ideal .75" toe out.

How much toe out is perfect? lets just say it's .75". What is or how much does the toe change when you steer? Is it still .75"? How much Ackerman the car has will effect how much this changes.

No matter how you measure it, it's a reference point. Sure knowing the dynamic toe out can be useful if you going to alter stuff to have a different toe's between static and dynamic and anything in between that the car see's. However if your just adjusting the toe without altering anything else that changes the toe curve or Akerman then you can just adjust the toe what ever amount you want from either state and see if it helps the car. But doing it from static is a hell of a lot easier.

Using my first paragraph dimensions which are the exact same thing just measured different ways and both will measure the same in the other state, so what did you gain by making it harder to measure by going to the dynamic state after you did it once just to know that number?

.5" out static wheels straight
.75" out dynamic wheels straight

if you alter either states measurement a 1/4" more out you still end up with this:

.75 static
1.0" dynamic
Agreed. As long as you know both static and dynamic at some point for reference. Another fun thing to think about is.. put say 700# on the RF wheel and turn it 20deg. Put say 200# on the LF and turn it 20 deg. (Weights replicating how much weight is on each corner on corner entry). Where are both of the contact patches actually pointed? 🤔 Some road course cars run anti Ackerman because the outside tires contact patch turns at such a delayed rate compared to the inside/less weighted tire.. and their tires are much less floppy than ours

[95shaw]

Agree with both above posts.

My point was , as long as the ideal toe is achieved dynamically, bump steer becomes largely irrelevant.
Provided the front suspension stays on the bump and tether.