small 1/4mile oval tips, transitioning from road racing

[mod88s]

Get your shakin hand warmed up because I do the same thing every week. I talk to many of my buddies week to week bouncing new setups and ideas off of each other. For example, if I tried something and it helped my car to turn better through the middle of the turns, I could tell my buddy what changes to make and guess what?? It helps his car turn better through the middle as well! We don't have to weigh the same, or have the EXACT same ride heights, or have the EXACT same wheel weights, or have the EXACT same bar angles. The general effects are the same no matter what brand of car you are in. If I tell a guy to raise his right side lower bar to 10 degress from 5 degrees, I know it is going to loosen up his entry. Im sure thousands of racers around the country chat with all their racing buddies and share info, do you think they have the exact same ride heights/bar angles/wheel weights? So it really is comparing apples to apples. The reason car builders tell you to do things a certain way IS BECAUSE THEY HAVE EXPERIENCE AND KNOW WHAT THEY ARE DOING. At least most of the reputable ones anyway.

[Bcollins82]

Get your shakin hand warmed up because I do the same thing every week. I talk to many of my buddies week to week bouncing new setups and ideas off of each other. For example, if I tried something and it helped my car to turn better through the middle of the turns, I could tell my buddy what changes to make and guess what?? It helps his car turn better through the middle as well! We don't have to weigh the same, or have the EXACT same ride heights, or have the EXACT same wheel weights, or have the EXACT same bar angles. The general effects are the same no matter what brand of car you are in. If I tell a guy to raise his right side lower bar to 10 degress from 5 degrees, I know it is going to loosen up his entry. Im sure thousands of racers around the country chat with all their racing buddies and share info, do you think they have the exact same ride heights/bar angles/wheel weights? So it really is comparing apples to apples. The reason car builders tell you to do things a certain way IS BECAUSE THEY HAVE EXPERIENCE AND KNOW WHAT THEY ARE DOING. At least most of the reputable ones anyway.

Why is this concept so hard to grasp? Yes, adjustments work the same from car to car for the most part. But we aren't talking adjustments, were talking about what gets everyone on the most accurate and consistent baseline to have a good starting point to make adjustments from. If your buddies car is identical, but he starts off higher on LS percentage, has more wedge, more rear percentage, and less LR bar angle with him in the car because he's bigger than you, the same springs, shocks, and bar angles won't start his car off balanced like yours, it will take adjustments from where you began (even though your numbers were identical on the scale) to get his car working like yours when he could've avoided the tuning session and just started there to begin with by scaling with the drivers weight in the car... It's very simple. Track time is expensive, scale time isn't... And you still haven't explained to me how you get on an even starting point car to car without driver weight... that IS what we're talking about as we hijack Robs thread, right? Lol

[mod88s]

I have explained it several times, go back and read my posts. You are just too stubborn to see it. Im gonna say it one last time. No matter if you have driver weight in car or not, you go by what the manufacturer tells you to for a starting point/baseline setup and tune from there. If they tell you scale with driver in car, then do it that way. If they say no driver, 15 gallons of fuel, then do it that way. THAT IS YOUR BASELINE SET UP, TUNE FROM THERE. Its that simple. Give your car what it needs after that. Period. End of story. Just because a guy is a little heavier or a little lighter than you DOES NOT MATTER, IT DOES NOT MATTER, because the concept you are missing here is that ITS JUST A BASIC STARTING POINT AND YOU TUNE FROM THERE. The manufacturer gets you in the ballpark, the rest is up to you. I get your point that "what if the other guys weighs more than you, then you wont have the same ride heights/bar angles etc..." but the point you are missing is that IT DOESNT MATTER. IT DOESNT MATTER. EACH DRIVER HAS A DIFFERENT DRIVING STYLE, RACE ON DIFFERENT TRACKS ETC... You get a starting point, and go from there.

[Bcollins82]

Lmao Listen, you can get mad an TYPE IN CAPITALS all you want, but you've never explained why doing it your way is more consistent. That's because it isn't. I can explain why driver weight is more consistent, and give examples, but no matter how many times I explain it, and explain why, you will refuse to see it that way because that is how you've always done it. I'm not being stubborn, I have valid fact based points. Your argument is a chassis builder is there to get it halfway close, consistent ride heights and wheel weights as you roll on the track mean nothing, and let you figure it out from there... lol Of course you'll have to tune and adjust to track condition and driving style, why add having to tune from starting off base from the other guys that run the same cars? That's absurd. There's a better way for any chassis builder to start everyone from a more consistent platform to make information sharing more effective. Period.

[mod88s]

Not once have I said scaling without driver was MORE consistent. However I believe that it is just as consistent as scaling With driver. And Im definitely not mad, I was just trying a different affect to help you see my point, but it didn't work. I should have listened to stock car driver, you are still trying to get your point across about driver weight affecting ride heights/bar angles which I have ALREADY AGREED WITH YOU on, but for some reason keep trying to get that point across. You cant seem to move off that point and look at what Im trying to explain to you. You can twist and distort what Im trying to say to you but the fact remains that more races have been won by scaling cars without driver, and that's a fact. Im enough of a man to stop arguing at this point and I will just agree to disagree on your basic premise that scaling a car with a driver is better than scaling without. And my point remains, one way is not necessarily better than the other.

[Bcollins82]

Cute couple ^^^

Hahaha! Oh yeah, that dude loves me. Sorry to Rob Burgoon for the thread hijack, I've made my point, I'm done.

[rob burgoon]

Rob, I feel at times i was in the same situation as you and here is what i've done. My car is a 4-link imca mod. We always run on dry slick. I too ran a 602 although I did not have to. My track was 1/3 mile moderately banked D. I ran 5:29 gears and would hit the rev chip at 6200 on occassion. Not too often but every now and then. Why? Cause my overall setup was bad, I was spinning the tires and in expierenced. I really think you would be fine going to atleast 5:29 gears and a 6200 chip. As for setup, I was out to lunch pretty much every race. Its taken me close to 4 years to get the car dialed in mostly cause it was home built and I was knew. Finally a fella started helping me who was the only other guy that ran a metric clip, with metric lowers and metric spindles. The last few races have been night and day and the car is a million times better. I too had an underslung car and was hitting it. I cut that right out of there probably 2 years ago now. We just put an additional bracing bar from the tail section up. As for setup, what these guys are saying is right on the mark. Ride heights slightly higher on the left than right. if you have a chevelle clip 850 is way too high. Thats a spring for a metric clip with metric lower. The differnet clips and lowers have different motion ratios due to their length. One last thing, when the new fella started coming over to my garage and wanted to make all these changes that i just thought where bizaar I was really put off by it. The more I got to thinking I said to myself, we have 3 races left, I'm not racing for points. What do i have to lose? So we threw every change at it he told me to do and my god, I'm so happy i did.

Thanks ask! Yeah, I coming to believe the 602 can do 6200, I'll switch the gearing for that at some point. On this last practice I discovered that there are some bumps at the end of the back straight, and also if the rear grip is kinda bad, the rear tires can spin in something like a controlled fashion and have the tach steadily climbing, but reading 1,000 high compared what the ground speed should be.

I think you are right, a modest shortening of gear and rev limit extension together is probably the ticket.

The 850 spring went on just as a experiment to answer 1: what happens if I try the old factory setup? and 2: can I make this thing push?

[rob burgoon]

Hahaha! Oh yeah, that dude loves me. Sorry to Rob Burgoon for the thread hijack, I've made my point, I'm done.

No worries.



Did a test on friday, I some of the parts I ordered haven't arrived yet and temps have been near 100 lately, so not much happened in the garage since you gave me the list of suggestions. I have some schedule conflicts coming up so wanted to get out there. Had fresh rears on hand as spares, but ended up using up the old inventory AND I believe I managed to learn something on the dying rears.

DISCLAIMER: What follows are my theories, they may or may not be correct.

Even though the droop chain isn't in place yet, your suggestions got me thinking about the role that a limiter plays in on throttle handling. Specifically, what happens when you run out of LR travel. When that happens, any additional attempt by the axle to apply force vertically attempts to stretch the chain instead of lifting the car. I suspect this means that as you raise the LR upper bar, you will reach a point where raising it further won't seem to tighten it much more. It might lift the back of the car faster, but once it gets there, there's no additional bite for the LR to tighten the car.

Since I wasn't able to lengthen the travel before the test, I figured I'd do the next best thing, drop the RR upper a hole and decrease the load on the RR as well as decreasing the roll steer.

Even on rear tires that were starting to look thin, the ability to mash the gas and have the car go straight-ish was noticeably improved. The car was much more drivable in the black slick on exit. I suspect that extending the chain without the change to the RR upper would have been similarly effective.

As I mentioned in the previous post, I was feeling carefully for wheelspin this time and was noticing subtle wheel spin as the rears wore, eventually getting to the point where they would zing, but before that, slipping in a sneaky fashion. A somewhat shorter gear is in my future.

Sessions 1 and 2 were dry and a mix of brown and black, featured improved handling at full throttle, and periodically a death push would occur off throttle or slight throttle (probably the 850 spring and RF height). During this session to avoid the push by keeping the rear up I started getting fond of putting weight on the nose under braking, shifting the weight over from the nose to the right side in a smooth motion. I think I'm starting to see what you're getting at about having the RF softer and the car leaned to the right slightly when sitting still.

At this point I dropped the RF ride height an inch, to get closer to your suggested ride heights and see what would happen. The session 3 the rears started spinning on exit due to loss of tread on the LR, and the offthrottle push had gotten milder.

I wanted to ditch the 850 spring, but didn't have time so I figured I'd retest the last change with less-dead tires.

Sessions 4 and 5 felt that the off throttle push was indeed reduced, but it's difficult to be certain since I was still rotating lots on entry.




Conclusions:
Your suggestions seem good. I should try more of them.


My setup theories:
Trying to change on throttle handling with RF spring isn't that effective.
Trying to change on throttle handling with cross/bite isn't that effective.
Trying to get a push by raising LR upper stops working at a certain point.
Change the rear bars to make on throttle behavior changes.
Rear bars settings tune "dynamic bite" between the rear tires under power.
Rear ride height and springs *might* not matter much (indexing could play a role with LR spring, don't understand it yet)
Handling can be split into at least two states: on throttle, off throttle. On uses bars and a subset of the springs, off uses cross weights and all springs. My on throttle handling is ok, I need to fix the off. Going back to softer RF spring will probably help.

Known unknowns:
What the heck does a floating LR brake do? The physics makes my head hurt. I need to draw a picture or something to try to understand it.

"That's racing":
This morning I learned that at the current ride height, when backing off the trailer the oil pan will catch the trailer bringing the car to an abrupt halt. F&*#!

[rob burgoon]

Videos available upon request. If anyone is curious to see a particular session, I'll upload it.

[Bcollins82]

No worries.



Did a test on friday, I some of the parts I ordered haven't arrived yet and temps have been near 100 lately, so not much happened in the garage since you gave me the list of suggestions. I have some schedule conflicts coming up so wanted to get out there. Had fresh rears on hand as spares, but ended up using up the old inventory AND I believe I managed to learn something on the dying rears.

DISCLAIMER: What follows are my theories, they may or may not be correct.

Even though the droop chain isn't in place yet, your suggestions got me thinking about the role that a limiter plays in on throttle handling. Specifically, what happens when you run out of LR travel. When that happens, any additional attempt by the axle to apply force vertically attempts to stretch the chain instead of lifting the car. I suspect this means that as you raise the LR upper bar, you will reach a point where raising it further won't seem to tighten it much more. It might lift the back of the car faster, but once it gets there, there's no additional bite for the LR to tighten the car.

Since I wasn't able to lengthen the travel before the test, I figured I'd do the next best thing, drop the RR upper a hole and decrease the load on the RR as well as decreasing the roll steer.

Even on rear tires that were starting to look thin, the ability to mash the gas and have the car go straight-ish was noticeably improved. The car was much more drivable in the black slick on exit. I suspect that extending the chain without the change to the RR upper would have been similarly effective.

As I mentioned in the previous post, I was feeling carefully for wheelspin this time and was noticing subtle wheel spin as the rears wore, eventually getting to the point where they would zing, but before that, slipping in a sneaky fashion. A somewhat shorter gear is in my future.

Sessions 1 and 2 were dry and a mix of brown and black, featured improved handling at full throttle, and periodically a death push would occur off throttle or slight throttle (probably the 850 spring and RF height). During this session to avoid the push by keeping the rear up I started getting fond of putting weight on the nose under braking, shifting the weight over from the nose to the right side in a smooth motion. I think I'm starting to see what you're getting at about having the RF softer and the car leaned to the right slightly when sitting still.

At this point I dropped the RF ride height an inch, to get closer to your suggested ride heights and see what would happen. The session 3 the rears started spinning on exit due to loss of tread on the LR, and the offthrottle push had gotten milder.

I wanted to ditch the 850 spring, but didn't have time so I figured I'd retest the last change with less-dead tires.

Sessions 4 and 5 felt that the off throttle push was indeed reduced, but it's difficult to be certain since I was still rotating lots on entry.




Conclusions:
Your suggestions seem good. I should try more of them.


My setup theories:
Trying to change on throttle handling with RF spring isn't that effective.
Trying to change on throttle handling with cross/bite isn't that effective.
Trying to get a push by raising LR upper stops working at a certain point.
Change the rear bars to make on throttle behavior changes.
Rear bars settings tune "dynamic bite" between the rear tires under power.
Rear ride height and springs *might* not matter much (indexing could play a role with LR spring, don't understand it yet)
Handling can be split into at least two states: on throttle, off throttle. On uses bars and a subset of the springs, off uses cross weights and all springs. My on throttle handling is ok, I need to fix the off. Going back to softer RF spring will probably help.

Known unknowns:
What the heck does a floating LR brake do? The physics makes my head hurt. I need to draw a picture or something to try to understand it.

"That's racing":
This morning I learned that at the current ride height, when backing off the trailer the oil pan will catch the trailer bringing the car to an abrupt halt. F&*#!

1. You are correct on LR upper angle. That is why most people suggest 45 degrees of angle at maximum droop. After that seems to be the point of diminishing return.

2. Lowering the RR upper will do exactly what you were thinking. Try to keep vertical separation at the chassis around 14 to 14.5" that's just a starting point, but farther apart causes the RR to feel stiffer, closer together and the RR feels softer.

3. I disagree with the RF spring not being an effective way of changing on throttle handling. It plays a large role because that is what the LR is shoving against as it picks up and transfers weight, so it affects chassis attitude, and how easily the LR is able to get up. So it definitely is an effective way to tune. That's why it's usually the first question most racers will ask each other.

4. Changing on throttle handling with cross is effective. A small change in static cross weight isn't as dramatic as changing bar angles. Once you get everything closer, its a very effective way of tuning.

5. Rear ride height and springs are very important. I feel the LR spring on a 4bar spring behind is really only used as a tool to get the LR up more quickly/easily (softer) if you need it. The RR spring is very important, as it tunes entry by making it tighter as you stiffen it, it has a large influence on side bite, and exit because the rate of the spring can change RR drive/loading not only straight through the spring, but it can also change the RR thrust angle because of dynamic ride height changes. You learned in your test that changing the RR bar angles can make a drastic change in handling, and ride height goes hand in hand with those angles. That is why they are so important to keep consistent.

6. A LR floater applies force to the chassis through braking energy, keeping weight over on the RF, and keeping the LR from settling as far on entry braking.

[rob burgoon]

6. A LR floater applies force to the chassis through braking energy, keeping weight over on the RF, and keeping the LR from settling as far on entry braking.

Drew the picture. This checks out. Sitting outside of the LR tire looking at the tire and brake with the brake fixed to the axle, the tire rotates CCW, the brake exerts force CW, the reaction on the brake caliper mounts (the axle) is twisted CCW.

With a brake floater, the reaction force on the floater is still CCW, if you attach it on top using an upward inclined rod, wham-bam you're now attempting to lift the rear end using the brake pedal. Clever.

[Bcollins82]

Run a bar 2" longer than your upper 4 link bar, and run it parallel to your upper 4 link bar. The floater rod has a lot of force on it so they can over center or "cam over" the longer rod elimates that trouble.

[rob burgoon]

1. You are correct on LR upper angle. That is why most people suggest 45 degrees of angle at maximum droop. After that seems to be the point of diminishing return.

I don't think 45 is the limit I'm running into. Once you use up your travel, *clang* the axle smacks into the limiter (undertube in my case). Once this happens, changing the static angle on the LR bar to be steeper won't change much. When the clang happens, the angle on the bar could be 30, 35, 45, but none of those should be very different other than how fast the rear of the car came up.

Adding more droop travel should allow the clang to occur later and for more dynamic LR bite from the "vertical force".

[Bcollins82]

I don't think 45 is the limit I'm running into. Once you use up your travel, *clang* the axle smacks into the limiter (undertube in my case). Once this happens, changing the static angle on the LR bar to be steeper won't change much. When the clang happens, the angle on the bar could be 30, 35, 45, but none of those should be very different other than how fast the rear of the car came up.

Adding more droop travel should allow the clang to occur later and for more dynamic LR bite from the "vertical force".

That's correct. No more dynamic loading if its against a travel stop and staying there no matter what spring, shock, or bar angle you have in the LR. You effectively make the LR solid on throttle. Watch your LR in the under car video you posted before. The LR stays pretty much solid on throttle. The RR is the only one moving as you are on throttle. That is why LR drop is a very critical and effective adjustment on these cars.

[Toywagon]

I want to throw out something, even tho it is slightly bringing up the gear ratio topic again......

I run on mostly flat and medium banked 1/4 bullrings. Almost all of them go to dry slick, or even dusty slick at times.

I do not gear for maximum power/rpm/mph at the end of the straightaway on these bullrings. IMO having the most mph or track speed at corner entry isn't as much of an advantage as being able to drive from mid corner and off with a bit deeper gear as well as being in a better rpm range etc.

I do not like changing gears on a 9 inch either. During hotlaps, and if we manage to get a tacky track for heat races, I just lift up off the throttle slightly as I near the end of the straight away if I run up on the chip. I don't lift much, just enough to let the engine stop climbing or just banging on the chip.

IMO on these bullrings, it just works better for me to get from the middle of the corner to mid straightaway better than the other guys. Maybe something for you to try when you put the 6.20 in and it gets on the chip too soon.

Jim