How much does over steering cost?

4wheel,

There was not any special amount of track tuning done on my SS Scout car. I built it over the week prior along with polishing axles and doing wheel bores, put the wheels and axles in on Friday between noon and 1 and then off to Milwaukee we went. With that said, there is no doubt that you have to have a solid foundation to build off of(reference John's roll test before doing anything).

Here is where it gets interesting to me. I was only able to gain a couple thousandths out of 5 runs on the track(Also, I was a bit afraid to do any more tuning since the car was running good). After a Staging lesson from Quicktime, I am not sure that I tuned anything out of it. You can look at my national times which I was staging the cars versus SSPro Add1 - which was my car staged by QuickTime for a make up run for a missed car.

The big BUT is that my tuning table and the one available at the track showed drastically different results!

This immediately made me think that the rolling surface has a huge impact on drift. The next thing that came to mind was that possibly the slope of the table could have an impact on drift readings(not as convinced of this idea, but will test with my table/board).

If my slope test shows no difference, then in my opinion simulating the track surface should be a priority to get consistent results.

A slow roll against a center rail to check for dog tracking will also reveal a possible alignment problem that could cause rear wheel contact(which I understand is a major time killer).

I have much to learn in this area, as I hope I can get some more speed out of my car in this area.

Hope this helps some or is at least some brain fodder.
 
I've wondered this too, knothead. I remember reading an old thread where it was recommended to use a lot less steer on a wood track than on an aluminum one. I didn't understand why, but assumed it had to do with better traction/more friction on a wood track. I have no idea though, but it made me then think if I should use less steer on a wood tuning table.
 
I think the tuning surface is a legitimate factor. I was watching a street video the other day on another forum and the car looked like it wanted to swap ends. I was surprised at how slick the track surface was cause the car looked like it was on ice.
 
Here are my down and dirty quick test results.

Right front wheel dominate.

Test 1 - Slope
Took roughly half the slope out of the board - same drift results.

Test 2 - L-R Slant (left side high - opposing drift)
3/8" under elevated left corner
negligible difference in drift at 4'
appeared that it took a slightly different line but virtually same result at 4'

Test 3 - R-L Slant (right side high - favoring drift)
3/8" under elevated right corner
sizeable difference in drift at 4' - approximately 50% more

I would not take this as gospel - but I think it is legit.

This is where some pros advice comes in. You need to find what works for you and that is consistent.

My suggestion if you cannot simulate the track surface and your having trouble - would be to do the following.

Build a car with a predrilled block from John send it back to him for a tune. Then when you get this car home, immediately drift check it and use that as your starting point.

Or

If you have someone that has a proven car close to you, see if they will bring it over and let you roll it on your board so you can get a starting point.

That is the best I can tell you after rolling on my own board and then on the one at nationals.

I rolled my car on the board at nationals before I ran it on the track and that is when the concern set in, but I left it as is and put it down the track without any wiggles. If I had adjusted to my target number on the nationals board I think I would have had way too much steer.

So use caution when using someone else's numbers unless you are using the same surface as they are.
 
MERKIN THE WORLD!!!!
rofl
 
Not to drag up an old thread, but I had a warmed up car, twenty minutes to kill before work today, and I remembered this question on here. I ran the car in groups of five runs at steer settings of 4" in 24", 4" in 36", 4" in 48", 4" in 60", and finally 2" in 60". The results looked like this:

4" in 24" ave. time- 2.7244 std dev- .0012

4" in 36" ave. time- 2.7021 std dev- .0021

4" in 48" ave. time- 2.6962 std dev- .0009

4" in 60" ave. time- 2.6946 std dev- .0009

2" in 60" ave. time- 2.7084 std dev- .0169 (!)

On the runs set to 2" in 60" the car had the wobbles on most every run and the deviation reflects that. I did this test on a wooden track which I would say probably has more "traction" than an aluminum track and, therefore, doesn't need quite as much steer to keep the wobbles at bay.
 
Due to popular request, I reran the test but this time all steers are at 48". Apparently, some of y'all have a short tuning board. I did these as a four run average this time. At anything under 1.5" in 48" I had to delete a run or two from the session so what you see here is a "best case" scenario. Remember also, this was run on a wood track so you may not get the same results on an aluminium track.

OK, Here's what I saw:

Steer- 6 in 48- 2.7055 std dev- .0013

5.5 in 48- 2.7024 std dev- .0004

5 in 48- 2.7004 std dev- .0009

4.5 in 48- 2.6994 std dev- .0015

4 in 48- 2.6987 std dev- .0010

3.5 in 48- 2.6988 std dev- .0013

3 in 48- 2.6970 std dev- .0011

2.5 in 48- 2.6961 std dev- .0012

2 in 48- 2.6955 std dev- .0011

1.5 in 48- 2.6967 std dev- .0004
1 in 48- 2.7028 std dev- .0019

.5 in 48- 2.7099 std dev- .0039
 
Thanks for that bit of testing and write-up, Bracket. /images/boards/smilies/thumb.gif

We had our AGP race this weekend. I had spent a lot of time helping other kids (and leaders) get their cars prepped. As I was cutting my daughter's car, the blade on the bandsaw snapped. After getting the track set up on Friday night, I ducked over to my in-laws' house to use their bandsaw. This was ~7:45p -- the race was scheduled for 8:30a Saturday morning. I had the kids polish their wheels and axles, and pick out their paint colors when I took off for the track setup. I cut, filled with lead, covered, and painted two and half cars (I was hoping to get my Street Rod finished with AGP wheels and axles -- but quit when I realized it was a lost cause) completed in 6 hours.

We only mustered 3rd place. /images/boards/smilies/frown.gif After the races (and the reason for this post), I was able to do a quickie test and tune. First run, in the same tune it raced in, it ran a 2.60. After adjusting the steer (to less steer - sorry, no numbers) it ran a 2.58. Which would've won the whole thing. /images/boards/smilies/frown.gif

Long story short: Being able to test is invaluable. For me, testing was worth .02 s.
 
I'm extremely new at this derby stuff and only built our first railrunner this year. Without everyone sharing their experience on here we would be stumbling in the dark. We race scout races and that's all so far. I only want to encourage some out there that don't have a Block and lose sleep at night wondering how they'll figure out the alignment puzzle. I believe we got extremely lucky this year with our build. Here's what we did. 2nd place in Pack and 1st in Distrcits. Probably would not compete with the pros but a scout level it worked.

We use a simple axle hole jig to drill extended wheelbase and straight holes with the hand drill. I bent rear axles 1.5 degrees and front DFW to just under what will fit through the wheel hub. I think if the rears were bent more that it would be difficult to get it to run straight. We align on the kitchen table with a straight DFW axle first and get the rears to go the heads and the car to go straight. While doing this I held the car on its side so the rear wheel would lay against the head. I then eyeballed the rear wheel to confirm that it was parallel to the body.

Once it was running straight we installed the bent DFW and steered in 3 1/2" of drift with a COM of 3/4". It ran straight and came in 2nd to a car with 4 fenders at the Pack race. First heat we ran 3.00XX and the remaining three heats were under 3.0.

For Districts we moved COM back a bit and increased drift to 4". I had taken the wheels and axles out and installed non-prepped ones so my boy could have it on his table in his room for people to see. This meant realigning for Districts. Again on the kitchen table with one end of table raised 1 1/2". We added homemade rear fenders and this won us 1st place in Districts with times of 4.04-4.05 on a 46' track. Fastest time was 4.0448 I believe.

I have no idea how this would compete to the awesome cars I see pros making on here. For us, this hack job of a build and alignment process netted my boy some smiles.
 
Best thing to do is send it in. I was in the same boat you're in, wondering how it'll do and not having a test track you never know. So I made 2 and sent them in. I had an idea on how the punisher would do since Spirit helped me tune it, but my other car I had no clue. Trying to compare times on different tracks to John is almost impossible. You can estimate how close you'll be, but sending it in is so much more fun than wondering month after month how you'll do. If your car is slow or fast, it doesnt really matter to anyone that races. It's fun no matter what, and if you need help fine tuning or making adjustments there's a ton of people on here with knowledge that can help you along the way. Rome wasn't built in a day and QT I'm sure can vouge that he wasn't the fastest car on the track month after month (until this year). It'll take time, patience, a notebook and a good pen. Learn as much as you can and keep trying things. There's a TON of information here on the forum, but your first step is to send a car in and work from there.
 
Just to reiterate what we teach here on this forum. DO NOT BEND YOUR REAR AXLES. It is far more difficult to tune and in the grand majority of cases will slow you down. Some might get lucky but I promise they are few and far between.
 
bracketracer said:
Steer- 6 in 48- 2.7055 std dev- .0013

5.5 in 48- 2.7024 std dev- .0004

5 in 48- 2.7004 std dev- .0009

4.5 in 48- 2.6994 std dev- .0015

4 in 48- 2.6987 std dev- .0010

3.5 in 48- 2.6988 std dev- .0013

3 in 48- 2.6970 std dev- .0011

2.5 in 48- 2.6961 std dev- .0012

2 in 48- 2.6955 std dev- .0011

1.5 in 48- 2.6967 std dev- .0004
1 in 48- 2.7028 std dev- .0019

.5 in 48- 2.7099 std dev- .0039

Not to drag up older threads, but I ran a single car doing the same test and found too much over steer to be similar in the manner in which a car is slowed. At some point for the car I was using, adding an extra inch of steer increased the time by about .01, similar to what is shown above; but, the sweet spot on the car I was testing was much smaller, maybe only an inch or so. Too little steer really made me times suffer, sometimes by as much as .05 to point .1, with the rear of the car just banging against the rail all of the way down; it could be because of my cr*ppy build skills though. Being a novice, I found more steer to be better than too little, unless you have a way to test your car.
 
Makes sense that a perfectly aligned car would need less steer to maintain stability and every car has it's own sweet spot.