For those of you with tracks, how much time do you gain after a tuning session? I know it's probably different for each car, but do you have a rough estimate? Have you ever taken a car that runs smooth at 3" in 4', written down the time, adjust the steer to 2" in 4', confirm it runs smooth again, and then compared the time? If it was faster, by how much? If it was slower, by how much? I would only expect it to be slower if a wobble was introduced by reducing steer... but I'm not sure.
How much does over steering cost?
- Thread starter Minions Racing
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I can say that there is a gain by removing steer if you have too much of it. I do not profess to be an expert tuner, but at Nationals I had the chance to play around with the steer after the event was over. My car had an excessive amount of steer and by removing some I gained about .010 seconds. This was the first time I ever had a chance to tune on a track, as I do not own one myself. Now, I could not say this would be standard across the board, but I saw a gain. I'm sure it could be said the same if you had too little steer also. I'm sure others will chime in on this that have more experience in this area of tuning.
Once the car has its holes drilled and weights in place there will be set "best" steer for that car. My estimate is there can be .01 gain by using the bent axle steer vs drilling the hole for the DFW at a pre-set angle then using a straight axle. There will be also be a tendency that the the fastest cars will have the least amount of steer. That doesn't mean to always aim for 2-3 inch drift over 4 feet. A car could need a steer of 6 inches over 4 feet to reach maximum speed, but that car tends to be slower than another car that needs only 2-3 inches.
Wow, GravityX, .010 is quite a bit! What was your steer before and after your tuning session?
pony express, everything you said makes sense except why would a bent axle (with straight axle hole) be inherently better than a pre-drilled axle hole (with straight axle) if they use the same steer? I understand the bent axle is better because it allows you to fine tune your car to the optimum steer for that particular car. But if you had foreknowledge of the optimum steer and were able to pre-drill a canted hole it should be just as fast, right?
pony express, everything you said makes sense except why would a bent axle (with straight axle hole) be inherently better than a pre-drilled axle hole (with straight axle) if they use the same steer? I understand the bent axle is better because it allows you to fine tune your car to the optimum steer for that particular car. But if you had foreknowledge of the optimum steer and were able to pre-drill a canted hole it should be just as fast, right?
You're right that it should be the same. I tried drilling the exact angle for the DFW, but I could then take that same car and use a slight bent axle and fine tune it further. I used to drill the hole at 0.9 degrees with a cant of 3.75 and got consistent cars most of the time. You have to drill the back holes exactly the same. Drilling consistent holes has been described by the God Father and 5 Kids. You must have a good squared drill press. Even with a squared drill press you can still get inconsistent holes for lots of reasons. You can check how good your holes are by inserting a 6 inch drill bit into the hole and using a good quality machinist square to check the squareness of the hole. You can get great predrilled blocks from the God Father. I know everyone likes to drill their own, but you'd better square up your drill press and have a very good chuck. The higher the speed the less walking of the bit. You can use a centerline drills to help prevent walking. Colletts are better than chucks, but a good quality Jacobs chuck will be sufficient. The key then is having a perfectly square drill press. Getting it squared is another subject.
I thought one of the advantages of the silver bullet was to allow drilling of perfectly parallel holes even with non-square drill press because of the way you flip it from side to side without removing the car. But I can see the out of round chuck producing larger holes than necessary causing axles to not align perfectly when fitted in. Regardless, after trying to drill many myself, I can see that it is very difficult to get it right and can be worth it to buy them pre-drilled.
Anyway... I really wanted to get at how much time is gained by an average tuning session. Hearing GravityX and pony express say at least .010 is huge.
Anyway... I really wanted to get at how much time is gained by an average tuning session. Hearing GravityX and pony express say at least .010 is huge.
+1 on pony and gravityx, tuning board gets you close but finding that sweet spot can only be achieved on the track. And every car is slightly different on the amount of steer. That sweet spot for my builds seems to be between 2-3inches. but Ive heard other fast racers use a little bit more steer.
For me it seems the longer I tune a car the sower I make it. Usually if I can't get it where I want within the first few runs it's tare back down and see what I screwed up. A lot of the time my first pass down the track is the fastest. I'll start another post about my views on COM, wheel base, and steer. It is just going to take me awhile so when I get a extra hour I'll do it.
irvin said:
Looking forward to hearing your commentary on this subject QT. From what little I know, I'm still learning of course, but I was with the idea that a more aggressive COM often benefited from more steer. My cars are fairly aggressive when it comes to COM and steer. My SP is my favorite one right now, one bad run at Nationals messed up my chances to place better than I did, but that's racing. Anyhow, it's quick and has never been tuned, other than rolling it on my "tuning board" and I use that term loosely.
Irvin, the car in question that had the .010 gain, had over 12" of steer over 8'. I haven't checked how much steer it has after the tune, yet. Car still has some other issue that need to be worked out, but the steer was a major factor. Cars are still sitting in the boxes. I'll get to it when getting ready for the next event.
Quicktimederby said:
Irvin, the car in question that had the .010 gain, had over 12" of steer over 8'. I haven't checked how much steer it has after the tune, yet. Car still has some other issue that need to be worked out, but the steer was a major factor. Cars are still sitting in the boxes. I'll get to it when getting ready for the next event.
Irvin said:
I can sometimes get .005 out of a car during tuning, but usually like QT said I end up making it slower. In the first few runs I can tell if the car is good or a dud. I think that the more experience you have the less tuning you need. I am sure I could send a decent car without tuning at all these days, but not a couple years ago. I guess what i am saying is that I could put together a car badly that I could tune .010 out of it, but I know better. I think the amount of speed you can get during tuning is related to your build skill level.
I end up using the tuning board as a reference. I check my steer on the tuning board then send it down the track. If I'm not satisfied with the time I'll rotate the DFW bent axle run on the tuning board then send it down the track. I watch for what difference my times are doing in relation to the steer. I never aim for a set amount of steer.
Irwin: you're correct that the block helps even if the drill press table is not perfectly square to the drill bit. What happens if your table is not square is one of two things depending how you place the block. 1. both back holes will toe in or 2. both back holes will point in the same direction ie one is toe in and the other toe out. The best situation here as 5 Kids has said is #2. If your table is far from perfect then what happens is your back wheels steer more than you think. At extremes you would have to steer your DFW in the opposite direction to get to go straight.
Irwin: you're correct that the block helps even if the drill press table is not perfectly square to the drill bit. What happens if your table is not square is one of two things depending how you place the block. 1. both back holes will toe in or 2. both back holes will point in the same direction ie one is toe in and the other toe out. The best situation here as 5 Kids has said is #2. If your table is far from perfect then what happens is your back wheels steer more than you think. At extremes you would have to steer your DFW in the opposite direction to get to go straight.
I find this thread interesting (great feedback) but discouraging as well. I know there isn't a blueprint for automatically making a fast car, but I do believe there are integral steps to get you there. I also recognize buying all of the various products doesn't automatically = fast car.
But based on what I've been able to pick-up on this forum as well as others, I believe we had a car that had pretty much all the pieces of the puzzle in place. 2gram wheels, polished bores and polished axles, 1/2" COM, special oil, jig applied to axles, etc. Alignment was done on the dining table with 2.5" drift over 4', with zero toe on the rears, slide glide applied to body, etc.
We averaged 3.0078 in the scout class, and while I figured there could've been some more polishing done to the wheels, I figured that'd gain thousands and not hundredths. So I was figuring most of our gains could've been made by doing a better job on alignment if we had a track.
But I'm surprised to see feedback that final tuning may save a hundredth or so. So I'm kind of at a loss in terms of where to find 3 hundredths. We ran a long wheel base car without fenders, but it still it sounds like fenders = thousands. And I get it that a few thousands here and there will add up.
I hope this doesn't come across as a rant, especially from a new racer. But I do find myself kind of lost when I go out into the garage and wonder what I should focus on next considering I really believed we needed a track to optimize alignment.
But based on what I've been able to pick-up on this forum as well as others, I believe we had a car that had pretty much all the pieces of the puzzle in place. 2gram wheels, polished bores and polished axles, 1/2" COM, special oil, jig applied to axles, etc. Alignment was done on the dining table with 2.5" drift over 4', with zero toe on the rears, slide glide applied to body, etc.
We averaged 3.0078 in the scout class, and while I figured there could've been some more polishing done to the wheels, I figured that'd gain thousands and not hundredths. So I was figuring most of our gains could've been made by doing a better job on alignment if we had a track.
But I'm surprised to see feedback that final tuning may save a hundredth or so. So I'm kind of at a loss in terms of where to find 3 hundredths. We ran a long wheel base car without fenders, but it still it sounds like fenders = thousands. And I get it that a few thousands here and there will add up.
I hope this doesn't come across as a rant, especially from a new racer. But I do find myself kind of lost when I go out into the garage and wonder what I should focus on next considering I really believed we needed a track to optimize alignment.
You can't break 3 seconds unless the back wheels are perfect.
Without a track I'd shy on the oversteer to eliminate the bad wobble from understeer. Oversteer would be about 1.1 - 1.2 degrees.
Without a track I'd shy on the oversteer to eliminate the bad wobble from understeer. Oversteer would be about 1.1 - 1.2 degrees.
If it's any consolation, I ran the same COM, 2g wheels, slick pads on the body, etc. same as you, plus I have a track to tune on, and still only ran 3.0002 in the Scout class. I don't think steer was my problem. I had 4" in 42" and I ended up there by slowly taking a TINY bit of steer out until the car developed a wobble then adding a touch back in to clear it up. I drilled the rear axles at 3.5 degrees, maybe too much, but I think that the slightly nose high attitude of the body caused unintentional toe that I did not even know at the time to look out for. I still don't know for sure, but I'll be testing a few options before August. Hopefully I can get it figured out by then! Good luck to you guys!
4wheeldrift said:
In this thread DD4H reports and shows an increase in speed by shaving .005 -.010 off the times with the addition of fenders properly installed. Do not be discouraged with your results. Keep trying and tweaking your process, do not make too many changes at once or you'll never know what worked. With fenders you can have a sub 3.00 car, I did not make a sub 3.00 car my first time out.
I did not see any mention of how the body was drilled. A fast car starts out with a properly drilled car using the "Silver Bullet" or similar fixture and is key to alignment. Rolling your car on a tuning board or table top is the best you can do without having a track. I do not have a track and I just go with the "Trial by Fire" method each month. Jot down all specs before the race, send your car in, record specs upon return and make adjustments from there, this is where I am at right now. Print out your results after John posts them and write the specs right on that sheet for each car you send in. Again, this is what I do and I've seen increases each month and sometimes you will plateau. It's going to happen.
Keep at it and don't be discouraged, there are some guys here that have yet to break the sub 3.00 barrier and have been at it much longer than some, but yet they continue to send in each month reaching for the sub 3.00 badge. You'll get it I'm sure and when you do you'll be reaching for the next badge. Welcome to the addiction.
I did not see any mention of how the body was drilled. A fast car starts out with a properly drilled car using the "Silver Bullet" or similar fixture and is key to alignment. Rolling your car on a tuning board or table top is the best you can do without having a track. I do not have a track and I just go with the "Trial by Fire" method each month. Jot down all specs before the race, send your car in, record specs upon return and make adjustments from there, this is where I am at right now. Print out your results after John posts them and write the specs right on that sheet for each car you send in. Again, this is what I do and I've seen increases each month and sometimes you will plateau. It's going to happen.
Keep at it and don't be discouraged, there are some guys here that have yet to break the sub 3.00 barrier and have been at it much longer than some, but yet they continue to send in each month reaching for the sub 3.00 badge. You'll get it I'm sure and when you do you'll be reaching for the next badge. Welcome to the addiction.
I also have experimented with different cant in the back. 2.75 to 3 is about the same. Beyond that I found you had to steer harder to get any speed.
4wheeldrift said:
Don't get discouraged... There could be one little thing you are doing wrong that is scrubbing off a ton of speed..... We have all been there.
5KidsRacing said:
Most of the time the major loss in time is from prep. This is what I have seen with the new builders I have talked to. You think your doing everything just right but your missing one key step somehow.
Thanks everyone for the feedback and support. Believe me, I'm not under the illusion that speed will come overnight.
Regarding the idea about documenting the car details after each race, we'd started doing that with mid-America, but as discussed in this thread, you can have 2 cars with seemingly exact builds and one will run better than another.
Either way, I'm jonesing to get another car going for August. ;-)
Regarding the idea about documenting the car details after each race, we'd started doing that with mid-America, but as discussed in this thread, you can have 2 cars with seemingly exact builds and one will run better than another.
Either way, I'm jonesing to get another car going for August. ;-)
