Autocross Alignment Specs

Suspension, including wheel, tire and brake.
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icehouse
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Re: Autocross Alignment Specs

Post by icehouse » 18 Feb 2018 12:14

Dang and 3.5 gears. I listened to Keith and swapped to 4.44's in my car. So much better at the track. I actually still want a close ratio trans though. 3rd is to tall still. I'm curious to hear how your car does.
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funwithmonkeys
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Re: Autocross Alignment Specs

Post by funwithmonkeys » 18 Feb 2018 12:18

With 3.7 you will need some pretty big power. I have 4.44 and am building up a 4.6. I went down to 4.11 for one of our drives and my car felt like it gained 500lb.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

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jeffball610
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Re: Autocross Alignment Specs

Post by jeffball610 » 18 Feb 2018 18:25

The results are in. I suck.

The autocross course today was a bit sketchy. Loose pavement and slow speeds. I don't blame the car, but it could definitely use an LSD and sticky tires. It was tough to get a read on the alignment, as any grip at the limit turned into understeer with my tires and the poor road surface. I was easy to go from grip to held oversteer (even with an open diff) when I did things right, so maybe something is working right. Time to gather more data and upgrade more parts.

Thanks for all of the suggestions. I learned a lot and hopefully others can use what you have shared in their own learning process.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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jeffball610
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Re: Autocross Alignment Specs

Post by jeffball610 » 18 Feb 2018 18:30

For those asking for more gearing and smaller tires, I don't see the need in my car. This is not strictly a track car. I have no issues spinning the tires all the way through 2nd gear with the limited boost I'm running. 1st gear is pointless at anything over 30% throttle unless it's completely straight. I hope to make more use of the power with better tires and an LSD. I'm also planning to run gear based boost control as soon as I figure out how to highjack the speed signal from the R154 for ECMLink to use. The stock signal comes from a reed sensor.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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funwithmonkeys
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Re: Autocross Alignment Specs

Post by funwithmonkeys » 18 Feb 2018 18:49

Look at the Yokohama A048's or A052 if they are 16's. As long as you are not driving in the rain they are amazing. I got almost 10000k out of my set of A050's.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

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cambo
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Re: Autocross Alignment Specs

Post by cambo » 18 Feb 2018 21:51

I would agree with the stickier compound, smaller diameter tire suggestions. A 205/45R16 tire would be almost 1" smaller, 23" compared to 24", and would offer you more clearance and better gearing. Sticky tires will change your thought about gearing as well. When I first got my turbo 510 on the road, with the old Bridgestone RE71's, first gear was worthless, and with a quick shift the car would bake the tires in third gear. I was thinking, with all this power, why would I want lower gears? Now I'm running BFG Rivals, and they are so much stickier, I have to really abuse the car to get the tires to spin in to third. Because the car isn't just spinning the tires when I shift, but laying the power down to the ground, I want to switch from my 3.70 gears to 4.11's to improve my acceleration.

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bertvorgon
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Re: Autocross Alignment Specs

Post by bertvorgon » 19 Feb 2018 07:18

Just as a comment, at the Slaloms...that clock always ticks.

No sense having eleventy seven million HP, when 150 will do. If you are spinning your tires, you are NOT moving forward. For me, what I found, in my 27 years of Solo, was tailoring the boost to the event. Best thing I ever did was put in an adjustable boost control in the car. I also would change my turbine housing ( smaller) for the slower and tight events. The boost would spool up in a heart beat and I would limit it to 10 - 12 PSI, which put me right at the traction limit of my race tires. That let me go to full throttle and be able to use my rpm range without going up in smoke and I had as good a throttle response as my best competitors naturally aspirated. Top end was never an issue at 99% of Solo events, so the restriction of the small housing was a non-event.

Many, many years ago, one of our top Solo competitors and math whizzes calculated that in a given competitive class, the difference in time was like 17", think about that. Wasting forward motion by spinning tires was a no go.

So, you are on the right track to fine tune the boost level. Making sure your launch is good is very important and getting that balance can be hard at times. Pay attention to how your car is set up, at the start line, in terms of where the first gate or cone is. Minimizing any additional turning input only unsettles the car.

As any turbo guy knows, when that full boost hits, it can be at the worst spot on a course. So making the car more like a naturally aspirated one is the key. I made sure all my piping was short and that my BOV did NOT open till greater than 16" of vacuum. That way when you are part throttling it, the system is still pressurized. which translates to throttle response.

Reality is too, that getting both the right rear gears and then a final tire diameter that really lets you use 2nd and 3rd to the max is what really works at most slaloms, at least from my experience on courses that were available to us. Minimizing shifting is key also, as that just unsettles the car and usually at the worst spot.

Good luck, keep us posted.
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1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
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jeffball610
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Re: Autocross Alignment Specs

Post by jeffball610 » 05 Mar 2018 20:57

Autocross using this setup. The surface sucked. The tires are all season. I'm not very good. I'm open to criticism.

https://youtu.be/smhBX35d-O0
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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duke
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Re: Autocross Alignment Specs

Post by duke » 07 Mar 2018 12:14

jeffball610 wrote:Autocross using this setup. The surface sucked. The tires are all season. I'm not very good. I'm open to criticism.

https://youtu.be/smhBX35d-O0
Don't really have any driving critiques, but I will suggest mounting your camera in a way that you can see what you are doing during the run. I mount mine so that I can see where I am looking and what I am doing in terms of steering input etc so that I can better analyze my driving. Just seeing the course only gives half the story in my opinion.
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bertvorgon
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Re: Autocross Alignment Specs

Post by bertvorgon » 07 Mar 2018 13:10

NOT a criticism, just a comment..

You have to be more aggressive, which is part of learning to solo. I know you said the tires suck but, learn with those, you need to be ON that throttle way more, to the point it feels like the car is going to either slide or break loose. As I watch that, and the guys here at work, who are racers...we all went.....STEP ON IT!!!!

I know, we are not in the driver seat but, as an instructor, I would have advised you to be more aggressive.....

Sometimes, the only way to lean the limit of both YOU and the car...is to spin out, that way you finally know where the limit is.

Part of Solo driving is being right on the EDGE, for the whole course, and only seat time will get you there and EXPLORING the outer reaches of the traction circle.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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RMS
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Re: Autocross Alignment Specs

Post by RMS » 07 Mar 2018 14:56

im at the other end of the spectrum.... too aggressive, sliding in and out of every corner. I may be slow but everyone said it was entertaining. lol

all winter I have been practicing "slow in" "fast out" and trying not to turn in before the corner..... I just need to keep telling myself: drifting is not racing
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jeffball610
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Re: Autocross Alignment Specs

Post by jeffball610 » 07 Mar 2018 15:59

bertvorgon wrote:STEP ON IT!!!!
Especially as I watched in the video, I realize I need to be more aggressive. I think I'm treating it too much like driving on the street, because that's all I've known to this point. As each run goes on, I do get more aggressive, but I know I have more in me.

I'll be on the same surface this Sunday, so we'll see if I learned anything.
1972 Datsun 510
7-bolt 4G63T, EVO 9 pistons & rods, Garrett GT3076R, "Flipped" Stock Intake Manifold, Toyota R154, Z31 R200 w/ CVs

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bertvorgon
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Re: Autocross Alignment Specs

Post by bertvorgon » 07 Mar 2018 18:58

Do not be afraid to use the brakes either. I found most new students did not really know how hard they could get on the brakes. Getting close to incipient lockup is a technique that can help steer the car also, that will be down the road.

Make sure you take some shoe polish with you and mark your tires on the side wall, just where the tread rolls over. That way you can see what the tire is doing and adjust tire pressures too.

Having your video is GOOD, that way YOU can review your driving as you have done. If there is a good driver there, whom you could maybe ask for some tips, watch your run, that really helps! My ego was never big enough that I did not want to ask where was I going wrong. That help me tremendously.

I also asked one of the top drivers at the time, to drive my car, just to see what it's potential maybe was and, it's short falls...I did listen to that too. He put 3 seconds on me.....so...I could not blame the car and need to be smoother and use my power, at the time, where it was advantageous, try to be aware of what your cars STRENGTH is, and maximize that on a given course. I became good at analyzing a course and where my car would be best, and then really concentrated on getting those parts right.

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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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icehouse
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Re: Autocross Alignment Specs

Post by icehouse » 07 Mar 2018 23:27

I agree with Duke! It's cool to be able to see the driver. I need to make a camera bar for my car as well.

This may not apply to the other guys but my car is fastest if I slide just a little through almost everything (THIS DOES NOT WORK IN THE RAIN). I like to carry to much speed into the corners, trail brake and use the extra speed to slide the back of my car around the cones, using a touch of throttle if I need extra rotation. The guys I race with say it looks like I bend my car around the cones haha. A regional SCCA autox champion shows up every once in a while at our event. it looks like he does the same thing with his S2k. I've tried to get him to ride with me. No luck so far. I also rev the piss out of my car. I've found in the slalom upshifting can help off throttle rear wheel braking. If I shift to 3rd gear I can't accelerate as much but I can carry speed a lot better. It's scary though. Our track has lots of walls. Some track layouts I can hit 70 through that area. A dude in a new Ford Focus RS looped in the other day and clipped his rear quarter pretty bad, bent his trailing arm too. :(
"People don't like it when shit doesn't match their rule of thumb." Sam

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