some auto-X vids from today

I was about 6 seconds back from the fastest time of the day and 9th overall out of 30 entries. I was within about 1.5 seconds of 5 of the guys who finished in front of me and the others just blew the field away by a huge margin.

I won ESP again but it was just me and the caddy CTS-V you see in the video in that class. I usually take him but he's getting closer and closer with every event. I suspect he'll be beating my by next year 

Came into the stop box at about 95km/h with cooked brakes on this run - almost DNF'd
(stop it at 2:30)


From inside the cab on a previous run - both within about a tenth of second or two of one another

Awesome, thanks for the ride along 

I switched to vimeo because photobucket was being a beeotch but I have no idea to how to embed their vids here.  Anyway, here are few more from the event I ran last night.  The second one isn't a great angle but I had a good powerslide into the stopbox 

https://vimeo.com/45584193

https://vimeo.com/45584194

A few vids from a 3 day slalom event I ran this weekend.  The course was almost exactly 1 mile long.  Placed 3rd in FSP, ~3 seconds back and the two cars ahead of me were on slicks.  My front tires (Toyo Proxes T1R's) were actually showing cords by the end of the second vid so there's a lot of room for improvement (especially when I eat 2 cones near the end of the second vid  )

https://vimeo.com/47111519

https://vimeo.com/47111517

Man does that thing roll, we have to figure something out for you. What's your alignment set to up front?

Alignment is -0.5 camber, +5 caster, 1/8" toe in.  I could use a bit more negative camber but it's a delicate balance between chewing up the inside or the outside of the tires.  -1 was too much but - 0.5 is not quite enough. I don't want to go any stiffer with springs so a custom swaybar is the only option.  Roll doesn't feel bad on course but I'm sure it'll get worse when I put slicks on it. 

Tires are always #1, nail down the size that will fit, then the tread/compound, then air pressure and alignment to get even tire temperature.

With your problems with your locker being scitzophrenic, I'm back to thinking an electric locking diff with either a control box or just a manual button to control it is the way to go for Auto-X.

IMHO, you can either get a custom bar bent up, or go to a full nascar style bar, and if the rules for your class will allow it, the Nascar style bar will have a LOT of benefits.

I replaced the G80 with a Torsen earlier this year so the rear diff is about as good as it can be for the moment.  Having the diff built cost far too much money to go back and screw with it now. 

It's fun to win in ESP/FSP but I really don't care much about class rules.  I just want it to be as quick as possible in the end.  I have some maintenance issues and little things to take care of first (including front tires so it will pass safety inspection).  After that I'll try to get my 'vette brakes on and start looking at slicks.

I'm currently shopping for some cheap 17x9's (f-body or older 'vette) and will run 275/40 R-compounds all around. I don't want them staggered (like my current ZO6 setup) - I need to be able to rotate them front-to-back to get the most wear out them.

Even though I've always bought them used, tires eat up a lot of my budget during race season so mods tend to take a back seat this time of year. Realistically I spend >$600/year in tires when I average it out.  When it comes time to get slicks I'll probably look into scrubs - they're about $100/tire with 75% tread left.  I run at least 15 events/year so I need to do things on a budget.

A few more pics from a pro photographer that was at the last event, H. Merklinger

You're lifting the inside tire, more front swaybar isn't going to help without rear swaybar to help push that tire back down.

In theory that works but in practice it always results in much slower lap times.  I've done back to back comparisons with and without the rear swaybar on multiple occasions and I'm consistently quicker without it.  I've run something like 80 auto-x events in the last 5 years so I have a pretty good feel for beneficial changes in the truck's setup. 

I have much finer control over the rate of roll in the rear by changing shock settings than I do with the rear swaybar.  I did ~10 test and tune runs on the first day of this event and I almost exclusively tinkered with rear shock settings to see if I could improve things.  The pics you see have the settings that gave the best compromise between traction on corner exit and handling feel (with a strong bias toward understeer).  Adding the rear swaybar instantly causes oversteer - it's flashy and fun to drive but it's slow. 

I'm intentionally trail-braking in the longer turns of the top 2 picks to load the outside front and rotate the rear.  That's something that I also played with in the test and tune and it seemed to help.  For comparison's sake, the mustang below ran the fastest street car time at the event and the suspension looks to be loaded in a similar way to the truck's - it just has a lower ride height to start with (and slicks, and power, and a good driver...)

You're lifting the inside tire, more front swaybar isn't going to help without rear swaybar to help push that tire back down.

i disagree and agree with rentedmule.
bigger front bar is what you want to control the roll. or maybe experiment with a higher roll center up front as well if you dont want to sacrifice ground clearance. lowering CG while maintaining RC would be better to start though.

i still disagree with tuning the shock before settling on the springs (including bar)
yes the shocks are the easiest to tune on track, but those should be one of the later things to play with. even if you get a shock tuning you are fast with, as soon as you change geometry or springs etc, you are gonna have to start from scratch.

id say aside from tires, you'd feel the biggest change by dropping ride height

I actually spoke with a custom spring shop this morning about de-arching my leafs so lowering ride height is high on my list.  I want to get the rear down 1.5 or 2" without making things softer - you can see from the vids that I occasionally get wheel hop when I launch so I don't want to make that worse by pulling a leaf or going with drop springs.  I can easily drop the front by adjusting the coil overs but I wanted to figure out the rear first - it's already got too much of a rake for my tastes. 

At the moment I think my LCAs are close to level with the ground and I think I can lower ride height at least an inch without changing that appreciably.  Ground clearance isn't really an issue as long as my front bumper clears the entry to my driveway and I have a ways to go before that.

I know the shocks are a band aid but they're easy to play with and it allows me to quickly change between street/track.  The truck is trending progressively away from daily driver toward dedicated race rig but I still have to drive a minimum of 25 miles to each event.  The last event was more like 120 miles away.  With race seats and stiff, low profile tires it can make those trips seem very long.

What is your current setup out back besides the adjustable shocks?

I agree that the larger front bar and getting it lower to the ground without sacrificing geometry up front would be the #1 move, then more and stickier tires #2, but I think as soon as you conquer the roll up front with a lower CG and a bigger front bar, you're going to need that rear bar back. Right now, I agree, you don't have enough weight in the rear or enough roll to necessitate it, but you will. *Unless* you just have so little weight out back the the rear bar automatically starts to lift the inside rear tire, which is what it sounds like you have right now.

Right now I have Z85 leafs (4 leafs plus overload), 3" blocks and single adjustable QA1 Stocker Stars.  I had a set of ZQ8 leafs at one point but decided not to install because of the potential wheel hop issue.  From what I've read traction bars are shite for handling so I wanted to avoid that.

Yeah, traditional slapper bars are TERRIBLE, the newer pivot bars are only really bad. instead of just a hop shock like GM used, you could go to a full spring loaded third link like the dirt track guys use. A shock alone can't kill the hop, but the sprung third link in place of the hop shock might do it. You can do a single stage just for torque absorption and powered traction, a dual stage for controlling twist in braking as well, or a full three stage that has a poly bushing for when you really have to slam the power down. See here:

http://www.speedwaymotors.com/Pull-Bar-Spring-Coil-Mount.html?first_answer=1

http://www.circletrack.com/techarticles/ctrp_0612_race_car_forward_bite/viewall.html

I never thought the ZQ8's would be worse for wheel hop than the factory leaves.  Pretty much any S truck will have wheel hop no matter the leaves used.  Using blocks certainly doesn't help either since they act like an extra 3" of a torque arm to the spring.

More leafs in the pack help to stop it from wrapping up under torque - the old school drag guys add more leafs to the front side of the pack for this reason (I can't remember the term they use for it but they did it on one of the Muscle Car builds on Spike TV). 

I've heard a lot of stories about people swapping to drop leafs and getting loads of wheel hop so I'm wary about it.  I haven't compared different leaf packs back-to-back but the ZQ8 pack has half as many leafs in it than the Z85 pack so it seems reasonable that it would be much easier to deform it under power. 

I don't get hop anywhere on course other than launching it out of the start gate.  If my tires are warm and the pressures are bang on it will often hook up without hopping there too so it works pretty well as-is.  If it ain't broke...

I know blocks are not ideal but I'm looking for a total of ~5" of static drop in the rear so they are probably required if I stick with leafs.