Just wanted to share some of my shock tuning video's with you from Wednesday night.

All video's have the shock settings, two step RPM, and boost information overlayed at the top of each video in red text.

All numbers are clicks from full tight. So R13C8 would be 13 clicks from full tight on Rebound, 8 clicks from full tight on compression.

Aside from the Run #1 (which was lower RPM/Boost) in the video, all of these runs resulted in spinning. But you can really see from the shock settings how it changes the way the tire is being hit, and how far it's traveling/rotating before spin starts.

Run #1 and Run #2 has the EXACT SAME shock settings, just more RPM/Boost on the launch. You can clearly see by how hard it smashes the sidewall, that "hit" changes with power of the car even on the same shock settings.

Explains a lot why one car to another can't use the same shock settings, even if it's the same brand shock.

Still tuning... but just thought I'd share. It's AMAZING what you can see in slow motion. Really the 2nd run and 5th run both just felt like it spun right at the hit... but that is not true.

You can see run 4 was ALMOST there. Turned about 1/2 or 3/4 of a tire rotation before it spun. Run 5 was with the tighter shock, and you can see I went to far. Car spun nearly right at trans brake release (not enough hit).

Enjoy... I will try to keep this up to date as I continue to learn/make the car leave on more power.

https://www.youtube.com/watch?v=jr1VILyS7WE&feature=youtu.be

As you are seeing and most find it hard to believe...........is that rarely does anything EVER spin "at the hit". Now what it does 2 tenths out is an entirely different matter.

Your goal, especially with radials is to get a shock setting and power level that maintains the hit. What I mean by that is to watch your videos and see how much the sidewall of the tire bulges at the hit. THEN you want to maintain that bulge for as long as you can. This shows the amount of "hit" on the tire and how well your setting maintain that hit. If you squash it hard, but then the sidewall springs right back, it will smoke the tire every time if you have power

What I'm still struggling with to learn is this.

1) How does compression effect hit. What I see now is that the rim doesn't bounce back into the body at all when the sidewall recovers. It appears to launch the body up. But I don't know if too tight of compression doesn't let the sidewall come back round again (get up on the tire). Is the body launching up taking the tire with it?

2) How does front shock rebound effect hit? If the car is out of travel at the front, and spins after, it means full weight transfer as soon as possible. However, does that mean tighter shocks will always make early spin worse, or can it help by delaying the full weight of the front brakes/wheels from being applied to AFTER the spin is starting.

Rear compression doesn't control the "hit" at all, because the suspension is separating at the hit........AFTER the initial hit is where the bump or compression comes into play. If the extension is soft and really lets it hammer the tire and flex the springs and tire HARD and you have the bump stiff, the shock won't settle easily, which will make the car "hop" on the tire and springs, because the shock is fighting those two things. Its a balance. You want to control the hit with extension and then "hold the hit" with the bump. So this tells you that when you adjust one side, you will also likely need to adjust the other to maintain a balance of action and reaction.

Keep this in mind.........on high HP big tire cars that run "shock boxes", we run the extension tight and the bump is locked up on the shocks and then softens the bump as you go out, to absorb the track. So the tight setting both ways really controls the housing and the hit. Obviously YOU can do that, so it's balance. This also tells you though, that really tight extension and loose bump won't work, nor will really loose extension and tight bump. For all intents and purposes, forget what the body does and watch what the tire does. The body is hooked to the springs and will do as they dictate........so if you control the tire and housing, the body will take care of itself

"You want to control the hit with extension and then "hold the hit" with the bump. So this tells you that when you adjust one side, you will also likely need to adjust the other to maintain a balance of action and reaction."

So does this mean with looser extension (more hit) the shock needs to be tighter on compression to hold the tire down? Or looser to absorb the inevitable bounce back without launching the car? (Or is somewhere in between depending on the symptom?)


Monte what do you think of the 4th run? Close on tire sidewall hit or do I need more?

How about front shocks.

Thanks a lot by the way for taking time to respond so far.

Excellent info guys. Thanks for sharing!

I agree!! Great info guys!

Cool, well timing info for me. I just got a set of DA shocks for my car. I plan to hit the track next week.

I have not looked at the videos and was just answering in generalities. But to answer your question........if the extension is pretty loose, it is going to "throw" the housing hard and hammer the tire. With this scenario, if the bump is too stiff, the reaction is going to be too stiff as compared to the action and can make the car "hop" on the springs or on the tire...........Now, how to fix it? and the answer is, it depends. If the tire really NEEDS to be hit that hard, you would need to soften the bump a little to let the housing "settle" easier and keep it from hopping. Most of the time though, the tire should not need to be just pounded into submission at the start and in that case you stiffen the ext. Seldom do you need to just hammer the tire, especially when you have power. You want to control it smoothly. When the car "feels" smooth and slow, is usually when it's fast. When it leaves like a dump truck hit you in the azz, the settings are off.

A radial has a VERY stiff sidewall, so if you actually see it bulge, you are hitting it pretty hard. If you HAMMER it and flatten it out, it WILL spring back, because you will NOT have enough power to hold it there, I guarantee it. So the goal is to bulge it a little and keep it there.

Power is another consideration. If you make a decent pass and decide to go back and "stand on it" power wise, you will most likely need to stiffen the extension. Because more power, will hit the tire harder with the same settings. This is where guys miss it. They go back, hit it hard, it knocks the tires off and they think they overpowered the track. Usually not the case. Usually they overpower the shock, hammer the tire and it bounces back and spins. A more power hit usually requires some attention in the front as well. Hit it too hard too fast, top the fronts quick and it will spin the tire

A certain track surface will maintain a certain g-meter reading, as it relates to your car. Learn to tune by the g-meter and keep detailed logs. When you look at the track, note the condition and determine the Gs you think it will hold, you put in the tune that produced that number in the past. I can usually tell you within a hundredth what our car will 60ft before we go to the line.....provided I have read the track right. I have 1.20 tunes, 1.15 tunes, 1.10 tunes, 1.05 tunes and so on. Each of these will require shock changes to be optimum

Cool videos!! Thanks for sharing... I am always trying to learn more about how everything in the suspension works together to launch the car! Thanks Monte for the technical help!!

Most guys buy some shocks, throw them on there, get some general settings from a buddy and never touch them again. That doesn't work. Where your buddy runs his settings on his shocks means nothing to your car and where it wants them. Optimizing a setup is WORK and frankly, most guys are too lazy to put in the time, nor have the knowledge and equipment to do so anyway. Now that may sound harsh and a dig at people but it is not meant to be that way at all. Most are ok with "good enough" and we see a proliferation of that when you get those inevitable responses of "my C-body rears and 90/10s work fine" whenever the shock selection threads come up. Working "fine" is a relative thing, depending on who you ask and what you are trying to do with the car.............Many guys WANT their car to 60ft better, or think it SHOULD 60ft better, but when you start rattling off changes and it may need this, or this and try this, they generally run out of patience pretty quick if they don't get instant results.........Like I said......it's WORK

Love this thread thanks again for good info dizuster and everyone contributing!

Never thought about focusing on the sidewall as a gauge for the "hit". That is good stuff right dare!

Dizuster and I just went through this my car. Using the Go-Pro we saw the housing bounce. My theory was to tighten the compression. The more I tightened it the worse it got. Then we attempted to loosen the front rebound to help it pitch rotate. We ended up with a car that went from running inconsistent 1.32-1.36 to 1.45. We rethought it. Tightened the front rebound, tightened the rear rebound and put the rear compression back in a reasonable starting area one click tighter than what we had been running. The result is a string of 1.29's. Is there more in it? I 'll bet there is. But now with a balance between rebound and compression at least it's consistent.I would have attempted more this weekend but I broke the car.
Doug

Very interesting!
Thanks, Don

my question on this subject is, how much effect does tire pressure( in my case 14X32 slicks) have in shock tuning, to me higher pressure would keep the tire from mashing as much and lower pressure would allow the tire to mash more with a given shock setting, or is this a small percentage of the equation.

bump just for some re-reading.

I'm getting a go pro for Saturday. This was my 1st pass today. Hope the go pro helps me.

tire shake, not enough power down low, low air pressure tire wadding up?

More air pressure will make it shake WORSE more than likely. More air, puts MORE rubber on the ground by flattening the tire out. NOT something a car already shaking needs.

It needs WAY more wheelspeed early, or way less hit on the tire. Impossible to know without knowing some of the settings.

Many think slicks are EASY. Just throw them on, hammer it with power and away you go...........LOL!!!........if it were only that easy. More power equals more problems.

Prime example.........I have a customer with a big tire Corvette. With a 648 on nitrous, I had it 60footing in the low 1.0s on an ET Street tire. Getting after it REALLY hard and setting the tires on fire early.........Fast forward to now and they have an 865in motor on spray and a slick. Should be easy, right? So far is hasn't been 10ft cleanly. We can't get it on the tire. Even tried leaving on TWO nitrous kits at the hit and it just rattles the tires. I have the bar out as far as I can get it realistically, lowered the tire pressure, lowered the wheelie bars, tied the front down, stiffened rear shock extension and it STILL crushes the tire. Looking at moving the motor forward about 3" now to get some more front percentage