SuperSlow02

iTrader: (16)

I figured thats what the DA fronts were for, to keep the front up in the air, and the SA in the back kept the back from squating too much....Guess it just varies between cars. The way you explained it makes sense too.

airforcemanss

iTrader: (23)

is someone here willing to explain why it is recommended for the fronts to be SA and the rear DA?

it seems like a lot of stock suspension cars are in the 10's (true street cars). isn't the stock suspension pretty good (springs/shocks) for the strip when running a street car? from what ive seen on here a 300lb front spring with qal shocks in the front (rear spring/shock???) are what a lot of members ive seen running on here seem fine. this thread is confusing me as i have no knowledge or understanding of SA/DA combos or setups for street cars that go to the strip often. help please

223HAWK

iTrader: (11)

Basicly from what Iv got from Wes(Greatwhitess) he owns a speed shop close to me, done work on my car and is very knowledgeable about cars. But basicly the DAs are just more controlling and have more ajdustments as far as compression and expansion, I think. He could exlpain it a lot better lol..but You can adjust them separately and have more control as far as "tuning" the suspension

DanZ28

iTrader: (5)

Like Wes said, The DA's in the back help keep the rear planted instead of popping back up when it starts to lose it's energy. SA's control compression only, which allows the front to to extend as fast as it wants, especially with drag springs. DA's on the front are also valuble for cars that like to pull the wheels up high as you can set them to not extend so fast and control the weight transfer better, but not typically needed on 10 sec cars.

airforcemanss

iTrader: (23)

thanks for the info. so judging by what you said, 95% street 5% strip car, a SA front shock and rear DA paired with the stock OEM springs 298 front/115 rear should be great?

im thinking a street car would be fine with SA all the way around should be fine? the reason im saying stock springs is what is the point of getting a 300lb front spring (members usually run a stock rear spring) the fronts are stock 298?correct me if i'm wrong....

keep in mind this thread seems for guys like the OP an my self i looking for realistic 1.5x-1.6x 60 fts for are street cars without compromising too much an aiming for the best of both worlds

Top Fuel

iTrader: (8)

rebound not compression.

DanZ28

iTrader: (5)

Depends on the shock. Some SA shocks only do rebound (Strange and AFCO), some only do compression (AFCO again), and some do both (varishock and QA1 for example) but as one adjustment simultaneously limiting your variables. But you are correct, I should have said Rebound as that is much more common and the compression is factory set. I learned something myself as I had to look that up , thanks!

DanZ28

iTrader: (5)

I agree, SA's would be fine for what you want.

SuperSlow02

iTrader: (16)

Pretty much takes everything I thought I knew about shocks and threw it out the window....******* suspension.....

Top Fuel

iTrader: (8)

I was just saying that rebound should of been used instead of compression. if I understood you right.

were you saying, SA's control compression only, which allows the nonadjustable rebound to extend as fast as it wants. in that case compression is right.

or were you saying, SA's control compression only, compression allows the front to extend as fast as it wants. in that case rebound is right.

Its bugging the **** outta me now so which one did you mean?

Mikey 97Z M6

iTrader: (37)

To re-iterate why it's important to have a D/A shock in the rear of a 6sp car, here's a vid of my car from last year with some Competition Engineering 3-way adjustables on the rear. Notice the wheel completely flattens out the tire (14psi ET Street), then immediately unloads the suspension and starts to spin the tire. The CE shocks just didn't have enough rebound or compression stiffnes to control the axle movement at launch.

http://www.youtube.com/watch?v=0yqJAuRxs1o

Mike

DanZ28

iTrader: (5)

This is what I was thinking when I wrote that for sure .

What I wasn't thinking is that SA's could be either rebound OR compression adjustable (I had in my head Compression adjustable only) while some SA's will do both based off of the one adjustment ****.

Strange and AFCO's that we seem use often have factory set compression and adjustable rebound so I can see where it would be less necessary to have a DA in front for alot of cars if you can control rebound.

dreamls1

iTrader: (25)

I went with Afco double adj. i wanted the best. But i am sure Strange are just as good. Its all about how much you want to pay.

As far as hooking on Drag radials. You will not have an issue. Their are guys running 6 sec passes on DRs.

JL ws-6

iTrader: (50)

Actually, what was happening to you, is that you didn't have enough air in the tires/too much weight for the tire, and it was causing the rim to bounce right off the track.... if you were on a 26 inch tire, I can tell you with a full weight car that they work best with about 15 to 17 lbs in them. Seems like alot I know, but I've helped too many cars running about the smallest set of et drags you can get, the 26x8.5's (a set that have been thru several people's hands by loan-outs, like a cheap **** set of drag rims/tires LOL) and every car liked that little tire up at 18, hell it kicked the driveshaft out of one car, I have the busted one in the garage to prove it LOL. 26 inch tires with heavier cars, also work better with a tube in them, as it helps stiffen the sidewall some.

The shocks weren't the problem, the lack of air pressure was killing you. The car also didn't spin until it set the front back down, which means you have a front shock problem, it's allowing the weight to set back down too quickly, which unloads the rear. Your car's also rolling over like a 3 legged dog... which never makes these problems any better, meaning you need a real swaybar on the car.

KP's used that 3 way shock on his 8 second transam, that used to cut bottom 1.3 and high 1.2 60 foots like clockwork.

Mikey 97Z M6

iTrader: (37)

Yeah, the car def had some issues last year lol.... and I'm working on fixing many of them this winter.

But, the tires (26-10.50-15 ET Streets) were spinning waaay before the front settled down. If you watch it very closely, you can see the wheel speed picks up almost the exact time the wheel bottoms out, unloading the suspension and then the front starts coming down afterward. Trust me, I've watched this vid about 900 times before I even hosted in on youtube lol....

If you think about it though, a much stiffer valved shock would not allow that much initial axle movement to begin with regardless of air pressure in the tires. You can watch the gap between the fender and the tire in that vid and see that the axle/wheel is being pushed down to the ground (wheel well gap gets larger). This alone proves that it's not a "weight" issue causing it to flatten the tire out, it's too much axle movement from the hit. I agree that higher tire pressure, taller sidewall or stiffer sidewall should help, but it's only masking the real problem, especially with a smallish tire. In my case, higher tire pressures didn't help 60' times at all, which also back up my claim that it's a shock issue.

After talking to a local drag racer (who runs a 4th gen) that has been racing clutch cars for about 25 years, his number one point he made to me was running stiff as hell shocks in the rear. He custom valves his shocks and puts them on a shock dyno. He told me the graph looks like a square wave because they're so stiff lol.....

The swaybar issue has been fixed and ironically, the name of this vid on my youtube account is "slowmo vid without antisway bar" lol... I have an identical video angle after the custom antisway bar was installed and the rear bumper comes down nice and even.

I tried tire pressures as high as 19psi and they all got worse 60's than at 14psi. The car wasn't exacty full weight, prolly about 150-200lbs lighter than stock. I have very detailed notes taken from each track day highlighting my changes that were made each time I went etc. All my changes were made in small increments and only changing one thing per track event.

BTW, was KP running a 6 speed or auto? From everything I've learned this last year, 6 speed cars require alot different suspension tuning than an automatic car.

I deffinitely appreciate your comments, although I don't agree with some of them.

Mike

sho-me speed

iTrader: (55)

Single adj's change the compression and rebound at the same time, so if you adjust them for the front end to come up easy then it will also allow the front to drop easily. One of the exceptions to this is the QA1 R series as they have a fixed compression so when you adjust them they only adjust the rebound.

For the post above:
You need weight transfer so if you have so stiff of a shock that it keeps the car from transfering the weight to the back tires then you are still going to spin. You need just enough squat to allow weight transfer to aid in planting the tire but not so much that you are wasting power going up rather than forward.

heavy6.0

iTrader: (69)

Refer to my car joey, what he is saying is right on!

DanZ28

iTrader: (5)

Directly from AFCO's tech section:

TWO TYPES OF ADJUSTABLE SHOCKS
A single adjustable shock is typically adjustable in only one direction. However, variations of this type of shock are currently on the market. The AFCO single adjustable shocks are only rebound (extension) adjustable. This style of shock is offered because much of the tuning can be made with only the rebound (extension) of the shock. The compression (bump) valving is preset at the factory. But don't worry--the compression (bump) valving is sophisticated. It is also velocity sensitive, responding to input ranging from a 13 (thirteen) second street machine to a door slammer running deep into the 9 (nine) second range.

A double adjustable shock allows compression (bump) and rebound (extension) to be adjusted separately. This shock is the top of the line and will allow the maximum performance to be squeezed from the given combination, provided the chassis tuner has properly adjusted the shocks. An example of when a double adjustable shock can be used to enhance performance is when the starting line is less than ideal. The chassis tuner can soften up the rebound setting to apply the tires more quickly and with more force. The chassis tuner may also want to stiffen the compression (bump) setting to hold the tires on the track, thereby eliminating wheel slippage and also possible tire shake or wheel hop.

SHOCK BASICS
A shock is a hydraulic device that dampens or resists chassis movement by passing fluid (oil) through a set of orifices and valved passages. In an adjustable shock, manipulating the fluid movement through the valving of the shock changes the dampening characteristics -- softness and stiffness. The range of softness to stiffness is an important consideration when evaluating a shock's quality. A shock with a broad adjustment range will give more bang for the buck, because a broad adjustment range will give more opportunity to find the optimum setting for the chassis. Dyno testing has proven that AFCO's shocks offer one of the widest adjustments ranges in the industry.

Rebound is the shock's resistance to being pulled apart. It can be used to control chassis separation, the point at which the axle housing is pushed away from the chassis and the tires are applied to the track. During separation, many things occur. Vector forces push the chassis up and forward -- and the axle housing sees the opposite force, the tires become compressed and the sidewalls wrap up. As the car moves forward, torque is created as the tires create traction to start this movement. Excessive separation can lead to some undesirable side effects. For example, wheel hop, can occur as the tire tries to return to its original form, the tire unwraps. Stiffening the rebound can control wheel hop if excessive separation has occurred. Tire shake is similar to wheel hop and can be addressed similarly. As a rule of thumb, a "bad" or "bald" starting line will require a softer rebound setting to apply the tires with more force. A "good" starting line can use a stiffer setting, as inherent traction exists and a sitffer rebound setting provides quicker vehicle reaction times; excessive separation only wastes time and energy.

Compression (bump) is the shock's resistance to the chassis moving down or the axle housings moving up or into the chassis. The compression adjustment is an important setting, as it determines how long the tires are held down on the track after chassis separation. When a soft rebound is selected, a rule of thumb seems to be to use a slightly stiffer compression setting, so as to control the rebound of the tire. Track testing can determine the correct setting.

This brings us to AFCO's innovative Velocity Sensitive Valving. This system can enhance performance in many ways. This valving package is extremely sensitive to the speed at which the shock piston is moving. At the starting line, because of the intersection point, engine torque, gearing, tires, center of gravity relative to ground, the shocks will see the highest shaft or piston speeds. To control the suspension, the shock needs to be stiffer at the launch than down track. The AFCO shocks with their new valving actually react more stiffly when needed at the launch yet stay softer for riding the track's irregularities down track. Also, this new valving system is extremely sensitive to chassis tuner input: small changes in the valving will make a noticeable change in the performance of the chassis.

Mikey 97Z M6

iTrader: (37)

Thanks, I was going to post a link to that in my earlier thread.

Here's another valuable piece of info from AFCO's tech section and I think it's even more crucial for a clutch car.

TUNING TIPS
Shocks are just one of many suspension variables on a race car. However, a current trend is to focus on the importance of the effects of shocks on the performance of a race car. With this in mind, we have included a few tuning tips and observations about our series shocks.

Virtually every car will separate at the launch. The rear suspension system forces the chassis upward while pushing the axle housing down. This is typically the first movement for most drag cars. For this reason, the extension, or rebound control, of the shock is extremely critical. The chassis tuner will need to have a shock that has a broad range of adjustments--a shock that will make a noticeable change in suspension characteristics when the shocks are adjusted.

The key elements to tuning the chassis are how quickly and with how much force the axle housing separates and drives the tires into the starting line. Starting lines that are bald, slick, or extremely hot will usually lack good traction. Therefore, a shock that has had the extension (rebound) softened will create more traction (greater separation). As the tire wraps up, the axle is driven down, and the chassis pitch rotates, the sidewall of the tire is compressed. At some point, the torque from the engine will decrease or the chassis will reach maximum pitch rotation. When this occurs, the tires will start to return to their original form perfectly round. This action can cause wheel hop or can "unhook" the tire. Here is where the compression setting becomes critical. The compression valving can now be set stiffer to hold the tire down on the track. This method of shock tuning is used by many of the most successful drag racers in the sport today.

Mike

camscam02

iTrader: (21)

good find Dan. Exactly what was explained to us when Theo scaled our car along with some other little things.

The rear single qa1's I had on the rear before both had a fixed compression and rebound setting so when you turned the **** to adjust one you were adjusting both. Would of rather had it just with a rebound adjustment only.

I now have Strange Double Adjustables on the car and love them.