MichaelB145

With the worn out stock suspension, I was cutting killer 1.63 60 ft times at the dragstrip. Unfortanately I blew one of the shocks out so I bought the Tein coilover kit. What setting should I set them to? I'm guessing the rears need to be as soft as possible to get the rear to squat when launching. What should I set the front too. I know I should have bought the HKS Hiperdrag kit, but then I could never autocross it. Any sugestions?

Rhymin

Didn't you get that figured out?

Jodeny

iTrader: (3)

I have the HA kit on my car, however I havent fiddled with the settings yet. But, as an old time drag racer I am going to start off with the front soft(weight transfer) and the rear stiff. My normal street settings for regular driving as per Howard Coleman's suggestions are 6 clicks from full soft- front and 2 from full soft- rear. Also- If you set the rear camber at 0 degrees this will also help greatly with launch.
John

DamonB

You don't want the rear stiff, you want it soft. You want the car to squat and give the rear tires more time to absorb the power. A stiffer rear end will make the tires easier to break loose at launch.

Shocks dictate how fast the weight transfers. The softer the shock the slower the weight transfer and the more time the tire gets to react. That's exactly what you want for a drag launch. Be certain the car doesn't squat so much it hit the bump stops though; that's even worse.

If you had a double adjustable shock on the rear you'd want just enough spring and compression damping to keep the car off the bumpstops and you'd want a boat load of rebound.

If I were drag racing an FD I'd put a tad bit of positive camber in the rear so that when the car squats at launch I'd be closer to zero. If the camber is already zero at static ride height it's going to go more negative during the launch than it would if it were slightly positive at static height. This is another reason why a solid axle is wonderful for drag racing.

Jodeny

iTrader: (3)

Agreed- on a 60's musclcar but a car woth teins or any lowering springs does not have enough travel to squat enough, so on the stiff side was where my car worked better with street tires.

Agreed

Rebound in the rear?


I know you have a wealth f knowledge about suspensions but did you ever measure the temp of parts f a tire after drag launch? The zero camber gave a significant difference in grip and an even heat pattern across the tread. We prob feel the same way about my next quote: You'd have to be a moron to put a solid rear ale in an FD unless it was strictly a trailer queen.


John

DamonB

Right. You want as much squat as you can get without the car bottoming out. Once you're on the bumpstops your wheel rate shoots way up and the tires will break loose easily. A spring stiff enough to keep the car off the bumpstops would be better than a softer one that lets the car bottom out at launch. Adjustable shocks can help this though as they will let you tune how fast the car squats.

Yeah. You'd want lots of rebound in the rear so that the car stays squatted and the rear rises very slowly as the car travels off the start. This again keeps weight on the rear end as long as possible and also makes the transition very slow as the car regains ride height. All good for keeping the rate of change of rear tire loads as slow as possible.

Undoubtedly zero camber would have better grip in a straight line than any negative camber. As the car squats at launch the rear suspension gains negative camber so a car with zero camber at static ride height does not have zero camber at the instant when it needs the most help from the tires: squatted at launch.

Were the temps literally read after a launch (like at the end of 60') or were they measured at the finish? If at launch were the temps up were you want to see them? I would think they have to be low unless you did a burnout and that may be misleading as well because the tire isn't stressed much during a burnout; it's just spinning. Not as much weight transfer during a burnout.

If temps were measured at the finish this is not an indicator of the tire at launch, only an average temp of the tread through the entire pass. I'm not a drag race setup guy and have no experience with it but reading rear tire temps on an IRS car after a 1/4 mile run could be misleading IMO. The car places the most stress on the tires during launch and acceleration off the line. As the rate of acceleration tapers off the car requires less and less from the tires. When you read rear tire temps after the run what your seeing is the average temp of the tread through the entire run. However, the start is where the tire is used the most and this is the most important time for the tire to be at zero camber. I'd fully expect a car with slight positive camber at the rear to have hotter outside temps at the end of the run. If I knew the tires were working and I was screwing around with camber on an IRS I'd be looking at 60' times and not tire temp. I could be crazy; I don't know everything. It makes enough sense to me to try it though.

I think all this would only apply to an IRS street type car that is not wheelspin limited for much of the track. I'm sure many drag tires are very forgiving of camber since their sidewalls are so soft but if I drag raced much I would definitely try it. If testing camber settings my measuring stick would be 60' times and not tire temps.

DamonB

If everybody leaves their adjustable shocks at the same setting all the time or merely uses settings someone else does why do you need an adjustable shock?

Rhymin

And all this time, I thought I just put them on to make the car look cool...Sorry guys I had to...too funny!

MichaelB145

I guess we will just have to experiment....It seems much easier to get killer 60 ft times with the worn out stock suspension.

gnx7

iTrader: (10)

After 6 passes down the strip with M/T Drag Radials (255/50/16) I could only muster a 1.89 best 60 foot! My clutch is on/off and wouldn't allow me to slip the clutch off the line easily. I would blow the tires off! Best 11.56@124mph.

This is with road race suspension and the front sway bar attached. 550/450# springs, GabSuperR shocks, delrin bushings, and TriPoint adj speedway style front bar.

Drag racing is all about 60' and road racing is about a balanced car. Difficult to have both with a RWD car.

I'm curious what your best 60' will be. What rear LSD unit are you running? If it is the stock Torsen plan on replacing it before it explodes.

-Mark

APEXL8T

like DamonB said I set my adjustable shocks to the softest to quit the wheel spin or shock(squats).
On 265 35 18 streets I hit 1.78 60' many low 1.8ts.Ito said he kept watching the video over and over to see what I was doing......you just have to listen.hahaha

potatochobit

iTrader: (1)

im buying coilovers cuz its cheaper and more convenient than buying shocks, springs and all the rubber perches and rubber pieces that go with it....

:/

vxturboxv

iTrader: (2)

I'd say don't over complicate things. When I had my IRS. I ran all the 180k+ original OEM suspension/springs/coils etc. With nothing but a set of 255 60 MT DR's @ 17psi I woudl cut constant 1.6x 60 foots. Later I installed an adjustable camber brace and pulled soem high 1.5x 60' times.

Since I've switched to a solid rear axle setup with AGX adjustable shocks. The car hooks no better than it did with the IRS! I wish I would have left the OEM shocks installed. I'm looking to lower my rear spring rate to 150 and my fwd SR to 250. Hopefully this will help. I may try swapping some OEM original high mileage junk yard struts as well.

Now I was runnign an AUTO. This makes things easier on me. Manual guys will have to master slightly preloading the suspension right before a launch. But I don't see why high 1.6 low 1.7's can't be had with all OEM suspension.

Good luck!

(wow this is a really old post!)