drag racing suspension

[Nismoknightska-t]

Originally Posted by whereda40at

just to follow up.....

i was at the track on nov. 4th for imports vs. domestics and mickey thompson had some 275/60/15's on sale so i got them mounted at the track. turned my anti-lag to 5k, tire presure at 16psi and heated the tires up a little bit. launched the car and BOOM broke my dss 600whp axle. no wheel hop, just saw the front come up and down real fast. i moved a total of 7" off the line. haha i found traction. so now i have to get it repaired and try again next season with my 600whp set up im doing in the off season. also i have to roll the rear fenders for the tire to fit.

thanks for all the help. m/t ftmfw!!!!

same thing happen to me @ boti last sunday.. i left on the trans brake @ 4800 and boom!! here is a video of my first run..

YouTube - NISMO KNIGHTS @ BOTI 2009 FONTANA

next time try to preload the car before launching it, to get all the slack out of the drivetrain so you dont shock it..

[whereda40at]

new follow up...........
i made a nice pass this season. went 11.2 @ 121mph. had a 1.56 60' car now makes 380whp on a mustang dyno

mods are: port polised s13 head
kelford step 3 cams
everything else supertec
brian crower 2.3 stroker
gt2876r @ 18 psi (internal wastegate)
stock susp.
sub frame spacers
300zx manual trans
1 piece drive shaft
dss 600hp axels
1.5way carbonetics lsd
launch set at 4900
tires at 16 psi
air temp at the track was 97 F

new goal is to hit 10's without touching the motor. maybe new final drive or wait for a colder night?

suggestions are welcome.

[Slo_240sx]

Those are nice numbers. What size tire are you running now? I would try to get some adjustable coils to help you fine tune the launch. Your 60' is good but I think it can be lowered a bit. You'll lose MPH on the top end but your ET will show. My IRS friends (Im running a solid axle in my 240) gained by getting some adjustable RUCA's. We dialed it in to run the rear wheels flat during squat, it helped alot. Your power should be good enough for 10's with a good 60".

[whereda40at]

yea i think that it needed to be cooler out too to get get a lower time. i might go to the track this weekend and ill report back.

im in the black car. YouTube - sherrodsmith22's Channel

[Vetal]

To the OP, what did you do to improve from 11.6 to 10.8 seconds?
Are you on stock suspension?
Did 1.5way LSD help much? Is it much better than stock VLSD?

Our trap speeds are similar, it's only that you run 1.2 seconds faster )

[S@nt0s]

He's .520 quicker in the 60ft then you.
Rule of thumb is for every tenth you can cut off out the hole is good for 2 tenths up top

Originally Posted by Vetal

To the OP, what did you do to improve from 11.6 to 10.8 seconds?
Are you on stock suspension?
Did 1.5way LSD help much? Is it much better than stock VLSD?

Our trap speeds are similar, it's only that you run 1.2 seconds faster )

[Vetal]

Thank you..... You just helped a lot lol!
"You're much faster, what did you do? - Hey, he's much faster."

[DallasTXjdm]

Two year old thread but excellent information! whereda40at did you end up upgrading your suspension? Which tires did you use to cut your 10.79@124 MPH 1.48 60' pass?

[steve shadows]

Sorry if someone has already mentioned this but the stock S chassis shocks and springs in good condition have always been my favorite for a solid launch with some MT et streets or some M&H tires for street slicks.

[S@nt0s]

Originally Posted by steve shadows

Sorry if someone has already mentioned this but the stock S chassis shocks and springs in good condition have always been my favorite for a solid launch with some MT et streets or some M&H tires for street slicks.

They work to a degree but there are better ways to go about it

[Vetal]

Originally Posted by steve shadows

Sorry if someone has already mentioned this but the stock S chassis shocks and springs in good condition have always been my favorite for a solid launch with some MT et streets or some M&H tires for street slicks.

good condition? I remember reading somewhere that people used BAD stock shocks to help launch

Santos, what's better then? Except HKS Drags, of cause

[S@nt0s]

Originally Posted by Vetal

good condition? I remember reading somewhere that people used BAD stock shocks to help launch

Santos, what's better then? Except HKS Drags, of cause

His doesn't make one for s13 last time I checked.
Fortune auto makes some but I haven't heard anything about them.

I personally will be using sme QA1s. I will be machining a top mount to bolt up to the stock location then dial it all in

I will be using the biggest sway bar I can find for the rear or I'll fab up a anti roll bar set up with heim joints for adjustability

Basically be using my car to find every way possible to put all the power I can to the ground

[Vetal]

Are you going to use QA1 HALs? For which car?

[S@nt0s]

Originally Posted by Vetal

Are you going to use QA1 HALs? For which car?

Still researching that so I don't want to put I of out their till I know it works

[inopsey]

[QUOTE=Vetal;4587221]good condition? I remember reading somewhere that people used BAD stock shocks to help launch [QUOTE]

typical zilvia style. who in their right mind would drive over 100mph on blown shocks; never mind recommend it ? sounds like a smart thing to do

[Vetal]

Originally Posted by inopsey

typical zilvia style. who in their right mind would drive over 100mph on blown shocks; never mind recommend it ? sounds like a smart thing to do

Here: Tune Your Ride - Car Craft Magazine

For the front suspension, the old racer trick was to use "dead" stock shocks.

"Zilvia style" enough for you?

[inopsey]

whatever. if you think a few tenths in the quarter mile is worth the risk of losing control of your car into the wall then who am i to tell you what common sense is.

[steve shadows]

Another good setup is stock GOOD shocks and Eibach sportlines, used this to get 1.5s in the 60 ft with 440 whp for a while.

I also had some old Tien HEs that we would soften all the way up on BF goodrich comp tas.

The biggest thing in my past experience is TIRES and making sure you are soft and weight transfer goes where you want it. Next is the clutch you are using and your launch point. This is really where it will all come together.

BF goodrich Comp TAs were the best for me, then came the M&H street slicks and then the MT ET Streets.

[Vetal]

Steve and other fast guys... Can you give me some advise on my car, what's the best I can do? I have basically stock suspension with lowering springs, old S13 VLSD, 26x8.5 ET Drags. What could I do to improve launch/weight transfer/60ft? I see whereda40at runs stock shocks/springs and other suspension but with subframe spacers, should I copy that setup?

[Vetal]

Good old thread here...
Since last post I have swapped lowered springs back to stock and I THINK it improved traction a bit. However there is big downside to that - car looks like stupid offroader now, with probably 3-3.5" between tire and arch in front. Not so bad in the rear.
Please help me to invent something that could retain stock springs BUT allow me to change ride height! I would gladly use some coilovers for the front if they they would cost reasonably AND not hurt traction, but I don't know of any...
Maybe we could come up with some idea?

[Vetal]

Anyone?

[ashtonroche]

the key on rwd cars is to keep the weight transfer to the rear. Reason why the op went faster on a stock setup is because his old coilovers were probably too stiff and not valved correctly.

Stock suspension is not the best but a properly valved shock even on stock springs would do a pretty good job. Basicly you want 0 damping on the initial compression of the shock and full damping on the rebound of the shock to keep the weight from transfering back to the front too quickly.

Key is to keep the weight planted at the rear.

Hell even stock springs and a proper drag shock that is two way valved would work great. They make drag specific coilovers for this reason, just gotta pay up for them. They will have soft rear springs and two way valving so you can play with settings. But most from what ive seen you use zero damping on compression and full dampen on rebound.

For FWD this is exactly the opposite. Stiff as hell rear springs, Full damping on compression and 0 damping on the rebound. This allows the weight transfer to the back to be quickly "bounced" back to the front. Hell if I can pull 1.5 60's in my fwd Sentra, no reason when dialed in that a 400whp 240 couldnt pull 1.4's or better even on drag radials.

[ashtonroche]

Another thing people often forget to think about in drag racing is alignment. And even for rwd this applies.

What the hell do you think happens when your rear end squats down 4" or so on a launch. Your wheel alignment and camber change drastically. For you rwd guys you would want to set up your alignment so that when its in the launch and acceleration position that the contact patch of the tire is at its best. So both the toe and the camber are as close to "0" as you can get during that launch and acceleration.

So dependant on the suspension setup and actual squat you get, make you adjustments as necessary. Best thing to do would be to record the back tires with a Gopro during launch and see whats happening and then make changes from there.

You want to keep the ride height up as well but not too high. Basically about stock ride height would be fine or little higher if your fitting big tires. But i can bet you during launches your getting a bit of toe out and negative camber. Not the best for traction.

[ashtonroche]

And lastly, diff

Of course the stock vlsd isnt going to be the best diff for drag racing. You want something locks quickly and stays locked. Hell a welded diff would pretty much be your best bet but if you have other things going on with the car that arnt setup right, a welded diff can be not soo good. But seriously, a completely locked diff is the way to go. Full traction at the same time and same speed from both wheels together. Best way to go.

[ShakotanGazelle]

Ford 8.8 axle + full spool.

[whereda40at]

wow, my old thread was still alive. I still swear by this info for drag racing. I even have my 1.5 way carbon plate diff for sale.