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Thread: Setting up FWD suspension for drag racing / launch technique

  1. #1
    turbo addict
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    Setting up FWD suspension for drag racing / launch technique

    Warning this is a novel. I've been wanting to figure out something that can help me with my 60' times at the track but can't seem to find any real good info out there. My setup is a '91 Spirit R/T, 568 w/quaiffe diff., 23.5x8 or 23x8.5 15 M/H slicks on 6" steel rims(can't remember exactly and they are too far away to double check and they are 3 yrs old), Eibach springs F/R, Monroe sensatrack struts and generic airshocks out back. I've tried different air pressure in the air shocks and slicks with minimal difference. Air pressure in the shocks has ranged from 100psi to 60 psi with a few runs done with 0 psi. Air pressure in the slicks has ranged from 15 to 11 psi, best results and consistency coming with 11-13psi. My 60' times are normally in the 1.95-2.0 range, with one 1.89 which was also my PB e.t. 1/8 miles times range from 8.3-8.4 with one run being 8.16 all between 85-89 mph.

    When I launch I blip the throttle to keep the rpm between 5-6k trying to keep the turbo spooled a bit, doing my best to launch at 5500+. Last yellow the accelerator hits the floor and I dump the clutch; in that order.

    I feel that there are better times in the combo if I can get this all sorted out. The car doesn't bog off the line, yet I felt a definite difference in the 1.89 60' compared to the normal high 1.9-low 2.0; it just felt smoother off the line is the best way to describe it. Any advise you may have is very welcome.

    Here are some pics of how the car looks coming off the line if that may be of assistance. I don't have any pics of it with the slicks and 0 psi in shocks at rest.

    13 psi in slicks, 0 psi in shocks. 1.97 60'


    13 psi, 0 psi, 1.89 60'


    60 psi in shocks, 13 psi in slicks 2.04 60'


    60 psi in shocks, 13 psi in slicks at rest
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    Re: Setting up FWD suspension for drag racing / launch technique

    How much heat are you putting the tires?
    Also how my psi in the rear tires?

  3. #3
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    Re: Setting up FWD suspension for drag racing / launch technique

    2nd gear burnout until I see smoke come from the fenders. The car slarts to slide forward just before I release the parking brake. I have not measured the actual temp of the slicks right afterwards. Always 34 psi in rear tires.
    “If the people of the nation understood our banking and monetary system, I believe there would be a revolution before tomorrow morning.” -Henry Ford

  4. #4
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    Re: Setting up FWD suspension for drag racing / launch technique

    Try putting about 50psi in the rear tires (only at the track) to help roll out.

  5. #5
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    Re: Setting up FWD suspension for drag racing / launch technique

    I have been doing some testing with my air shocks. The back end of the car was getting too high with 60 psi in the shocks. I bolted a chain from the body to the trailing axle and then pumped up the shocks. It is kind of getto of a test but has worked well. I'm going to look at making a strut bar of some kind to replace the chain.

  6. #6
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    Re: Setting up FWD suspension for drag racing / launch technique

    This should be a good thread. I have similar set up as you. 24.5/8/15 m/t sicks at around 11 psi, air shocks at 140 psi, manual trans a-555 open diff, 1.9x 60 foots, 5.398 330 foot, 8.1 1/8 mile 88.9 mph.

    I found if I tried for a high rpm launch, I spun the slicks, my heating technique is similar to yours. Around 4500 rpm works for me.

    More little bits I changed are alignment settings. I went with a compromise between street driving and track settings. As you know the front end rises at the starting line and the camber goes more positive and the toe goes more positive, so I went with a compromise between the spec and where it is with the front of the car raised about an inch or two.

  7. #7
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    Re: Setting up FWD suspension for drag racing / launch technique

    -1 deg camber, 1/16 toe in has been my alignment choice for these vehicles for many years

    personally i like to bang the car off the limiter when im staged. 7K rpm launches and consistent high 1.7 60 footers with a best of 1.71. 24.5 x 8 x 15 slicks, 7" wide rim and the 568 w/quaife


    running 13" bogarts this year so im hoping to get into the 1.6's with the rim weight loss and gain in sidewall

  8. #8
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    Re: Setting up FWD suspension for drag racing / launch technique

    I have no rev limiter, for some silly reason the P.O. opted to have it removed. I don't trust stock rods to take that abuse for too long.
    “If the people of the nation understood our banking and monetary system, I believe there would be a revolution before tomorrow morning.” -Henry Ford

  9. #9
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    Re: Setting up FWD suspension for drag racing / launch technique

    you can put in you own 2 step, just need an msd box with the changable chips, i know it is an expense but well worth it for a lil insurance.

  10. #10
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    Re: Setting up FWD suspension for drag racing / launch technique

    23x8.5 15 M/H slicks on 6" steel rims
    i think this may be a big part of your problem, the 23"s compared to others 24"s, and the big one is your rim width. its very important to run the correct rim with the tire. others are running 7" rims with 8" tires, but your running 6" rims and 8.5" tires, and thats not a good combo.

    also, what is your ring and pinion ratio, what is your shifting rpm, and trapping rpm?

    the alignment setting will help you a lot, and a two step is a very good idea, launch and rev limiter, plus the benifits of msd (sometimes?)...

  11. #11
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    Re: Setting up FWD suspension for drag racing / launch technique

    The problem with air shocks is that when you air them up they will lift the body off the coil springs. So then when you launch the car squats and compresses the air shocks and then the coils instead of all at the same time. They need to work together. Last fall I did a test and put rebound straps from the axle to the body and pre-loaded the air shocks against them. Back to back runs with and without the straps, similar squat and 60' ... only difference was the straps helped keep it from bouncing between gears and made it bound during the shutdown. I ditched the air shocks in favor of a pair of Koni's and the car doesnt bounce in between gears anymore.

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    Re: Setting up FWD suspension for drag racing / launch technique

    +1, 24.5"x8.5: slicks make a BIG difference over 23's

    JT
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  13. #13
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    Re: Setting up FWD suspension for drag racing / launch technique

    dont forget the 6" wide wheels

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    Re: Setting up FWD suspension for drag racing / launch technique

    JT, you would suggest keeping the air shock pressure lower to keep the car closer to level? Got a pressure in mind?

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    Re: Setting up FWD suspension for drag racing / launch technique

    It will vary from vehicle to vehicle with air shocks due to vehicle weight. I would say only as much pressure as you can put in and not lift the car up off the coil springs... so not much.

    Now, air bags are different.... I havnt personally played with those but think they could be tuned a little better.

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  16. #16
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    Re: Setting up FWD suspension for drag racing / launch technique

    Quote Originally Posted by OmniLuvr View Post
    plus the benifits of msd (sometimes?)...
    When everything is working there's very little benefit to an MSD. When everything's not working the MSD is amazing. I forgot that I didn't change my rotor in my old mustang when I did a tune up (out of stock). One day the car died and wouldn't run. I disconnected the MSD first then I replaced the cap and rotor after my brain started working... When I started it up it was barely running on 5 cyl because the plugs where fouled. Hooked up the MSD and it cleaned the plugs almost instantly and ran on all 8 with no problems.

    IMO an MSD is worth having because if you have a plug starting to go or just blow out a flame for whatever reason the MSD will light it back up.

    The Two step will help you be more consistent too. As for me I'm going with megasquirt and will have launch control...

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    Re: Setting up FWD suspension for drag racing / launch technique

    I am seriously considering a N2MB two-step/wotbox for next season.

    I can't make it out the rest of this season due to a cracked windshield and rust complications around it.
    “If the people of the nation understood our banking and monetary system, I believe there would be a revolution before tomorrow morning.” -Henry Ford

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    Re: Setting up FWD suspension for drag racing / launch technique

    Quote Originally Posted by OmniLuvr View Post
    dont forget the 6" wide wheels
    FWD MT cars don't mind a narrow rim. It gives you more sidewall flex. Ask M&H.
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56

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