Help with HEAVY A4 launch
Help with HEAVY A4 launch I'll start out by saying my susp. set-up would deadhook w/ 404/370 to the wheels. 1.62 60' (no spin)
The changes: 408 / iron block. 478/435 to the wheels.
At the launch, she hits the tires HARD and snatches the front wheels but then begins to spin. Best 60' 1.77 (30+ ft spin).
I flashed the converter from 1200 and from 1500.
UMI adjustable tunnel mnt. TA / front attatched at the highest bolt hole.
Adjustable LCA's and relocation brackets set in the lowest hole.
Stock shocks and springs.
Rest of the mods in sig.
Any ideas on how to keep the power planted .. without replacing anything??? If possible.
The changes: 408 / iron block. 478/435 to the wheels.
At the launch, she hits the tires HARD and snatches the front wheels but then begins to spin. Best 60' 1.77 (30+ ft spin).
I flashed the converter from 1200 and from 1500.
UMI adjustable tunnel mnt. TA / front attatched at the highest bolt hole.
Adjustable LCA's and relocation brackets set in the lowest hole.
Stock shocks and springs.
Rest of the mods in sig.
Any ideas on how to keep the power planted .. without replacing anything??? If possible.
Well it sounds like it is unloading the tires away from the line , which could be helped by tightening the rear shocks 2 to 3 slicks but you cant do that with stock shocks. Maybe add 3 to 5 lbs of air pressure to the rear tires.
What tires are you running and what air pressure. This is very important for traction. I finally found what my car likes. 26-10.50/16 ET streets like 19-19.5 lbs of air pressure for 1.5 60'. If you are running 17' wheels, I don't have much advise, but to play with air pressure and make sure your pinnion angle is 0* to -2*. Mine is at 0 for now, but think it might be more consistant at -2*.
I agree .. I believe it's unloading too. Just gotta' sort out the "why".
M/T 315/35/17's.
Yank SS3600 (N20 in the future)
I ran at 18psi. Next trip, I'm thinking I could start them at 24 so I can always work my way down.
Pinion is @ -2. I suspected that maybe it was rolling past 0 but didn't know, exactly, what the effect it would have on the car at the launch. Could that cause the susp. to unload?
I think a buddy got a video of it .. I'll see if I can get that posted!
Stock shocks so .. no adjustments there
Some day though 
M/T 315/35/17's.
Yank SS3600 (N20 in the future)
I ran at 18psi. Next trip, I'm thinking I could start them at 24 so I can always work my way down.
Pinion is @ -2. I suspected that maybe it was rolling past 0 but didn't know, exactly, what the effect it would have on the car at the launch. Could that cause the susp. to unload?
I think a buddy got a video of it .. I'll see if I can get that posted!
Stock shocks so .. no adjustments there
Some day though 
Teching In
Joined: Feb 2003
Posts: 23
Likes: 0
From: Oklahoma
On that adjustable TA, putting it in the lower hole up front should make it soften the hit to the rear tires, that may give it just enough to quit unloading... Thats what I've been told about the adjustable instant center anyway, the higher the front of the TA is, the harder it will hit.
need to hit the tires easier, i'd suspect the tq arm position is your first step as said above, also try footbraking higher and higher
next biggest problem is the rear shocks, probably move to quickly not pushing the tires into the ground as the body rolls... front shocks could be contributing as well by letting the car rock back forward after launch
*EDIT* i dont think my car does an awesome job, still working on it, but click my best pass link in my sig you see the nose goes up and stays up and that the tires get hit rather easy
i run my tires about 20# most days, on an avg track avg day i am in the low 1.5's. I have qa1's set up pretty tight all around, no front sway
next biggest problem is the rear shocks, probably move to quickly not pushing the tires into the ground as the body rolls... front shocks could be contributing as well by letting the car rock back forward after launch
*EDIT* i dont think my car does an awesome job, still working on it, but click my best pass link in my sig you see the nose goes up and stays up and that the tires get hit rather easy
i run my tires about 20# most days, on an avg track avg day i am in the low 1.5's. I have qa1's set up pretty tight all around, no front sway
Last edited by MIGHTYMOUSE; May 6, 2008 at 07:58 AM. Reason: update
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Thanks for all the input guys! You've given me plenty of areas to look into.
I'll start by lowering the TA front mnt. and raising the tire pressure a bit and go from there. I'll try the higher stall rpms too.
Hopefully, next weekend I'll be able to make to the track again.
I'll start by lowering the TA front mnt. and raising the tire pressure a bit and go from there. I'll try the higher stall rpms too.
Hopefully, next weekend I'll be able to make to the track again.
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