running slower after suspension mods
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
running slower after suspension mods i've recently done the following mods, and i'm actually running slower now. went from a 12.42 at 111.6 to a 12.60 at 108.9mph and 1.8x 60ft
k-member/poly mounts, BMR lowering lower a-arms, bmr upper a-arms, strange single adjustable shocks up front /w 300lb springs, bmr springs out back /w competition engineering springs, removed front sway bar.
torque arm pinion angle is set to -1. front shocks are set to a '3', rear shocks are on middle firmness i think (whatever was recommended on this site for street/strip car). suspension height is on a slight rake (due to the front suspension settling)... maybe another 1-2cm would level it.
car is a manual trans, tires are MT DR's. launch technique was burnout in 2nd just till i saw smoke, then clutch dump at 4800rpms off a 2-step.
any suggestions on what i should change? i tried launching at 5200, but that didnt help. i'm thinking either letting off the clutch easier, or i need to adjust the front shock height/firmness or pinion angle.
here is a vid:
k-member/poly mounts, BMR lowering lower a-arms, bmr upper a-arms, strange single adjustable shocks up front /w 300lb springs, bmr springs out back /w competition engineering springs, removed front sway bar.
torque arm pinion angle is set to -1. front shocks are set to a '3', rear shocks are on middle firmness i think (whatever was recommended on this site for street/strip car). suspension height is on a slight rake (due to the front suspension settling)... maybe another 1-2cm would level it.
car is a manual trans, tires are MT DR's. launch technique was burnout in 2nd just till i saw smoke, then clutch dump at 4800rpms off a 2-step.
any suggestions on what i should change? i tried launching at 5200, but that didnt help. i'm thinking either letting off the clutch easier, or i need to adjust the front shock height/firmness or pinion angle.
here is a vid:
Last edited by slayer_taunu; Nov 14, 2011 at 10:14 AM.
Well testing and tuning comes to mind as you need to re learn the car and also like others said if its hooking better, it could be bogging and trying to go @ a higher launch speed your running into the On / Off switch that some tire combonations run into. Thats why its recommended that m6 cars run a bias ply and possibly a 2 step to dial in the launch.
D/A can certainly be a factor, dragtimes.com has a calculator you can run to see.
I also want to mention GMHTP had a Red LT1 car run slower after a bunch of suspension and it was a A4 car but due to the fact it actually launching better they need to work on putting more power into it to actually go faster.
Dont think of it as a step back, rather a step forward.
IF I were to bet, I would stay dump the Drag Radials, bolt on some ET Drags (26's or maybe a 1-2" taller) and even with out the 2 step the car would run like a hero.
D/A can certainly be a factor, dragtimes.com has a calculator you can run to see.
I also want to mention GMHTP had a Red LT1 car run slower after a bunch of suspension and it was a A4 car but due to the fact it actually launching better they need to work on putting more power into it to actually go faster.
Dont think of it as a step back, rather a step forward.
IF I were to bet, I would stay dump the Drag Radials, bolt on some ET Drags (26's or maybe a 1-2" taller) and even with out the 2 step the car would run like a hero.
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
according to the calculator, my DA was 1752. Previous run was in the neighborhood of a 572.
60' is about the same. 1.8x. its hooking well enough to pop the front tire up... but i'm still getting some wheel spin, as you can see the car isnt really travelling far while the tire is in the air. before i got the 2-step, i had some low 1.7s 60' times... so i might just be hitting those tires too hard now. even though i'm launching at a lower RPM, i'm now doing it at WOT when the clutch is dumped instead of part throttle to hold the RPMS's as before the 2-step.
i wont rule out back tires... they are like 4+yrs old. if i was to step up to bias ply tires like ET Streets, i think i'd need to get some 15" wheels... as i dunno if there is much point in a tire like that with the thin sidewall on the 17's.
60' is about the same. 1.8x. its hooking well enough to pop the front tire up... but i'm still getting some wheel spin, as you can see the car isnt really travelling far while the tire is in the air. before i got the 2-step, i had some low 1.7s 60' times... so i might just be hitting those tires too hard now. even though i'm launching at a lower RPM, i'm now doing it at WOT when the clutch is dumped instead of part throttle to hold the RPMS's as before the 2-step.
i wont rule out back tires... they are like 4+yrs old. if i was to step up to bias ply tires like ET Streets, i think i'd need to get some 15" wheels... as i dunno if there is much point in a tire like that with the thin sidewall on the 17's.
1200 ft in difference is HUGE! So only losing a couple hundredths between those runs is actually an improvement if you put it all into perspective
Personally, i lose as much as half a sec with 1,000 ft more in DA.
Personally, i lose as much as half a sec with 1,000 ft more in DA.
