Got a TH400 with brake....how to launch?
Trans break and sitting on the 2-step infront of McDonald's!!!!!
Yes, get a 2 step so you can leave off at a certain rpm rather than sitting on the transbreak and guessing when to leave.
Yes, get a 2 step so you can leave off at a certain rpm rather than sitting on the transbreak and guessing when to leave.
Thread Starter
10 Second Club
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From: Champaign Il
I have played around with different rpms lately using the brake and mine likes 4000. At 4000 I was sixty footing around 1.45, setting it lower letting the converter flash up slowed it down to high 1.4s. Every car is different and the chassis will react different. Just have to experiment.
__________________
95 Pontiac Formula- Stock engine with ATI Procharger, Moser 12 bolt w/4:30 gears, Rossler trans, Neil Chance 4000 stall, M/T ET streets, 10.914@ 121.90mph, 1.452 60ft. GMHTP November 2010 Feature Car. Check it out at:
https://www.motortrend.com/features/...ebird-formula/
http://www.youtube.com/watch?v=abZ1z...ature=youtu.be
95 Pontiac Formula- Stock engine with ATI Procharger, Moser 12 bolt w/4:30 gears, Rossler trans, Neil Chance 4000 stall, M/T ET streets, 10.914@ 121.90mph, 1.452 60ft. GMHTP November 2010 Feature Car. Check it out at:
https://www.motortrend.com/features/...ebird-formula/
http://www.youtube.com/watch?v=abZ1z...ature=youtu.be
rule of thumb is 200rpm below your max stall, honestly your going to have to play with it at the track. My cousins car likes leaving at 4000, we tried 4200 and we went slower in the 60
Mine is an ATI one that came with my turbo 400.
actually looking to sell my my turbo 400 transmission
https://ls1tech.com/forums/showthrea...197&highlight=
actually looking to sell my my turbo 400 transmission
https://ls1tech.com/forums/showthrea...197&highlight=
I have yet to find my optimum launching rpm on the TB. So far all my best times have been footbraked. Everytime I launch off the TB I spin really bad and cut like a high 1.6X-1.7X sixty foot. It is super fun to play with at the track though. I need to make a few more passes though on it so I can find that sweet spot you guys talk about.
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Its something you have to experiment with, its easier to start out low with a 2 step and work your way up. Plus using the 2 step low is a lot easier on the converter..
1.2X is a SERIOUS 60' for a 4th gen IMO. Doing it off idle on he footbrake is CRAZY. I would LOVE to get to 1.35 and I think I could pull a 9.50 on a pretty low boost street car.
Okay rub it in! I noticed you mentioned in another thread hat you have repeatedly (sp?) detailed your suspension set-up. Link?
1.2X is a SERIOUS 60' for a 4th gen IMO. Doing it off idle on he footbrake is CRAZY. I would LOVE to get to 1.35 and I think I could pull a 9.50 on a pretty low boost street car.
1.2X is a SERIOUS 60' for a 4th gen IMO. Doing it off idle on he footbrake is CRAZY. I would LOVE to get to 1.35 and I think I could pull a 9.50 on a pretty low boost street car.
Its not all the suspension, its the power delivery also. Plus some tracks vary, but a blower is very easy to make 60' well. You cant foot brake a turbo unless its too small
But for the last time this is all I had under the car:
Strange single adjustable front shocks (usually set at 4 on the left and 6 on the right), Qa1 300lb 'generation F' springs, travel limiters at about 3.5" of travel, UMI rod end lower A arms, stock uppers.
Rear end was some sort of rod end LCAs I bought used off the board, Spohn drag sway bar. UMI LCA relocation brackets on the lowest hole, random tech torque arm on a BMR TH400 crossmember/TA relocation bracket on the 4th set of holes from the bottom, -1.5 degree DRIVELINE angle, stock springs that came on the car in 1998 and a pair of CE cheape 3 way drag shocks set at 40/60. Thats with a regular 9" Moser rear end housing/torque arm mount.
weights with me in the car were:
LF 952 RF 871
LR 813 RR775
Had about 1/4" more preload in the LF spring, swaybar was nuetral with no driver.
So there you go, use it as you wish..
Well thanks for the final final! Looks like you had LOTS of very detailed settings as far as pre-loads and other things. Must have taken a SOLID couple seasons with lots of track days to R/D what works and what didn't. I have always enjoyed watching your car leave. Always seemed so effortless.
Well thanks for the final final! Looks like you had LOTS of very detailed settings as far as pre-loads and other things. Must have taken a SOLID couple seasons with lots of track days to R/D what works and what didn't. I have always enjoyed watching your car leave. Always seemed so effortless.
Thread Starter
10 Second Club
iTrader: (41)
Joined: Sep 2004
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From: Champaign Il
I didnt say off idle, I said 1000rpm
Its not all the suspension, its the power delivery also. Plus some tracks vary, but a blower is very easy to make 60' well. You cant foot brake a turbo unless its too small
But for the last time this is all I had under the car:
Strange single adjustable front shocks (usually set at 4 on the left and 6 on the right), Qa1 300lb 'generation F' springs, travel limiters at about 3.5" of travel, UMI rod end lower A arms, stock uppers.
Rear end was some sort of rod end LCAs I bought used off the board, Spohn drag sway bar. UMI LCA relocation brackets on the lowest hole, random tech torque arm on a BMR TH400 crossmember/TA relocation bracket on the 4th set of holes from the bottom, -1.5 degree DRIVELINE angle, stock springs that came on the car in 1998 and a pair of CE cheape 3 way drag shocks set at 40/60. Thats with a regular 9" Moser rear end housing/torque arm mount.
weights with me in the car were:
LF 952 RF 871
LR 813 RR775
Had about 1/4" more preload in the LF spring, swaybar was nuetral with no driver.
So there you go, use it as you wish..
Its not all the suspension, its the power delivery also. Plus some tracks vary, but a blower is very easy to make 60' well. You cant foot brake a turbo unless its too small
But for the last time this is all I had under the car:
Strange single adjustable front shocks (usually set at 4 on the left and 6 on the right), Qa1 300lb 'generation F' springs, travel limiters at about 3.5" of travel, UMI rod end lower A arms, stock uppers.
Rear end was some sort of rod end LCAs I bought used off the board, Spohn drag sway bar. UMI LCA relocation brackets on the lowest hole, random tech torque arm on a BMR TH400 crossmember/TA relocation bracket on the 4th set of holes from the bottom, -1.5 degree DRIVELINE angle, stock springs that came on the car in 1998 and a pair of CE cheape 3 way drag shocks set at 40/60. Thats with a regular 9" Moser rear end housing/torque arm mount.
weights with me in the car were:
LF 952 RF 871
LR 813 RR775
Had about 1/4" more preload in the LF spring, swaybar was nuetral with no driver.
So there you go, use it as you wish..
Just to clarify, when you say the sway bar was set neutral with no driver you mean it had no preload at all with no driver in the car? Just hook up one side and adjust the rod end on the other to slide right on?
Yes, so it was preloaded a little more then they called for, I forget the Spohn directions exactly.
Well thanks for the final final! Looks like you had LOTS of very detailed settings as far as pre-loads and other things. Must have taken a SOLID couple seasons with lots of track days to R/D what works and what didn't. I have always enjoyed watching your car leave. Always seemed so effortless.
But if you cant get a 4th gen to hook then something is wrong, these torque arm suspension are pretty forgiving overall so I give GM more credit than myself. Interesting thing about everything I had it was 100% bolt on and you could take everything right off and put it another car with no welding (except for the away bar end links but they actually do bolt on first to the stock holes) thats the amazing for a 1.2x anything suspension..
