View Full Version : T-Brake + Gearing ?'s


ssmoov1
10-19-2007, 10:20 PM
My car is a full weight Convertible 3800lbs+ off the brake all i can get is a best of a 1.60 short time this is with 27x10.5 Hoosier qtp's a 4.10 gear and spool.I would think I should be in the mid 1.5's at least N/A.Is this possibly too much gear or could it be too tight of a converter?The TC is a 8" ATI 4000 it was built for the spray but I would think it would perform a little better than that N/A even if it was built for the spray.Any help or ideas on getting this figured out would be appreciated.


Joe

PRAY HRD
10-19-2007, 11:07 PM
i would think so too. my old '00 ss vert was 3850 with me in it and had stock 5.3 heads, ls6 intake, baby 224/228 cam, tci ssf 3500 stall, 3.90's in 12 bolt, same size m/t et street and cut a best 1.68 60' time through a stock 4l60e and ran 11.92 @ 114 mph.

do you know what you stall to off the spray? if you're setup to stall at 4000 on the spray & brake, chances are you've got something closer to a 3000-3200 stall on motor max.

what is your 1/4 time on motor?

on a side note, my 3.90's with a 3.08 first gear vs your 4.10 with a 2.52 1st gear is a HUGE difference. it's equal to having a 3.35 rear gear with a 4l60e when leaving in 1st gear. in other words, you'd need a 4.77 rear axle gear with your th-350 to launch with the same final 1st gear ratio as soemone with 3.90's and a 4l60e. understand?

1st gear final drive ratio...
4.10 x 2.52 = 10.332
3.90 x 3.08 = 12.012

chrismorales75
10-19-2007, 11:25 PM
My car is a full weight Convertible 3800lbs+ off the brake all i can get is a best of a 1.60 short time this is with 27x10.5 Hoosier qtp's a 4.10 gear and spool.I would think I should be in the mid 1.5's at least N/A.Is this possibly too much gear or could it be too tight of a converter?The TC is a 8" ATI 4000 it was built for the spray but I would think it would perform a little better than that N/A even if it was built for the spray.Any help or ideas on getting this figured out would be appreciated.


Joe

What mph are you running? Have you had the car dynoed?

If you can list this then you can gear the car to hit the lights closer to your peak power.

Also where do you have the lower control arms, torque arm and pinion angle and shocks set at? If any of these are off it will effect the 60 ft.

So tell us this info and we can have a better idea which way to point you in.

ssmoov1
10-20-2007, 07:05 AM
What mph are you running? Have you had the car dynoed?

If you can list this then you can gear the car to hit the lights closer to your peak power.

Also where do you have the lower control arms, torque arm and pinion angle and shocks set at? If any of these are off it will effect the 60 ft.

So tell us this info and we can have a better idea which way to point you in.

The car dynoed 396rwhp N/A through the TH350.In the 1/8th mile i'm hitting 7.37 @ 94mph.The LCA's are on the lower holes of the relocation brackets and pinion angle is at -2.5
I'm still on the stock shocks and dont have any problems hooking up outta the hole off the brake on motor but i know i need some shocks soon so i guess that would be a big factor also.I have seen quite a few people here still running on the stock shocks and have pretty good 60's.I have got the Spohn rear drag sway bar that i will install today and hope that it will help me from leaving all twisted up in the rear.

ssmoov1
10-20-2007, 07:17 AM
i would think so too. my old '00 ss vert was 3850 with me in it and had stock 5.3 heads, ls6 intake, baby 224/228 cam, tci ssf 3500 stall, 3.90's in 12 bolt, same size m/t et street and cut a best 1.68 60' time through a stock 4l60e and ran 11.92 @ 114 mph.

do you know what you stall to off the spray? if you're setup to stall at 4000 on the spray & brake, chances are you've got something closer to a 3000-3200 stall on motor max.

what is your 1/4 time on motor?

on a side note, my 3.90's with a 3.08 first gear vs your 4.10 with a 2.52 1st gear is a HUGE difference. it's equal to having a 3.35 rear gear with a 4l60e when leaving in 1st gear. in other words, you'd need a 4.77 rear axle gear with your th-350 to launch with the same final 1st gear ratio as soemone with 3.90's and a 4l60e. understand?

1st gear final drive ratio...
4.10 x 2.52 = 10.332
3.90 x 3.08 = 12.012

The TC will stall up to almost 4000 on the brake.I haven't tried to spray off the brake yet..On the dyno it flashed to about 5200-5400 on a 100 shot.No 1/4 mile times yet just got 1/8th around here.That is a good point on the 1st gear drive ratio on the th350. I know the th350 felt kinda soft outta the hole compared to the 4l60 thats why i stepped up to a 4.10 but i guess that still aint enough gear and would have to go with a 4.56 or 4.88 to get to the 1st gear ratio the 4l60 has.

JL ws-6
10-20-2007, 08:35 AM
For a car as heavy as your is, with stock shocks and that tire you aren't doing all that bad. I didn't care for that tire much on my car personally, but some people have good luck so it's a hit or miss.

Try putting the pinion angle a little closer to 0, you put too much in and it causes a bind that robs some power. Other then that, a set of shocks, and getting some weight out are probably gonna help the most.

If you loosen the converter up to get it to run n/a it's probably gonna be too loose for nitrous use, kinda leaves ya with the car running good n/a or good running on spray, you'll never get a converter that works great with both.

Navy David SS
10-20-2007, 09:44 AM
The converter you have if set up for nitrous is not going to give you the launch rpms you need for N/A. You have to decide, nitrous or N/A. Your gear (4.10) is fine. A good set of aftermarket shocks will also help a good deal.

David