i'm running about 350HP maybe more through an 1800 stall (soon to be a 2400) in a turbo 400. I currently have 3.23 LSD in the back. my launches suck and my 1/4 times are suffering. I'm planning on swapping out the 3.23's for either a set of 3.55's or 3.73's.

I'm more leaning towards the 3.73's but i'm getting alot of flack from a few friends who think i should use 3.55's instead because of the low gearing of first gear in the TH400...


What do you guys think? I'm looking for best launch/ 1/4 times and maybe the ability to pull the front off the concrete a little.... it'll expand the suspention right now if i launch at 4K rpm but i wanna shock the riceboys with a nice jump in the front


thanks for any info...


Dave

 

what rear do you have and what do you do with the car? i'd lean towards 3:73s without more info.

 

A TH400 has a 2.48 first gear vs. s 700R4's 3.06 first. That's higher, not lower. You would need a 3.73 with your TH400 to equal the launch ratio of a 700R4/3.08 combo. You would need a 4.56 rear ratio with your TH400 to equal the launch ratio of a 700R4/3.73 combo.

 

You drive it around much, or is it mostly a track car? 65 mph oh the I-state is gonna drive you crazy. its right about 3000 or 3200 RPM if I remember correctly. Buddy is running a 400 w/ 3.73s and won't take it on the interstate anymore. Of course he is running low 11s/ high 10s w/ a lt1 355 and a procharger...

 

thanks for the info...

it's more of a saturday night special / drag car than an every day driver. i still take it to work once in a while just for the hell of it.


Thanks, looks like i'll be going with what i was thinkin all along, 3.73's for me.

I'm well aware of the PITA to install the gears but other than shimming them to mesh right, is there anything else i should know before tearing into the pumpkin ?




Dave