It seems commonly accepted that 4.10s are too much for cars that spray, at least ones that are modded too due to running out of gear near the end. Will 3.90's work, or should I just go with 3.73's?

 

It all depends on how big you want to hit the juice. Up to a 150 shot I would go with the 3.90's. Bigger than a 150 shot I would go with the 373's.

Mike

 

Actually I've looked around and I think 3.90s are for 9" only. So 3.73 it is. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

i needed to make a choice last week, either to go with a 3.73, or a 4.10 in my moser 12 bolt that i am getting installed wed @ speed inc. i just got my nitrous installed this winter, so i have yet to run it with nitrous. i talked to larry from speed inc. and he told me 99% of the people that order new rear ends get a 4.10 (M6 owners i mean). i told him that i want to spray, and that it might just be too much off the line. and he told me that well how often do you go to the track, which i will probably only go like 4 times this summer. so i will be doing a lot of street racing, and also a lot of N/A runs. so that is what convinced me into getting a 4.10. get a 3.73 for a lot of track use and N20, get a 4.10 for N/A use.

Also i have some questions that i need answered:
(i will list my mods bellow, so u can see my setup and how much power i have)

1. How bad will i spin if i spray in first with a 4.10 gear (i am only using my 75shot but want to do 100shot)?
2. Should I wait until second gear to start spraying?
3. Am i always going to have to manually hit the arming switch when i hit second gear (my setup is a WOT switch) i mean that will be hard to do, shift from first to second and then flip a switch fast or do they make something that it wont spray until second gear, ive heard something about a mallory switch or something but dont really know much about it?
4. What RPM to drop it in at?
5 What gear will i finish in both N/A and with NO2, and how far into the gear will i finish it in?
1998 Trans Am WS.6 M6
Lid, Borla, Mac Headers w/ offroad y-pipe (02 sims), SLP air temp module !CAGS, descreened MAF, ported MAF, MAFT, MSD window switch, NX wet (75shot),NX bottle heater, MSD spark plug wires, NGK TR6 plugs,BMR SFC's, BMR LCA's, Z06 clutch, 315 NITTO drag radials

<small>[ February 16, 2003, 11:06 AM: Message edited by: jeff ]</small>

 

6400 rpms in 4th gear is 119 mph, most modded nos cars trap way higher than this, close to 125-130, so 3.73 is the gear for a nitrous or F/I car. If NA, get a 4.10, or even a 4.30.

http://www.f-body.org/gears/