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View Full Version : 3.73 gears over 3.42


Overboost
10-15-2006, 02:31 PM
I was thinking about swapping out my stock 3.42 gears in favor of 3.73's
I see most everyone is using stock. I blew the posi out of the car at the track today (now its a one wheel peel) and was going to go with an eaton posi and 3.73 has anyone done this and is it feasable for a low 12 sec ride? :chain:

PaCemkr86
10-15-2006, 03:49 PM
is your engine mostly stock? how tall are the tires you are using?
I would consider it if you were using a 29 inch tall tire

Overboost
10-15-2006, 04:33 PM
the block is stock with a slight cam. 27 1/2 inch MT drag radials, TE60 turbo and enough intercooler for 3cars with 65LB injectors. my MPH today at the track was a measly 106 and a 12.41 ET:tdown: (funny, I've been told I should be in the 10's with these things, I am not even in the 11's) my 87 GT mustang was pulling 11.72 at 117 and it had about the same power level as this engine is doing. it had a stick with racing spec stage 3 clutch
(6500 RPM launches tends to incinerate a zoom clutch) :flame:
the guy who builds my trannys and rear ends told me to go with a 3.73 and eaton posi. being that I like to waste money it sounded pretty good to me.

PaCemkr86
10-15-2006, 04:39 PM
click the link in my sig for "my turbo buick".. the 3.42's are perfect for me and im running 28x9 tires pulling 1.50 60ft'sand lauching @ 3500 on the transbrake.



and here is a link to my mustang that runs 3.73's and pulls 1.30 60fts
http://www.ccstreetscene.com/forums/vbgarage.php?do=view&id=16

PaCemkr86
10-15-2006, 04:43 PM
can you post a scanned copy of your track times? maybe we can see where the HP is falling off

Overboost
10-15-2006, 06:43 PM
time slip attached. dont pay attention to the V6 sebring with slicks :stooges: that was trailered that I raced on this slip. I am car 213

PaCemkr86
10-15-2006, 07:32 PM
the MPH is low.. for those mods
what converter are you using?
Do you a scan tool, is it pickin up any knock reatrd?

kenmosher
10-16-2006, 09:48 AM
I agree ... 60 foot is a little lazy, but the 1/8 looks like it pulls pretty good and then lays down at the end of the run.

You should pick up 25 MPH or so from the 1/8 to the end ...

It looks like you have something not right about your tune (or slipping converter or something). The 3.73s will make that worse unless you are running taller tires.

I'd start thinking about 3.73s when you are closer to the 10s... until then, they will cause more problems than you already have.

Overboost
10-20-2006, 08:50 PM
there is no knock retard. scanner picks up one knock but that is only at startup. converter is a 3200 stall, but it is shifting at 4500 R's. I cant get it to go any higher, I just leave it in D. I dont manual shift. maybe I need more stall? car is sluggish on the shift 1-2 and 2-3 but bangs firm and fast when cruising

Keller
10-22-2006, 04:08 PM
Really should not shift until 5200. Probably would cure many ills for you.

Ormand
11-01-2006, 11:39 AM
Some of the faster cars are going the other way, to a 3.23 or a 3.08. The 3.73 would be good for smoking tires, but not much else. If the engine is running out of revs with the 3.42, the 3.73 would make that worse.