trans gear
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
page 12J sheet 6 in the 74 AIM only shows drive and driven gears up to 3.70, you might have to call a few vendors to find a set for 4.56.
Drifting
Joined: Oct 2007
Posts: 1,317
Likes: 22
From: Marina CA
You'll have to get a ratio correction box made up at a speedometer shop. With 4.56 gears and a T-400 you wont get close with any possible drive and driven gear combinations.
The box attaches to the transmission where the cable attaches and the the cable attaches to the ratio ciorrection box.
It must be quick out of the hole but the engine has to be screaming at 70 mph.
The box attaches to the transmission where the cable attaches and the the cable attaches to the ratio ciorrection box.
It must be quick out of the hole but the engine has to be screaming at 70 mph.
Burning Brakes
Joined: Nov 2006
Posts: 954
Likes: 40
2022 C3 of the Year Finalist - Modified
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Why bother? With that gear you can't go very fast, anyway. You just get there really quick!!! 
Seriously, you will have to get a conversion box. The internal drive gear would need to be changed to accommodate the new 'driven' speedo gear also. That would mean removing the tranny. Call some tranny shops around your area or check on the internet for "speedometer ratio adapter".
Seriously, you will have to get a conversion box. The internal drive gear would need to be changed to accommodate the new 'driven' speedo gear also. That would mean removing the tranny. Call some tranny shops around your area or check on the internet for "speedometer ratio adapter".
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Good for Drag Racing ONLY, now, I would ditch that 456 gearset as being totally useless on the street....even with overdrive, unless you had a .5-1 overdrive ratio.....like a 6th gear....and THAT would cost a fortune....
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
yes, you will have to do the math and fiqure out exactly what ratio conversion you need based on speedometer drive gear, speedometer driven gear, tire diameter, rear end ratio.
you need to figure out what conversion ratio you need by installing a ratio adapter that will force your speedometer cable to spin 1000RPM at 60MPH.
use a GPS to get real 60 MPH speed and eyeball your speedometer to get your error factor at 60 MPH.
for example, if your GPS says 60 MPH and your speedo says 70 you need to slow down your cable spinning.
the speedometer shop should be able to help you
you need to figure out what conversion ratio you need by installing a ratio adapter that will force your speedometer cable to spin 1000RPM at 60MPH.
use a GPS to get real 60 MPH speed and eyeball your speedometer to get your error factor at 60 MPH.
for example, if your GPS says 60 MPH and your speedo says 70 you need to slow down your cable spinning.
the speedometer shop should be able to help you
Thread Starter
Advanced
Joined: Aug 2009
Posts: 59
Likes: 0
From: Newburgh in
i originally had 2.73 and had a hellve deal for a complete rear off a front end totaled 68 with 4.56 for $100.00 i couldn't say no to that..but your right i was thinking maybe 3.73's?
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