Another rear gear/speedo gear selection thread

[FirebirdTN]

Hi everyone, new member here, but long time lurker.

I bought a 94 vert that was completely stock except for some 40 flows out back.

Well, the performace bug has bit. Only mods the car has now are an or/h, and some tranny mods (automatic).

From everything I have read, gears are the first mod to do. However, there is a lot of conflicting info on gears and speedo gear selection.

Looks like I have 3:27s stock. So, would 3:73s even be a noticable upgrade, or do I go staright for the 4:10s? Also, if I go 4:10s, do I skip the speedo gear entirely and get a speedcal? I was under the impression speedcals didn't work with our cars (94-95). In any case, the car feels like a pig. With the flows and orh is makes a lot of noise but just doesn't seem to want to go. There is nothing wrong with the car, I just also own an 06 coupe, so the 94 would feel awefully slow comparatively.

The funny part about this is I rebuilt my tranny about 4 months ago, and I never bothered to count the driven gear on the output shaft as I didn't think I'd be bit by the upgrade bug, nor did I put in a stall converter, but now wish I had.

-Alan

 

[Inspector13]

Yeah 3:73's would be a noticeable upgrade for ya. I'm not real familiar with the autos. Depending on the final drive ratio of your trans (if you have an overdrive or not) 4:10's may be a tad aggressive (unless you like having a maximum cruising speed of 45 mph or so). Depends on what you plan on doing with it though.

Personally my $.02 is that for an auto 3:55/3:73 maybe 3:90's are good gears and for a Manual 3:73's are a minimum.

 

[duh09]

Speedcals do work with the 94-95 cars, I have one. I think its just more of a personal preference as to which one to go with. Speedcal was my choice because I don't plan on keeping 4.10s forever haah

 

[toyman]

The auto with stock 3:27 gears will require a 21 tooth driven gear with 3:73's and speedo is reading true. Anything higher will require a speedcal type device for accuracy. I had 4:10's before my KB and that really made a difference especially with a shift kit. 60 mph in OD with 4:10's is about 2300 rpm. Not excessive by any measure.

 

[FirebirdTN]

THANK YOU! That was just the info I was looking for. The main part of confusion I see is which driven gear on the speed-o to select. I guess the contradictions on the net stem from there being different output shafts in the AODE (different speedo drive gear).

I know someone said above that 3:73s would be notable upgrade, but since I am starting with 3:27s, I am very tempted to go 4:10s. 2300 rpm @60 isn't bad. I think most of the pre overdrive cars I used to own turned 2K @60.

Thanks,

-Alan

 

[Inspector13]

60 mph in OD with 4:10's is about 2300 rpm.

Dang what is your OD ratio???

 

[toyman]

AODE standard ratio OD is 0.67:1. The wide ratio AODE is 0.7:1.

 

[CanaryGT]

I have a 5 speed with 4.10's. I love it. And a SpeedCal. I personally am super glad I went 4.10.

 

[95_5.0]

so just to confirm the Speed Cal does work on 94-95 5.0 T5 trans right?

 

[CC'S95GT]

yes

 

[keeno]

I believe a 94 gt came stock with 2.73 gears, 3:08 optional. Wasnt until 99 they started putting 3.27's as the standard gear. A 215 horse 5.0 with 2.73's = DOG. Get the 4.10's with the automatic. You won't believe the difference. You just need a plastic speedo gear change, not the expensive speedcal.

 

[atlanticblue98]

I believe a 94 gt came stock with 2.73 gears, 3:08 optional. Wasnt until 99 they started putting 3.27's as the standard gear. A 215 horse 5.0 with 2.73's = DOG. Get the 4.10's with the automatic. You won't believe the difference. You just need a plastic speedo gear change, not the expensive speedcal.

i believe different gears came on automatics than on manuals, for 94-98 GT's of course. but that statement is true for V6's, all of the 94-98 V6's came with 2.73 gears no matter than transmission