2.73 -> 3.73 gear change

[Dragkid1917]

my one concern with this whole thing is how its going to affect the speed of my car at 120+ mph. With my 273's with a 245/50/16 tire, in 3rd gear (1:1) ratio, the car goes 152 - 153 mph at like 5900rpm. It does not however let it shift into overdrive or the 4th gear. My concern is that when I would put 3.73's on my car that in that same 3rd gear at 5900 rpm i would be going only 113 - 115 mph, and that it wont let the car shift to the 4th gear at wot. Now, can the car not shift into that 4th / overdrive at wot or, is the reason it doesnt shift outof 3rd because of the speed limiter? and if i were to take that off or sharpen the rear gear it would shift into 4th even at wot?

[Trash man]

long as the speedo is correct ur top speed limitor will be still at 159mph. as for the other stuff, i really dont kno

[Dragkid1917]

I kinda need to know.... does anyone here have a 2.73 - 3.73 swap?

[Christopherrr]

2:73 - 3.73 swap here.

I never gotten up to 150+, 140 is as fast as I've gone. I do shift into forth, but I can't recall if my car did before a tune. It does now and I don't have a rev limiter...well, it moved at 6500.

I hated the 2.73s, it was sluggish and made the car sound like it was drowning.

Can I ask why you'd want to go that fast anyways?

[ConElite]

Seriously, Why do you need to know. Do you do 150+ runs all the time?


p.s. If you ease in the gas it will stay in 4th gear and go up to the 150 mph range.

[Dragkid1917]

i dont go that fast all the time, but with the 3.73's and the stock 245/50/16 tires it will need to shift into 4th gear about about 113-115 mph (5800-6000 shift point) Its not so much for the 150 + runs as it is the needing it to shift from 3rd to 4th at wot if im racing someone and i need to go faster then 115. I cant be backing outof the throttle to trick the car into shifting into 4th while racing someone.

[toddwirges]

You need to get a tune to correct the speedo. Tuning will also allow a WOT upshift 3-4. You have no choice, the tune is mandatory for driveability and shift behavior, not just the speedo.

It's just my humble opinion, but 3.73 is too much gear for 245 tires. You could save a bunch of money just get a good 3.23 or 3.42 donor axle and do a full swap.

I have street 275's on my vert (heavier) and am traction limited with 3.42's. I did a full axle swap from a donor manual car. 3.73's will just roast 245 tires.

So, don't forget about the cost of tuning and realize you'll lose ~2mpg.

[MunsonGTA]

my one concern with this whole thing is how its going to affect the speed of my car at 120+ mph. With my 273's with a 245/50/16 tire, in 3rd gear (1:1) ratio, the car goes 152 - 153 mph at like 5900rpm. It does not however let it shift into overdrive or the 4th gear. My concern is that when I would put 3.73's on my car that in that same 3rd gear at 5900 rpm i would be going only 113 - 115 mph, and that it wont let the car shift to the 4th gear at wot. Now, can the car not shift into that 4th / overdrive at wot or, is the reason it doesnt shift outof 3rd because of the speed limiter? and if i were to take that off or sharpen the rear gear it would shift into 4th even at wot?

i can somewhat comment on this with experience from my car. your car doesn't shift into 4th at WOT because of the way it was designed. Basically the tranny limits it to keep from breaking parts. you can have it changed though. i believe in the ls1 cars it's electronic, in my car it's mechanical. i think you'll go faster in third gear then you think. i have 3.70 gears and a 700r4. i hit 126 at 5k rpm in 3rd. i also can't shift into OD at WOT in my car, it really is a pain in the ass. reguardless of what gear you put in there, your car won't shift into OD at WOT.