I thinking about swapping my 3.73 for a set of 4.10, what kind of rpms would I expect to see cruising on the highway at say 50-75mph. My tranny is a 700r4 with a 2400 sc.

 

3.73 and 4.10 gears are only 1 tooth difference (11/41 vs 10/41). I doubt you'll really notice any difference at all.

Its probably not worth the trouble for only a 1 tooth change.

 

thanks Air_ Dam, for some reason I didn't think they were so close.

 

Not sure why this is under exhaust but...

On the left, it shows that you have a blown stroker motor. You also quote dyno #s. We haven't seen the graph but you may see nice gains if your curves are peaky because steeper gears may keep you in the meat of the power better.

As for the RPMs, you should be 10% higher than with the 3.73s if everything else is the same and the TC is locked up.

Also, what rear end do you have?

 

I have a strange 12 bolt with eaton posi, 31 spline axels.

 

There is a calculations section on the main page that will tell you what your RPM differences will be. It is simple math.

 

4.10-3.73
3.73

=37
3.73

=10%


1500rpm->1650
2500rpm->2750
4000rpm->4400

 

Thanks guys, Air_ Adam was right, I don't think the swap is gonna make too much of a noticeable difference...might not be worth the headache afterall.

 

hmmm even though this is under exhaust it was still a bit helpful popping in real quick. So do you all recommend someone with a 400+ hp setup like me to just stick with 3.73 out back and a 2800-3200 stall converter?

 

I'm at about 63mph and 2550rpm. Not the best, but it's bearable. Just can't speed anymore if I want any kind of economy. It's a 700R4 with .70 OD, 4.10's, and 2800 stall converter. It's a lockup though, so it don't matter on the highway

 

It all depends on where your powerband is at, and what RPM you are exiting the quartermile at.

 

but will 4.1s almost always benefit me more than 3.73? Because unless 4.1 is hurting my performance then i may as well avoid 3.73

 

All depends on where your powerband is. Like if you have a stock TPI that runs out at 4300rpm or so.

This is just an example, I don't have the actual numbers. Say with 3.43's you finish the 1/4 mile at 4500rpm in direct drive. You are just out of the powerband at the end of the race. If you had 4.10's in it you could be at 5800rpm at the end of the race, out of your powerband and needlessly dragging the motor to higher RPM's. Either that or shift to OD. Either case you'd be loosing performance by going with the taller gears. That's why some people report a loss by going with taller gears on an otherwise stock motor.

It really just comes down to what is best for your particular car. Do you have a ton of torque down low? You can get away with a lower gear then. Does your heads/manifold/cam choice leave you without power until 3000rpm? Then you'll likely need a taller gear to get moving.

Stoplight to stoplight racing though, a taller gear will almost always be better as long as you have traction.

 

forgive me for not staying on topic but shouldnt a blown stealth-rammed 383 be pushing more than 410hp? maybe you shouldnt think about gears and start thinking about tuning....

not trying to be a smartass, only trying to help

 

Is that 2500 rpm in overdrive? I was told I have 3.73 posi and i'm running 2200 at 70 in OD but 3500ish in 3rd at 70

 

its 417@ the wheels streetroc, thats about 570@ the crank, I don't know about you but thats more than adequate for an almost everyday driven street car. A simple pulley change and i'll be knocking over the 600hp door but do I want so much power for my purpose of my car, NO. I drive it regularly and I don't get FREE gas so 6miles to the gal. ain't gonna cut it.

 

If this question is directed at me, then here's the answer

Yeah, it's overdrive with the stock 700r4 gearing. IIRC, .70:1 4th. Direct drive for the same speed is something like 3800-3900 rpm. Definately not doable for a non OD street car