Picking the right gear

Fuelie74

Fuelie74

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Joined
May 7, 2008
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Location
Monroe, WI
The clutches in my rearend are giving it up, so I am thinking about pulling the diff and fixing it. That means that I might as well regear while I am at it.:nuts: When I did my T5 swap I was originally planning on changing to 3.73 down the road, but a friend started to second guess my decision suggesting that a 3.90 might be a better option. While playing with an online selection calculator I started to think that 4.11 might be the best option. I am currently running a 92 350 TPI and have a LS1 swap in the works for the near future. I am running 255/60R15 tires out back and have a GM WC T5 with a 2.95 1st, 1.94 2nd, 1.34 3rd, 1.0 4th, and 0.63 OD.

The car is a cruiser most of the time, but I drive it hard and basically never use 5th gear right now with 3.08 gears. Am I totally nuts on the 4.11 gears?
 
Yes, I have a T5 in a Camaro w/ a 3.48 gear (9 bolt) and it's about perfect for cruising and stomping on it. You can drive in 5th gear on the highway at a comfortable rpm and the gears are not too short down low. I wouldn't want anything higher in it unless you want to run no faster than 70mph.
 
If you're planning an LS swap and you're doing a lot of hiway, dont go too high. I'm running a 6.0 LS/Richmond 6 speed/3.08 rear. The Richmond 3.27 1st/0.76 OD is about perfect. The LS motors have a great torque range, and you dont want to be shifting halfway through the intersection or spinning over 2200rpm on the hiway.
You might consider 3.4-3.7 max for your rear gear.
 
keep in mind that the LS1 can easily run at 1400 rpm in 5th gear on the highway..... 3.55 or 3.73 is about as high as I would go.... 3.55 is probably your best choice.....
 
I'd recommend a 3.36 rear end gear ratio. If you multiply the RE gear by the first gear ratio, you should target about 10:1. With a 3.36, you'll get 9.9 total. If you go to more than this, first gear will be nearly useless because you won't be able to hook up.
 
May I jump into the thread.
It seems common sense to aim for a 10 first gear ratio, what about the final gear ratio?
As far as I understand it's related to the engine optimum efficiency RPM, so may change from an engine to another, but isn't there some kind of usual ballpark value?
 
Kind of depends on the motor. When I put the 6.0 LS motor in my 68 with 3.08 rear I didn't want a 0.6x OD, so I went with a Richmond 6 speed with 0.76 OD. You dont want to have to downshift a manual at every hill.
I completely underestimated the low end torque and could have gotten a lower OD. I'm just under 2000 rpm at 75mph, but could have gone way lower.
If you've got a big cam, lots of overlap, you might be better off with a 22-2400 rpm hiway cruise.
If you want optimal gas milage with a fuel injected motor, pick the lowest rpm that will get you by in hiway driving. That's why a new vette get 26mpg with 400+ hp.
denpo said:
May I jump into the thread.
It seems common sense to aim for a 10 first gear ratio, what about the final gear ratio?
As far as I understand it's related to the engine optimum efficiency RPM, so may change from an engine to another, but isn't there some kind of usual ballpark value?
Click to expand...
 
Garys 68 said:
Kind of depends on the motor. When I put the 6.0 LS motor in my 68 with 3.08 rear I didn't want a 0.6x OD, so I went with a Richmond 6 speed with 0.76 OD. You dont want to have to downshift a manual at every hill.
I completely underestimated the low end torque and could have gotten a lower OD. I'm just under 2000 rpm at 75mph, but could have gone way lower.
If you've got a big cam, lots of overlap, you might be better off with a 22-2400 rpm hiway cruise.
If you want optimal gas milage with a fuel injected motor, pick the lowest rpm that will get you by in hiway driving. That's why a new vette get 26mpg with 400+ hp.
denpo said:
May I jump into the thread.
It seems common sense to aim for a 10 first gear ratio, what about the final gear ratio?
As far as I understand it's related to the engine optimum efficiency RPM, so may change from an engine to another, but isn't there some kind of usual ballpark value?
Click to expand...
Click to expand...

THIS is the part of the equation I need to know.....and I have to ASSume that any 10-1 ratios are with stick shift in first gear, not a automatic....
as I never had any problems burning rubber off the line even with a heavy loaded work truck and automatic....

:hissyfit:
 
Automatics are a totally different animal. The torque converter give more torque multiplication so you can reun a much lower (numeric) rear end.
F bodies came with 3.42 or 3.73 rears with manuals and 2.73 with automatics even though they had similar 1st gears.
 
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MYBAD79 said:
mrvette said:
That's why I built the 700 for the Clamper, 411 rear, not that we will ever use it, so it turns out.....:hissyfit::crap:
Click to expand...

why not ??
Click to expand...

Bluntly said, old women live forever, and so wife's aunt has no one left at age 79 and wife's mother is still around at 81, so every other weekend we have both of them, and the alternate weekends we have alone for just 2.5 days....

women are the nursing home patients, NOT men....maybe 5% men, if that.....

and so with health and althsheimers i'ts been going on for over a year now, naturally happening just after the camper project was under way.....

I would rather have seen Key West in the vette, but wife wanted this campground type thing.....to me I95 to US 1 and have over with it, she wants A1A all the way much as possible....which is fine too....but we not going at ALL now....

:hissyfit::crap:
 
big2bird said:
Fuelie74 said:
Am I totally nuts on the 4.11 gears?
Click to expand...

At $4.00 a gallon, maybe............:huh:
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I would be at 2000 rpm at 60 mph with a 4.11 and my .63 OD. Right now I am only using 4th which is 1:1 putting me at 2300 rpm. So I would still be better off.

With that low of an OD gear you aren't effected nearly as much by the steeper gears at highway speed.

By the way no one has ever accused me of being sane.:nuts::nuts::nuts:
 
larrywalk said:
I'd recommend a 3.36 rear end gear ratio. If you multiply the RE gear by the first gear ratio, you should target about 10:1. With a 3.36, you'll get 9.9 total. If you go to more than this, first gear will be nearly useless because you won't be able to hook up.
Click to expand...

This is the route I went. I have an .82 overdrive and cruise at about 2k rpm @ 70 mph.

I used Richmonds' gear calculator and a tire height of 27" and played with the numbers until I found the 10:1 first gear and O.D. cruising rpm's I wanted.
 
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