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Which rear gear is better?

  • 3.73

    Votes: 10 90.9%
  • 4.11

    Votes: 1 9.1%
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Discussion Starter · #1 ·
Is it worth spending the $225 on a 3.73 gear set to switch from 4.11s
4.11s suck on the highway with a th400 trans

I'm on a budget OD trans is out of the options because I can't afford to build a 600 hp OD or get a 5/6 speed manual.

How much a difference will switching from 4.11 to 3.73s make? Both mileage and loss in acceleration?
I have 225/70/15 rear tires

I can't go any higher because I have a stage 4 eaton posi unit, the highest are 3.90s but I can buy a special 3.73 gear set that has a thinner ring gear to fit inside the stage 4 carrier. A stage 3 carrier would be ~$450.

I would like to make driving on the highways a bit more bearable going 65 mph
Is it worth getting 3.73s over 4.11s on the street?
If it's not going to make that much of a difference I won't get them
 

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John
I'm sure someone will pipe in with the rpm's @ 60 mph. but I would guess there won't be enough of a difference unless you go to 342's or 331's.
I'm running 342's with tb400 bb & I wouldn't want to go any lower. good luck.
hmardown
 

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Going from a 4.11 to a 3.73 will not make much of a difference. I have a 3.73 rear and it's pretty bad even at 60mph. You probably won't get a noticeable mileage increase, but you also probably won't be able to notice a performance loss either.

I would just save up for a t56 w/ .5 OD in the future. Or if you want to keep the auto then save up for a built 200r4.

If you want to get a noticeable decrease in rpm, and gain 1 or 2 mpg, then a 3.55 is probably your best option, but you would need to find a used 3 series carrier from a junkyard and you would probably see a slight decrease in performance at the track.
 

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Hi John,
I agree with Freddie. Either keep the 4.11s or purchase an Eaton 3 Series Posi and 3.42s. Make sure that you use a Timken Master Kit. I get good pricing on them.
PM me if you need any help.
 

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I am not a fan of the thin 3.73 Ring Gear on a 4 Series Carrier. However, if you want to put a thick 4.10 Ring Gear on a 3 Series Carrier, that will make a strong 12 Bolt.
 

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You really need to go to a 3.53 or 3.42 to see a noticeable difference in the engines rpm at 60 mph.
Anything less is a waste of money and time IMO.

Larger tire diameter helps slightly.
 

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What power are you putting to the gears? If it is relatively low torque engine, the 373'S may still be fun. If you have a decent torque maker in a BBC, going to a 342 or 331 will still provide a good feel while slowing the rpms a lot.
 

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Not worth the trouble and expense. Save some more money and get a 3 series Eaton Posi and go to at least a 3.42 gear. Don't forget that you will need a good installation kit to go with this.
I was also thinking 3.42....
 
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