What gears do I need?

[HEG77k10]

I have a 1977 k10 with factory axles. 12 bolt rear end and Dana 44 front. I wanna re gear it to 4:10/4:11 but I’m not sure what gears I need. It has stock 2:73 gears which is a little tall for 35 inch tires lol. Thx for the help!

 

[HEG77k10]

If anyone has a specific brand too that they like let me know, cheaper the better!

 

[Turbo4whl]

The GM 12 bolt has different differential carriers for the gear sets. The tall gears, like the 2:73 has a much larger pinon gear than the 4:10. This means the place where the ring gear mounts is farther away from the pinon center on the tall (2:73) gears. You can use a ring gear spacer, but I would not recommend it turning those large tires.

This would be a good time for some type of limited slip or locking differential.

 

[nvrenuf]

Any chance an overdrive trans has been swapped in?
Type of use?

If you’re not traveling with it, I’d go with 4.56’s.

 

[SquareRoot]

Big block

 

[HEG77k10]

I’m 16 so I can only afford one vehicle and it’s my daily driver right now, rebuilt th350 tranny and a 400sbc.

 

[HEG77k10]

So would I have to get the “thick” gears if it has 2:73s stock? I was looking at rigid axle, they have some cheaper ones.

 

[Turbo4whl]

So would I have to get the “thick” gears if it has 2:73s stock? I was looking at rigid axle, they have some cheaper ones.

Yes

 

[HEG77k10]

Yes

Ok thanks!

 

[HEG77k10]

Has anyone used rigid axle? My dad bought his truck with 4:56 gears and it’s awfully wound up going down the freeway

 

[Vbb199]

I would recommend a 3.73-4.10 range with a 35" tall tire and a th350

4.10 being more bottom end power, less High speed

3.73 maybe being a happy medium

 

[dvdswan]

IIRC, the cutoff for a new carrier would be 3.73 and lower. At least for the D44.

 

[Vbb199]

^didn't even think about that, but I just browsed over to Randy's ring and pinion and supposedly there's 4.11 thick cut gears for your 12b rear axle.

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[HEG77k10]

So is there a thick gear set for Dana 44s? Or would I need a whole new carrier if I wanted to go down to a 4:10 from a 2:73

 

[Vbb199]

So is there a thick gear set for Dana 44s? Or would I need a whole new carrier if I wanted to go down to a 4:10 from a 2:73

Yes

Like @Turbo4whl said,

For some axles, instead of getting a whole new carrier, you can purchase "thick" gears which is basically a thicker ring gear to make up the difference.
I agree with him though, I wouldn't recommend it for larger tires, as it's putting more sheer stress on the ring gear bolts.

Might would be best to get the 3.73 and up carrier(s), and then get your desired 4.10's