Change from 2:73 to 3:73

[JDCHEVY5]

Yeah I feel you there. I take my burb out to Colorado from New Hampshire every so often and it handles the highway just fine with the 3.73s. Especially with the 700R4 my gas mileage isn't even so terrible. If that's all you're looking to do then you'll be alright. Lol I've had my truck over 100 several times but with that stock steering shaft it's a little scary at anything over 85-90. But that's besides the point. With my 31s it's pretty much tapped out at 105-110 pushing 4K+ rpms screaming at me, but with 33s and 3.73s you should be alright at those speeds. You'll still eat gas if you plan to do that for extended periods of time but it'll still be capable for sure. I'm assuming you have overdrive? I can go 85-90 for an hour with no worries besides the fuel gauge, bigger tires will only make it cruise more like slightly taller gears. Not what I would go for personally because I can't stand how much of a dog it is acceleration-wise even with the 31s (especially since I tow cars fairly often), but it will still be wayyy better than having 2.73s for sure lol

Yeah I got a 700r4 and I've had it up to 120 on the highway going downhill but overdrive doesn't kick in till I'm doing about 85-90.

 

[MikeB]

IME a 10 bolt is a 10 bolt, the rear carrier in my 87 V10 burb is out of a 79 Z28 Camaro. T

Well, first there was the 8.2" 10-bolt, introduced in mid-late 60s cars. They were used behind most small blocks, but big blocks and even high performance small blocks got a stronger 8.875" 12-bolt.

Then there were 2 versions of the 7.5" 10-bolt used in the previous generation Camaros, as well as Impalas, and S10 trucks. Later versions were actually 7.625" and had stronger axles and a larger pinion "head" bearing. If you see one of these for sale, runaway, runaway, unless you have a stock small block and auto trans, preferably a 305 or smaller.

And finally there's the 8.5" 10-bolt, which is what most of our trucks use -- at least the 81-87 C10 and R10 models, and possibly late 70s trucks.

The only parts that are interchangeable among the 3-types above are maybe some of the bearings. The R+P sets and carriers are totally different.

The 8.5" is fairly strong, unless you're running slicks. And the same carrier is used for "2.73-up", although "up to what" I'm not sure. But I do know standard 3.73 gears work in the same carrier as 2.73 gears.

8.2" and 7.5"/7.625" 10-bolts have different "breaks", such as "3.08-up".

 

[1low4x4]

Well, first there was the 8.2" 10-bolt, introduced in mid-late 60s cars. They were used behind most small blocks, but big blocks and even high performance small blocks got a stronger 8.875" 12-bolt.

Then there were 2 versions of the 7.5" 10-bolt used in the previous generation Camaros, as well as Impalas, and S10 trucks. Later versions were actually 7.625" and had stronger axles and a larger pinion "head" bearing. If you see one of these for sale, runaway, runaway, unless you have a stock small block and auto trans, preferably a 305 or smaller.

And finally there's the 8.5" 10-bolt, which is what most of our trucks use -- at least the 81-87 C10 and R10 models, and possibly late 70s trucks.

The only parts that are interchangeable among the 3-types above are maybe some of the bearings. The R+P sets and carriers are totally different.

The 8.5" is fairly strong, unless you're running slicks. And the same carrier is used for "2.73-up", although "up to what" I'm not sure. But I do know standard 3.73 gears work in the same carrier as 2.73 gears.

8.2" and 7.5"/7.625" 10-bolts have different "breaks", such as "3.08-up".

Pretty sure 2.73 is a different carrier than a 3.73. Different series such as 2 vs 3 or 4. Maybe could use a ring gear spacer to make it work

 

[Pender1]

I had 2.73's in my '84 10 bolt and swapped in 3.73's when I put 33" tires on. It's the same carrier and I'm basically back to stock final gearing with the tires and ratio change. Could have used 4.10's for a little more ass, but it drives just fine like it is.

 

[1low4x4]

I had 2.73's in my '84 10 bolt and swapped in 3.73's when I put 33" tires on. It's the same carrier and I'm basically back to stock final gearing with the tires and ratio change. Could have used 4.10's for a little more ass, but it drives just fine like it is.

My bad, I meant you cant use the same carrier for 2.73 to 4.10

As far as 3.73 or 4.10 on 33s, you wouldn't feel a difference between the two.

 

[Wildjoe330]

Honestly, if you have 33s I would go for 4.10 instead of 3.73. I have 3.73s and 31s, I already feel underpowered. I'm getting 33s when these tires are done (which is probably soon, they're already getting down there) and when that happens I am also switching to 4.10 gears. You'll still be able to drive it with 3.73s sure, but if you want to be able to get out of your own way at all I would suggest getting something a little shorter than 3.73s. They're great for cruising on the highway 2K rpms @ ~70-72mph with the 31s, but they feel a little tall and I'm dreading what even bigger tires will feel like.

I was wondering what gear ratio (3.73?) my 14 bolt would need for 70-75mph instead of the 4.56 in it, I took off my 33's (I should sell all 6 rims tires) and switched to 16's street/city.


77 K20, 50 to 65 Vibration, Replaced front axle u-joints, Cab Body Bushings, Front Wheel Barrings gone thru, New front pads, New Lockouts, Used Part time Kit, Rear drive line Balanced New U-joints, New Tires/Rims Balanced, New Transmission Mount, 350, TH350, NP203, 7/12 4:27

 

[bucket]

I was wondering what gear ratio (3.73?) my 14 bolt would need for 70-75mph instead of the 4.56 in it, I took off my 33's (I should sell all 6 rims tires) and switched to 16's street/city.


77 K20, 50 to 65 Vibration, Replaced front axle u-joints, Cab Body Bushings, Front Wheel Barrings gone thru, New front pads, New Lockouts, Used Part time Kit, Rear drive line Balanced New U-joints, New Tires/Rims Balanced, New Transmission Mount, 350, TH350, NP203, 7/12 4:27

3.73 would be fine for general highway use with stock size tires.

My bad, I meant you cant use the same carrier for 2.73 to 4.10

As far as 3.73 or 4.10 on 33s, you wouldn't feel a difference between the two.

You can indeed put a 4.10 gear on a 2.73 carrier. There is however a different carrier for 2.56 and numerically lower. This is just the 8.5 10 bolt, the 7.5 and 8.2 split at 3.08 I believe.

 

[yevgenievich]

I have a suburban wirh 3.73 and a truck with 4.10. Both have od. With od, I would lean with 4.10 if the motor is low hp, otherwise 3.73 is fine. But with no od highway speeds would be limited even with the 3.73 gears.

I was wondering what gear ratio (3.73?) my 14 bolt would need for 70-75mph instead of the 4.56 in it, I took off my 33's (I should sell all 6 rims tires) and switched to 16's street/city.


77 K20, 50 to 65 Vibration, Replaced front axle u-joints, Cab Body Bushings, Front Wheel Barrings gone thru, New front pads, New Lockouts, Used Part time Kit, Rear drive line Balanced New U-joints, New Tires/Rims Balanced, New Transmission Mount, 350, TH350, NP203, 7/12 4:27

 

[Wildjoe330]

I have a suburban wirh 3.73 and a truck with 4.10. Both have od. With od, I would lean with 4.10 if the motor is low hp, otherwise 3.73 is fine. But with no od highway speeds would be limited even with the 3.73 gears.

So then what would be the next one down from the 3.73?

 

[Wildjoe330]

8.2 split?

 

[yevgenievich]

I had a 85 swb with 3.08 rear gears and a th350 trans. It was borderline for me. Close to 3k rpm at 85mph. But to stay around 70mph could go with 3.42(2.6k rpm) or 3.73(3krpm) gear set. There are calculators online where you can choose exactly your desired speed vs gear ratio. You also have to regear front, which gets expensive.

So then what would be the next one down from the 3.73?

 

[RecklessWOT]

I had 2.73's in my '84 10 bolt and swapped in 3.73's when I put 33" tires on. It's the same carrier and I'm basically back to stock final gearing with the tires and ratio change. Could have used 4.10's for a little more ass, but it drives just fine like it is.

Yeah I was bitching about my 3.73s thinking it was gonna be the end of the world once I put the 33" tires on it and how I needed to switch to 4.10s and all, but once I put the 33s on it I realized it's not so bad.

Once that rear end I put back together without shimming properly starts to go bad and needs to be replaced (been over a year and several thousand miles with no issue, so it may be a while) I probably will still go for 4.10s at that point, but for now there's no real noticeable loss of torque and if anything it just helps me cruise on the highway a little easier.

Long story short, the 3.73s are working out just fine with the 33s.

 

[spanky55amg]

Digging up an old thread because.
Ok... I got half way through the first page and....


In the 4th gen F bodies, they still used a 10 bolt. I was putting down over 430 hp on a stock 10 bolt with a 3 series carrier and a girdle on an 4l60e (with stock converter and later a 4800 stall) car with 3.23 gears. And I drag raced on the weekend with drag radials.
I know people with manual cars and 4.10's on a 3 series putting down over 500 hp no problem... that said, they didnt drag race their car. It was only highway racing.
The 10 bolt, if built correctly, will most certainly hold anything any of us are throwing at it.

Lastly, I know that all automatic F-body cars with 2.73 gears had a 2 series carrier... those things blew up from the factory.

So it all depends on the series carrier and who builds the rear end.

 

[Honky Kong jr]

Digging up an old thread because.
Ok... I got half way through the first page and....


In the 4th gen F bodies, they still used a 10 bolt. I was putting down over 430 hp on a stock 10 bolt with a 3 series carrier and a girdle on an 4l60e (with stock converter and later a 4800 stall) car with 3.23 gears. And I drag raced on the weekend with drag radials.
I know people with manual cars and 4.10's on a 3 series putting down over 500 hp no problem... that said, they didnt drag race their car. It was only highway racing.
The 10 bolt, if built correctly, will most certainly hold anything any of us are throwing at it.

Lastly, I know that all automatic F-body cars with 2.73 gears had a 2 series carrier... those things blew up from the factory.

So it all depends on the series carrier and who builds the rear end.

Are these the goofy 9 bolt things they put in the Camaros and Fbirds? Or a for real 10 bolt? Also look what the GNX guys are doing with 10 bolts granted they have 30 spline axles but it's still the same housing.

 

[spanky55amg]

From my understanding, they are the "same ****** 10 bolts they put in the third gens."