Stock rear-end - how much power

[rrent]

What are the biggest differences in rear-ends used on my 250 6cyl vs. the 454 trucks? Will the prior work with the later or is finding a rear end out of a big block truck the only way to go, when increasing power.

 

[Arkansas_V8]

Depends on whether you intend on alot of traction.

 

[idahovette]

Depends on whether you intend on alot of traction.

As in how heavy is your right foot?

 

[Arkansas_V8]

As in how heavy is your right foot?

Yeah, but it's honestly with most rears. The FF is about the strongest and best you could swap in. But if you want a light weight truck. Chromoly axles for a 10 bolt are the best uprgrade.

 

[Blue Ox]

Depends on what you're trying to do, but a turbo 6.2L literally took the teeth off the ring gear of the 10 bolt in my Suburban. It's not a strong rear.

 

[Arkansas_V8]

Depends on what you're trying to do, but a turbo 6.2L literally took the teeth off the ring gear of the 10 bolt in my Suburban. It's not a strong rear.

It had to be on it's way out. I ran the 10 bolts in an old M1009 with a banks kit. Broken axles, joints and the usual. No ring gears.

 

[Blue Ox]

It had to be on it's way out. I ran the 10 bolts in an old M1009 with a banks kit. Broken axles, joints and the usual. No ring gears.

The only prior problem it had was an axle bearing. We'd had it apart at that point and the rest of it was fine except for the gov-bomb's latent risk. Got it stuck on a trail a few months later, used 4-wheel low and a tug from another vehicle to get it out of a ditch and I was lucky to make it home.

Maybe I was the exception, but it gave up the ghost in a hurry when it got stressed.

 

[legopnuematic]

AFAIK, there is no difference between a 6cyl or big block rear, regardless of being a 10,12,14sf, or 14ff, other than the gear ratios and the appropriate series carrier for the gear ratio. Housings should be exactly the same.

But for a good upgrade in a half ton would be a 14sf with either 6 or 5 lug axles (6 lug is much easier to find, 5 lug was only 454SS GMT400's)
Or a Ford 9" since it has a dropout center section so gear changes are quick

 

[Frankenchevy]

AFAIK, there is no difference between a 6cyl or big block rear, regardless of being a 10,12,14sf, or 14ff, other than the gear ratios and the appropriate series carrier for the gear ratio. Housings should be exactly the same.

But for a good upgrade in a half ton would be a 14sf with either 6 or 5 lug axles (6 lug is much easier to find, 5 lug was only 454SS GMT400's)
Or a Ford 9" since it has a dropout center section so gear changes are quick

I think there are 14 bolt sf 5 lugs in gmt400 half tons with the 6.5 as well. Probably more numerous at the junk yards than the 454ss.

 

[Frankenchevy]

Like these...
http://www.2040-cars.com/Chevrolet/...esel-cust-driveshaft-new-tran-153-626-505101/

 

[Rusty Nail]

My super hot small block beat the snot out of an 8.5" 10 bolt for ten years - factory 3.73 posi - and it never so much as blinked. I only put tires on it...I have zero experience with anything like all these other dudes are you talking about.
No difference between I6 and BBC rearends to my knowledge.

If you want to change rear, go 91-up I think. Better bearings or someshit. Like it matters lol. The previous bearing size used for twenty years all of a sudden wasn't good enough ..I guess.

A factory differential will hold a ton of power..400-500 HP. I'm thinking 500 is about maxxx thrash.

 

[75gmck25]

In a squarebody truck the rear end was usually based on the GVW, not the engine size. For example, my '75 K25 with 350 and 8400 lb GVW would have used the same 14 bolt FF with a 454.

Bruce

 

[HotRodPC]

AFAIK, there is no difference between a 6cyl or big block rear, regardless of being a 10,12,14sf, or 14ff, other than the gear ratios and the appropriate series carrier for the gear ratio. Housings should be exactly the same.

But for a good upgrade in a half ton would be a 14sf with either 6 or 5 lug axles (6 lug is much easier to find, 5 lug was only 454SS GMT400's)
Or a Ford 9" since it has a dropout center section so gear changes are quick

You could always swap in 5 lug axles to the 14b SF. Just a matter of finding them.

But true, rear ends weren't decided by the engine, but whether it was a 10, 20 or 30 truck. Now in the 80's the 3/4 ton trucks started getting the 14b SF in the small block and 6 cyl trucks and the Big Block trucks did get the 14b FF.

 

[TubeTruck]

My super hot small block beat the snot out of an 8.5" 10 bolt for ten years - factory 3.73 posi - and it never so much as blinked. I only put tires on it...

Of course it held up, you didn't get traction

 

[QBuff02]

Of course it held up, you didn't get traction

There's a lot of truth in that! Not enough power or too much power can be beneficial in both directions against parts breakage. Its that middle road where you might have "just enough" that gets you into trouble and start breaking parts. If you can break traction, you generally can keep from breaking parts. Lol