gear ratio help for a newbie

[1998_K1500_Sub]

I know it has 10 bolts on it and I've heard nightmare stories on having a 10 bolt so I'm not looking forward to doing a 14 bolt swap from a 1 ton

What size (diameter) tires will you be running?

What do want your RPM to be when you go through the lights? In what transmission gear (3rd?) and expected speed?

Pick a rear gear that helps you get that RPM.

Others will have valid comments, I’m sure.

 

[Hipster]

Don't drag race your daily, find a toy. You break it and now you have no way to work either. Tired 10 bolts and 4l60's are not a good start. Start racing and you will find one weak link after the next until it's all rebuilt to handle it.

 

[Erik the Awful]

I know it has 10 bolts on it and I've heard nightmare stories on having a 10 bolt so I'm not looking forward to doing a 14 bolt swap from a 1 ton

Just to clarify, the bolts you need to count are on the ring gear itself, not the cover. Back in the day there were both 10 and 12 bolt rearends that had 12 bolts on the cover. Many people scrounged 10 bolts out of junkyards thinking they were getting a 12 bolt rearend. As far as I know, you're safe believing a 10 bolts has a 10 bolt cover and a 14 bolt has a 14 bolt cover.

The Dana 70 has a 10 bolt cover, but it's easily distinguishable from a 10 bolt by the floating axles.

 

[HiItsRem]

Just to clarify, the bolts you need to count are on the ring gear itself, not the cover. Back in the day there were both 10 and 12 bolt rearends that had 12 bolts on the cover. Many people scrounged 10 bolts out of junkyards thinking they were getting a 12 bolt rearend. As far as I know, you're safe believing a 10 bolts has a 10 bolt cover and a 14 bolt has a 14 bolt cover.

The Dana 70 has a 10 bolt cover, but it's easily distinguishable from a 10 bolt by the floating axles.

Oh, I didn't know that. that's good to know, thanks for the info! Explains why some refer them as 8.5" and 9.5" and not particularly the cover

 

[HiItsRem]

Don't drag race your daily, find a toy. You break it and now you have no way to work either. Tired 10 bolts and 4l60's are not a good start. Start racing and you will find one weak link after the next until it's all rebuilt to handle it.

I do not plan to drag race it a lot, I Just want to do a small amount of track but keep it a daily with a little pep to it, nothing serious, I plan to get an S10 and build a drag truck out of that instead in the far future, just trying to get info on what good upgrades I should start with when trying to beef up my truck for a bit more power than stock

 

[HiItsRem]

What size (diameter) tires will you be running?

What do want your RPM to be when you go through the lights? In what transmission gear (3rd?) and expected speed?

Pick a rear gear that helps you get that RPM.

Others will have valid comments, I’m sure.

I want to use stock size or something close to keep the rpms around 2200-2800 so I keep good oil pressure but don't cause excessive wear on my engine around 75mph in 3rd I know there is calculators out there to determine the size of tires and rpm but I have trouble understanding gear ratios in scenarios like that because change tire size, it can throw numbers out of whack and I'm not exactly the best at math, if you can suggest a good size for a decent amount of efficiency because I actually plan to tow with this thing, not a lot but I know I'm going to be towing a decent amount over time

 

[Schurkey]

I know it has 10 bolts on it and I've heard nightmare stories on having a 10 bolt

Yes, that axle is junk. It's a hand-grenade with the pin out. In most cases, they came with crappy rear brakes, too.

GM had no business putting the 8.5" axle under a full-size pickup.

The 8.5" works great in compact and intermediate cars with small-blocks.

so I'm not looking forward to doing a 14 bolt swap from a 1 ton

You wouldn't be swapping from a 1-ton. You'd be swapping from a "light duty" 3/4 ton, using a 6-lug axle shaft and 11.x Duo-Servo rear drum brakes. Wonderful set-up.

14 bolts on the cover, semi-float design like most folks are used to, 9.5" ring gear which--maybe--has 12 bolts holding the ring gear to the differential case. Get the axle from a 4X4 truck, so it's the same width as the axle you have. The 2WD axles are different.

The "1-ton" axle has 14 bolts on the cover, full-float design, and 10.5" ring gear.

 

[HiItsRem]

Yes, that axle is junk. It's a hand-grenade with the pin out. In most cases, they came with crappy rear brakes, too.

GM had no business putting the 8.5" axle under a full-size pickup.

The 8.5" works great in compact and intermediate cars with small-blocks.


You wouldn't be swapping from a 1-ton. You'd be swapping from a "light duty" 3/4 ton, using a 6-lug axle shaft and 11.x Duo-Servo rear drum brakes. Wonderful set-up.

14 bolts on the cover, semi-float design like most folks are used to, 9.5" ring gear which--maybe--has 12 bolts holding the ring gear to the differential case. Get the axle from a 4X4 truck, so it's the same width as the axle you have. The 2WD axles are different.

The "1-ton" axle has 14 bolts on the cover, full-float design, and 10.5" ring gear.

Oh, cool, okay. Lot of specifics that seem like way over complicating a simple design of the gmt400 platform it seems, I knew there was a few "gotcha" things to look out for but it just seems to keep getting sillier and sillier the more info I learn about this platform

 

[Erik the Awful]

GM had no business putting the 8.5" axle under a full-size pickup.

They made it through warranty. That's all GM cared about.

 

[Supercharged111]

You guys are killing me here. Drag racing a stock pickup truck is not gonna hurt it. You can do far worse just by putting a trailer behind that anemic 4L60.