99 Suburban LT K1500 - Slow build

[99'Subourbon]

4.56s. I'm gonna turn the bend 90 degrees on the drive side header, and run it behind the transmission, then X and dump.

The front diff is just getting a new stronger carrier (not sure which, the dude recommended it though) and the master rebuild with the gears. The shop has a great reputation in the off-road scene and at MOAB, so I am taking his word for it.

 

[99'Subourbon]

What gear are you swapping to? Did you say truetracs? What are you putting in the front differential?

I have a lowly RCX kit and also had to have a bent length of pipe patched in to clear the front driveshaft. It works for now but what is right for any of us is bigger headpipes anyways. Sounds like you have that with your headers, but they're in the way. Maybe you could just move the O2 sensor bung somewhere else.

Oh, and I don't think the RCX is lowly, but I am glad I went with Superlift; Ride is great, and the parts are really beefy. I've gotten nothing but compliments from the people who have looked at it, especially from others with lifts.
Any kit will need to reroute the headpipes if its 4-6". I'd imagine the only way you wouldn't is with a 9-12" full throttle lift (or SAS, lol).

 

[99'Subourbon]

Just got into the valley, 3.5 hr drive. This was the first time it's been on the highway since well before any mods were done (since October 2013), and WOW! It made the trip 20x better than stock. It had 0 issues with the mountains, even with 35s.

The headers, exhaust and tune are so much more apparent at 65+, and really worth it.

Edit: went back and looked at the emails from the diff shop, it's Yukon carriers.

 

[slowburb]

That's what I'm running. Yukon duragrip clutch style LSD with 4.56 gears in the rear and a set of 4.56's in the front. I'm on 33's and plan to mount a set of 34's or 35's when these Duratracs are done.

4.56's and 35's is about the same as stock tires and 4.10's. You are going to think you're driving a different rig after the gear swap.

 

[SwampHound]

Dunno why people think 4.11s are good for 35-37s. More gear is where it's at. I always get a kick out of driving my dad's old 01 Silverado. 2WD, automatic, 4.8l BONE stock except the fuel pump. It's got 3.42s and will roast the little 235s with ease. So much fun. Only thing that would make it more fun is 3.73s

 

[SwampHound]

In other words, I agree with slowburb. 4.56s are gonna be great

 

[slowburb]

Dunno why people think 4.11s are good for 35-37s. More gear is where it's at. I always get a kick out of driving my dad's old 01 Silverado. 2WD, automatic, 4.8l BONE stock except the fuel pump. It's got 3.42s and will roast the little 235s with ease. So much fun. Only thing that would make it more fun is 3.73s

Right. 35's and 3.73's is about the same as stock meats and 3.08's. Nothing impressive there unless you like the acceleration of a dump truck.


A guy I know has a hopped up 4.8L powered ECSB NBS with 4.30's.

 

[99'Subourbon]

Yeah, I wanted 4.88s, but the shop won't warranty the work if I went that low, so 4.56s it is. I'm excited for the gears tho - better than stock; I'll take it.

 

[mistaake]

Yeah, I wanted 4.88s, but the shop won't warranty the work if I went that low, so 4.56s it is. I'm excited for the gears tho - better than stock; I'll take it.

Why not?

 

[99'Subourbon]

Not enough splines; going down to 4.88s makes each tooth too thin for him to guarantee it. If I had the 8.6 10b, which is 30 spline, he may have. But ours is the 8.5 28 spline.

At least I believe that's the case, or its 30 vs 32 spline.