'98 K2500 RCLB 454 NV4500 Daily/Hauler

[Supercharged111]

Truck struggled in OD with that? You have a BB tune, right?

 

[Justin S]

I'm not sure that I ever saw what it is you tow? How big are the tires again?

Has 3.73s and the tires are 315 75 16s. I have a 18' dual axle car trailer and would just like some more grunt when hauling a full-size truck or something that heavy.

 

[Supercharged111]

315s, that's the piece I was missing.

 

[Justin S]

Finally started the 4.56 gear change today at work. So far everything has gone fairly smooth, besides two of the pinion housing bolts snapping. They came right out with a little heat at least. One other was pretty rusty so im going to try and find 3 new ones. They seem to be a weird thread pitch so hopefully I can find some locally. Also took the drums off for the first time since I've had the truck. The adjuster on one side was froze and I had a hell of a time getting the drum off because of the rust ridge. Glad I checked because the shoe material was cracked pretty badly on all 4 shoes. Also found that 3 of the 4 caps on the rear U joint were seized, one of them I can even get apart! Hoping to have it all back together tomorrow.

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[454cid]

Wow, that's beefy looking!

 

[Justin S]

Wow, that's beefy looking!

It is certainly the biggest differential I've ever worked on, I've worked on a few 10 bolts but they don't compare to the size and weight of these parts!

 

[Supercharged111]

The 14 BFF is rated to hold 8,600#.

 

[83GMCK2500]

So far everything has gone fairly smooth, besides two of the pinion housing bolts snapping. They came right out with a little heat at least. One other was pretty rusty so im going to try and find 3 new ones. They seem to be a weird thread pitch so hopefully I can find some locally.

These?

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[Justin S]

These?

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Yup, found some at the local Tractor Supply. Ended up being 7/16 coarse thread. Everything I had laying around was either 3/8 or 1/2.

 

[Justin S]

Rear 4.56 swap complete! Has quite a bit more get up and go now, which is what I was looking for. The tires definitely chirp more around corners than I anticipated, but still worth it. My speedo/odometer were off already because of the big tires and now its off exactly the same amount just in the other direction. Before if I drove 10 miles, it would only show 9. Now it shows 11. Speedo at 60 is approx 12mph too high. Before, RPMs at 60 were close to 1600, now sit at about 2200. Only other thing is my ABS light comes on whenever I start driving, but im assuming its because I still need to swap the front diff and the module sees a speed discrepancy. Also gave it a good clean, which might last a day

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