Locking differential

viperapex · October 11, 2001

Hey guys. Just picked up my first GMC ( 2500HD SLE, 8100, allison, 3.73 locker, ext cab, short box, summit white),and have a couple questions that you guys might be able to answer.

First off, can someone explain the locker differential to me? I've heard varying stories about its operation. Is it governed for speed? Does it actually have full lock up at less than 20mph? posi greater than 20 mph? It'd be handy to know for sure.

Also, I'm sure somebody has already answered this, but what is the story on the K and N FIPK gen II assembly? How does this go together? How much? Is it worth it? Any problems?

Something else is the tire size and rim size? What is acceptable on the stock rig without having the tires rub like hell in turns or in full compression of the suspension? 265/75 R16?? 16*8?? I'd like to know as I'm going to put on some different tires and wheels. Thinking of the Les Schwab TXR (if anybody has some input on this please chime in.)

I think that's all for now. If you guys have any other helpful tips, it'd be greatly appreciated. This is a pretty big jump for me from my '86 F150 so i'm kinda new to this new truck stuff.

Thanks so much,

Sean :stupid:

Shaners · October 11, 2001

First off welcome viperapex,

The locker in the rear end is made by Eaton. It's a true locker and will lock if one wheel makes approx a full revolution more than the other. I tried it in my garage and now have a short and a slightly longer black mark on the floor and I could feel it lock up.

I had the FIPK on my '00 Silverado and I liked it. It added about 1/2 mpg's. With the 8.1L in your new truck, I doubt you'd notice the power increase!!! LOL

I'm sure you can run 265/75/16 with no problem, and 285/75/16 with maybe a couple of cranks on the torsion bars up front.

Enjoy your new truck, and keep us updated...

Shane

chevy4x4trucks · October 11, 2001

I'm sure you'll soon find the locking differential is worth it. Not just for snow and off-road traction, but when you've got all these people laying burners w/ just one tire you can blow them away and smoke 'em both. And w/ an 8.1 big block I can only imagine how it will smoke up the 245's

IMO any cold air intake is worth it, just make sure you compliment it w/ a more free flowing exhaust. My fist choice is a flowmaster dual exhaust.