Help with drive line please

[TonyJohnson]

Hey guys, I just used 4x hi on the highway this morning and it felt different from last winter. ('71 blazer 350, SM465 & np205, 1/2 ton Dana, 33s)

I haven't engaged it this winter and don't use it on the highway very often, but this morning I locked my hubs, pulled it into high and left for work (clear roads with no snow or ice). I felt more resistance than normal and it would make a gear buzz sound on decelleration and I could feel it in the shifter. Sounded like a russian saying no. Sorta Neyt, neyt, neyt... I could also feel a little clunk on initial decell. Feels fine on accelleration, just a little like pushing uphill. With the hubs unlocked and in 2 hi, there is very little driveline sound and everything feels smooth.

This evening, I'm going to crawl under and check the u-joints for slop. That might explain the clunk. I haven't driven other 1st gen 4x4s, so I don't know what's normal.

How does yours feel in 4 hi on the highway?

Thanks in advance,
Tony

[Yukon Jack]

Was the highway snow packed?

In our era of trucks, 4Hi shouldn't be used on a highway unless it is snowy or I guess maybe wet. If you use it on a dry surface you can get bind in your drivetrain as these transfer cases don't allow any differentiation to happen. If your drivetrain gets some bind in it you can definitely feel it - not sure if that is what you are dealing with or not.

[TonyJohnson]

Good to know. So you only use 4 wd offroad or in bad conditions? That's what I've always done anyway, but I always assumed you could go full-time if you wanted...

Thanks, Tony

[Yukon Jack]

Yep, offroad or in bad weather conditions for our years. The later full-time setups have a t/c that allows for some slip to prevent binding. One of the more knowledgeable guys here can probably tell how that actually happens.

Sometimes when you get your drivetrain bound up you will need to go in reverse a bit to relieve the bind - otherwise you'll have a heck of a time getting out of 4wd.

[TonyJohnson]

Thanks. One last question. (trying to get you to that 10K post mark... lol) What's the downside of running in 2 hi with the hub locks on? I'd just do it if the weather was funky and I wanted to be ready without stopping in traffic...

[Yukon Jack]

Your front axle shafts and driveshaft will be turning if you have the front hubs locked even though it's in 2wd which will equal a bit of drag, but no big deal.

[TonyJohnson]

Thanks. That K20 is way cool, btw...

Later, Tony