scott85 said:
Doing an axle swap between an 87 k5 and an 86 k10 (the 86 is the keeper). The 87 has auto hubs, and the 86 has manual ones. How do the auto hubs work? engage? disengage?
They usually DO cause trouble, however - I've got a 87 diesel 3/4 ton Suburban with 520,000 miles on - and it still has the original auto-hubs - and they work great. It has seen a lot of towing and heavy use. My 94 1 ton Ford also has the original auto-hubs and has 300,000 miles on it. Ford uses the same make hubs as GM. They work great -when they are working - and are a pain in the a*s when they screw-up.
They are not weak - just prone to half-engaging when you don't want them to. I've put over a half a dozen on my 86 and 88 diesel Blazers - but never replaced with new. Used are easy to find since so many people remove them and convert to manual after the first problem. So, whenver they get removed, there is usually just one bad one, and still one good one.
According to GM, the problems with them are usually due to the wrong, or too much grease. I don't know, never tried to actually fix one. I have taken a few apart that gave me trouble -and all the parts inside looked like new - i.e. nothing worn or broken. Maybe the grease-story has some truth to it.
I wouldn't have the auto-hubs on a vehicle that rarely uses 4WD except for off-roading. But, I live on top of a mountain, and in the winter, I am needing 4WD, or and off, every day in the winter. And, I also need it to get into and out of my fields the rest of the year. I don't want to be getting out of the truck and locking my hubs everytime I want to come home - not do I want to drive all the time with the hubs locked. So, in my situation, I really like them.
Only draw-back is . . . you cannot shift into 4WD while moving. You have to be at a full stop, engage 4WD - then start moving and let them lock. To disengage, just put the transfercase into 2WD, and then backup a few feet.