HUB LOK problem on '67 K-10

[Justinjob]

Grrrr.....I'm having problems with the 4 wheel drive on my 67 K-10....when I engage the hubs (these are the original HUB LOK's that came on the front Dana 44 closed knuckle axle) to lock and put it in 4 hi, or 4 low and drive in forward gears, I get this nasty "pop" noise from the front axle about every revolution of the tires or so and the whole axle shudders. I'm kind of stuck on this one, I'm not sure what the problem i. When I disassembled the front knuckles, the upper and lower bearings (ball joints) are good-no play, and the u-joints are good too. The interlocking hub gears appear as if they could be slipping out of each other, there are a few little chew marks on the gear teeth-but they're still fine, none of them are broken or worn, and they mesh together well. I'm suspecting that maybe the multiple springs that push the gears together are worn and maybe do not have as much tension as they used to??? Then again, when I go to take it out of 4 wheel drive and unlock the hubs, they stick, they won't disengage-until of course I jack up the truck-then they come free easily....funny thing is last time I did this, as the front wheels started to come off of the ground-the passenger side wheel slipped and turned slightly as though there was tension, like it was under load, and that would explain why they won't disengage...but why would they be under load? (now that I think about it the truck may have been in gear, I'll have to try it again making sure that everything is in neutral) I'm also possibly suspecting that the drive ratios of the front and rear axles differ form a possible rear axle change someone may have done before I owned it. I'm not sure how to check this, I've ID'd the front axle (Dana 44's only have one ratio right?), but I still need to find out what the rear axle is, or should be and how to ID it. Anyone have any ideas?

[jeffspower]

It sure sounds like lockout problems. A '68 I bought in '83 (my dad still has the truck) done the same thing when I bought it. I was 15 then, & didn't know squat about repairing it. Nobody in my family was good at repairing anything either, so I took it to the shop my grandpa went to. They checked it out & said it was troubles in the transfer case. So they rebuilt it. No IMPROVEMENT.

Next, they said it was the front driveshaft splines were worn out & skipping over each other. Rebuilt the shaft. STILL NO CHANGE.

Then, they said the rear end was the problem. So at this point, (I was then 16) I took it into high school auto shop & put in a good used rear end. Yep, no surprise. STILL NO CHANGE.

At that point, I new the truck pretty well. I always thought it felt like it was in the frontend, But the "pros" said they checked over everything in the front end & it was all good. I tried something that I thought was silly at the time, and BINGO- I found it! I pulled the rear driveshaft & drove around until it acted up. When it did, it sounded like spinning a ratchet & made a BUUUZZZ. I kept my foot on the gas while it buzzed and it wasn't pulling the truck along so I crammed the park brake on & got out to see what was going on while it was buzzing. The front shaft was just spinning away. BAD LOCKOUT!!!

I had spent more money letting the pros try to fix it than I had paid for the truck! And all it needed was a cheap pair of lockouts & 1/2 hour's work!

I applied for a job at that shop the week after high school. I told them politely with a grin that I fixed what they couldn't. I went to work there the next week.

[jeffspower]

Oh yeah, your rear should be a GM 12 bolt or maybe a dana "44" (if it is a GMC). Pull the covers & get the #'s off the edge of the ring gear. You should see something like 41 -blank space- 11. 41 divided by 11= 3.73

Don't be alarmed if they are a few numbers off. This is common & ok. Like a 4.09 front & 4.11 rear.

[Justinjob]

I posted this same topic over in general discussion and another memeber suggested the same, to disconnect the rear axle and drive it in 4 hi and see if it still pops. If so, then I know it has to be something with the front axle. I'm really suspecting the lockouts like you said, just want to make sure before investing. Know a good source for new ones? LMC truck seems to sell mile markers for my application-but they want 300 bucks for 'em! I wonder if I could rebuild mine....then again that may be more of a headache than I want to deal with...

Thanks for the suggestion!

[1969 GMC]

i have the hub-loks also, they can be pretty tricky...mine didnt want to lock at first, the know would just spin and nothing would happen. don't bother with those $300 hubs...just buy a disc braked open knuckle junkyard dana 44 from a '71 up K10 or K5 blazer, ideally with the same ratio as yours.

[wildwood]

I have seen a problem something like this caused by installing the C-clip in the hub in the wrong location. There is 2 spots for it. I'm talking about the very first piece in the hub when you take the chrome part off the outside. In this case the c-clip was on the outside spot when it should have been on the inside. Thew front drive shaft would turn but not the wheels as the gears in the hub were not meshing. It made a clunking noise. I don't think your gear ratios would be different. Driving in 4x4 on dry pavement for a short time with incorrect gear ratios would break something or cause alot of noise from tire slipping. Good luck.

[Justinjob]

Well, I tried taking the rear drive shaft off-and the front axle still pops, so I'm almost positive it's those locking hubs that are the culprit. I've searched high and low on the internet for aftermarket replacements, but it seems that no one sells a set for my application , oh well, right now, I'm taking both of them apart and trying to rebuild them with stiffer springs (there's four small springs on each hub, rather than one large one) and see if that fixes my problem. If not, I don't know where I'll go from there. If it does work, I'll try to get some pictures up and describe exactly what I did, maybe it will help someone else.

[jeffspower]

I can't picture in my mind what your '67 hubs look like. My 68 took the same as the later trucks. post a pic if you can

[1969 GMC]

here is a pic of one of my Hub-Loks, notice it isn't shiney chrome like the later models, and the dial protrudes from the face. I know it doesn't help, but one of 'em on my truck is almost brand new. When I took both off to clean them (they were malfunctioning) I discovered one had no scratches in it, and looked NEW when cleaned with mineral spirits. The internals looked new, also. But who knows how old it is, just its definitely not the original.

[wildwood]

You can forget about what I wrote in my other post about the c-clip thing. Your hub is totally different. I didn't realize they would be different. What front end is in that truck? Dana 44? That's a K20 isn't it? 8 bolt wheels mean K20 I thought. You could try to find a blow-up diagram of the internals of the hub and make sure it's all put together the right way. Sometimes the pieces can fit the wrong way and cause problems.

[1969 GMC]

yeah, that is the hub off of my GMC K2500 (K20). It has a dana 44 closed knuckle drum braked front axle.

[Justinjob]

I fixed it! The problem was not what I thought it was, after rebuilding both hub lockouts with new springs and making sure they functioned properly (and giving the outer lockout faces a nice polish job too) I put everything back together, put it in 4 wheel and took off....POP! Still doing it! Hmmmm....I decided to take the lockouts off again and check everything over, everything seemed okay. Then I was thinking, maybe the outer part of the lockout isn't reaching far enough into the hub assy. to engage to the inner part for some reason....so I measured it. Sure enough, the outer lockout didn't go far enough into the hub to mesh with the inner lockout! Why could this be??? I pulled on the splined axle that the inner part of the lockout rides on, and It pulled out about about a quarter of an inch, which is exactly how short the measurement I came up with was. I don't know if the splined axle is supposed to pull in and out like that, but it does it on both sides. Anyhow, the inner part of the lockout was riding back and forth on the splined axle shaft that quarter of an inch, slipping in and out of engagement and making that loud "Poping" noise. How did I cure this problem? I went to the hardware store and bought some washers that fit right over the splined axle to shim up the distance I needed the inner part of the lockout to come outward and get rid of the inward and outward play of the splined axle shaft. I installed the inner part of the lockout in front of the washers and put the retainer ring back on to secure it. This cured the problem of the splined axle moving in and out on me, and secured the inner lockout in the right position to engage with the outer part of the lockout when engaged. I had to use three washers on the driver's side hub, and two on the passenger side hub. After getting it all back together, the 4 wheel drive worked just like it should, the lockouts stayed engaged and that dreaded pop was gone! I'm not sure if I repaired this problem properly, but it's the only thing I could think of and it seems to work just fine. I may not have explained what I did very well, hopefully someone understands what I just tried to explain, if not I will try and get some pics posted of what exactly I did and see what you guys think. Anyhow, here's a few pics, the first is of the outer view of the hub lok assembly, as you can also see the wheel mounting is a six bolt pattern-and it has some nifty vintage aluminum mags on it right now-came with the truck and I don't know how old they are or what brand they are. The second pic is the inside view of the sealed axle, pretty unique I think- the drums in front kind of stink but it's livable-I had this sealed end apart once and it's pretty cool-the two caps you can see bolted to the top and bottom have short shafts on them that bearings ride on that function as the upper and lower ball joints-by the way this is a 10 bolt Dana 44 axle. The last is just a quick pic of what my truck looks like in case anyone was wondering. Like I said, I'll try to get some pics of what I did to repair the problem-pics can always explain better than words! Thnaks all for the suggestions and help!

[1969 GMC]

i think i know what you are talking about...as I remember, when i took my hubs apart the axleshaft did move in and out some. anyways, congrats on the fix, and thats a nice lookin truck!