65 4x4 4wd not working. Could it be transfer or hubs?

[ChevyFreak60]

Hey dudes, I am wondering if you can help me figure what might be going on with the 4wd on my 65 chevy. When I bought the truck it didn't have a front drive shaft and the guy said he had no idea if the 4wd worked. I put drive shaft on with new ujoints and locked the hubs. Got in the tuck and put the shifter in 4high then 4low and nothing. Not sure if it is a bad transfer case or bad hubs. Any help will be greatly appreciated.....

[argonaut]

When you say nothing, what exactly do you mean? What did it do, or not do?
In 4 Hi and 4 Lo does it turn the rear axle only, or neither axle?

If its got factory parts then it has an SM420 trans and a Rockwell T-221 transfer case.

First thing i'd do though is with the motor not running, remove the driveshafts, put the transfer case into 4wd, put the transmission into any gear and try to spin each output yoke. You shouldn't be able to move either one in either direction.

Next put the transmission in neutral and leave transfer case in 4wd. You should be able to spin one output yoke by hand, and the other output yoke should turn the same.

Note that friction between freewheeling gears and shafts will want to make the output shafts turn, even if they aren't actually engaged in gear. So put you hands on both outputs to be sure.

Let us know what you find out.

[69GWC]

A quick easy test would be to put it in 4wd and drive real slow and have someone watch and see if the shaft is spinning or not.
Thats what I did, put it in 4 low with the hubs lock then got out and looked to see if it was spinning I have a bad lock out on my so the front tires dont pull.
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[ChevyFreak60]

Thanks for the info guys. When I engage the 4wd only the rear tires turn, so i'm thinking maybe its the hubs?

[69GWC]

Is the front drive shaft turning? Make sure it is turning and if so I would say its a good chance your right and its the hubs/lockouts.
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[ChevyFreak60]

Ok I did the test yesterday and the front shaft does spin in both 4hi an 4low but its not pulling w the tires. What do you think it is?

[argonaut]

Okay, its either one of two things:
1) the differential has exploded and so the driveshaft does not transmit torque to the axles
2) everything is fine in the axles and the hub locks are not functioning, or not locked.

For the next test, take the front driveshaft off and spin the fron pinion yoke by hand. While spinning it watch the axle joints to see if they are spinning. (Note: this will only work if a later model open knuckle axle has been swapped on. If you have a stock closed knuckle axle you won't be able to see it, so refer to the next step)

Next start by removing the hub locks and inspecting them. While they are off, you can do the test I described above and watch to see that the axles are turning.

Lastly I would also remove the diff cover and inspect the gears. Many times on these old work trucks the gears can have had a rough life. Its worth the small cost of a gasket and some gear oil to do the inspection.