popping noise?

[blake22]

Im new here and would like to start by saying hi. Ive been reading on this site for a few months now but just joined. Ive got a 79 k5 blazer i just got going in te last few weeks. Its 6in lift with 38.5 super swampers 355/granny 4 speed/205 with stock axles (as far as i know). Im sort of new to the 4wd thing but i have a good basic knowledge. today was the first day i tried to engage 4x4. put the transmission and transfer case in N, locked the hubs and put the TC in 4 low. let out the clutch and it was crawling along but after about 10 feet or so it poped and kind of jerked the truck. im pretty sure its not my driveshaft as i have ground all the tabs down and added a angle shim under the front axle but maybe? What could happen if i had diffrent gears in the front than rear? would the TC just bust open what? maybe my hubs have some sort of problem?

[Stocker]

Welcome from NorCal.

As soon as I read 'popping & jerking', I thought 'different gearsets front to rear'. Definitely check that.... they need to be the same! If different, any number of things might break -- or the drivetrain could just bind up with no breakage, if you're lucky.

You might have a broken hub, broken u-joint, broken axle / splines.... just gonna have to get underneath and start inspecting everything. Are the driveshafts long enough for your lift? if not, the splines might have popped out of the yoke.

[blake22]

well i have been through alot with the driveshaft and i think i have it right as far as length. After i made the post i went outside and tried to get it out of 4wd and the hubs wouldnt turn and the tc wont come out of gear so i started it and rolled it forward a little and nothing changed so i just messed with the tc shifter a little and started to drive it around back but no popping or anything. But i can tell its in a lot lower gear now. so after driving it around for a little while and no problems i popped the clutch and the front tires seem to have spun so i guess the shifter was just not happy? could this be true?

[JPBrecheisen]

Was it just a single pop? Did it act like it was in nuetral when it popped?

Is it a possibility the TC shifter wasn't "fully in" when you brought it into 4L?

I have had my TC "pop" once because it felt like it was in gear (4 Wheel), but it apparently was only about 1/2 way when I engaged the front axle. No grinding, it just simply popped into nuetral when I put a load on the gears when i started moving forward. Maybe that was it?

[blake22]

i think thats just what it was. it wasnt ingaged all the way. i have a few more questions thow.. i cant seem to get it out of 4x4? the tc wont come out of 4lo the hubs wont unlock either? do i need to roll the truck and try to unlock the hubs or something then put the tc in 2 hi?

[Stocker]

Probably just in a bind, try backing up a few feet or so. If you just can't get it out of 4WD, jack up one of the front corners. Be ready for it to unload quickly (brief sudden spin of the tire). If that's your problem, it's a good illustration of why not to engage 4WD unless you're on a slick surface where the tires can slip.

[blake22]

I think i have a problem!!! after changing the oil in the front diff i went to the back and the ring gear looks alot thinner like a higher gear would! If i remember correctly the stock 12 bolt in the rear has a larger ring gear than the front 10 bolt dana 44 right? so wouldnt that make the ring gear in the back thinner? or am i thinking about this wrong? i found these numbers on the ring gear in the rear.
439798 17 47 gm 2 801 does this mean anything?

[blake22]

after welding the rear together i spun the wheel one time and the pinion spun 2.6 ish times? my gears are diffrent arent they?

[Stocker]

I think at this point I'd pull the covers off and count the teeth on the ring & pinion, front and back.

Divide the number of teeth on the ring gear by the number of teeth on the pinion. That's your gear ratio.

[JPBrecheisen]

439798 17 47 gm 2 801

17 and 47 should be your teeth count on your ring and pinion gears. 47/17 = 2.76 gear ratio. This would coincide with what you saw out of the driveshaft rotation of about 2.5 times.

the 439798 should be the part number.

Looks like you might have different ratios in that thing after all?

[blake22]

yes after counting the teeth on the ring and pinion i got that same 2.76 well i think this will be the only time ill be happy to hear i have 2.76 gears in the front because im supposed to be at a mud bog tomorrow morning at 10. hopefully i did something wrong checking the front the first time!!

[blake22]

ended up taking the front drive shaft off for the bog and breaking the rear one it the mud pit! Well actually the pinion yoke but it was fun!! going to dana 60s soon