My 1984 K5 Plow Teeruk 6.2 Rear Diffy Is Bad...

CORVAIRWILD · Jan 28, 2020

I've been plowing for 10 years with a ratty K5 6.2 Blazer, and a few days ago the rear differential all of a sudden made some death noises. So I jacked it up and pulled the driveshaft. I've got about 75 degrees of rotation-play in the pinion yoke. So I left the drive shaft off and plowed my yard, a couple of times it felt like the rear differential was binding up, even though there was no driveshaft, I was driving it in front wheel drive. I haven't pulled the cover, but what what can I expect to find inside?

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PrairieDrifter · Jan 28, 2020

You're gonna find destruction lol. Possible missing teeth, possible razor sharp teeth.

If the rear was locking up I'm sure there are some broken teeth.

CORVAIRWILD · Jan 28, 2020

Interestingly, it wasn't making a sound until the crack. And I definitely wasn't beating on it, but sometimes I plow in four-wheel drive and then I hit the pavement, and I put it in two wheel drive ASAP, but this truck obviously takes a beating plowing for years and years and years. I've broken a couple of front axles over the years, and there is the beating part, and all of the yolks are worn, and all of the U-joint bearing caps rotate in their yokes

PrairieDrifter · Jan 28, 2020

CORVAIRWILD said:
Interestingly, it wasn't making a sound until the crack. And I definitely wasn't beating on it, but sometimes I plow in four-wheel drive and then I hit the pavement, and I put it in two wheel drive ASAP, but this truck obviously takes a beating plowing for years and years and years. I've broken a couple of front axles over the years, and there is the beating part, and all of the yolks are worn, and all of the U-joint bearing caps rotate in their yokes

I've got a set of 3/4 ton axles that are just like the video of yours, granted I haven't opened them up yet. The ring and pinion gears are most likely worn very badly, could have got too thin and the beating could have created fractures/broken teeth and obviously less metal so less strength, and plow trucks definitely take heavy beatings. The bad u-joints also just add to the jolt on the diffs, since they're sloppy, it just hammers everything.

Sorry to say but I think it's swap or rebuild time for both axles.

CORVAIRWILD · Jan 28, 2020

What is a questimate of the cost to fix this? And where the hell am I going to find a used set of 3.73 gears? I've got two parts trucks in the country, but I'm sure they're 3.42 ratios. My truck has the optional 3.73s, according to the inner fender sticker

yevgenievich · Jan 28, 2020

Suburbans are sometimes more likely to have 3.73 optioned. Or a base 3/4 axle usually had 3.73

PrairieDrifter · Jan 28, 2020

My 84 k10 suburban came with 3.73's. I don't think your front axle is far behind on impending doom, so if you found a donor truck just swap both axles and your good with matching ratios.

Depends if you can rebuild an axle or not. If the rest of the truck is decent I would just swap to 3/4 tons, you would have a lower gear ratio which would probably help with plowing.

CORVAIRWILD · Jan 28, 2020

Prairie... I had a plan many years ago to put in a rebuilt 700 transmission that I had modified to fit a full-time 203 transfer case. It's sitting just ahead of the truck in my shop, all rebuilt and ready to go). and I somewhere have a Dana 60 for the front, and a 14 bolt full floater for the back. That sounds like a job I'll never get to

TubeTruck · Jan 28, 2020

Sounds like you blew up your spiders. Open the diff and show us :popcorn:

You might get lucky and be able to just swap the spiders but we won't know until we see :shrug:

CORVAIRWILD · Jan 28, 2020

Spiders you say??? Hmmmm... I guess I know what I'll be doing in a couple of hours... I haven't worked on a differential in years and years and years. Can I change the spider gears without upsetting the backlash?

Nonstop · Jan 28, 2020

CORVAIRWILD said:
Prairie... I had a plan many years ago to put in a rebuilt 700 transmission that I had modified to fit a full-time 203 transfer case. It's sitting just ahead of the truck in my shop, all rebuilt and ready to go). and I somewhere have a Dana 60 for the front, and a 14 bolt full floater for the back. That sounds like a job I'll never get to

Unless they are waiting for another project, there is your answer if they are the same ratio (and the 14 bolt is out of a 3/4 ton). It will be cheaper and faster to bolt those in than rebuild the rear differential. I hate to say it, but even throwing in spiders, if that is the problem, is just a bandaid. You still have a bad yoke and bearings which are contaminated with metal shavings.

CORVAIRWILD · Jan 28, 2020

I would love to do my above-mentioned project, but I know from reality that nothing is ever so simple. I do have the two arm shifter which is different than the part-time transfer case, and nothing is ever simple. Everything is always a matter of getting the parts, distractions with all my various projects etc etc etc

Rickf · Jan 28, 2020

Did you check out the "can this be welded?" string in the technical section? Might be what your diff looks like.

Poppy 87 · Jan 28, 2020

CORVAIRWILD said:
I've been plowing for 10 years with a ratty K5 6.2 Blazer, and a few days ago the rear differential all of a sudden made some death noises. So I jacked it up and pulled the driveshaft. I've got about 75 degrees of rotation-play in the pinion yoke. So I left the drive shaft off and plowed my yard, a couple of times it felt like the rear differential was binding up, even though there was no driveshaft, I was driving it in front wheel drive. I haven't pulled the cover, but what what can I expect to find inside?

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I believe you will find zero fluid, and severe mechanical carnage! Pretty sure 75 degree pinion travel is more than spider gears. By the way, I would be very reluctant to plow with a 700R4 transmission.

PrairieDrifter · Jan 28, 2020

CORVAIRWILD said:
Prairie... I had a plan many years ago to put in a rebuilt 700 transmission that I had modified to fit a full-time 203 transfer case. It's sitting just ahead of the truck in my shop, all rebuilt and ready to go). and I somewhere have a Dana 60 for the front, and a 14 bolt full floater for the back. That sounds like a job I'll never get to

I also agree about the 700r4, save it for a street machine, or a cruiser. The 700 won't last in a work truck very long, that first gear in it would be good for plowing I will admit, but you'd end up pulling it out in pieces.

My 1984 K5 Plow Teeruk 6.2 Rear Diffy Is Bad...

CORVAIRWILD

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PrairieDrifter

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CORVAIRWILD

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PrairieDrifter

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CORVAIRWILD

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yevgenievich

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PrairieDrifter

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CORVAIRWILD

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TubeTruck

I'm from Boston. Deal with it.

CORVAIRWILD

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Nonstop

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CORVAIRWILD

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