Rear Differential
 

I have a 1984 K10 4x4, 350, sm465, 10 bolt diffs
Well I popped off the cover to my rear diff and found this...

http://i1250.photobucket.com/albums/...psb7df087b.jpg

Turns out the fluid was way low. I just popped the cover on for now and filled her up with fluid.

I don't know a dam thing what to look for when checking gears.... I do have to mention that I do have a bit of chatter when releasing the clutch off 2nd, i really have to rev the engine to take off.

Could this be the cause? I'm thinking of changing gears, I plan on putting 35" tires on and haul wood every year. What gears should I go with?

Re: Rear Differential
 

They are simple mechanisms, the difficulty is the SETUP. They have to be precise and the relationships and clearances set up have to be so exact that an experienced installer will pull it out three or four times to get it right, and an inexperienced will pull it out seven or eight times. You'll be installing shims less than the thickness of a piece of paper, moving components to the left or right literally the width of a hair.

The big thing in the middle that all the gears attached to is called the "carrier" and yours looks to have taken some damage.

Re: Rear Differential
 

That is from the pinion gear hitting the carrier. Remove the driveshaft and see if the pinion yoke has any in and out play or up and down also. In the mean time id look for a new rear axle. Personal opinion though as yours may have been repaired and might be ok.
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Re: Rear Differential
 

What obijuan said, thats pinion damage to the carrier. I'd say it warrants a thorough looking over. That may be old damage that has since been repaired, but if you found it with no gear oil in it and you have a suspicious chatter, its time to take a look. The pinion bearing may have failed due to lack of oil and now it's sloppy, allowing the pinion to contact the carrier, causing your chatter. Of course, it may have been repaired, if you didn't find any metal in the remaining oil, and the chatter is your clutch going out or needing adjustment.

If that rear is no good, you may want to think about stepping up to a 12 bolt, or a Dana 60 rear for that truck, if you plan on running 35s. Depending on how you drive it and how healthy the 350 is, a 10 bolt might not last too long if there is any amount of tire spin involved. You could probably find a 12 bolt in good shape at a wrecking yard for what you'd be into that axle for with new gears and bearings and paying to have them installed (and hoping the shop knows what they're doing) and at the end of it all having an axle with a compromised carrier just begging to crack the first time you're stuck in the mud or snow.

Re: Rear Differential
 

I would like to mention 2 things;

1-I just installed a new clutch/pressure plate/flywheel about a month ago
2-My rear diff isn't making any noise whats over.

I didn't find any metal shavings inside or in the little fluid it had so maybe you your right in saying maybe it was fixed a while back.

Well I'll be looking for some axles. I'm gonna check the junkyard and try my luck. Dana 60's are rare so I've heard, Anyone recommend a gear ratio? 3.73? 4.10?

Re: Rear Differential
 

Depends on what you want to do with the truck. Pulling a trailer? Hitting some trails? Maybe want to go with a lower gear. Just cruising on the highway and throwing it in 4WD when the snow starts to fall? Maybe go with a taller gear. Just be sure you know what gears are in the front axle, the ratios have to match so you don't break everything the first time you put it in 4HI.

Rear Dana 60's shouldn't be too tough to find, it's the fronts that are a little scarcer. Though it occurred to me that they're 8 lug, and you're probably 6 lug right now. You should be able to find a 6 lug 12 bolt pretty easily and cheaply, I'd imagine, which should be fine, unless you plan on taking it off road abusing it.

Re: Rear Differential
 

I would not hesitate to rebuild it yourself...looks like a good candidate for a limited slip or posi carrier. A pinion depth gauge helps out a lot to keep from having to pull the whole thing back apart to get your pattern right, and getting the backlash right just takes some patience.

Pinion depth gauge.
http://completeoffroad.com/i-122837-...epth-tool.html

Re: Rear Differential
 

I plan on hauling truck loads of wood in the summers, pulling a camper trailer, and taking it out to cruise every now and then other than that. It looks like I have 3.08 gears so I think I'll be looking for a change.

When it comes down to messing with the differential, I have no clue what I'm doing. I think I'd end up making it worse if I attempted doing it myself.


Anyone mind telling me whats the difference between auto and manual hubs on the front axles on these older trucks?

Re: Rear Differential
 

Manual hubs are the ones you hop out and twist the knob to lock in. Auto hubs are just crap.

Re: Rear Differential
 

Thanks!

Alright well I got my hands on a set of 3.73 10 bolt axles. I know 10 bolt are weaker but these axles are free. I'll be opening them up this weekend, what are the things to look for other than metal shavings and play in the gears?

Re: Rear Differential
 

they are not weaker than what you have now, or even weaker than a 12 bolt. 2 more bolts wooooo.

look for any broken lug studs, or missing ujoint straps or broken yokes, make sure the moving parts move freely and not gritty. check rear end gear wear and see a nice polish in the middle of the teeth basically. no heavy scars or pitting.
balljoint play and wheel bearing play. see if the locking hubs work and actually lock the axle shaft when engaged. worn out tie rod ends etc etc etc etc

driver pullouts or junkyard sitters for years? if this 10 bolt rear came from a manual transmission truck it will have a 1350 ujoint on the pinion.

Re: Rear Differential
 

These were from a 1985 gmc k1500 that was totaled last year and is just sitting in my parents yard. The axles look good, may have to replace a rotor and brakes. I'll put up some pics when open them up to get opinions from more experienced people then myself.

Re: Rear Differential
 

That is just plain funny right there......some of the funniest stuff you ever here is simply clever wording of the absolute truth.

Re: Rear Differential
 

Thanks man. :lol: I'm not good at sugar-coating things.

Re: Rear Differential
 

For 35's you'll want 4.56 gears, especially hauling wood. If you'll be in the mud you'll want a posi or a locker too.

Re: Rear Differential
 

Unless you plan on using a big block. Then 3.73s are just fine.

Re: Rear Differential
 

Yeah but a bbc with 456s is *****in. Especially with a 6.5:1 and 4:1
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Re: Rear Differential
 

I run 3.07s with 35s and a 350. I've even towed a 6.5k trailer 630 miles with it, but I have a TH350 so that helps with running such a high gear. I would imagine 3.73s would be fine with a SM465.

If I need more gear I drop my 203 in low, and I have all the gear I want.

You don't NEED 4.56s.

Re: Rear Differential
 

3.42-3.73 gears. 4.10s would be to low unless the truck is used like a farm vehicle. I have 32" tires and 4.10s and spin the motor at 3k+ RPM every day on the interstate. 3.73 is a real nice compromise.

Re: Rear Differential
 

Well i finally had some time yesterday. I popped open the rear axle and this is what it looks like.

http://i1250.photobucket.com/albums/...ps65ba9818.jpg

http://i1250.photobucket.com/albums/...ps9bfd262c.jpg

I didn't see any loose parts, i wiggled it and there was no play. I didn't see no metal shavings. I did see 1 chip on a tooth, wasn't that big at all, could this be a problem?
Let me know what ya'll think!

BTW it wasn't sticking or getting stuck when I was turning the gears, I did my best doing 1 turn at a time with 1 hand!

Re: Rear Differential
 

Looks like open/open to me. Long as the gears look good and there is no slop, run 'em.

Re: Rear Differential
 

I know you said you checked for loose items, but be sure you double check the spider gears and pin. Replace if they have slop. They are relatively cheap, and it is a huge pain if they go kaboom.

Re: Rear Differential
 

By the looks of the video, would you say there's slop?
When i start turning, the gears react quickly. again I'm a noob to checking this out so I'd say slop was minimal.

Re: Rear Differential
 

What goes away on the 10 bolts is the small bolt that holds the pin in the case. Bet if you pull the bolt out it'll be pretty beat up. Have a new one ready to install. they are in pretty tight with loc-tite. 5/16-- 6 point socket

Re: Rear Differential
 

Well just to give an update. Got the rear axle installed this weekend. Bolted everything up and topped it off with gear fluid. My brother followed me on the first test drive and noticed my rear passenger side wheel (rim and tire) has a wobble. I do notice a bit of a jumpy ride when going slow. Anyone experience anything like this? Is there an easy fix or am I screwed?