Differential gears, 67 c10

[RTHarvey]

I recently acquired a 1967 c10. There is quite a whine at highway speed, and I believe it is coming from the differential. My experience has been that this kind of noise is usually due to worn out ring/pinion gears. I am getting close to having it taken apart and examined. Assuming that I am correct and the ring and pinion gears need to be replaced, where is the best place to buy new gears? (hopefully without breading the bank) The SPID makes no mention of any rear axle option, which I think means it is standard, which I think is 3.73:1. This will generally be a gently and infrequently used truck. It is a 283, 4-speed, long-narrow. Any suggestions would be appreciated. Also if any of the assumptions I have made above (like gear ratio) are incorrect, I would appreciate being set straight.

[demian5]

if its just the gears, put a 3:73 back in it, or 3:42. Both will work on the carrier. A 3:07 requires a different carrier.

I bought this kit when I redid mine.

http://www.jegs.com/webapp/wcs/store...rsistYmm=false

[harpo231]

check axle bearings.....

[demian5]

Originally Posted by harpo231

check axle bearings.....

Agree, but would be most noticeable when turning. turn right, left bearing, turn left, right bearing.

If noise is there when on the gas or off the gas (coasting) but not between letting gas on and off, its the rear end.

[Mike C]

3.07 carrier is good up to 3.42 as well. I just bought a set of thick 3.73 to run on my 3.07 Posi in my short bed.

Carrier breaks on truck 12 bolt are 2.73 and less, 2.76-3.42 and 3.73 and up.

[RustyBucket]

You did check the lube level ?.... just asking, it's not leaking around the pinion or an axle seal is it? Does the truck look like it's really high mileage? Just asking 'cause I've had quite a few of these trucks over the years and never had a noisy differential in one. Maybe just lucky with these..... had several noisy ones in Dodge trucks.

[ElKotze]

If you find out it's R&P, I usually get Yukon gears, most of their sets are made in USA and the master overhaul kit is very good.

[Killer Bee]

check fluid level? change with proper weight/type?

limited slip? friction modifier added at last fluid change?

[RTHarvey]

Thanks for the tips. I did check the fluid level-it is proper level and appears as new. It is not limited slip (I don't believe). I have no idea how many miles the truck has travelled. Everything seems to be in decent shape, but these trucks are pretty repairable. Rebuild engine, I really don't know about other stuff.

[RTHarvey]

It appears that Yukon does not provide ring and pinion set for 67 c10. As near as I can tell.

[RustyBucket]

this is just an example, there are several big driveline parts suppliers:
RANDYS Worldwide Automotive - Home
1-866-631-0196 they have a nice website too

High performance Yukon Ring & Pinion gear set for GM 12 bolt truck in a 3.73 ratio - YG GM12T-373
Image may vary from actual product
YG GM12T-373 [24128] $277.77 ... + the cost of an installation kit.

Hopefully, there's an honest reputable driveline shop in your area. A guy that knows his business will supply the parts and fit the rear end so that it will run quietly pretty much forever. Shop the prices around, maybe somebody on this site can make a recommendation or maybe even do the work for you. ... Unless you want to buy the parts and learn how to fit one.

[RTHarvey]

Well...thanks for the response. Indeed you found what I was looking for at Yukon. Searching by vehicle on their website does not find this, which I would say is unfortunate for their website and business. If I search by "axle type" then "GM 12 bolt" I can get to it, or I can search the pn you gave me. Anyway--like I said, thanks for the guidance. I think I can find someone to do the job--I don't really want to do it myself. That is kind of heavy work, and I am kind of old, so I think I will hire this one done. The instructor showed us how to do this when I was in auto mech in high school, which was just about the time my truck was made, but that is just a little too long ago for me to remember. The price on those Yukon gears is pretty reasonable.

[RTHarvey]

Rear axle partially disassembled. Gruesome. The guy I have doing this says it looks like I will be able to save the housing, not much else.

[RustyBucket]

WOW!!, I'll bet that sounded AWFUL..... At least you have a ballpark figure on the cost of the parts to fix it. Hopefully the guy doing the work does a good job for you and is reasonable on his labor rate. Now would be the time if you'd like a different rear ratio.

[RTHarvey]

Sorry--not sure why that got repeated, other than somehow I told it to. I have done a few calculations--it currently has a 3.73. that should work out, with stock-size tires, to be 2700rpm at 60 mph. With a 3.42 it would be about 2500. I think anything taller than 3.42 could be difficult for a 283 V8. I would slightly prefer the 3.42, but that would require a new carrier, which is about 350-400 $. So, unless my carrier is unusable, I will probably stick with the 3.73.

[trac209]

Actually I’ve seen far worse pitted and rusted gears that with new oil didn’t make a sound. I don’t know how yours were that noisy. The pinion does look the worst of it

[GASoline71]

You can get 3.73 gears cut to fit a 3 or 4 series carrier. 3.73 and numerically higher is a 4 series carrier for a truck 12-bolt.

Gary

[Bigdav160]

The noise is the pitting on the bearing.

Not likely from the gear.

[Mike C]

Agreed. If this were mine, I'd throw bearings in it and see what was up before dropping any more $. But I wouldn't have to pay a shop to do that so it definitely figures into your calculations.

You can buy an open diff case for about $100 and swap your spider and side gears into it if you wanted to run the 3.42. But I've seen much uglier gears than that run for thousands of miles with no issues or noise.

Put a 1" drop spring in the back and a 2" taller tire. It will sit the same and knock the gear down to 3.42 :-)

[RTHarvey]

Actually the tire size idea isn't that bad. But I will probably just stay at 3.73 and keep the almost new tires. I placed an order for parts this evening, including ring and pinion. Mostly Yukon parts. I'll post results when to job is done. Hopefully all is quiet, and the transmission won't need work. Is there a "cross you fingers" emoticon?

[RTHarvey]

OK--so the differential rebuild is complete, and the truck sounds good. I think the transmission is going to be fine. The M420 is not a whisper quiet trans, but it sounds like it should now (yay). The only parts reused were the housing and the carrier. All gears, all bearings and both axles replaced. A few pics of the new stuff.

[RTHarvey]

The diff looked like it had water in it at some point. Lots of rusty gunk mud. About 3/8" deep in both axle tubes. Gears and bearings badly pitted, etc. What a mess. The vent hose didn't look very old--I am thinking maybe the hose rotted away, and someone backed too far down the boat ramp at one time or another. By the time I got it, it had like-new looking gear oil, and yowled like a banshee.