'79 K20 axle issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

zac · 10-22-2009, 08:09 PM

'79 K20 350/th400/203/10 bolt/14 bolt ff

I thought I was ready to go, but then I hear a funky noise from the front right during some turns and braking. Comes and goes. Afraid it might be pinion bearing. Front right wheel bearings loose, pitted, missing spring retainer in hub both sides. I buy all new parts, but pop the cover off the diff (10 bolt) just in case. Strange burrs sticking up off ring gear in some places. Pinion depth setting off? I bought a used 10 bolt with 3.42's that I was going to use later when I was ready to swap the rear gears or axle (14 bolt full float), but now I'm thinking I might as well just go for it, since trying to put that front axle back in service may just be a waste of time. Stupid me, I thought a 3.42 14 bolt rear or gears would be easy to find and cheaper than the 4:10's or 4:56's. So I can buy new gears for the rear, I guess. I have read through the 14 bolt bible and all that. Has anyone here done the gear swap themselves? Is it really that easy?

Mudder · 10-22-2009, 10:21 PM

It's not easy. Has to be right or you will ruin them fast. Sometimes you have to take it all apart several times to get the right amount of shims.

**special-K** · 10-23-2009, 06:21 AM

It`s not that it`s hard to do,but you`re peeing into the wind if you don`t get it right...and not almost.The best thing since sliced bread are assembly bearing kits.they are made to slide,not press,into place and allow for easy install/remove until you get a good wear pattern.

LONGHAIR · 10-23-2009, 07:08 AM

The 14 bolt uses screw style adjusters on the carrier bearings, so shims are not really an issue there....but the biggest factor is dealing with the pinion depth anyway, and there are shims there. The one under the pinion head is the hardest one to deal with. It has to be pressed on/off.

As stated, it is not an easy job, and generally not one for the average driveway mechanic. It takes a lot of patience and a few special tools. The investment in time and money is generally not worth it to learn to do a job that you may only ever need to do one time.
Done by a professional, you should get some kind of warranty too.

zac · 10-23-2009, 03:39 PM

I guess "easy" was a poor choice of words. What I really meant was "is it that possible" , as opposed to other axles where it really is not.

Your points are well taken, though. Peeing into the wind is pretty much what I do. Since Aug 24th when I purchased this truck I have had the engine down to the short block and put in a transmission, transfer case (which I had to twin stick) and a front driveshaft. It will not be a daily driver, just used for truck stuff, not off-roading except to hunt and fish. So what I'm taking from this is that due to the beauty of the cheapness of parts for these things, I would probably be best off getting a matched set of 3.73 axles for the time being, which can be had for less than the price of a a professional gear install by a good bit. Wait for the 3.42 to come along (or not, maybe I won't want it). Maybe later take a crack at it or pay someone, depending where all this goes. The main thing is I'm trying to get it operational by the time our driveway turns into a sheet of ice.

I liked the idea of not having to drag axles around that weigh as much as a Honda Civic. Oh well.

10-22-2009, 08:09 PM	#1
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	'79 K20 axle issues '79 K20 350/th400/203/10 bolt/14 bolt ff I thought I was ready to go, but then I hear a funky noise from the front right during some turns and braking. Comes and goes. Afraid it might be pinion bearing. Front right wheel bearings loose, pitted, missing spring retainer in hub both sides. I buy all new parts, but pop the cover off the diff (10 bolt) just in case. Strange burrs sticking up off ring gear in some places. Pinion depth setting off? I bought a used 10 bolt with 3.42's that I was going to use later when I was ready to swap the rear gears or axle (14 bolt full float), but now I'm thinking I might as well just go for it, since trying to put that front axle back in service may just be a waste of time. Stupid me, I thought a 3.42 14 bolt rear or gears would be easy to find and cheaper than the 4:10's or 4:56's. So I can buy new gears for the rear, I guess. I have read through the 14 bolt bible and all that. Has anyone here done the gear swap themselves? Is it really that easy?

10-22-2009, 10:21 PM	#2
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,339	Re: '79 K20 axle issues It's not easy. Has to be right or you will ruin them fast. Sometimes you have to take it all apart several times to get the right amount of shims.

10-23-2009, 06:21 AM	#3
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,863	Re: '79 K20 axle issues It`s not that it`s hard to do,but you`re peeing into the wind if you don`t get it right...and not almost.The best thing since sliced bread are assembly bearing kits.they are made to slide,not press,into place and allow for easy install/remove until you get a good wear pattern. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

10-23-2009, 03:39 PM	#5
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	Re: '79 K20 axle issues I guess "easy" was a poor choice of words. What I really meant was "is it that possible" , as opposed to other axles where it really is not. Your points are well taken, though. Peeing into the wind is pretty much what I do. Since Aug 24th when I purchased this truck I have had the engine down to the short block and put in a transmission, transfer case (which I had to twin stick) and a front driveshaft. It will not be a daily driver, just used for truck stuff, not off-roading except to hunt and fish. So what I'm taking from this is that due to the beauty of the cheapness of parts for these things, I would probably be best off getting a matched set of 3.73 axles for the time being, which can be had for less than the price of a a professional gear install by a good bit. Wait for the 3.42 to come along (or not, maybe I won't want it). Maybe later take a crack at it or pay someone, depending where all this goes. The main thing is I'm trying to get it operational by the time our driveway turns into a sheet of ice. I liked the idea of not having to drag axles around that weigh as much as a Honda Civic. Oh well.



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