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14 Bolt Swap and Gearing

BDK

BDK

Red Skull Member
Joined
May 19, 2020
Member Number
143
Messages
937
Loc
San Diego, Kingman
I have a 2008 1500 Silverado with a 5.3. I like it and want to keep it. My 8.6 10 bolt rear axle is making noises, and from what I understand it's a relatively easy swap to get a 6 lug 14 bolt under there. I tow horse trailers with it monthly.

The issue I'm having is in Southern California, they are unobtanium. They seem to be mostly in the southern states.

The other issue is 90% of them have 3.42 gears and my 8.6 has 3.73's. That gear difference seems slight, but if I like the power with the 3.73's would I hate the 3.42 gears?

I found what appears to be a nice axle out of a wrecked 2013 with 160xxx out of Texas, but it has the govlock and 3.42's. Regearing it's not a deal breaker, but it will cause me to go through the entire axle while I'm in there, including replacing the govlock with a Eaton TruTrac.
 
Car part says there is one out of a 2009 with 3.73 gears about 25 miles away. I sent them a message through car parts system, hopefully I will hear from them tomorrow.
 
Mine is a two wheel drive truck with drum rears. Been wanting to dump the drums since I bought it new in 2008.

From what I've been reading, the brake lines are compatible and I don't need to change the master cylinder. The ABS computer will read the axle, same sensors. It's programmed for drum rears, but from what I've read it's not a issue.

The only thing that's not compatible is the drive shaft. Some on-line are saying that I can swap the yoke from my 10 bolt to the 14 bolt, or get an adaptor U-joint. Driveshaft is close enough length so also not a issue. I have one of those goofy aluminum drive shafts.

Is this really all there is to it? I've done some axle swaps before, but they were a lot more work than this seems to be.
 
Taking a drive up to Corona. Getting one local that's been under a California based truck is much better than one from the south. They are including all the U-bolts and plates, brake lines and cables and the drive shaft. Donor truck is a 2010 with only 78,000 miles on it, so I don't think I'll need to do any repairs to the axle for a while. After I get it home, I'll clean it up, replace the rotors and pads, measure everything out and get whatever else I need, then swap them out.

Guy was funny on the phone. He says we don't take credit cards so I'll just get it pulled and hope you show up. Then he added "Please don't show up in a mini-van." It's Indiana Truck Salvage.
 
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BDK said:
Taking a drive up to Corona. Getting one local that's been under a California based truck is much better than one from the south.
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Wouldn't be an issue if GM didn't insist on those stamped bolt plates that trap mud. :flipoff2:
 
BDK said:
Taking a drive up to Corona. Getting one local that's been under a California based truck is much better than one from the south. They are including all the U-bolts and plates, brake lines and cables and the drive shaft. Donor truck is a 2010 with only 78,000 miles on it, so I don't think I'll need to do any repairs to the axle for a while. After I get it home, I'll clean it up, replace the rotors and pads, measure everything out and get whatever else I need, then swap them out.

Guy was funny on the phone. He says we don't take credit cards so I'll just get it pulled and hope you show up. Then he added "Please don't show up in a mini-van." It's Indiana Truck Salvage.
Click to expand...
Loading a rear axle into a mini van with forks on a front end loader is some teeth gritting ass puckering shit. Been there done that in my younger years.
 
Axle is in great shape and I found a new go to place for used truck parts. Evan has what I think are factory air bags that appear to be intact. Good people. I think the only fabbing I'll be doing on this swap is for the upper air bag mounts. The only leak I could see was from the diff cover when they pulled it to make sure it worked.
20230831_133623.jpg


It was almost worth being completely stopped in traffic for seven minutes in 102 degree heat while these idiots merging kept trying to creep closer. Nobody's fucking moving assholes, relax.
20230831_142922.jpg
 
ANGRYBLACK said:
Loading a rear axle into a mini van with forks on a front end loader is some teeth gritting ass puckering shit. Been there done that in my younger years.
Click to expand...
It’s way easier than the same job with a real forklift because the bucket doesn’t hit the hatch where the mast would.
 
The air bags hold air, bonus. I neglected to ask them for the upper bag mounts. I called them this morning. He sent me a picture of the mounts and said his yard guy is removing them. I asked for them to be mailed to me, but he doesn't ship anything. I also asked for as much of the airline as they can pull so I can have the fittings if the line is compromised, and run it to a Shrader valve I can mount under the bumper.

My punishment for not getting everything the first time will be another drive up the I-15 to beautiful Corona.

Good news is I got ahold of a friend who lives in Idaho and does all kinds of conversions, axles, V8 swaps, etc. He has done several of these, says the axle bolts right in, the 14 bolt yoke is the same as the 10 bolt, and the driveshaft is the same for both versions. I'll see how it goes when I get to the swap. Waiting for new rotors and pads, a Lube Locker gasket, and other misc crap to arrive.

Upper air bag mounts are held in place with one bolt into the bump stop mount.
IMG_1727.jpg
 
I got the old axle out and the new axle in. Same U-joint perches, same everything. I can see that all the plumbing is the same, brake lines, park brake cables, ABS wiring, etc. The driveshaft does bolt to the new axle yoke, but it's an inch too long with the new axle. There was 1-3/8" of slip yoke shaft showing with the axle hanging on the leaf springs, now there is 3/8". I have one of those goofy aluminum lightweight driveshafts. Called San Diego Driveshaft Pros, which is a shop I have been using for a few decades now. They do all kinds of specialty car driveshafts. They said they can shorten mine no problem because the ends are welded to the shaft. I'll bring it in tomorrow and have them swap out the U-joints while its there. This would have been an axle swap record for me. It would have been wrapped up by tomorrow. Now, it will be sometime next week. Shit happens I guess. Still beats rebuilding a drum brake 10 bolt.
Old axle out
20230907_132410.jpg

New axle in
20230907_152846.jpg

Pic of my plain old 1500 Crew Cab
20230901_104813.jpg
 
I almost have this swap finished. Things I learned along the way:

This is a swap for a 2008 Crew Cab (4 door), short bed (5'8") two-wheel drive 1500 Silverado with the 5.3 V8, 4L60E transmission, and a 10 bolt, 8.6" rear axle.
Donor vehicle is a 2010 Crew Cab 1500, standard bed (6'5"), four-wheel drive 1500 Silverado with the 6.2 V8 and a 14 bolt, 9.5" rear axle.

It is an almost direct bolt in swap. The 14 bolt that was in this generation of Silverado's with the larger 6.2 engine is sometimes referred to as a "baby 14 bolt". It is not the same as the full float 14 bolt, which have a larger housing and ring gear. This axle is semi-float with C-clips and 9.5" gears. A 2008-2013 donor truck is what I recommend. I found mine through car-part.com search at a salvage yard.

I was told this by an off-road based axle shop:
Some of the 2014 and up 14 bolts have a 9.75" ring gear. The axles have the same housings and look identical, but nothing internal is interchangeable. No aftermarket support, no aftermarket lockers/carriers available, and limited gearing options. The 9.5" gear 14 bolts have lots of aftermarket support. If your 14 bolt semi-float has 3.73 gears, it's a 9.5" gear as they are not available for the 9.75.

Axles are the same width.
ABS wires are the same on both vehicles.
Brake lines from the axle to the truck soft lines mount at the same location with the same fittings.
U-bolts, plates and nuts are the same.
Both are the same 6 lug bolt pattern.
Both drive shafts use 1350 U-joints and the yokes appear identical.
Shock mounts are the same.
Bump stops and plates are in the same location. If axle comes with air bags, need both top and bottom brackets and they replace the bump stops. Bags air line fittings are 1/8 NPT.
10 bolt Drive shaft does bolt to the yoke of the 14 bolt, but the 14 bolt is a little bit longer.

What is different:
Drive shaft will need to be shortened 1" to regain the slip yoke play. This might be different with a 4x4 model, might have more play in the slip yokes. If your aluminum drive shaft has welded ends, it can be shortened. Mine is currently over at Driveshaft Pros getting shortened, rebalanced and new U-joints.

Park brake cables are about a foot longer, but the sheaths are the same length. I did not pull the park brake cables on my old axle to see if they would fit the 14 bolt axle. It will be easier to shorten the cables than pull apart the drum brakes. I used cable clamps.

Once I got the axle in place, it took me about 45 minutes to get the U-bolts torqued, and all the plumbing done. I'm waiting on the drive shaft, brake pads and rotors. Once I get the drive shaft and rotors installed all I will have left to do is flush and bleed the brake lines. Should be back on the road by this Thursday. I'll install the air bags after I get the upper mounts and air line from the yard. They are holding them for me whenever I get up there. The yard will take my old axle for scrap so I don't have to figure out what to do with it.
 
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Thanks for the write up. What spline axle shafts does the baby 14 use?
 
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