14 bolt swap questions

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abrasumente

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Folks, I've finally gotten together pretty much everything I need for a 14 bolt swap. I've ran into a couple gotchas though so I figured I'd ask here:

1) The guy I bought the axle from didn't have the leaf springs off the other truck. Can I use the springs that are currently installed on my suburban? It has a 5 spring pack on it.

2) The axle vent tube has been broken off essentially flush- you could weld a nut to the round part of the vent tube and bust it off that way, but I don't have access to a welder anymore. Has anyone run into this situation, and what did you do to remove it without getting metal shavings inside the axle? I'm going to attempt getting it red hot and busting it loose with a pair of vice grips, but idk how well that's gonna work. I plan on replacing it with a new vent valve anyway.

3) What are the correct axle seals for this dude? The axle bearings are making a little noise but the diff itself is quiet, so I plan on replacing the bearings+seals- but I'm seeing a lot of different options for seals on RockAuto. Some are obviously for the FF axle, but I want to be sure of the correct choice. I'll be doing this swap over the weekend soon- the brakes on my 8.5 are shot and I pull a trailer regularly, and I'm not trying to kill my fronts.

Any help would be greatly appreciated.
 

454cid

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2) The axle vent tube has been broken off essentially flush- you could weld a nut to the round part of the vent tube and bust it off that way, but I don't have access to a welder anymore. Has anyone run into this situation, and what did you do to remove it without getting metal shavings inside the axle? I'm going to attempt getting it red hot and busting it loose with a pair of vice grips, but idk how well that's gonna work. I plan on replacing it with a new vent valve anyway.

That vent tube may not be threaded. I know that on the 11.5" AAM axle (for GM) the vent tubes were a friction fit that get air-hammered into place.
 

someotherguy

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Folks, I've finally gotten together pretty much everything I need for a 14 bolt swap. I've ran into a couple gotchas though so I figured I'd ask here:

1) The guy I bought the axle from didn't have the leaf springs off the other truck. Can I use the springs that are currently installed on my suburban? It has a 5 spring pack on it.

2) The axle vent tube has been broken off essentially flush- you could weld a nut to the round part of the vent tube and bust it off that way, but I don't have access to a welder anymore. Has anyone run into this situation, and what did you do to remove it without getting metal shavings inside the axle? I'm going to attempt getting it red hot and busting it loose with a pair of vice grips, but idk how well that's gonna work. I plan on replacing it with a new vent valve anyway.

3) What are the correct axle seals for this dude? The axle bearings are making a little noise but the diff itself is quiet, so I plan on replacing the bearings+seals- but I'm seeing a lot of different options for seals on RockAuto. Some are obviously for the FF axle, but I want to be sure of the correct choice. I'll be doing this swap over the weekend soon- the brakes on my 8.5 are shot and I pull a trailer regularly, and I'm not trying to kill my fronts.

Any help would be greatly appreciated.
1. Yes your springs will be fine. The other ones wouldn't fit your truck anyway unless they were also from a Suburban. You will need the spring saddle plates though as the ones for your 8.5 are smaller, and you absolutely should use new u-bolts.

2. Sounds like you're averse to opening the cover up while you handle the vent tube issue. You want to open it up anyway as the condition of the gears and gear oil are an unknown quantity at this point. So kill two birds with one stone. Also be sure to go back only with 80W90 GL5 gear lube, NO posi additive regardless of what anyone says or whether the differential is open or has the Eaton Gov-Loc unit. Be sure you can get the drain plug out first; buy a 3/8" square socket if you don't already have one as it will do a better job than sticking a ratchet extension in there.

3. Beats me.. if the application says 9.5" ring gear, or 7200 lb GVWR, you're likely looking at the correct parts....assuming your 14 bolt is the semi-floating 9.5" unit that most people seek to swap in place of the 8.5".

Richard
 

abrasumente

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1. Yes your springs will be fine. The other ones wouldn't fit your truck anyway unless they were also from a Suburban. You will need the spring saddle plates though as the ones for your 8.5 are smaller, and you absolutely should use new u-bolts.

2. Sounds like you're averse to opening the cover up while you handle the vent tube issue. You want to open it up anyway as the condition of the gears and gear oil are an unknown quantity at this point. So kill two birds with one stone. Also be sure to go back only with 80W90 GL5 gear lube, NO posi additive regardless of what anyone says or whether the differential is open or has the Eaton Gov-Loc unit. Be sure you can get the drain plug out first; buy a 3/8" square socket if you don't already have one as it will do a better job than sticking a ratchet extension in there.

3. Beats me.. if the application says 9.5" ring gear, or 7200 lb GVWR, you're likely looking at the correct parts....assuming your 14 bolt is the semi-floating 9.5" unit that most people seek to swap in place of the 8.5".

Richard

Im not so much worried about opening it up (has to be done anyway to replace seals and bearings) but more a concern of not getting all the metal shavings out and something working its way into the Gov-lock. I’d rather not have to rebuild the whole thing because I missed a chunk of metal drilling the valve out. I’ve already drained the old fluid, the gears look great (no chatter or missing pieces).

As far as ubolts and etc are concerned, I got a flip kit coming from offroad designs that should have me squared away.
 

abrasumente

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That vent tube may not be threaded. I know that on the 11.5" AAM axle (for GM) the vent tubes were a friction fit that get air-hammered into place.

From the pictures I’ve seen online, the 8.5 and 9.5 vents are the same- they’re threaded and also slathered with good ol red loctite
 

454cid

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From the pictures I’ve seen online, the 8.5 and 9.5 vents are the same- they’re threaded and also slathered with good ol red loctite

Are you sure they are actually threads and not just ridges? The 11.5" could be done differently, I'll give you that.
 

abrasumente

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Are you sure they are actually threads and not just ridges? The 11.5" could be done differently, I'll give you that.

That's a good point. No, I'm not sure- I haven't seen one in hand. With that said, let's say they are installed identically to the 11.5 axle. What would be my approach at that point, if it's hammered in? There is basically no meat left on the actual tube part of the vent to attach anything to.
 

454cid

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That's a good point. No, I'm not sure- I haven't seen one in hand. With that said, let's say they are installed identically to the 11.5 axle. What would be my approach at that point, if it's hammered in? There is basically no meat left on the actual tube part of the vent to attach anything to.

Could a slide hammer be attached? Failing that'd think the best approach would be to pound it out from the inside, if a straight shot with a drift is possible. I've never removed one.
 

abrasumente

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Could a slide hammer be attached? Failing that'd think the best approach would be to pound it out from the inside, if a straight shot with a drift is possible. I've never removed one.


I think I answered my own question. It's been a while since I worked on the truck (had a major injury last year) and forgot I had a digital copy of the service manual. Apparently, the tube that sticks up out of the axle is literally just a nipple- the actual one way vent is installed at the end of the rubber hose. I guess my best bet is to drill the old nipple, tap it, and put in a 1/8 NPT nipple- leaving the housing of the original nipple intact. I'd like to go 1/4" NPT but I think the housing itself is only 1/2".

I'll just have to make sure I thoroughly clean the inside of the axle out.
 
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