Front differential Sounds

OK So I have some clicking sounds coming from my front diff under medium to heavy acceleration and when turning. I thought it was the CV shafts so I changed them. Then replaced the wheel bearings and still have the noise. My brother said it was the front drive shaft CV so I changed that out and still makes the noise. If I take the front drive shaft off its fine no clicking sounds when accelerating or turning. I thought maybe the transfer case shift fork sticking but with the front shaft off it goes into 4 hi lock and can move on its own. Switch it back to four hi and the truck goes nowhere the front of the transfer case just spins. I did notice that with the drive shaft off I seem to have about 20 to maybe 30 degrees of play in the front pinion maybe more. I have taken it to a few shops to have the front diff looked at but they will not give me an estimate for inspection they just say we won’t know until we get it out and take it apart. I would love to just let them at it, but the cancer treatment center gets a large portion of my monthly check so I am kind of on limited funds. If you guys think it’s the internals on the diff what do I need to look at when inspecting a replacement because I can swap out the diff but I know I can’t do the internals. I’m down in the Louisville KY area for work but live in northern Michigan. So any place along that route that you guys know of that I might get the needed parts would be great! Any input would be greatly appreciated and thank you guys!

I'm not a diff guy but there should be zero perceptible play in the pinion shaft. If it moves at all either in or out, up/down side/side then the bearing is toast and the gear teeth probably are now as well, especially with how much play you say it has (though I doubt it is anything close to 20 degrees, unless all the needles have fallen out, and it'd make a LOT more noise than clicking).

I'd at least drain the diff fluid and check for metal particles on the magnet on the drain plug.

You're looking at a full rebuild on something like that most likely. Or get a new/used diff.



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I just realized you might be talking about 20 to 30 degrees of play in the lash. That seems like an awful lot, pretty sure it should only be a degree or two. More than that and it is an issue that will likely need a tear down to adjust the lash, but odds are it still would need a full rebuild.

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Thank you JPaul, yeah I’m sure it’s the lash I’m trying to explain. I thought that was a lot too especially because the back has no where near that.

Probably a pinion bearing...very common issue. If its been that way for awhile, the gears are probably due for replacement.

Checking the diff fluid will tell you a lot. The drain plug is magnetic, and they often collect the metal shavings from the worn teeth. So if your plug looks like a big cockle-burr, you got a problem.

I’m just north of Bloomington, IN and I can do your axle rebuild/setup or swap in a different one. Shoot me a PM if interested, and we can schedule something.

Jack, I think you'll need a full rebuild if you're not getting any movement in regular 4HI. I'd take 4pseed up on his offer. Your least expensive bet might be an eBay front diff but talk it through with him first.

I think your probably right, I did send him a message, and have been sourcing another assembly as well just in case. If I don’t hear from him or find another assembly it will be a fun Weekend home. Carrier assembly, power steering pump, water pump and clutch fan. I love my H3... when I’m not under it! Lol!

Jack_M said:

I think your probably right, I did send him a message, and have been sourcing another assembly as well just in case. If I don’t hear from him or find another assembly it will be a fun Weekend home. Carrier assembly, power steering pump, water pump and clutch fan. I love my H3... when I’m not under it! Lol!

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Thankfully each of those aren't horrible repairs to do, but all of them together? That's a lot of work! Good luck.

You ready for a SAS on your truck, Alex? 6.6L swap? Duramax swap? :hack::grind::weld:

Ls1 swap and an axle swap and my H3 would be perfect!!!

MaxPF said:

You ready for a SAS on your truck, Alex? 6.6L swap? Duramax swap? :hack::grind::weld:

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SAS with an LT4? :giggle:

alrock said:

SAS with an LT4? :giggle:

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Why not? It's your money :deal:

Wouldn’t an LT4 be too much weight for the torsion bars to support?

Never mind!! The axle swap would fix that.

MaxPF said:

Why not? It's your money :deal:

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Well, I guess that option is out of the window.

alrock said:

Well, I guess that option is out of the window.

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Can't afford it? F***in' FINANCE IT!

Jack_M said:

Wouldn’t an LT4 be too much weight for the torsion bars to support?

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The LT4 isn't that heavy. But, it's not really the most practical or ideal engine for a V8 swap. IMO, once the new 6.6L engines start showing up in the wrecking yards I think they will be an excellent semi-big-boy swap candidate. Not as good as the new 7.3L Ford pushrod V8, but until GM gets with the program and makes a direct injection big block the 6.6L is what we will have.

Or, not. It's actually trivial to buy a crate HT502 big block from GMPP, put a port injection manifold on it, and run it off of a "411" LS PCM. You can even use the LS coil packs to fire the plugs - no distributor. If not for the Cummins swap I'd probably have such a beast under the hood of my Blazer right now :gears: