Kaboom, screeech

[Crimson93Ty]

Re: Kaboom, screeech

What Merk is talking about is inside the transfer case and is a component called a viscous clutch. This clutch has a silicone like substance in it that heats up and expands making the steels in the clutch drag more on each other. The hotter the fluid, the more they drag. There is a certain amount of air in the sealed viscous coupler for expansion. Two things can go wrong. You drive it without a front propshaft or do massive/constant burnouts and over heat the viscous coupler and the clutches fuse together(unit will have a blue/brown look to it). This makes a constant 4wd situation causing the hopping condition you are describing. The other is you heat the unit up so much that the coupler explodes. Sounds like you haven't done that yet.
Here's a page that talks about them:
viscous clutch
Click on "OPEN" and the pic will open the clutch. Click on it again and the contents will expand even more.

See the two different kinds of plates inside there? If those plate fuse together, you get the hopping you are taling about.

 

[Crimson93Ty]

Re: Kaboom, screeech

Here:

ALT1372-Viscous Viscous Coupling BW4472 OEM#1372-625-001 1992-On $259.90
From:
Drivetrain.com

 

[dustinwinkle]

Re: Kaboom, screeech

One thing to watch for when you get it fixed is the govenor gear in the transmission. I blew out the rear end in my Corvette and it also took out the Govenor gear. If this happens you will not be able to shift out of first gear. The part is only a few bucks. Took me a ton of searching to figure out what the heck was wrong, just wanted to give you a heads up.

Dustin Winkle
Ty#0036
Boise, ID

 

[Syclones rock]

Re: Kaboom, screeech

na how bout a 9 inch :tup: or a dana 60 that should hold :lol: :roll:

 

[MR_MNZTR_SY]

Re: Kaboom, screeech

The idea of throwing in an 8.5" would be nice, I've done some searching and it looks like they come from a 98+ (2k+ if I want rear discs) S10, 5spd, 4wd, and matching our gearing (3.42's right?).

so wait, can we swap the entire rear axle out of a 2k+ truck and get a more stout rear end AND disc brakes?


uh, not to hijack the thread or anything.

 

[big gear head]

Re: Kaboom, screeech

The bucking that you are feeling when turning tight corners is probably from the clutches in the new posi that is in the rear end. I'm assuming that you didn't go back with the Governor Lock, but instead you used a new Eaton or Auburn posi. If this is the case then you might be able to fix it by just adding another bottle of the limited slip oil additive to the rear end. If you installed an Auburn then you might need more than one bottle. The Governor Lock that came stock in these trucks don't do this because the clutches are only applied when one wheel spins and the governor locks.

 

[sleepy]

Re: Kaboom, screeech

I hate to add a different swing here, but what about the front diff? If it is locking up inside the front, when you turn, the different distance traveled could cause this bucking to happen. Just another place to look. good luck

 

['JustDreamin']

Re: Kaboom, screeech

so wait, can we swap the entire rear axle out of a 2k+ truck and get a more stout rear end AND disc brakes?


uh, not to hijack the thread or anything.

Yes. Trick is finding them. The rearend you're looking for is in a 1998+ 4.3l v6 / 5speed / 4wd Blazer or S10. Must be 4WD but not the ZR2 option (its 4" wider, so you could use it if you're current wheels are using 2" spacers). And most salvage yards that have them know what they are & charge accordingly. Disc brake rears with Posi go for the most money.

Also, your choices are either an open diff or the POS Gov-Loc, which means both of your differential choices are LOUSY.

'JustDreamin'

 

[MR_MNZTR_SY]

Re: Kaboom, screeech

ah just another thing to add to the list of mods i wanna do but probably will never get around to. however, if my rear end ever did blow up its nice to know there is an interesting upgrade out there, rather than just swapping diffs.

 

[jayty]

Re: Kaboom, screeech

Yes. Trick is finding them. The rearend you're looking for is in a 1998+ 4.3l v6 / 5speed / 4wd Blazer or S10. Must be 4WD but not the ZR2 option (its 4" wider, so you could use it if you're current wheels are using 2" spacers). And most salvage yards that have them know what they are & charge accordingly. Disc brake rears with Posi go for the most money.

Also, your choices are either an open diff or the POS Gov-Loc, which means both of your differential choices are LOUSY.

'JustDreamin'

Does it have to be a five-speed? My other truck is a 98 4.3 4wd gu6 but its an automatic.

 

['JustDreamin']

Re: Kaboom, screeech

From what I understand, only the 5 speed equipped trucks got the 8.5" 10-bolt. All the auto equipped trucks got the 7.5"

'JustDreamin'

 

[AlaskaTy]

Re: Kaboom, screeech

I got an auburn posi unit put in. I think some anti-slip fluid (whatever it's called) was put in the rear. Apparently I should add some more. I'm in Oregon for the next 2 weeks so I can't test out the truck, but it was bucking just like my truck locked in 4wd did...so it was pretty bad. I guess after I add some more fluid I'll either fix it or rule it out. If it still hops, is it most likely my transfer case?

 

[big gear head]

Re: Kaboom, screeech

This problem is more common with the Auburn. For some reason it takes 2 bottles of the additive to smooth them out. Use the GM or Ford additive, not anything else.