Gear Fluids

[Richard D.]

Thought I'd post this question here, as you folks are some of the most knowledgeable on this kind of stuff that I know.

I'm doing some maintenance on my '00 Tahoe (want to use it as a tow vehicle for my 68).

Have a slight clunking sound (driveline lash) that's annoyed me for years.

Got some Redline "ShockProof" Heavy Duty dif fluid, and changed out the rear fluid, but found out that the noise is actually coming from the transfer case (seems to be excessive lash in it), all other parts of the driveline (u-joints, etc.) seemed tight and OK.

The transfer case calls for GM Trac II fluid (blue colored) only. Can I use the Redline shockproof (either lightweight, medium weight, or heavy) in place of the Trac II fluid? The Redline helps compensate for excessive lash is why I ask.

Next, do you think that this Redline shockproof would be good for the 68 (rear and trans)?

Thought I'd check with you folks and see if anyone had any direct experience with these fluids, and what your experience was, before I went any further.

Thanks,

Rich

[John H.]

Re: Gear Fluids

I'd stick with the GM-recommended lubricants, especially in the transfer case.

[John H.]

Re: Gear Fluids

I'd stick with the GM-recommended lubricants, especially in the transfer case.

[Rich Puleo]

Re: Gear Fluids

I'd like to stick my 2 cents in there.
First, do not substitute anything for versatrack or autotrack fluid. If it calls for transfer case fluid, that is dex III. Do not sub with dex 6. It's very easy to mix up the applications.
I worked as a tech for GMC & Chevy, there's a common problem with the transfer cases that might be causing your clunk. There is a bulletin fingering a retaining clip as the source of an oil leak. What happens is the clip wears out & allows the clutch pack to slop around in the case, eventually wearing a hole through the case & causing the leak. This clip will also cause an annoying clunk noise intermitant from the slop. Get under your truck, in park, engine doesn't have to be running. Grab the front driveshaft at the transfer case & twist it back & forth quickly. If you hear a similar noise, that's the problem. Hopefully you're under warranty. That $2 clip was redesigned to hold better, but the transfer case needs to come out & apart, like a rebuild.
Rich

[Rich Puleo]

Re: Gear Fluids

I'd like to stick my 2 cents in there.
First, do not substitute anything for versatrack or autotrack fluid. If it calls for transfer case fluid, that is dex III. Do not sub with dex 6. It's very easy to mix up the applications.
I worked as a tech for GMC & Chevy, there's a common problem with the transfer cases that might be causing your clunk. There is a bulletin fingering a retaining clip as the source of an oil leak. What happens is the clip wears out & allows the clutch pack to slop around in the case, eventually wearing a hole through the case & causing the leak. This clip will also cause an annoying clunk noise intermitant from the slop. Get under your truck, in park, engine doesn't have to be running. Grab the front driveshaft at the transfer case & twist it back & forth quickly. If you hear a similar noise, that's the problem. Hopefully you're under warranty. That $2 clip was redesigned to hold better, but the transfer case needs to come out & apart, like a rebuild.
Rich

[Richard D.]

Re: Gear Fluids

Thanks a lot Rich.

I did have the truck on a lift last weekend, and did just as you said, and made the case clunk by twisting the shaft back and forth (rotating it), thereby figuring it was the TC.

It was not leaking though, but now that appears to just be a matter of time.

I did do a fluid change on it though last year, with the GM Trac II fluid purchased from the dealer.

Sadly, the truck is out of warranty.

Just curious, as an ex-GM Tech, would you have any idea what a rebuild would cost?

Again, thanks for you advise.

Rich

[Richard D.]

Re: Gear Fluids

Thanks a lot Rich.

I did have the truck on a lift last weekend, and did just as you said, and made the case clunk by twisting the shaft back and forth (rotating it), thereby figuring it was the TC.

It was not leaking though, but now that appears to just be a matter of time.

I did do a fluid change on it though last year, with the GM Trac II fluid purchased from the dealer.

Sadly, the truck is out of warranty.

Just curious, as an ex-GM Tech, would you have any idea what a rebuild would cost?

Again, thanks for you advise.

Rich

[Rich Puleo]

Re: Gear Fluids

Well, some places get as much as a transmission. There's really just the one set of clutches, a few bearings, It's kind of like a bit of a manual tranny & a bit of an auto tranny together. If it were my own, it's a tough call. I'd probably just pull it, split the case, & change the clip (& the gaskets & fluid) that would probably be 4 to 6 hours of labor, minimal parts cost. To do an exchange unit would be about the same labor hours, but 1 or 2 grand for the unit. It depends on the milege you've got now, what condition the truck is in. If it's a nice truck & you want to invest, look into an exchange unit near you & sucker in a buddy or two with the old beer & pizza trick, especially if you have the lift. (I'm in NY, give me directions!) I could get the how to from GM Dealerworld if you need it, whether to replace the clip or the whole unit.
Good luck
Rich

[Rich Puleo]

Re: Gear Fluids

Well, some places get as much as a transmission. There's really just the one set of clutches, a few bearings, It's kind of like a bit of a manual tranny & a bit of an auto tranny together. If it were my own, it's a tough call. I'd probably just pull it, split the case, & change the clip (& the gaskets & fluid) that would probably be 4 to 6 hours of labor, minimal parts cost. To do an exchange unit would be about the same labor hours, but 1 or 2 grand for the unit. It depends on the milege you've got now, what condition the truck is in. If it's a nice truck & you want to invest, look into an exchange unit near you & sucker in a buddy or two with the old beer & pizza trick, especially if you have the lift. (I'm in NY, give me directions!) I could get the how to from GM Dealerworld if you need it, whether to replace the clip or the whole unit.
Good luck
Rich