jlenkows

So I thought in preperation for the 70 degree weather in December in mid-New York, I should give the transfer case in my Tahoe a workout. Nothing major - just throwing it in Neutral and putting it in 4H then 4L and back. Well.... when I turned the **** to 4L, there was a loud bang from the transfer case. I couldn't believe my ears!!!

I moved it back to 4H and there was the bang again.

Not only do you hear it, but you sure feel it too!!

Is this normal? I have owned many a 4x4 and NEVER have I had this happen.

I already called the dealer to get it in for them to look at. I'm kind of thinking that the fluid is low (or missing). Even the service manager didn't think it should do that.

Anyone else have this 'problem'???

jasonw75

Mine clunks a little, I just assumed it was normal. I'm going in for service today, I'll have them check on it.

Jason

tj

I think it is recommeded to be moving 1-3 mph with tranny in N when you engage 4L. Try this and see if the noise is reduced.

jlenkows

The rule that I was taught is never to free-roll. It's also a bit odd to have to do that if you're stuck in the snow or mud for which reason you're putting it into 4L.

dhoughton

As many of you may know, the Southern part of the US got a major snow storm. As a result, we got 8 to 10 inches here in central Oklahoma and with the high winds, lots of large snow drifts. Perfect weather to try out the new LTZ!! For what it is worth, I read my manual a second and third time, then out in the snow with my Tahoe sleigh for some winter fun. I had NO clanks, clunks or noises at all shifting into 4WD Auto, 4H or 4L, or in and out of those gears to others in various combinations. It worked beautifully.

I can confirm having just read the manual again that yes, only put it into 4L from stop or less than 3 mph. I thought it performed beautifully and had lots of fun. Hope this helps.

73shark

Also must be in neutral to shift to 4 Low.

jlenkows

My Tahoe went to the Dr. today.... Many issues were addressed including the loud clunk.

According to TAN, the loud clunk is normal. They referrenced bulleting number 1860971 and PIP3408B. The jist of these documents said that the 4H and 4L will make that loud earth-moving clunk because the gears are not synchronized. The document also suggests to switch between these gears with the engine off.

DFQ - with the engine off, doesn't that defeat the whole idea of simplifed electronic shifting??? I understand the neutral part. Even the roll a bit in neutral... but killing the engine????

I say nay-nay.

ZX1100F1

The TSB you mentioned is only referring to shifting into and out of 4LO, and it basically states that; the clunk noise is normal and will not harm anything however, if you don't want to hear the noise or are worried that you might damage your truck then turn the engine off before shifting into or from 4LO, once the shift is accomplished restart the engine and go.

Remember; 4LO is to be used Off-Road only.

jlenkows

It's just very odd that no other 4x4 that I have owned has done that. My Avalanche was a Chevy and it never happened. Neither on any Ford or Isuzu.

I guess there is no pre-engagement synchronization happening.

brian thomas

I have owned 7 Tahoes and 3 Trailblazers, they all made a significant clank into or out of 4 low.