Transmission Question
 

Hello, I am a newbee hre and have liked the information I have seen on this forum! I have a 2005 Silverado 2500HD that has developed a problem I am attempting to figure out. Here's what is going on:

When I come to a complete stop and then accelerate the truck bumps into gear, it feels like it down shifts from 2nd to 1st then takes off. Now, if I come to a stop and barely roll forward just a bit ( idle speed) then stop, then accel it does not bump,jerk. Any suggestions where to start. I think I am going to do a trans fluid/filter change this week to start with.

Thanks!
Don

RE: Transmission Question
 

I've not noticed that with mine, but I have read posts about that on other boards... Which tranny do you have?

RE: Transmission Question
 

something about some kind of yolk lube something? i dont remember, but my dads 05 avalanche and my truck both do it and it hasn't caused any problems yet

RE: Transmission Question
 

Yes..its probably a slip-stick condition on the slip yoke..if its 2wd,remove the driveshaft and insert some waterproof grease in the yoke

RE: Transmission Question
 

What if its four wheel drive?

RE: Transmission Question
 

If it is the "clunk", you guys are right... If it is actually staying in 2nd, and downshifting at takeoff.....I hope the fluid/filter fixes it. Reading I've done elsewhere coulddraw the conclusionthat the tranny's getting ready to take a dump.

Hey Hunt, on a 4wd it's between the tranny and TC[:'(]. GM can fix it with a plated prop shaft....Argon could elaborate I'm sure. I had the service dept throw some extra grease in mine while they were replacing the tranny:eek:.

RE: Transmission Question
 

its not in 2nd..its just that the slip yoke "stuck"..then clunks as it relaxes...
a 4wd...gm has a new,blue transfer case fluid to use for a fix

RE: Transmission Question
 

Would the blue stuff work on the diff of my 99' or is it only for newer rearends? Right now they say to use full synthetic. I bet the blue stuff is expensive as hell.

RE: Transmission Question
 

Okay I went by the local trans shop last night and had the owner chek it out and this is what he showed me. With a helper in the truck holding brakes he applied power and the drive shaft actually spun around alomost a full revolution before it stopped due to the brakes being applied. He said that the rear diff needs to be rebuilt or replaced. Witht he drive shaft doing this under load does this sound right? Sounds right to me but I wanted to check with you guys first.
Thanks

RE: Transmission Question
 

thje blue stuff is for a transfer case..not a rear end

RE: Transmission Question
 

Oh my bad, wrong end of the shaft. Ok well would that work in the tranfer case to resolve the yoke issue? My truck only "clunks" when putting it into reverse. Otherwise it is silent.

RE: Transmission Question
 

Just for the heck of it (even though the trans shop said it wasn't the problem) I followed your advise and had them take the drive shaft off and lube the slip yoke. Guess what! No more clunk! The new diff 2600.00, the look of the tech when a few shots of grease solved the problem (priceless). Thank to everyone who helped me save 2600.00!

RE: Transmission Question
 

way to go!

spread the word on that shop in your area as a rip-off shack

RE: Transmission Question
 

This is purely an expression of my curiosity.

Just because the "clunk" is gone doesn't mean there isn't an underlying problem, right? If the drive shaft spins half a turn before the rear end engages the sudden load on the suspension could be slamming the drive shaft into the tranny and lubing the yoke is like putting a pillow over your mouth before someone cracks your skull with a hammer,the problem is still there but no one hears you scream. Am I way off base?

RE: Transmission Question
 

I thought about that and under normal load or with the truck off I cannot move the drive shaft any at all, no play whatsoever. The drive shaft was turning 1/2 turn with the brakes locked and the 360c.i. almost floored, I mean really laying the torque to the rear end. I don't know if the diff has clutches in it or not but I think if they do thats where the 1/2 turn was coming from. You could be right though, I am just going to monitor this thing and hope for the best and not the 2600!