Slip yoke bump-clunk solutions?

[AKlowriderZ71]

My 2001 LB7 has the famous "bump-clunk" from the rear prop shaft slip yoke when coming to stops and leaving stops. After working in the dealership for all those years, I'm very familiar with this issue. I've always been successful with cleaning up the yoke's splines, and lubing them with a marine-tec moly lube. But not on this truck....

After lubing the splines, it's good to go. But only for about a week or so, then it comes back. It's getting old....

Looking for some insight here from you guys. I searched here, seems to get brought up once in a while, discussed, but never resolved. Who has found something that works, AND LASTS??

Thanks in advance guys!

 

[beanpole209]

A new yolk!?

 

[MACKIN]

Years ago most slip joints in this case the yoke had a zerk fitting to grease properly. IMO it really cannot be greased properly or enough. Is there any way to drill and tap a grease fitting in? I never really looked.

 

[AKlowriderZ71]

Bump!

I guess I could spring for a new nickle plated yoke, but I read old threads on here that the bump/clunk came back after a couple weeks. Looking for ideas...

 

[Dirtymaxx03]

my truck does it and it drives me nuts. i havent greased mine at all yet.....do you just pull the yoke out of the tranny and lather grease on it and slide it back in?

 

[MACKIN]

Pretty much.

 

[Dirtymaxx03]

is trans fluid gonna spew everywhere?

 

[beanpole209]

Not trying to sound cocky, but how do yall think the grease replaces lost material? The grease helps, but you'll be greasing it every couple of weeks from now on.

Mine feels like a public transit bus too BTW :banging:

 

[AKlowriderZ71]

Lost material from what? Are you saying that the splines are worn out?

On my truck, I know they are not worn out, I've looked at them several times. What's happening is the splines of the yoke are sticking to the splines of the t-case output shaft. So when it needs to plunge in or out of the back of the t-case when leaving stops, it sticks, then slips. That causes the annoying bump/clunk when you just start to pull away from stops (or just come to stops).

So, nobody has found a super-fantastic slip yoke lube? Everybody just puts up the the clunk?

 

[beanpole209]

Ill say, i'm no expert on the situation. I was under the impression gm slip yolk's have a nickle plating, or some coating that prevents it from binding/sticking. And that, combined with grease does the trick.

Maybe you could clean up the edges of the teeth

I'm not sure what grease officially to use, but I think the marine grease is probably good!

Anyway, that is my 2c

 

[formyla]

i would think a high pressure grease with molly.

 

[jlawles2]

If its in the back of the t-case, check the fluid level. I would hope that there is enough oil in the case to lube the yolk.

Other than that I would look for a good heavy NL-G3 grease and try putting extra in the bottom of the yolk before putting it back into the t-case. that way it keeps feeding itself over time.

You may want to check to see what lube is in the case as it could be dissolving the grease you are using.

 

[AKlowriderZ71]

I'll look up that NL-G3 grease and give it a shot. Any other ideas guys?

 

[AKlowriderZ71]

Just to follow up on this, I pulled the rear shaft & cleaned the splines again, then used a Valvoline synthetic grease on them. It's been okay for the last 2 weeks now, no bump-clunk at all. Yet.

I'll update this thread again later if it stays fixed. The grease I was using previously would only last about a week or so.

 

[jc1843]

It is important to clean all the old sticky GM grease from the splines, before you lube it. Mine had the "Bump and Run", and after I serviced it, it has been great.

 

[workin' diesel]

I had this a few years ago too. Told the mechanic to lube it and I'll replace it later. When I do the t-case fluid change I do 3qts 5w30 synthetic as opposed to the 2qts ATF. Maybe that makes a difference??? Only a thought, maybe there is nothing to it.

 

[adeso]

had this issue for a while, lubed it and still had it so I replaced the carrier bearing, and for a while it was really bad then just went away after some time

 

[AKlowriderZ71]

I had this a few years ago too. Told the mechanic to lube it and I'll replace it later. When I do the t-case fluid change I do 3qts 5w30 synthetic as opposed to the 2qts ATF. Maybe that makes a difference??? Only a thought, maybe there is nothing to it.

How do you get it full past the filler plug? Are you filling it through the vent? That would be a PITA...

had this issue for a while, lubed it and still had it so I replaced the carrier bearing, and for a while it was really bad then just went away after some time

My truck has a one piece rear shaft, no carrier bearing. The slip yoke splines are on the t-case output shaft.

 

[Harbin_22]

How do you get it full past the filler plug? Are you filling it through the vent? That would be a PITA...

Take the speed sensor out and use that hole.

 

[workin' diesel]

What he said^. Have to use a hand pump though.