Transmission Clunk Felt Rolling from a Stop

[Garlic Cruton]

I might have a little insight to offer up to this discussion :wave:

I have a 99' 4runner and have the same issue as you guys are describing. It usually happens after I come to a stop and then I get a solid "bump" coming from the transmission area. It seems to come and go and a few times I've been sitting at a light and it's been a strong enough bump that I thought for sure the person behind me had bumped into me, but generally it's a soft bump every now and then.

I checked the driveline, rear brakes, etc... but never fixed the problem. About a year ago I mentioned it to a good friend of mine that has been a Toyota tech for over 25 years and he said "oh yeah that's the torque converter unlocking after you've come to a stop, it's a very common issue that Toyota has never felt needed addressing." He also mentioned it's relatively harmless and he has never seen a transmission failure that he could directly attribute to the torque converter "bump" issue.

I've had my 3rd gen for over 5 years now and with 295,000 it's running as strong as ever, I've towed a lot with it since I've had it and never an issue.

After keeping up with all the maintenance over the years and never having any issues, I've pretty much made up my mind it is in fact the torque converter unlocking late for whatever reason and I quit worrying about it long ago.

Just some food for thought...

 

[allwheeldrive]

I've been with Toyota for over 15 years now, and have never heard of a torque converter being locked all the way to a stop. That's nearly impossible without some other issues. The torque converter unlocks with a brake switch input or reads it off the tps. Simple as that. And it only locks in 4th gear on the 4Runner.

As for the bump, it's most likely the slip joint in the main driveshaft. You can pump it full of grease through the fittings all you want, but probably won't solve anything. You need to separate it and use a good grease. There was a ford grease, if I remember correctly, was smurf blue that worked pretty well. Coat, reassemble and then lube as needed.

What's happening is the slip joint is binding when coming to a stop because the splines are dry. When it unsticks, that's the thud or bump you feel. Feels like you get rear ended sometimes if it's bad enough.

 

[mtbtim]

I've been with Toyota for over 15 years now, and have never heard of a torque converter being locked all the way to a stop. That's nearly impossible without some other issues. The torque converter unlocks with a brake switch input or reads it off the tps. Simple as that. And it only locks in 4th gear on the 4Runner.

As for the bump, it's most likely the slip joint in the main driveshaft. You can pump it full of grease through the fittings all you want, but probably won't solve anything. You need to separate it and use a good grease. There was a ford grease, if I remember correctly, was smurf blue that worked pretty well. Coat, reassemble and then lube as needed.

What's happening is the slip joint is binding when coming to a stop because the splines are dry. When it unsticks, that's the thud or bump you feel. Feels like you get rear ended sometimes if it's bad enough.

I did exactly what you suggested and took the slip joint off the rear driveshaft but I used a multi-purpose moly grease. I then pumped the zerk fitting until I saw a slight movement in the driveshaft. I drove it a few laps around my neighborhood and no bump at a stop. The next day, thinking I might have overloaded the slip yoke with grease and possibly causing excess pressure against the transfer case, I pulled the zerk fitting, jumped up and down on the rear bumper escaping some of the grease and put the zerk fitting back. Now, the bump is back.

My first suspicion was this bump was originating from the transmission. The torque converter comment seems legit if it is indeed coming from a tech with 25 years of experience. How could a tech with that much experience be that uninformed. But you're a tech with a lot of experience too and you're saying otherwise.

Anyway, I appreciate your comments on this thread. If you have a suggestion for a better grease for the slip yoke, I'm all ears.

 

[mtbtim]

I might have a little insight to offer up to this discussion :wave:

I have a 99' 4runner and have the same issue as you guys are describing. It usually happens after I come to a stop and then I get a solid "bump" coming from the transmission area. It seems to come and go and a few times I've been sitting at a light and it's been a strong enough bump that I thought for sure the person behind me had bumped into me, but generally it's a soft bump every now and then.

I checked the driveline, rear brakes, etc... but never fixed the problem. About a year ago I mentioned it to a good friend of mine that has been a Toyota tech for over 25 years and he said "oh yeah that's the torque converter unlocking after you've come to a stop, it's a very common issue that Toyota has never felt needed addressing." He also mentioned it's relatively harmless and he has never seen a transmission failure that he could directly attribute to the torque converter "bump" issue.

I've had my 3rd gen for over 5 years now and with 295,000 it's running as strong as ever, I've towed a lot with it since I've had it and never an issue.

After keeping up with all the maintenance over the years and never having any issues, I've pretty much made up my mind it is in fact the torque converter unlocking late for whatever reason and I quit worrying about it long ago.

Just some food for thought...

Thanks for sharing your comment. I thought you just gave me the answer I've been looking for for the past 2 years but now I'm confused because the next comment on this thread coming from another experienced Toyota mechanic is saying otherwise.

Any other Toyota certified mechanics on this forum want to comment on this theory of it being a torque converter issue?

 

[LittleCaesar]

Not a mechanic but agree that it is a TC issue. Mine is on its last leg (have found TC shaving in my remote spin on ATF filter) and when I change it out later this year I will see if the bump comes back.

What has helped my A340F is the addition of Lubegard black in addition of clean ATF. It isn't a silver bullet by any means though so YMMV.

 

[4Runner4TW]

So many possibilities. I'm glad the OP is determined to figure this out. I gave up on mine a while ago but now my curiosity is back...

 

[Bstrom]

Gotta agree with fresh brakes this shouldn't happen - and apparently it doesn't.

Huh, didn't think it was TC cuz the feeling seem to come from the rear end. Maybe it's just manifesting itself there, even though the action is actuated elsewhere - from play in the driveshaft or rear end gear assemblies?

Maybe it's normal and 'built in' to avoid excess tightness and wear with no play. What does a brandy new 4Runner with super low miles feel like, anyway?

 

[mtbtim]

Not a mechanic but agree that it is a TC issue. Mine is on its last leg (have found TC shaving in my remote spin on ATF filter) and when I change it out later this year I will see if the bump comes back.

What has helped my A340F is the addition of Lubegard black in addition of clean ATF. It isn't a silver bullet by any means though so YMMV.

Thanks for the response. I'm going to drop my transmission pan to see how things look. I don't think it's ever come off and I'm wondering if I'm going to see a large accumulation of shavings down there.

Instead of doing the more involved full flush of the ATF, I just change my fluid every 10,000 miles draining around 5 quarts out on each occasion. I figure over a 30,000 miles period, I've effectively renewed the ATF.

 

[allwheeldrive]

Guys, there is literally nothing in a torque converter that is going to eat itself apart where you'd get metal shavings in the pan. The stator is the only component inside the torque converter that moves independently of the other components. And that's on a one way clutch. There's a bushing where it goes into the tranny, but if that were bad, you'd have a pretty steady leak.

So many other things can make metal shavings, like bushings, bearings, planetary gears, clutches, etc.

I'm not trying to rain on anyone's parade, just trying to help you guys and show you that you are thinking waaaaay too much into it. Think about the slip yoke, the geometry involved between the driveline and the body when accelerating and decelerating. I posted in another thread, Ford xg-8 grease. Give it a shot.

 

[mtbtim]

Guys, there is literally nothing in a torque converter that is going to eat itself apart where you'd get metal shavings in the pan. The stator is the only component inside the torque converter that moves independently of the other components. And that's on a one way clutch. There's a bushing where it goes into the tranny, but if that were bad, you'd have a pretty steady leak.

So many other things can make metal shavings, like bushings, bearings, planetary gears, clutches, etc.

I'm not trying to rain on anyone's parade, just trying to help you guys and show you that you are thinking waaaaay too much into it. Think about the slip yoke, the geometry involved between the driveline and the body when accelerating and decelerating. I posted in another thread, Ford xg-8 grease. Give it a shot.

Thanks for the information. I'm going to get some of that grease, pull the slip yoke again and try it out.

 

[jrruiz211]

Do you have to buy the grease at a dealership?

 

[mtbtim]

Do you have to buy the grease at a dealership?

Found it on Amazon:Amazon.com: Genuine Ford Fluid XG-8 PTFE Lubricant - 3 oz.: Automotive

 

[808islerunner]

Far stretch here but could it be the axle is winding up, possibly cause of worn suspension components? I always recommend LubeGuard trans additive, either in the red or black bottle, black bottle mainly for imports this is great stuff. As far as the TC, I strongly disagree it's the cause of the clunk. Nothing shifting in the cargo area or the spare tire moving around causing the clunk?

 

[mtbtim]

Far stretch here but could it be the axle is winding up, possibly cause of worn suspension components? I always recommend LubeGuard trans additive, either in the red or black bottle, black bottle mainly for imports this is great stuff. As far as the TC, I strongly disagree it's the cause of the clunk. Nothing shifting in the cargo area or the spare tire moving around causing the clunk?

Pretty sure in my case it's not a suspension issue. Installed new shocks not to long ago and the springs are still in good shape. Definitely nothing shifting in the cargo area could be causing that significant of a bump feeling. Like others have reported, it sometimes feels like somebody tapped you from behind with their bumper.

Thanks for the LubeGard trans additive suggestion. I looked it up on Amazon and it gets great reviews. I think I'll let my Subaru Outback with 320,000 miles on it be the test dummy for this product. I do get a hard shift from 2nd to 3rd gear so I'm curious if this product will smooth out the shift.

 

[mtbtim]

Thanks to [MENTION=75799]allwheeldrive[/MENTION] suggestion, I got some Ford XG-8 grease, pulled the slip yoke again, cleaned it up really good and re-greased it.

I did a test drive and so far so good. No bump feeling coming from the rear end.

I'll report back after I get some more miles on it to see how this repair is holding up. I'm really hoping this is the definitive solution for this problem. Many Ford owners who used this grease had good results with eliminating their driveshaft clunk so I'm hoping it will work for us Toyota truck owners as well.

Here's a link to a YouTube video showing the job:
https://www.youtube.com/watch?v=Jyltxe2nPEg

 

[giovannie23]

I had the clunk but I changed my front brake pads and rotors and added a cooler and front coils shocks and rear and my back was really shot idk which one it was but it's been about 3 months and I haven't had a clunk even when I would be at a quick stop and know alright it's gonna clunk but no I been surprised
Even tho now I probably jinxed myself ray:

 

[mtbtim]

Thanks to [MENTION=75799]allwheeldrive[/MENTION] suggestion, I got some Ford XG-8 grease, pulled the slip yoke again, cleaned it up really good and re-greased it.

I did a test drive and so far so good. No bump feeling coming from the rear end.

I'll report back after I get some more miles on it to see how this repair is holding up. I'm really hoping this is the definitive solution for this problem. Many Ford owners who used this grease had good results with eliminating their driveshaft clunk so I'm hoping it will work for us Toyota truck owners as well.

Here's a link to a YouTube video showing the job:
https://www.youtube.com/watch?v=Jyltxe2nPEg

I've driven around 700 miles since this repair. No bump experienced coming to a stop or rolling from a stop. Looks like this might be the definitive repair for people experiencing this in their 4runner, Tacoma or Tundra. When you actually take the slip yoke off and look down into the shaft, you can start to understand that a few pumps of grease every now and then is not going to properly lubricate the splines. Like I said in my video, I think the only people getting enough grease into the upper part of the splines are people pumping enough grease into the zerk fitting to start causing the driveshaft to move. But, packing that much grease in there could cause a harsher ride because it's not allowing the sleeve yoke as much travel when the suspension compresses.

If you've been experiencing that bump feeling, sometimes strong enough to make you think somebody rear-ended you, try out the service I document on the videos I've provided links to. I had that annoying bump since I bought my truck 2 years ago and it's been nice to be without it.

 

[floatingkiwi]

I just took my spline right out and found 2 things. I have been having the clunk for a while on and off, vehicle has 220000km and well looked after.

1) one of my unis was stiff and only loose in a few degrees around the center of movement. This was knocked around and freed up. Still perfect condition but must have had a bump somehow.

2) secondly, I saw that the metal housing of the outside of the spline (that slides in and out of the felt seal) was very very rough like it had been machined badly. I can't see this alowing the unit to slide in and out very easily, so I cleaned the whole thing up and emery papered it down smooth.

Greased the whole thing back up, installed without the zerk to allow air to escape, then pumped full of MP grease with small amount of Moly and it seems to be much better. There is a big sideways downish type of hump/curve that I go over every day and I always felt that my back end was shoving me around over it. That feeling has now gone.

I think there is no doubt that it is the spline or something to do with that that is causing the majority of people this problem.

 

[mtbtim]

I just took my spline right out and found 2 things. I have been having the clunk for a while on and off, vehicle has 220000km and well looked after.

1) one of my unis was stiff and only loose in a few degrees around the center of movement. This was knocked around and freed up. Still perfect condition but must have had a bump somehow.

2) secondly, I saw that the metal housing of the outside of the spline (that slides in and out of the felt seal) was very very rough like it had been machined badly. I can't see this alowing the unit to slide in and out very easily, so I cleaned the whole thing up and emery papered it down smooth.

Greased the whole thing back up, installed without the zerk to allow air to escape, then pumped full of MP grease with small amount of Moly and it seems to be much better. There is a big sideways downish type of hump/curve that I go over every day and I always felt that my back end was shoving me around over it. That feeling has now gone.

I think there is no doubt that it is the spline or something to do with that that is causing the majority of people this problem.

If you find your symptoms come back, give the Ford XG-8 grease a try. Using that grease definitely made a difference with my sleeve yoke binding problem. I tried a multi-purpose moly grease the first time and it didn't work for me. The problem came back within a day.

I just think the zerk fitting for the sleeve yoke doesn't get grease thoroughly into all areas of the splines for proper lubrication. A did a close inspection of my splines and I could see wear like a coating has come off in spots. Don't know what that coating is but you can tell something has worn off because there's different shades of silver on the splines.

This is a fairly common problem and I think the teflon based Ford XG-8 grease just might be the ticket to fix the sleeve yoke binding problem, as long as you do like I did in the video and clean it up really good first and then use the Ford grease for reassembly.

I'm now around 800 miles post maintenance and I haven't had a rear-end bump or clunk since.

I had myself convinced it was just the transmission shifting down into 1st gear and gave up trying to figure this problem out. I'm glad I got off my butt and finally found a solution. I love not having the rear-end bump anymore.

 

[mtbtim]

Reporting back with some results after driving my rig over 10,000 miles since I pulled the rear slip yoke off and greased it with the Ford XG-8 grease.

Here's some comments and thoughts I have regarding this repair:

#1 - For me, the Ford XG-8 grease makes a big difference on how well this technique of removing the slip yoke, greasing it really well, and reinstalling it. The multi-purpose moly grease didn't fix the problem while the Ford XG-8 grease did.

#2 - Greasing the zerk fitting for the slip yoke does a very poor job of lubricating the upper splines. All the grease is in the bottom of the slip yoke and does nothing to properly lubricate the upper splines.

#3 - Because greasing via the zerk fitting does a poor job at best to lubricate the splines, you'll have to pull the slip yoke off again at some point because it will start binding when the lubrication wears out. I think an interval of every 10,000 miles is about right but definitely grease it earlier if your symptoms return before that interval. I started feeling the bump symptom again right around the 10,000 mile mark.

Finally, I forgot to post the videos I did for the repair on this thread, so here they are. I suggest you watch both videos.

<iframe width="560" height="315" src="https://www.youtube.com/embed/oKX5UeE2Txs" frameborder="0" allowfullscreen></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/Jyltxe2nPEg" frameborder="0" allowfullscreen></iframe>