Transmission Slipping

I'm experiencing a weird slip in my autotranny. (2008 Off-Road Dbl Cab, 67k). Several weeks ago, I was sitting in a left turn lane when my truck lurched forward. The jerk was so hard it made a tire squeal and I thought I was hit from behind. (In retrospect I think I was just taking my foot off the brake and starting to accelerate). No-one was behind me so then I thought a passing vehcle clipped me and continued on. I pulled over and checked out my truck and found no damage. So then I was thinking I just must have had a brain fart and for some reason had my truck in neutral and shifted it into D just as I accelerated. But this 'jerk' has happened several times since then so now I know it wasn't me. It even happened as I approached an intersection trying to beat a light that was going to turn red. I came in fast, braked hard, and made a right turn. In the middle of the turn (when I stepped on the gas) the same thing happened. It's like the tranny downshifts but then goes into neutral before going into a lower gear. I called the dealership and the service guy there said he has had this issue before. Has anyone else experienced this?

 

It may be a shift solenoid for first gear or second gear. Easiest thing to do is disconnect negative battery terminal overnight to see if its something that can be reset. Just take it wasy on your truck for a while and don't launch from a stop.

 

I was getting a very strange shudder at the about 38mph going up hills, just before the point where the trunk wanted to downshift. I thought it was carrier bearing or drive shaft related. I took it to Toyota, they ran it through all sorts of tests, even took out the drive shaft and drove it in 4WD (then front-wheel drive), could duplicate the issue.

They didn't know what the problem was, were suspecting the torque converter but weren't convinced that was the issue. They went through the procedure for checking tranny fluid level, I guess found it to be a tad low. They topped it off and it hasn't happened since.

Thought I'd share, sounds like a worth while option to explore the tranny fluid level maybe?

 

A lot of guys are having a lugging issue around that speed in OD. Checking the fluid level on these transmissions is no easy task, but definately worth doing.

 

these trannies are so sensitive to fluid level. if off by a little they will shifty funny.

 

I left out (on purpose) that I just had the dealer flush the tranny about three weeks ago. I would assume it is related to that event. I'm curious what they will say since there was a 30-day warranty on the service. My guess was that they flushed some particles into a valve somewhere. But the fluid level could be off too based on what the previous posts have said. I'm sure their first response will be something that will cost me >$500. And then after I bitch it will probably be, "Oh the fluid was a tad low, no charge".

 

I'm guessing 08's are the same as 09 but did you have the recall/TSB done? It solves the cornering/downshift issue.

 

You have perfectly described what will happen in these, and other, automatic transmissions when the fluid level gets low. Tacoma trucks are very sensitive about fluid level.

Sounds like you had a similar fluid level condition, however the Tacoma also has a history of trouble with one of the solenoids causing a shudder condition at speed.

I would def take it back to dealer and ask them to check the fluid level. Let them know what has happened since the service was done.

 

Here is what the dealer said. The rear drive shaft is building up tension. The tension is released at the moment between deceleration and acceleration. There is nothing that can be done about it because there is no way to lubricate the drive shaft on the Taco. They said this is an occasional issue with Tundras and FJs but never have seen on a Taco. I am going to request they check my tranny fluid level before releasing it back to me if they did not do that already.

 

Quick update, I called about the fluid and they said that was their first thought too and they did check it. I didn't know they had to use a scanner to do this. Sounded like a rather complicated issue since the tranny is sealed.

 

Picked up the truck and talked to a service tech. He said it was a known problem and Toyota has issued service bulletins on it. It comes down to the non-serviceable slip joint they put in the rear driveshaft.

My service rep gave me the number for Toyota USA to file a complaint and basically said that since my power-train warranty expired 7000 miles ago (what are the odds of that?), I will have to ask them to extend it. I had to do this with a spiral cable on a 94 Camry and they came through, just a lot of hoop jumping.

 

A lot of the "bumping" can be reduced or eliminated the same way we did it with the Chevy trucks that had the exact same problem.

Remove driveshaft and clean splines.
Clean splines on output shaft of transmission or transfer case (depending on 2WD or 4WD)
Apply a VERY liberal amount of RTV silicone to the inside of the driveshaft slip yoke, ensuring that it is coating all of the splines for a good 2 inches deep.
Reinstall driveshaft and allow truck to sit for a minimum of 2 hours, preferably 4.
RTV silicone will fill the tiny gaps in the splines between the output shaft and the driveshaft, and will cushion the bump. Sometimes you will totally eliminate the bump, other times it will reduce it to acceptable levels. The good news is that you did nothing that would void your warranty.

 

Another possibility is it's the "axle wrap thump" these trucks get when the leaf springs get loose. Torque the U-bolts to 73 lbs and see if that helps.

 

You can pull apart the driveshaft slip yoke and grease.

Had the same problem with mine and it solved the issue.

Search and you will see a thread I made on the issue.

There is a clamp and a rubber boot you have to take off, not hard. About 30-45 minutes.

It is supposed to be non serviceable but can be so you do not get bent over dry by toyota for a new driveshaft.

 

I like the RTV over lubricating. If you lube it, you eventually have to relube. The RTV is a long term fix. No lubrication ever needed again. Just an opinion mind you. Lubing still works.

 

I saw this described in the 2005+ Toyota Service manual posted online. I am surprised that the dealer didn't do this quick fix just to shut me up. But they seemed to think that this will be covered by Toyota and they will get the warranty work and make some $$ anyways. Right now, I do not want to get into any repair work to void any shot at warranty work. It sounds like they altered the Tundra and FJ to fix this problem so perhaps working on one for the Taco. Thanks for the advice; will keep in mind if this doesn't pan out.

 

Based on your animated GIF, I understand your affinity for silicone

 

I am not sure what manual you are referring to but this is not supposed to be a serviceable part of the driveshaft so a tech will not typically service it. They will state to purchase a new driveshaft.

This has been a problem since 05. Toyota is not fixing this. They do not even have a zerk fitting to add grease. They do not care.

Almost all makers of trucks have a slip joint of some form which will eventually need maintenance or replacement. Some have had the shaft replaced under warranty but this is rare. Most are told this is typical and to live with it. Some have tried replacing rear leafs as well to reduce the effects it places on the shaft as well with less than favorable results.

The driveline angles are off on most if not all Tacoma's that are brand new and have vibes or shudders depending on if people notice them or not. They are not doing anything to solve this either.

There is a front end vibe from an out of tolerance bushing. Toyota looks the other way. Complain enough they will replace it with the same out of spec part, just stupidity.

It is cheaper for them to try and refuse service and to replace parts for those that complain enough rather than redesign, recall or validate a problem via TSB.

 

Sounds like axle wrap or the u bolts aren't torqued to spec. When this happened as you described in the first sentence, had you come up to that light fast and braked hard?

edit... also, i've read of some transmissions needing to get a re-flash because of weird shifts while cornering. Have you had that re-flash done that was part of the gas pedal cutting recall?

 

Service tech says it's, "wrap up" which I assumed is the same thing as axle wrap. I believe the tranny flash was done when the pedal was done.