Transmission fluid change out question

Also, just for clarity, the trans shifts perfectly. No hard shifts. It's just the shudder between 30-45 or so mph. Accelerating or decelerating through the shudder doesn't seem to change it and it's slightly more pronounced going uphill with weight load.

 

In some posts over the years , I havnt explained the brake tap test very well . My bad
It is imperative that you follow the steps properly when performing a brake tap test .

When you feel the truck begin to shudder keep your right foot " steady " on the gas pedal , then using your left foot , Gently but quickly tap the brake pedal only once . If the shuddering goes away for 5 seconds and immediately comes back , You have a converter shudder

At 247K , I can pretty much promise you that the reagents in your fluid are depleted . The friction modifiers in your old fluid are no longer working as they should . Dropping the pan and adding 4 or 5 quarts is going to be a good start

 

I did the brake tap test multiple times exactly like you just described. I did it at temp, going up hill, downhill, in overdrive, in 4th and in neutral as well.

None of that changed the shudder.

Part of my shudder elimination plan is front bearings, u-joints, carrier bearing and drive shaft rebalancing.

I'm retired and speed is not an issue.

So I'm attempting to eliminate possibilities as I go so I can share what I learn in here.

Bearings and drive line are after trans service.

 

Here's something I have learned. Times I've had to disconnect the battery for any length of time to perform maintenance and a better stereo install, the shudder got worse for about 10-20 miles.

Is that weird?

 

Not weird . Your transmission has adaptive learning . Its a super smart computer that compensates for transmission wear . When you disconnect the battery , the computers short term memory is cleared . Any fine adjustments to the way your transmission shifts take some time to be re-learned and re-adjusted to the way you like the transmission to shift .

I am glad you brought up universal joints and the rest of your drive line . That answers a lot of my questions
I created a vibration elimination thread that you can use as a tool to refine your shudder .
https://www.tacomaworld.com/threads/vibration-diagnostics-for-all-tacomas-write-up.520607/
I would still add Lubeguard Platinum to the transmission mind you . If the transmission does have a slight shudder , for best results all your fluid will have to be replaced before the shuddering goes away . Chances are 5 quarts may not be enough new friction modifiers

 

I read that thread twice

I'm gonna start with the trans. I'm gonna use the Platinum you recommend.

Gonna add 1 oz for every quart drained during each drain and fill. 4 total drain and fills, 100 miles between each.

Gonna drop the pan and install new filter on first drain and fill.

That's the current plan before moving on to bearings and drive line.

Give me about a month to get that done with my current driving habits and I'll post here how it went.

Sound like a good plan?

 

Sounds like an excellent plan .
My goal in your post was to get you to make sure the pan is dropped and cleaned .
Too many members here are simply draining the fluid and adding 5 fresh quarts without removing the pan or simply flushing the fluid without dropping the pan .
Thats when the trouble starts .

Even though the transmission shifts good ,once the pan is removed and you assess the contamination level , you have a darn good idea of the wear factor inside the transmission . You will create a base line for changing out the rest of the fluid .

 

I am still committed to this plan.

However, I read a thread yesterday, here in TW, about octane possibly causing this shudder. I spent the last half hour trying to find it but no luck.

I drove a bit and got my gauge a hair below 1/4 full and filled up with 93 octane at a good station.

The shudder is almost completely gone. And that's after only a few minutes of driving after fill up.

Gonna take it out in a while for a longer drive and see what it does.

I'm stunned.

 

Just took it for a long drive and the shudder is barely noticeable.

I'm almost convinced what I'm feeling now is slightly different and more drive line related. But it's barely there compared to before the Octane increase.

Any thoughts?

 

Everybody that has shudders calls it a converter shudder but is it really a converter shudder ?
Toyota,s idea to save fuel gets you shifted up to the highest gear possible then they lock the engine directly to the transmission with the locking converter .
A shudder occurs when the clutch inside the converter is commanded on . When the computer in your truck commands the torque converter clutch to apply , a shudder will occur for a split second as the converter clutch mates up against the converter dampener .
If you are experiencing a constant surging or a light bucking feeling after the converter is locked , the issue is no longer considered a converter shudder . The converter was commanded on by the computer in your truck and the clutch inside the converter did its job properly . The converter clutch did not slip as the clutch disc mated with the dampener .

Most members feel surging after the converter is fully locked and this is where things get interesting and you begin to feel it in the drivers seat .
There are hundreds of reasons for surging with these trucks and these tiny issues that cause surging can be incredibly difficult to diagnose . The engine is breaking in , the engine has a very very slight slight misfire , type of fuel , improper balancing of the driveline , a rear tire out of balance by .05 of a gram . a slight warp on the rear brake drums are only a few
When the converter locks directly to the engine, all these tiny issues get amplified X 100 when your sitting in the drivers seat.
Is surging a normal characteristic of the truck as the dealerships state ? it certainly shouldn't be .

 

Well in this case, atleast mostly, the higher octane seems to have eliminated about 80% of the shudder.

I'm now wondering if the trans fluid drain and fill may eliminate the remaining shudder. If not, I still have new front bearings, u-joints, the carrier bearing and rebalancing the drive shaft after that.

 

Also, new plugs going in on Thursday. Not sure if that will help. I don't feel any misfiring that may be plug related.

First trans drain and fill, with pan drop of course, will be Friday or this weekend. Changed my mind and ordered a FelPro gasket instead of another mfg after some reading in here. Waiting for it to get here.

 

If Toyota gets you shifted to the highest gear to save fuel, is there an easy way to change those shifts to what would be the more appropriate points?

 

Im still leaning toward this being a driveline issue. Worn components can cause issues at certain speeds or loads, but not others. Just a few weeks ago I loaned my spare driveshaft out to a buddy to troubleshoot a vibe he had near highway speeds. Instantly fixed. It was a worn carrier bearing. We are going to rebuild his with new u-joints and CB at some point and it will be good to go.

 

I agree.... partially.

In my case, so far, a higher octane just eliminated about 80% of my shudder.

And now I feel something more like a vibration.

So did the higher octane completely eliminate the shudder leaving a secondary issue exposed?

That's what I'm thinking.

My next step will be transmission fluid drain and fill with a pan drop to change filter and clean out the crap in the bottom of the pan.

We'll see what's left after that.

I'm currently assembling a drive line parts kit. New front bearings(not drive line, but applicable to vibs), u-joints and a carrier bearing.

I'm gonna have those installed at a local shop that can also rebalance the driveshaft.

 

When I bought this truck last month, the shudder was moderate, but enough that I was hesitant to aggressively accelerate through it because I felt whatever was the cause could be worsened. So I just kept a moderate acceleration until I could learn more about what it could be.

I've posted about the higher octane effect on the shudder.

Today, I dropped the tire pressure to the 29psi on the door jam. About a 4-5 psi drop.

Went driving around and the shudder/vibration is almost undetectable now.

Can anyone explain how a simple octane increase can make such an improvement to this shudder issue?

 

There are different ways to change the shift points but they all cost money .
Some members here at Tacoma World use computer hacking . They hack in to the factory computer in your truck and make changes to the factory tune to improve drivability . This can sometimes make your truck more efficient on fuel .
Some members drop the transmission valve body to make the transmission shift a little later with more holding pressure .This would require a Recalibration kit
Some members change the gear ratios in their differential to give the engine a better mechanical advantage over the driving wheels

As far as explaining the higher octane fuel ? easy way to explain it is that your engine doesn't have to work as hard to burn it .Its simply a better burning fuel giving you a slight increase in power .

 

I really appreciate the education. You make things easy to understand.

I'm convinced to just run the 93 and be happy with it.

I'm still doing all the other stuff, but the shudder is now an afterthought.

I wouldn't even feel it now if it had not been much worse to begin with. It's disappeared that much.

 

I dropped the trans pan this morning, installed new filter and cleaned out the pan. I didn't see anything in the pan or on the magnets to worry about.

I drained 4 quarts exactly. I added back 4.5 quarts and 10 ounces of the Lube gard Platinum.

I heated up to 105° and removed check plug and a few drips came out.

Went out for a drive and it's all good. No shudder, no vibration. Just a bit of feedback from the road. Which I consider normal. It's a truck.

I still plan to drain and fill every 100 miles, 3 more times. From this point, I'll add an ounce of the Lubegard Platinum for every quart drained which should be 2.5 quarts each time.

247k miles and she's running like new.

 

Fantastic news .
Glad you got the beast all serviced up .
Good luck with the remaining driveline