Shuddering when TC locks up

[mile-hi-bri]

The highly-touted Lube-Guard product claims to work well for this problem.

They actually have a specific product that addresses this issue, but their "normal" product does this as well, along with the other "virtues in a bottle".

I bought a bottle @ NAPA(about $11.00) for my folks Outback tranny. Did the usual figure 8's and wallah!! Works wonders!!!!

Good luck!

mile-hi-bri

[NikFu S.]

Originally posted by NikFu S.

I'll find out for sure tonight. If so I have the camcorder.

My TC won't lock at all.
Going to see the tranny guys.

[mbtoloczko]

Do you have an aftermarket ATF cooler installed? If so, the ATF is probably not becoming warm enough to allow the TC to lock.

[NiftySVX]

The converter will lock up in any forward gear except 1st.
The service manual says so!

My 94 does the same thing on occasion, and my mount is new. check the pitch stopper for tightness.

NiftySVX

[Earthworm]

Originally posted by NiftySVX
The converter will lock up in any forward gear except 1st.
The service manual says so!

Which page? (I'm too lazy to look it up)

Originally posted by NiftySVX
The converter will lock up in any forward gear except 1st.
The service manual says so!

Yeah, yeah, yeah. Ask Lee about that... He put together the SVX 4EAT files that are in the "How To" locker. It also says in there that the 4EAT is designed to allow TC lockup in any forward gear, but most people on the network know that realistically it will only do it in 4th.

When the TC is unlocked, it's purpose is to provide extra torque input for the transmission (by allowing the separate halves of the TC to spin at different speeds). When it is locked, it's purpose is to lower engine RPMs for cruising. Now, why would this ever occur in any gear other than 4th? Especially since the TC lockup creates extra heat inside the 4EAT!

Which is why, as I mentioned earlier, many members here will tell you to leave the gear selector in 3rd until 80kph/50mph... It does not allow TC lockup until it is really needed (cruising speeds above 80kph/50mph), and, thusly, can reduce the extra heat that TC lockup produces. And when you need to punch the accelerator, you don't have to wait for the TC to unlock, then wait for the 4EAT to downshift into 2nd.

Keeping it in 3rd until 80kph/50mph is really a great idea all around.

And no, your 4EAT does not perform TC lockup in any other gear than 4th.

[mbtoloczko]

Originally posted by NiftySVX
The converter will lock up in any forward gear except 1st.
The service manual says so!

The manual might say that its possible for the 4EAT to lock in any forward gear except first, but the only gear mine ever locked in was 4th.

Are you referring to the Endwrench pdf document that's floating around online?

[Earthworm]

Originally posted by deruvian
Especially since the TC lockup creates extra heat inside the 4EAT!

Actually when the TC is locked up there is far less heat buildup in the tranny. Anyone who installed a tranny temp gauge will confirm this. As soon as the TC unlocks the tranny starts heating up again.

Originally posted by Earthworm
Actually when the TC is locked up there is far less heat buildup in the tranny. Anyone who installed a tranny temp gauge will confirm this. As soon as the TC unlocks the tranny starts heating up again.

Really?! Prior to this, I had always heard that the TC lockup creates heat in teh tranny...

Can anyone else with a tranny temp gauge confirm?

[oab_au]

OK I'll stick my neck out, and say that 98% of the heat prouced in the transmission, is produced in the torque converter. The higher the difference in speed between the impeller and turbine, the higher the heat. The heat produced by the friction of engaging bands and clutches is very small, compared to the converter. So once it is locked, no heat.

Harvey.

[Earthworm]

Hence why a standard transmission does not need additional cooling.

Thanks Harvey
ps. How's the weather?

[oab_au]

Originally posted by Earthworm
Hence why a standard transmission does not need additional cooling.

Thanks Harvey
ps. How's the weather?

26degs C. sun shining, all hung out to dry.

Harvey.

[lee]

Originally posted by deruvian


Really?! Prior to this, I had always heard that the TC lockup creates heat in teh tranny...

Can anyone else with a tranny temp gauge confirm?

i can, it happens in mine anyway.

[dcarrb]

A know-nothing layman's opinion here, but it seems to me that driving with the torque converter locked is absolutely the best way for an automatic to travel. It stands to reason that the "gear hunting" and lock/unlock/repeat cycle that can take place at moderate, varied speeds (city driving, rolling terrain) would create heat within the transmission and wear internal parts, so that's the condition best avoided. In such instances I'll occasionally pull down to third, but I think the car is much happier, overall, with the selector in "D" and the TC locked.

dcb

[NiftySVX]

The converter will lock up in 2,3,or 4.

How many transmission classes have you attended?

Are you an ASE Certified automobile technician?

I am. I do this for a living. Plus I know hot to read a a/t powerflow and electrical diagram, and unless you have re-programmed your TCM, the converter will lock up under the proper circumstances. Go get a Subaru select monitor and do it on an OBD II car.

NiftySVX