Ls400dan

Can someone tell me what this piece is for? I took it off thinking it was the fill cap but apparently not haha. Off of a 94 ls400.

dicer

Looks like a servo cover. So did it have a snap ring holding it in? You may want to replace the oring before reinstalling it.

Ls400dan

yeah it had a snap ring I already put it in and ran it

Banshee365

That's the second coast brake piston cover. It's funny that you post the question but fix it before the first reply. Hehehe

Ls400dan

I know haha I wasnt really worried I was just curious of what it was.

dicer

Here goes the nomenclature deal again. Just search automatic transmission servo or servo cover.

And funny they call it a brake, maybe because that is one description of the band that the piston applies. "Brake Band" and its not a coast brake but a device that locks a member to prevent the sun gear from rotating. Just have some interesting nomenclature in other languages. Maybe they figure since when you pull a manual 2nd or 1st and you are kinda coasting when the band applies it acts like a brake because of the forced down shift.

Banshee365

dicer, brother, I never said what you said was wrong man. Different manufacturers like to call a device different things as you pointed out. I know exactly how the term 'servo' is used in the industry and am not in any way saying that is an improper term to call what the OP is showing. I'm simply adding to the thread. We really have the same answer.

FWIW the 'servo' that Toyota calls the second coast brake band is only engaged with the gear selector in '2' so that you can get engine braking when coasting. That's it. When passing through second in 'D' the band is never needed, only to allow engine braking in '2.' I think the band will even apply when 'L' is selected while the unit is downshifting from second.