OldLs400

Any aftermarket transmission pans that can hold more fluid? Was thinking of dropping the pan soon for a fluid change. I thought it would be a great idea to make a larger pan so the transmission can hold even more fluid. Bigger pan = more fluid = cooler transmission fluid = longer transmission life?

Also, are there any pans with a drain valve so you don't have to unbolt the whole pan?

Anyone try drilling a hole into the pan and installing a valve?

YODAONE

Attached are 1990-1994, 95-97, and 1998-2000 LS400 exploded parts diagrams depicting transmission pans and drain plugs....

If you wish more fluid capacity, then consider adding a transmission cooler.

timmy0tool

iTrader: (7)

regular service of the transmission will be enough to ensure long service life.
adding more capacity via larger pan is negligible, and probably doesn't exist in my experience.
as already stated adding a cooler is best to lower temps to "save" the trans.

also the stock pan has a drain bolt...35106A in the above pics.

oldskewel

iTrader: (1)

As I edited above, I don't think that more fluid directly translates into a significant reduction in temperature. As YODAONE said, if you want cooler, installing a separate cooler, as he is discussing in another thread would be a much more effective option. The only controversy there is whether these AT's need any help.

Are there any pans without a drain valve for these cars? My '91 certainly has one, and Yoda's pics seem to show up through 2000 at least they still have them.

The one on my '91 is just a little stripped, but holds without leaking. Next time I change the ATF, I will probably put a Timesert in there along with a new matching drain plug. I had previously considered replacing it with a bigger plug, just tapping a bigger hole, and putting in a magnetic plug. Last time I drained the ATF, I checked and found that there is virtually no room behind the drain plug, so a magnetic plug (with a little magnet sticking out the back end of the plug) would not fit - it would collide with the valves, etc. The current, stock drain plug is M12x1.75. Since I happen to have a M12x1.25 timesert kit, I would use that, which would have the added benefit (?) of making it match the engine drain plug. Not sure why they used coarser threads on the AT vs. the engine. Maybe it would be to prevent mistakenly putting a longer magnetic engine drain plug into the AT hole. Although, maybe that mix-up is what caused my threads to get messed up in the first place. Any ideas?

Regarding your last question about drilling into the pan to install a valve, you'd need to do that only in a spot that is carefully chosen, and you might not find one. The spot would need to be sufficiently thick. Also protected from impact since it would be weaker and would be protruding. So unlikely to happen.

dicer

Gen 1's have drain. Adding a deep pan is a bad idea, especially for those that like to lower and drag the bottoms of the cars on everything they drive over. Even at stock height, deep pan would hit something, the pan on it is fine as it. Its the usual trade off by engineers, they did it like it is for a reason.

OldLs400

Should I use 3309/T-IV or the bottle of MaxLife I have in the trunk?

spuds

I would use what car calls for,3309.Lot of threads here say car doesnt like its tranny fluid messed with.

OldLs400

Thanks guys. Anyone know what size bolt is on the tranny pan? I kind of want to replace it with a drain valve, so I can easily do a few drain/refills by flipping a switch.

Htony

IMO, as far as cooling goes cooler is better option. Tranny oil running too cool is no good either I think. Unless you are hauling a big trailer or some thing like that tranny as is OK.

spuds

Or get this....
https://www.ebay.com/itm/SHURFLO-OIL...72.m2749.l2649

sha4000

iTrader: (1)

See the above bolded words.

YODAONE

Any images of proposed drain spigot?

oldskewel

iTrader: (1)

Yes, and as I mentioned there as well about not much space available behind the drain plug, you'll need to be sure the valve does not protrude too far into the pan.

If you have some patience, you might find it worthwhile to jack the car up at an angle and let it drain overnight or more. I have a sloping driveway, and jack up the front end, so it's at a pretty good angle. And I can get close to 4 qts out when doing that. And doing one 4-qt D+F is more effective than doing 2x 2-qt D+F's.

YODAONE

Purchase an oil extractor to avoid all of this.

West Marine offers a durable fluid and oil extractor

spuds

Nephew uses that on his boat.Says its really slow but he is pumping cold oil.Also says it does do the job.