Bersaglieri

iTrader: (13)

Like many people I have always wondered just how much I am leaving on the table with my 4L80e. I found out I can get my hands on a stock TH350 for free or a TH400 with a FMVB for $100. I could pickup a cheap converter from Summit or ebay or something and I was thinking about doing some track comparisons. Anyone ever done anything like this? Better yet anyone got donation TH350/TH400 parts lying around?

I might try to get to a dyno also.

-Dustin-

b.d.d.

iTrader: (2)

With enough money, you can make a John Deere combine do wheelies. With enough money you can make a GM meteric tranny handle all kinds of power. Or you can spend a little and get a TH350 to handle more power than you will ever have on the street with a DD. Everything comes with a price. Going to a TH350/400 means you give up OD.

I am about ready to go TH350 on my TA. Just a matter of finding the tranz brake and manual VB I want. I could care less about OD. I am not a DD, but far from drag only car either...that is what the Camaro is for. The musclecars of yesteryear did just fine without OD. I figure I can too.

b00sted

iTrader: (7)

Best thing I ever did was a th400. I'm finishing up the quarterstick shifter and rmvb now, so that may be the new best thing. I know it was more fun in my mustang/c4

forcd ind

iTrader: (7)

in order to make it a decent test, every trans would have to have exactly the same stall, or it would be meaningless-then, if one trans made more power but was weaker, would it be worth it
comparing a 4l80e with a non lockup/non OD trans is apples to oranges, unless its just a racecar and you dont care about OD
just to give you an idea, i ran an 11.1 with a low stall 400(old school switch/pitch 400, 13" converter, stalled at 2200
i borrowed an ATI 400/converter better matched to my setup(a little R & D)
and ran 10.68-(all gains in the 1/8) this with basically the same trans, just a converter change
i now have a 4l80e with a matched FTI converter for my setup (actually made more for my fut stroker) on the street, it feels as good as the borrowed 400/converter, i havent made a pass yet, but hope to soon-but i wanted the OD/Lockup
prob with a well built 350, if it could hold up to the intended power, you could see a small gain-i believe they have a small gain in first gear ratio also

b.d.d.

iTrader: (2)

I think the TH350 has a higher first gear than the metrics. The TH400 robs a little more power than a TH350 and is a bit heavier than a TH350. They all can break, it just takes a lot more power and time to break a TH350/400. And there are a ton of options out there for TH350/400's.

Bersaglieri

iTrader: (13)

Other than forcd ind's personal experience I already knew the information stated here. I was just wondering if anyone in the 4th Gen Fbody would be interested in the data I might obtain. Thought it might help guys decide on whether it's worth the trade for overdrive. If everyone already knows the answers I'll keep the info to myself

-Dustin-

PS Doesnt take much money to get a JD combine to do wheelies...in reverse that is...good luck doing it in drive.

jakeshoe

iTrader: (14)

The info posted by forc ind is correct.
Info is good IF it is based on good testing.
The old adage garbage in = garbage out applies here.

Not to knock your willingness to share the info or what you find but all too often I see guys state "A TH400 takes more HP to turn". Which in theory sounds good but in reality the difference is more dependent on how fast you accelerate the rotating mass.
A heavier rotating mass would take more power to accelerate, not necessarily to keep at steady speed. In simple terms, a 9 second car will see a difference when a 13 second car won't.
With an automatic transmission you also have to account for parasitic and fricitonal losses.

I build quite a few transmissions for exclusively performance use and I have yet to see more than a .04 difference between a TH350-Th400 using the same converter when swapped.
It's not often we get good data on this swap (same car, engine, converter, gearing, weather).

We did a TH400 to 4L80E swap last year in a car running 6.60
s in the 1/8 and saw no change in ET or MPH using a converter built by the same vendor to match the TH400 piece he previously built. Converter had the same flash stall, car had the same 60', MPH, and ET overall.
IMO the 40 lbs additional added by the 4L80E would definitely show a difference if there is that much effect.
A TH350 short tail weighs 125 lbs, a TH400 weighs 135. The 10 lbs difference is pretty much entirely rotating weight.
A 4L80E weighs 178 lbs and I would guess than most of the difference is rotating weight...

forcd ind

iTrader: (7)

just to add a little more to this, when i first put the car together, it had a Z06 cam, and 3.31 rear gears
i switched to 3.55's, noticed the stall was less, better gear leverage, so car moved easier-i switched to 3.73's, partly due to 3.55's being def., would not pattern, they gave me 3.73's in swap-i noticed stall was reduced more, again because of better leverage-then i did a cam swap to a little wilder cam, the stall dropped even more, as now the power level was moved up a little, less torq down low, however small
the point of this is to optimize the setup, the right converter needs to be built
for each setup, so you can see swapping trans around w/o identical converter setups would not really show true diff-now if you wanted to rem weight off the front end, 4l80e prob would not be the trans of choice for weight transfer, lol-i just picked up 2 of them Sat. and had to carry each one about 35' to the truck, and they weigh what i do