KJL

Looking to build a blown 406 small block but if my drive train can't handle the power, whats the point? I am also concerned about my stock spindles.

Thanks

Corey_68

A Th400 is a brute as far as trannys go. I would not be scared to put a stock Th400 behind that 406. If it goes you can always rebuild (it's cheap, Th400 are VERY common) and have a damn near bulletbroof transmission.

My dad had no problems with his stock Th400 behined a 750hp Big Block in his Street Rod. :cheers:

KJL

Wow!! Are you in Atlanta?

Corey_68

Right outside of New Orleans. :thumbs:

Larry B.

TH400's are not common, twenty years ago mayber but try to find one. Not all TH400's fit chevy's so you do see a lot of them that are pontiac/olds. Even Jag's used 'em but they won't fit Chevy's.

desi

That's good to hear. I am building a 406 myself and was wondering if I needed to get the tranny changed....

Thanks for the info.

Corey_68

I guess it all depends on location. They are a dime a donzen here, you can buy them all day long for $400-$500.

Bad-79

GOOD rebuildable Chev TH400 are tough to find. Almost all are junk not worth rebuilding

Sigforty

:iagree:

DJ Dep

"How much power/torque can a Turbo 400 handle?"

Easy answer: More than any smallblock could EVER give it. :D

Actually, they have gotten LESS expensive, since everyone is installing slip 'n slide Powerglides now. THAT change was sometrhing that I would NEVER have predicted in a zillion years. The Powerglide was always the standing joke among hot rodders. I guess maybe people get off on that "one big shift" :lolg:

I wouldn't even bother looking in a boneyard for a Turbo 400. You can get one in Jegs for around $725-$750 already built.

Dep

Robby King

I built a 383 stroker from a 350 small block for a debt I owed this guy ran a TH400 a week after I dropped the motor in his TH400 blew up when he was burning out I told him the tranny wouldn’t handle the race motor I built him it was probably making 600+Hp easy no exact number I don’t have access to a dyno but I know that engine made a lot of power cause he was outrunning c7 corvettes till he blew the tranny

cv67

When burninig out its usually when the tires catch up that trannies go.
As said a stock T400 can handle some beans. If they can hold up to strain of large motorhomes a 400ish hp toy wont hurt it none. Use a good trans cooler heat is the enemy on most trans.

BKbroiler

You're replying to a 17 year old thread.

7T1vette

THM-400's are bullet proof. But they are also heavy and very inefficient. You would do better to go with a well built 700-R4, IMO.

jackson

location
kind like demographics ... some places are choked w/ one sort of "hyphenated" americans ... while you have to hunt for em in others. 400's are relatively heavy & inefficient ... but Very tough

If an overdrive is preferred, a 4L80-E is successor to tough TH400... but requires a controller ... and many were mfd after the TH400 era; theoretically should be more available.

https://en.wikipedia.org/wiki/GM_4L80-E_transmission

Jebbysan

Read this....
https://www.motortrend.com/news/1969...e-lt-2-review/

Although this is the clone.......the magazine testers of the day got the original to run 10.60's on slicks by revving it to 7000rpm and throwing the shifter in drive from a dead stop. It has a Th400 in it. There were next to zero aftermarket components for the TH400 in 1970.......I think that answers your question.

Jebby

7T1vette

4L80e is the electronic equivalent of the 700-R4. They are basically the same transmission with electronic selection of ranges and shift points on the 4L80e. There is no later equivalent of the THM-400. Too expensive to make and too heavy/inefficient for the "fuel efficient" paradigm.

jackson

True TH400 is relatively inefficient, but otherwise No; but don't take my word for it. Readily fact-checked.
---------------------------------------------------------------------------------------------------------------------------------------
4L60E is electronic 4L60 fka 700R4 ... all good transmissions but neither as robust as following trans and have different ratios than below trans as well
these also have a markedly deep first gear ratio.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4L80E is an electronic version with OD of 3L80 fka TH400 ... all VERY robust
4L85E is a much higher torque version of 4L80E ... either VERY robust; 4L85E even more so

with exception of addition of an .75 OD ... both 4L80E & 4L85E have identical (1-2-3) ratios as 3L80/TH400
in addition to OD, those with OD also a lockup torque converter

KJL

Yes, this is a very old thread. 17 years.....hard to believe that much time has passed. I still have my Turbo400 but it sits on my garage floor. I have since been through a 200r4 (also sitting on the garage floor) and now am running a TKO600 5 speed behind a 434 SBC. I miss the Turbo400. There was something special about just mashing the gas pedal and hanging on for the ride that I really miss.

Eric P

real old thread ! What didn’t you like on the 200R4 out curiosity ?