i have a 76 f100. it has a rebuilt 400 with an automatic transmission. truck starts fine, sounds good. only problem is i have to pretty much gun the gas to get it to go. it used to try to crawl forward just idling but now it seems weak. havent dogged it or anything. id like to make it 4wd eventually with a solid front axle, but for right now id like it to run just 2wd. any help would be great.
rick

 

Im not sure if that is a torque converter problem, it almost sounds like your clutch bands are going bad. You can try the converter and see it wont hurt a thing regardless if it is the bands and you have the tranny rebuilt, they will recommend a new converter. After it goes does it shift and work ok?

 

not to be mister obvious, nor to insult you, but is it low on tranny fluid? if it is not, then it sounds like bands, if it is the converter, the engine would street stall at higher rpms and rev higher at all mph.

 

Yea, that was going to be my next suggestion as well.

 

Smell the fluid. If it's slipping that badly, and the level is fine? One good sniffer will start pointing you in the right direction. Also try manual first/second/drive when taking off from a stop. That applies (for 1st and 2nd gear) a higher amount of fluid pressure to the bands/clutches....and it also removes from play the one way roller clutch used for first gear. (a clutch activates and does the job the roller clutch would normally do).

If in manual "Low/First" it takes off like a bat outta you know where? Your roller clutch is roached....Heck, something like that you should also be able to hear....they get kinda loud when they crap.

If everything checks out fine, and no changes? Then I would start looking at a rebuild on the auto---and install a new Torque Converter at that time. Trust me on this--You do NOT want to install a new Converter on a transmission that is starting to slip and wear out. It dumps all that old crappy fluid into the Converter, along with anything else that got ground up (metal shavings) If at some point you install a converter--and then rebuild the unit later? It's a PITA to get the converter fully flushed and cleaned out if you do not have the actual tools/device the shops use.

S-

 

Good advice there tedybear!

 

No worries, or as they say:

"Thank You, I'll be here until Thursday. Try the Veal, it's great..and tip your waitress"

Actually we have our own quarky C6. Off the line, nothing but PoWeR!. Get it to shift into 2nd by feathering the gas a bit (don't ask..new modulator and new vacuum line to the manifold).. Hits 2nd gear and it never feels like it hits 3rd. In fact, step on it hard enough? And it moves---but like someone is holding it back. My first idea was torque converter (overthinking stall speeds and such with the internal design of a torque converter)...But if that was the case? It would dog itself off the line until it got some speed up--and even then? Hit the gas and it would not fluid couple well enough for proper power transfer.

Haynes makes a fantastic rebuild manual for this ol' C6 (also covers other RWD models) I recommend it highly for general understanding and if someone feels the urge? Good pictures detailing the whole procedure of rebuild.

S-

 

Just so it's understood a torque converter is basicly a fluid coupler, they can and do go bad though.
Tedybear, are you sure your tranny is not actually going to 3rd and bypassing 2nd?

 

That is quite possible. I did a bit of a show-off LOL last Sunday and gunned it at 40mph. One the kickdown activated? I know it nailed first gear and not 2nd. The engine wound up and sounded like a fighter jet taking off (needless to say? Seeing the tach I installed going a wee bit to far up is not something I'd like to do again. It's hard to tell exactly what it's doing. When going about 50-55 we get some vib's..and it just seems like it's winding itself up to far.

Fun part is? We have a shift kit by B&M I'm waiting on installing until I get the energy to rebuild the C6. I have a feeling once I pull the valve body apart? There's gonna be all kinds of crud built up that is more likely blocking the spool valves from moving as they should.

S-