rkreigh

I'm looking into a resto mod build for an old 68 vette

I have two tranny and cradles

c6 6l80E and c5 4L65E

can either of these trannys be converted with factory parts or an available conversion kit to front drive?

by adding a new bell housing and tail shaft? or are the vette trannys a whole different case?

I've looked into the performance 4L65E and 4L80E stuff and to build it to 800 hp and get all the controlling electronics and wiring the price tag goes up pretty quick but I'm determined to stuff an overdrive auto into the old c3 as the old turbo 350 won't cut it for me (unless I go the BB chevy route which is looking better all the time)

I'm also curious if there is any new developments on building the 6L80E tranny for about 800 rwhp in a light 2800 lb car

I really want to do a 6 spd rear tranny mount c3 build but after looking at how much hacking you have to do to the floors and tranny tunnel, I'm wanting to see if either of these trannys can be converted

the 6L80E is out of a 300 mile wreck

from what I understand, these trannys are OK to around 500 at the tire but are very difficult to program and the internals are weaker

the stock 2013 6 spd auto vette I rode around in sure shifted nice and had a great feel to it

like to see if it's at all feasible to put this 6 spd into a front mount configuration and adapt the paddle shifters to the vette

I also have the c6 steering wheel and column, but the cheesy paddle shifters don't look too good to me

PCS seems to make the nicest paddle shifter and tranny controller stuff but I'm thinking of using the stock ECM and reprogram it for a nice BB chevy or TT 4.8 LS build on the C3

should be fun! any advice is appreciated

mrvedit

First, no stock ECM will control a 6L80E. A trans controller is actually built into the 6L80E, which in turn is controlled by the BCM (Body Control Module). There are aftermarket products like from PCS to control the 6L80E, but they are expensive.
A 4L60E from a C5 will not directly bolt up to an LS engine; it has different older-style input shaft (298mm) which bolts up the the torque tube. However, it will bolt up with additonal of a special spacer after the flexplate and the correct flexplate. It also cannot handle your planned power level.

Everything you have said so far indicates that a 4L80E is the correct choice. Any stock ECM will control it, it will bolt up to an LS engine and will fit your C3 much better/easier than the much-bigger 6L80E.

Those are my opinions.

rkreigh

thanks for the help

I did look at the PCS stuff as a primary option

so it looks like selling what I have is a the best option

fyi the RPM 4l65E in my TTiX twin turbo vette has held up on the street just fine at 800 rwhp

I typically don't pound it too much at 800 hp though and don't race the car with slicks

will the 4L80e fit the vette trans tunnel is what I'm wondering

it's for sure the stronger beast

thanks again for all the great advice!!

mrvedit

Not running slicks will help a trans live longer as the tires will break free before the trans "breaks".

I don't know how well a 4L80E will fit into a '68 Vette, but I suspect Jake knows as he is active on many other forums. (For example, he and I are also active on nastyz28.com, the Gen 2 Camaro forum.)

poorhousenext

Your C3 and my C2 have the same frame, just different body mount points. Not sure about tunnel differences that might make it a no tunnel mod install in a C3. Check C3 section of Corvette Fourm, I'm sure it's been done before.

A 4L80e will fit in a C2, but rquires a little bubble out modifcation of tunnel on drivers side so you can plug in wire harness. You might not have to do that if you change plug to a 90 deg angle one. On right side you will need to cut a small regtangular section out and hump out tunnel a little so you can install cooling lines. Done right no one will every know you modded tunnel. No foot space or leg room is lost.

Rear trans mount has to be modified of course.

rkreigh

the 4l80e looks like the way to go I agree

it does soak up more hp than I'd like but it's beefy and will be able to better handle what I have in mind

any experience with a manual valve body that could be set up for the street?

I don't think I really want to mess with the controller box and programming on the tranny side.

mrvedit

A 4L80e only "soaks up" 5HP over a 4L60E. Here is dyno proof:
https://ls1tech.com/forums/automatic...questions.html

Just about any PCM that controls a LSx engine can easily control a 4L80E too.
If you go with e.g. a 2008+ ECM on a LS3 engine, the TCM is only $100 on ebay.