Rich B.

Alternative C4 Trans Swap

Back in 2007, my DNE 4+3 overdrive spit it's seal into the reverse gear
yoke, locking it in reverse. I pulled the trans and had SK on Long Island
rebuild the overdrive. I also had a new driveshaft yoke and u-joints
installed by a truck outfitter in Buffalo NY. (Big mistake). The rebuilt
overdrive lasted approx 100 miles before overheating & spitting the seal
again. I believe this was due to excessive wear on the overdrive output
bushing brought on by a stiff u-joint. (The u-joints were not stress-relieved after installation).

I was not inclined to rebuild the overdrive again, as I don't use
overdrive at all. I contemplated a ZF or Tremec swap, but both were way
overpriced [IMHO]. So, I decided to make an adapter and install a Borg
Warner Super T-10 from an 82 Camaro. I selected this trans because
the 2.88 1st gear gearset from the DNE 4+3 could be swapped into the
Camaro 3.42 1st gear main case. The Camaro used a tailshaft & housing
that had the same 27 spline output shaft as the C4 uses (although the C4
driveshaft won't fit - too short). Space in the C4 transmission tunnel is
limited; I'm doubtful if the 32 spline output of the 'standard' ST-10
would fit, with the adapter I envisioned. The Camaro also uses the 26
spline input shaft as the C4, and the BW ST-10 has the same bellhousing
bolt pattern as the Vette. The C4 clutch was re-used.

I made up the adapter from 1" x 4 7/8" x 12" 6061-T6 aluminum and 6" x 4"
x 12" 5/16" mild steel angle. I also made up a saddle clamp from aluminum
as a safety feature.

A new driveshaft was required, as the Camaro trans is ~3" shorter than
the DNE trans. I chose a custom made 2 1/2" dia DOM steel tubing
driveshaft and the stock C4 yoke & u-joints.

The Camaro ST-10 has a 7/8" cable drive speedometer gear output spigot vs
the C4 integral signal generator, so I needed a pulse generator that
would send signals to the C4 speedometer, ABS, ECM, etc. Because of
clearance issues, a 90º angle cable adapter was needed, attached to a 48"
speedometer cable extension. The pulse generator was attached to a
fabricated bracket in the engine compartment.

I have what is basically a Hurst Street Super Shifter for the
BW ST-10 modified to mount to the C4 transmission tunnel, fitted with the
'short shift' links, and using the C4 linkage rods (threads on the reverse rod extended).

Everything worked out exactly as anticipated. The speedometer reads
correctly, ABS works, all 4 gears work flawlessly, and the car drives
just like it did with the DNE 4+3. Minus the troubleprone overdrive.

82 Camaro ST-10's can be had for $500 more or less, but because of
the 3.42 1st gear, a swap for the DNE 2.88 gearset is recommended. If
not, you'll spend a lot of time shifting out of 1st gear with the C4's
3.07 rear diff.

This swap may not be everyone's choice, but I like a 4-speed. A Muncie or
even a Saginaw might be a cheaper alternative, but the Camaro trans was
available, so I used that. The trans-to-C Beam adapter would be slightly
different, but the idea is the same.


Parts Suppliers

82 Camaro transmission = eBay
Adapter bracket = Online Metals
Pulse Generator & Extension cable = Speedometer Service Company
<Info@speedometersolutions.com>
90º speedo cable adapter = Davies Corvette <davies@corvetteparts.com>
Gearset swap & rebuild ST-10 = Don's Muscle Car Parts <DPRedneck454@aol.com>
Driveshaft, yoke, & u-joints = Denny's Driveshafts
[http://www.dennysdriveshaft.com/]

Here's the 82 Camaro Super T-10...



This is the adapter, shim, signal generator, and assorted hardware...



Final iteration of adapter, with driveshaft yoke clearance cut...



Bench view of [early] assembled adapter & trans...



Side/bottom view...



Top view...



Side/top view...



Installed view, from rear, with C-beam in place...



On jack, before C-beam installation...



Bottom view installed, C-beam & linkage hooked up...



Driveshaft installed...



Pulse [signal] generator, cable extension, & bracket in engine compartment...



BTW: I anticipated a transmission replacement when I bought this C4 back
in 1998 (it's my third Vette), so I bought an Eagle garage lift and a
Harbor Freight transmission jack (the hi-boy model). Makes the job a lot
easier...

[Edit]...Yes, that is a 140 amp alternator, from [IIRC] an LT1...another special bracket job...<sigh>...

Grumpy

title changed...

Rich B.

Thank You, Grumpy!!!

Pete K

Great job Rich
Threads like this are why I used to be a regular on this forum.
PK

Rich B.

Same here, Pete!!!

...that, and any post by scorp508!!!...

rodj

Innovative thinking outside the box
You can do things without a " kit" from Summit.
(I had suggested this in the past for cash strapped guys with O/d problems but everyone said ;
too hard / not worth the effort compared to a ZF swap)

grandspt

Nice work!
I am sure that the 1983 Camaro (unlesss there were some real early production cars) had the Borg Warner T5 5 spd. tranny I know this because I owned a 1983 Z28 with the 5.0 liter H.O. Engine. It was definately a T5.
However the 1982 did have the 4 speed T-10 non overdrive tranny.
Not trying to nit pick as I think you did a Great job

Rich B.

References to 83 Camaro trans deleted!

The only F-body I ever owned was a 75 Firebird, so your memory/knowledge is better than mine!!!

grandspt

383vett

Good work.