With more
power and steeper gears on our mind we set our sights on Tremec's T56
6-speed transmission for Project Bullitt. The Tremec T56 handles high
engine torque beautifully and the sixth gear helps get some drivability
back with PBullitt's 3.73 gears. We consulted with Tremec Transmissions and
they agreed that their T56 Tranny would be exactly what we needed
for our project car.
As with any transmission swap, we knew there would be some small hurdles
in making it fit properly. We did not encounter many, and at the writing
of this article, Tremec is currently working with Mr. Gasket to make
these conversions even simpler. Soon you will be able to order a T56
tranny and it will come with all the necessary hardware, including a new
shifter that has a built in button to control the reverse lockout. More
on this later.
This is not a step by step article, but it should give you a good idea
of what to expect if you decide to do a tranny swap.
Removing our stock Tremec 3650
Basically, we just want the old transmission out. We used jack stands
for this project and made sure we got the car high enough to allow us
all the room we needed, which turned out to be plenty. Once the car was
up in the air, we started work.
- Disconnect battery. (do this anytime
you work on your car)
- Remove the center console plate.
- Remove the shifter handle.
- Disconnect O2 connections. (4 of
them)
- Remove H-pipe or X-pipe. (need 1/2"
drive ratchet, 10 inch extension, swivel and 'half' deepwell 15mm
(about 1 1/2 long.. trust us)).
- Disconnect the clutch cable at the
Clutch fork.
- Remove the 4 axle bolts (12 mm).
- Slide the axle out of the
transmission.
- Remove Speedo and Reverse
connections to tranny.
- Support the tail shaft of the tranny
with a jack.
- Remove the 4 bolts holding the cross
member in place.
- Remove the starter (have patience).
- Release the jack holding the tranny
allowing it to hang, this will make room for you to remove the bolts
on top of the bell housing. (the 3650 bellhousing is mated to the
tranny, so you must remove them as one piece.)
- Once all bolts are removed from the
housing, slide the tranny out gently. Set aside.
- Removal is complete.
Things you need to do before T56 Install
- Have your driveshaft shortened 3/4
of an Inch.
- Elongate your Cross member holes
(see pic)
- Remove bellhousing from T56.
- Fill new T56 with Dextron Fluid.
(Right around 2 quarts)
- Use a hammer to indent the body
tunnel where top of T56 will rub. (not much to do)
Installation
- Install the new Bellhousing to the
motor.
- Attach modified cross member to new
Tranny.
- Install clutch fork and throw-out
bearing to new T56.
- Support Tranny and slide into place.
- Bolt Tranny to Bellhousing (need
good torque here, but remember this is aluminum, bolts will strip
holes).
- Here you will need to check for
clearance by pushing up on the Tranny and see where it rubs in the
body tunnel (must make clearance).
- Raise rear of tranny and bolt cross
member to body.
- OK, the transmission is in but you
need to reinstall everything else...
- Reinstall starter.
- Reconnect Speedo and Reverse sending
units to Tranny (we had to elongate a wire, as it connects to the
opposite side compared to stock)
- Reinstall shortened driveshaft
(torque those things good).
- Reconnect clutch cable to clutch
fork.
- Install new shifter if you are not
using one that comes with the T56.
- Reinstall console cover.
- Reinstall H-pipe or X-pipe.
- Reconnect O2 connections.
- Reconnect battery.
Things to remember
- Take your time.
- Driveshaft MUST be shortened 3/4" or
problems will come!
- Lower rear of stock transmission to
gain access to top bellhousing bolts.
- Contact Mr. Gasket for install kits.
- TTC now has cross member mounts so
you do not have to modify yours. (what we will install soon)
- Use several ratchet extensions to
get to starter bolts.
- Should not attempt this alone.
There is a reverse lockout mechanism.
You can use two hands for reverse, or you can wire up a power button to
push when going to reverse. Mr. Gasket has a shifter coming out to do
this as well.
WHAT WE DID: Connected one
wire from the Lockout Switch located on the transmission to the 'ON'
hotwire on the Brake Light switch located at the brake pedal. The
line you want to tap into is the RED/Green Stripe wire. You can
use a Volt meter to check which of the two wires goes 'HOT' when you
press the brake. The second wire from the reverse switch you just
need to ground to the chassis anywhere. We ran the wires up from
the tranny up through the shifter 'hole' in the body. The reverse
lockout switch requires a Chevy plug. Go to any parts house and
find their Electronics aisle and get a GM Coolant Temperature Sensor
Socket. (Mighty Might # 85100). Then just extend the wires to
reach the brake switch. It does not matter which side you use for
negative or positive on the switch, we just want power to it. Now
when you press your brakes on, you can shift into reverse with one hand.
| T56 Gear Ratios |
| 1 |
2.97 |
| 2 |
2.07 |
| 3 |
1.43 |
| 4 |
1.00 |
| 5 |
0.80 |
| 6 |
0.62 |
| Reverse |
2.90 |
Overview
We are completely in love with our new Tremec 6-Spd Transmission. It
shifts very smoothly, it has increased our drivability dramatically with
the 3.73 gears, and handles the 390 Ft/lb of Torque we are feeding it- no
problem. The T56 is actually quieter than the our stock Tremec 3650. We expected to gain some
drivetrain noise, but now there is none. Can't beat that.
For anyone out there looking for a heavy duty transmission, and you need to
solve the issues of gearing, drivability and power, the T56 is the
answer.
~SN Staff
|
T56 on left, T3650 on right.
Inside the Console cover must be removed.
Removing starter bolts requires LONG extensions.
After removing the X-pipe, remove cover and disconnect the clutch cable.
4 bolts hold the crossmember in place.
T56 Bellhousing. Install first before tranny.
Install Clutch fork before installing tranny.
We elongated holes with drill press.
Here you can see the 2 holes elongated.
We used a jack to help lift tranny into tunnel.
Tranny in place.
Pro 5.0 T56 shifter installed.
MGW Shifter Handle |
