Tunnel Modification

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Transmission Tunnel Modification

Transmission Tunnel Modification

The T5 is a little wider than the stock Alpine transmission and it is necessary to make the tunnel to be wider to accept the T5 transmission.  This is actually not a difficult  modification but does require some sheet metal skills and patience.

A word of caution:  Make sure all flammable materials are removed from the drivers compartment, and the underside of the car has been cleaned of oil buildup.  While performing the cut, it would be advisable to have a spotter to help keep an eye out for fire.

1. Mark the drivers side floor 1" away from the tunnel from the beam in front of the drivers seat all the way along the tunnel and up the firewall behind the gas pedal.  (Use a paint marker or masking tape.)
2. Using a 3-4" cutoff wheel in a die grinder (plasma cutter or cutting torch may be used but clean up of the edge will be more difficult), cut along the previously marked line.
3. The shifter hole will need to be expanded as well.  The amount will depend on your choice of a Pro shifter or stock.
4. Clean up and debur the edges. 
5. Using a jack, spread the sides of the tunnel making sure the floor of the driver side is on top of the lip that resulted from cutting the floor 1" from the tunnel.  A hydraulic jack will work for spreading the tunnel, but I've found a scissor jack to be a better choice.
6. Continue spreading the tunnel until the drivers floor butts against the outer wall of the tunnel.  More is better as far as clearance... 
7. Drive some sheet metal screws or tack weld the floor in place to hold while you remove the jack and test fit the transmission. 
8. Position the transmission in the tunnel on the transmission cross member with the front supported to confirm adequate clearance.  Make sure the transmission does not touch the tunnel or you'll get vibration. Adjust the tunnel width as necessary. 
9. Do not final weld the tunnel seam until the engine & transmission have been installed in their proper location for verification of clearance.
10. It may be necessary to make a floor notch for the speedometer connection.  This varies from installation to installation. 
11. .Complete the sheet metal work around the shifter.

•  My installation, without a pro shifter allowed me to use the stock shifter access cover, by jut recreating the rear curve and extending the top and side walls.

Step #1 - Mark the floor to cut.

Step #11 - Mark the tunnel for the shifter cut out. 

Step#11b - Make the cut out 

Step#11c - Rebuild the sheet metal to use factory cover