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[Datsun 1200 encyclopedia]


From Datsun 1200 Club

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Categories: Body | Transmission | Automatic Transmission

Datsun 1200 originally fitted with automatic transmission has a much larger tunnel. It makes it easier to swap in larger transmissions or larger engines.



Comparo: Manual transmission cover vs automatic transmission cover
18963.jpgAlbum click to view

Manual Tunnel is very small to fit the small stock transmissions and increase space inside the passenger compartment:
884.jpgAlbum click to view 2133.jpgAlbum click to view

The manual body has one piece lower dash panel with no joins whatsoever - the bellhousing part of tunnel is one piece with firewall.
26010.jpgAlbum click to view

By contrast the Auto body has separate dash panel and floor. The transmission cover is spot welded in. The welding seam is clearly noticeable on the firewall at the back of the engine.
7475.jpgAlbum click to view

Manual tunnel has no seam
7476.jpgAlbum click to view

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NOTE: Unlike a B110, the B210 has the same floor auto and manual - the stick and slushbox tunnels are the same on a B210.

Swapping Tunnel panels

You can swap the larger automatic tunnel into a manual transmission car. The B210 tunnel is nearly identical to the 1200 automatic tunnel. In turn, the 610 (180B) tunnel is nearly the same as the B210 tunnel. See #Tunnel Swaps below.

Modified Tunnel

Just take a big hammer and bang the tunnel sheet metal ("massage it") to get more clearance.
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Or cut part of the tunnel and weld on a bigger section
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You can also move the gearbox mounts back to suit various transmissions
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Maddat Tunnel

Product No TT1200SR Transmission Tunnel. Suit 1200 with SR20 or CA18 Gearbox. Comes with rubber gear stick boot. These can be installed in about half a day.

Note: fitment requires removal of heater box.

For 1200 SR conversions, it will allow the gearbox to be removed while the engine is still in the car. Very simple to install, just sit over existing tunnel, trace with texta. Then cut out inside the line by 10mm, weld the tunnel from inside the cab. From underneath now tap up that 10mm lip (can be made easier if heated up with oxy), run some seam sealer around the joint to finish off.

14580.jpgAlbum click to view

Custom Tunnels

Others have successfully bolted or welded in tunnels from:

  • B210
  • Stanza (1980 510)
  • 180B (610)
    4224.jpgAlbum click to view
  • Custom fabricated tunnels
    3039.jpgAlbum click to view

Tunnel Swaps

The standard B110 uses one piece lower dash. The Auto dash is two pieces (lower dash + cover).
26010.jpgAlbum click to view

The rear half of the tunnel is part of the floor
26009.jpgAlbum click to view

In actual practice when swapping, the "tunnel" is cut out of the dash and floor.

manual transmission
67300-H1000 ASS'Y-PANEL, dash, lower [manual transmission]
74300-H1010 ASS'Y-FLOOR, front [manual transmission]
automatic transmission
74306-H1020 ASS'Y-PANEL, A/T floor cover, front [automatic transmission]
67300-H1021 ASS'Y-PANEL, dash, lower [automatic transmission]
74300-H1021 ASS'Y-FLOOR, front [automatic transmission]

Auto Tunnel Swap

Auto tunnel is very large to fit the 71-series Automatic Transmission, but still fits under the heater box.
8539.jpgAlbum click to view

Auto Tunnel retrofit - tunnel can be cut out, then the new tunnel welded to the floor & firewall:
18965.jpgAlbum click to view

8710_4d510d896ac3e.jpgPost click for topic 8710_4d510dca2bb13.jpgPost click for topic 8710_4d8d9c50cdd42.gifPost click for topic 18964.jpgAlbum click to view

Shoey's diagram
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B210/610 Tunnel

Includes 120Y & 180B.

Fits into 1200
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Fits into a 1200 and still allows for a stock heater:
8527.jpgAlbum click to view 10242.jpgAlbum click to view

NOTE: All B210/120Y use the larger size tunnel

However the B210 floor pans differ:

  • from 1200 as to where the transmissions mount points are. You can move the brackets if necessary
  • B210 used eight different tunnels. See Tunnel Comparison.

A10 Tunnel

Several club members have fitted an A10 Stanza tunnel to the 1200.


the satnza tunnel in- looks ok, but i wouldnt recomend it as an easy swap(my first one but piggys 3rd or 4th one). 120y was most stright forward he said, but heaps of room around this one

A10 tunnel in 1200
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B310 Tunnel

B310 Sunny tunnel is same as A10, but for A-series gearboxes.

17554_598098d4d9f46.jpgPost click for topic

Shifter Location

Stock shifter location is well forward of the seat rail riser
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Photo showing where to cut the tunnel to fit a standard "short" L-series or CA-series transmission.
2118.jpgAlbum click to view

Cut the hole bigger ...
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Or just move the hole back and weld it back in:
9582.jpgAlbum click to view

1200 auto tunnel with shifter location raised and moved back | stock tunnel
003-1.jpgPost click for topic 26416.jpgAlbum click to view

71-series Modifications

71-series Transmission is used by later L-series engine, Z-series engine, FJ-series engine, CA and SR engines.

S13 gearbox clearance in manual tunnel
4696.jpgAlbum click to view

Rear of tunnel modification:
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Reverse Lamp

To fit a 60-Series Transmission 5-speed, move the gearbox Mounts 115mm back:
5009.jpgAlbum click to view 5008.jpgAlbum click to view

To remove the brackets, drill out the spot welds
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56A Modification

To clear that nasty clutch fork in the later type 56A trans
5843.jpgAlbum click to view 23057.jpgArticle click to go

See Also

Also see: Transmission tunnel Photo Index 

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This page has been accessed 20,311 times. This page was last modified 20:39, 1 August 2017. Content is available under Datsun 1200 Club.