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I'm in the process of replacing an automatic transmission with an 4-speed M20 in my HQ. It's a 253 V8. It was originally manual.
Questions: 1. With the M20 and a 3.36 diff, does anyone know what colour the speedo driven gear should be ? 2. How does the wiring route for the reverse switch ? Under the carpet and then penetrating through the tunnel ? Or through the firewall and then running on the underside of the floor (like the speedo cable).
Thanks in advance. Andrew.
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...I should add that it's a floor shift.
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Originally Posted by: HQ_SS_Andy  Questions: 1. With the M20 and a 3.36 diff, does anyone know what colour the speedo driven gear should be ?
The driven gear will depend on the tyre size, the closest will be a green (21 tooth) gear. If that is not correct you could try a white (20 tooth) gear or a dark blue (22 tooth) gear. Each tooth is worth around 5% (i.e. 5 kmh in 100 kmh). Originally Posted by: HQ_SS_Andy  2. How does the wiring route for the reverse switch ? Under the carpet and then penetrating through the tunnel ? Or through the firewall and then running on the underside of the floor (like the speedo cable).
The wiring runs under carpet, from the base of the steering column where it plugs into the 2-pin reverse light connector, down thru a grommet and hole in the floor pan, not far to the left of the floor-shift hole cut-out. Dr Terry. Edited by user Sunday, 12 January 2025 3:06:41 PM(UTC)
| Reason: spelling |
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Thanks very much. Excellent info as usual
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Go looking in HQ to HZ M21 boxes for the driven gear, most of them were 3.36. |
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You might want to try this online speedo gear calculator, I've found it useful in the past https://www.centauriaudi...tchc4878/speedocalc.htmlCheers Kev
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That's really useful. Thanks Kevrev.
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