I have a 120 mph speedometer out of an 85SD with a non-working odometer. I'd like to swap in a 165 mph speedo from an 89SE that has good odometer gears.

Will the the 165 mph speedometer be accurate If I do the swap? Is there an easy way to turn the new odometer to match the old?

As an aside, the plastic gears from the 89SE appear to match the gears from the 85SD. All gears are easy to move to another speedometer except for the drive gear which will break during the removal process.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

mileage will be off by diff in gears of 2:88. -2:47/2:25

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

In old mechanical gear driven speedos like on my 78 Datsun Z, the drive gear is in the transmission and one simply takes uses the drive gear that matches the rear end. With Zs, any speedo will work with any rear end and trans combo IF you get the right drive gear which must match the rear end. Zs are conveniently color coded. What times the MBZ speedo?

As an alternative, it looks like I only need the small gear in the odometer which other threads say can be bought.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

the gearing in the speedo itself. all transmissions are the same ratio, the diff changes, and the speedo matches. so different rear drive ratios need different speedometers.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!