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Old 02-13-2018, 01:05 PM
Frank Reiner Frank Reiner is offline
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Join Date: Feb 2011
Location: Modesto CA
Posts: 4,382
Quote:
Originally Posted by rkpbeme View Post
I just changed the instrument panel in my 300 se with one from a 420 sel. Now my speed reading is way off. How can I fix this? Or can I simply subtract from what it says?
1) There are no speedometer gears; the speedo is electrically driven.

2) The 300SE has a 3.46:1 axle ratio, the 420SEL a 2.47:1 ratio. The speedo heads are calibrated for specific axle ratios. The readings that are now observed can be corrected by multiplying by .71 [2.47/3.46=.71].
Example: 60 (observed) x .71 = 43 (actual)
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