Posted By: moparjo68
'88 Dodge w/904 tranny speedo pinion gear ? - 08/09/12 07:23 AM
Hi. My '88 Ram D100 w/904 tranny has incorrect speed reading. When I'm doing 65, actual speed (using GPS) is 58. Crawled under truck to pull out speedo pinion gear to see what number I have. The pinion gear housing (the part the speedo cable screws into) has 21 to 25 markings on it. No other number combo's on it. I know the identical part on the 727 tranny has 26 to 31, 32 to......to whatever and so on. The gear that came out of the '88 was a number 25 gear. I compared it to a speedo gear that came out of my 727 tranny. The '88 904 gear is the same length but the gear itself is SMALLER in diameter than the 727 gear.
From doing a visual comparison, I question if the 904 pinion gears and the 727 pinion gears are interchangable. Instead of looking for a #26 or #27 pinion to fit a 727, I need to find one to fit an '88 904??? Is this correct?
Next question: Since the '88 904 pinion housing only has the markings of 21 to 25 on it; if I put a higher number gear into the tranny, do I need to rotate the pinion gear housing or....or leave it in original position as thou it still had the #25 gear in it???
From doing a visual comparison, I question if the 904 pinion gears and the 727 pinion gears are interchangable. Instead of looking for a #26 or #27 pinion to fit a 727, I need to find one to fit an '88 904??? Is this correct?
Next question: Since the '88 904 pinion housing only has the markings of 21 to 25 on it; if I put a higher number gear into the tranny, do I need to rotate the pinion gear housing or....or leave it in original position as thou it still had the #25 gear in it???