[mopar56]

part of this question was asked on an earlier thread, "proper fluid for a833od" but as that issue has been addressed I thought I would start a new thread here, so after installing the a833od in my sons 1980 1/2 ton shortbed and removing the existing broken speedo cable and cruise servo we replaced it with just a speedo cable straight from trans to speedo but it dosnt work, dana44 suggested "indexing it", I went back through may manuals and found reference to this showing them aligning "32-28" reference marks on the speedo adapter housing in the six oclock position which it was not so we re-located it there last night, all seemed good as this put the speedo pinion higher in the tailshaft and closer to the trans pinion gear but after a road test an hour ago WHA WHA Waa! no speedo, when the cable was out of the trans last night we spun the cable at the trans and the speedo moves fine, any ideas? oh, forgot to mention, the speedo pinion we used was from his old 727 auto but we did not change the rear end gear ratio so I believe its the same unless the diameter of the four speed gear is larger?

 

[ImperialCrown]

Is there a 7-digit part # or tooth # on the plastic gear? What color is it?
It would make sense to have manual and automatic gears the same, but they might not be.
You want to rotate the speedo gear adapter so that the pinion gear meshes with the tailshaft worm gear.
It sounds as if they are not meshing.
These gears can wear and will visually show a slight concave across the tooth crown (they should be flat across). Adjusting them closer to the worm can restore speedometer operation.

 

[mopar56]

well I didnt count the teeth nor look for a part# but I know they are color coded, it is yellow, the speedo adapter can really only be indexed in about three spots as per the marks on the adapter and because there are notches in the adapter that the claw that holds it to the trans uses and the one I have it in puts the gear closest to the gear in the trans, it appears if I turn it the other way it will be further from the gear and keep in mind I already had it in one of the other notches?

 

[dana44]

Stick the end of the broken cable end into the gear and twist the holder until the cable can't turn the gear, this will mesh the gears to the output gear. If it doesn't turn, it is engaged, lock it down, see if it works.

 

[mopar56]

ok good idea except that the oring on the housing seats it fairly snugly against the trans making it difficult to turn but I will give it a try, thanks

 

[mopar56]

AHH dana44 you very smart man indeed! FIXED! I used a screw driver and small hammer to tap the speedo housing to the next setting after discovering that the speedo cable spun freely in the housing but when I went to the next setting the speedo cable would no longer spin, then took the road test and confirmed, I am a little suspicious though if the tooth count is correct for the gears as it seems it is reading faster than we were moving at time so I will drive in front of my son tomorrow with my 2011 ram and confirm via blue tooth the speeds we are going, now if it is off dose anyone know if I will need to go up or down in tooth count? the gears are color coded and each one dictates the tooth count, although we never changed the rear end ratio the speedometer never really worked smoothly before though, lastly we are also suspicious that the rear gear ratio was changed before we purchased the truck so short of removing the diff hat and counting the ring and pinion do you know if we could count driveshaft turns against tire revolutions and do the math that way?, thanks

 

[dana44]

OK, without konwing, there are places to get the proper tooth count to rear end and tire size, I think you may find it over at yearone (for starters). Next, determine the rear end ratio with the turning of the driveline/wheel method, there are only so many ratios, so, mark the wheel and the driveline, (rear wheels off the ground and blocked safely of course), then put the tranny in neutral, turn the driveline and count the times it rotates the number of times and percent of the final turn to one full rotation of the tire. Should be able to get it close enough to tell the ratio. You can double check to see if the rear cover has been removed and whether or not there is a tag on the rear cover bolt, but like you said, it may be off or wrong, won't know until you do the wheel/driveline rotation test.

 

[KOG]

The quick, accurate method of checking now is to use a GPS for speed comparison. Then adjust tooth count as needed to correct speedometer. The gearing is actually to make the odometer correct and a defective speedometer may no read the correct speed when the gearing is correct. BTW, these gears typically have the tooth count molded into them in addition to the color differences. Manual and automatic used the same gears for many years starting o later than early 60s.

 

[mopar56]

ok thanks, both good answers, also I forgot to take tire size into the equation and we have changed that many times with another change coming soon, possibly going 50 series so although we will check the accuracy for now, we may wait until the new tires go on before we change, thanks