Speedometer gear
 

I had the 727 recently rebuilt. I have a suspicion that the speedometer and odometer are different from what they used to be. Do you guys know if the rebuilt kits offer speedometer gears? If yes, then the rebuilder may have replaced it with the wrong one. If no, then the gear must be the same, and I need to look elsewhere for the potential change.


Thanks


D

demetri -

Speedos are usually off due to changes in rear end gear ratios or changes in tire diameter. The speedo gears are usually not included in rebuild kits.
























































https://moparforums.com/forums/attac...1&d=1400259869

Tire size calculation:

Tire Size: 245/60/15

245mm/25.4mm = 9.64 Inches Section Width

9.64 in. X 60% = 5.79 in. Side Wall Thickness

5.79 in. X 2 = 11.57 in. Total Side wall height

11.57 in. + 15 in. (Rim Size) = 26.6 in. Diameter

or just use a measuring tape!


See if the above helps.

Archer

Thanks, that was what I was looking for. Nothing else changed on the car since the tranny rebuild. I was just comparing the tach and speedo readings, and they did not seem to be consistent to prior the rebuild. I had to replace the tach because it started acting up, so I am wondering if this one is also not working properly, or may be the tranny rebuilders changed the gear. Based on what you said, the latter is unlikely.

Because of the vast differences in speedo requirements. I have never seen a rebuild kit with the gear included.
Now Your gear may have been damaged ? and they put a different one in during the rebuild ??. OR maybe your trans was slipping ? and now it is not ???? Or maybe a different converter ?

OK, thanks. I actually specified to use the same torque converter. The rebuilder could only find a converter for a 400, so I asked him to use the same one. It is hard to believe that the transmission was slipping 200-300 rpm at 75 for such a long time and not have burnt up. I was also suspecting bad ground on the tachometer, which I now made sure is much better. Have not tested the car on the freeway yet. I will ask the tranny guy if he replaced the speedo gear. I do not want to remove the housing and look at the color, b/c it is not easy to adjust the cable nut, but this may be the last resort (thanks archer for posting the color coding, looks like mine needs to be white).

You need to count the teeth on the speedo gear to be sure and make sure they have it clocked correctly.

check out this out fit. i have known these cats since the late 60s. if they cant do it for you NO ONE can. http://www.areds.com/

Is the speedo gear easily accessible? Do I have to remove the speedometer cable from the transmission? (hope not, it was not fun installing it). How can I know if it was clocked properly?

I can see there, I am supposed to have 24 teeth, the color is insufficient, since there is more than one white.

man o man it just hit me, i remembered. in the U.S. the speedo cable is to turn 1,000 revs per mile. this is for sure the older ones. but as all ways iam not up on the latest info. i remember that cause i helped a cat look that up a few months ago.

Well, may be we are not too far off. I drove the car on the freeway again. I was paying close attention, and I could hold speed longer. At 2500 indicated, the speedo was showing 85, not 90. So, we are fairly close to where we used to be. I expect true speed to be in the 75-77 range.


I also tested the tach with my analog dwell meter. At 1500 they were on top of each other. At 2,000, the dwell meter was showing 50-100 more, and its needle was not stable. I wonder if the analog or the digital are closer to reality.


I took the change to do a hard acceleration on 1st and 2nd gear, all the way to 4500 (which should be about 90). Not bad. Did not rev it more because I was feeling a vibration, as if there was a miss. I felt a total power loss momentarily. May be another heater hose is leaking again ...

in the area in Kansas where i live i was all ways told that the main roads was one mile apart. so have been driving since 1965 i have tested most roads. and i know the ones that are for real one mile apart, and the ones that are not. but i think having the roads like that in other places is mostly rare.