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Early A Speedometer Gear Source?
https://slantsix.org/forum/viewtopic.php?t=56839		 Page 2 of 2
Author:  63Valiant [ Sat Jan 03, 2015 5:31 pm ]
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Okay, I pulled the gear today, it's 17 teeth.

Next step I'll check the speedo against the GPS.
Uhhh, after I pick up a gallon of gear oil. :roll:
Author:  nm9stheham [ Sun Jan 04, 2015 4:50 am ]
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With smaller tires, then a 17 gear would indeed read way high. Well, it needed fresh oil..... BTW, if you have the early 3 speed, it calls for ATF (Dexron, or Type A) for the gear lube. (At least my '62 Dart FSM does....)
Author:  63Valiant [ Sun Jan 04, 2015 8:01 am ]
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I'll have to double check the FSM for the '63. I put this transmission in recently and I thought I put in what it called for, but it was definitely gear oil that came out.

I see that the drop in tire size increases the RPMs of the drive-shaft thereby raising the speedometer reading, but I would have thought the lower, (numerically), rear end would offset that. The 2.93 is 17% less rotation than the stock 3.55. But since the speedo is way off obviously it's not enough.
Author:  63Valiant [ Sun Jan 04, 2015 8:19 am ]
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Well doggone. You are right Ed; it does call for ATF. Now I wonder what I was doing. That happens more and more these days. :lol:

Now, what's interesting here is the FSM has on the same page as the transmission specifications a "Speedometer Pinion Usage Chart"!

The 17 tooth wasn't even an option in '63! Now I wonder WTH I did to get that in there? I repeat:
Quote:
Now I wonder what I was doing. That happens more and more these days. :lol:
For the '63 Valiant there are only 2 options, 19 tooth with the 3.23's, and a 20 tooth for the 3.55's.

And a 20 tooth with a ratio adapter for the 3.91's. <----- I guess that's if you use your Valiant as a truck.
Author:  SlantSixDan [ Sun Jan 04, 2015 1:21 pm ]
Post subject: 
Quote:
For the '63 Valiant there are only 2 options, 19 tooth with the 3.23's, and a 20 tooth for the 3.55's.
2.93 was the standard-equipment rear axle ratio with the 225 engine and automatic transmission starting in the middle of '62 production. That might've been left out of the '63 FSM, but it's there in the '63 FPC, along with all the others. Look only at the axle ratios and tire sizes, not at the car models (which don't matter -- they're only there because certain tire sizes were originally offered only on certain cars). Then use an old-to-new tire size chart like this to figure out what pinion you need.

Image
Author:  nm9stheham [ Sun Jan 04, 2015 2:07 pm ]
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Ever have an old Dodge taxi shut off it's 'on-duty' light and zoom off just as you were reaching for the door handle? That was what the 3.91 was for....LOL.

Yeah, my trannie had the gear oil in it when I got it..... put in ATF right away. Did not seem to shift or mesh any better or worse; 1st gear is still not synchronized.....doggone.

Looks like Dan provided all the info you need to know and reach a good decision.
Author:  63Valiant [ Sun Jan 04, 2015 3:53 pm ]
Post subject: 
Thanks Dan, that does clear it up some. That chart you posted shows it's for the automatic transmission, mine's a manual.

So, I turn the page of the FSM and volla, there's the 2.93 and a different "Speedometer Pinion Useage Chart" that matches the FPC you posted. And that 17 tooth gear I have. So somehow I ended up with a gear from an automatic in my car.

BUT, it does not matter since the next thing I see is there is no difference between the gears of the automatic vs manual with the 3.55s and 3.23s, so they, (the FSM), just left the 2.93 off of the page for the manuals since it wasn't an option for the manuals. (According to the FSM anyway.)

So that means ironically I somehow ended up with the right gear for my axle, but I guess it's my tire size that's messing my reading up. Assuming my speedo's okay; it does look it though, it's the steadiest early Mopar speedometer I've had.

Thanks again for all the help guys, I've learned a lot just in this thread!
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