Changing Speedo gear on 727

[Stumper]

I know this was discussed before but i'll be darned if I can find the thread. What's involved involved in changing the speedometer gear in a post 66' 727?
If i recall there was some allignment issue to watch for? My new gear has black marked on one tooth. Does that need to go in at a certain point?

 

[1badgtx]

The speedo housing has numbers n it...This will get you in the ball park for clocking it correctly..You,ll still have to turn the housing a liitle till it line sup correctly..
Petty Blue 67 gTx

 

[ply64post]

speedo

I know this was discussed before but i'll be darned if I can find the thread. What's involved involved in changing the speedometer gear in a post 66' 727?
If i recall there was some allignment issue to watch for? My new gear has black marked on one tooth. Does that need to go in at a certain point?

Stumper

Here is a picture that should help you out.

No you don't have to line anything other than to index the adapter as shown.

Jeff

 

[Stumper]

Great, thanks fellows!! So the adaptor is alligned to the 6 o'clock position to correspond the the number of the gear? With a 43 tooth gear I basiclly set it to around the 43 position at 6 o'clock???

 

[ply64post]

instalation

Great, thanks fellows!! So the adaptor is alligned to the 6 o'clock position to correspond the the number of the gear? With a 43 tooth gear I basiclly set it to around the 43 position at 6 o'clock???

Stumper

Yes you do, line up slash mark that corresponds with amount of teeth like in the picture below.

Jeff

 

[ply64post]

speedo

Stumper

This is a better picture.

Jeff

 

[Cranky]

Stumper

This is a better picture.

Jeff

Yup....align the smaller slot/line with the dot on the housing. The deeper slots are for the clamp to sit in. If you do this wrong, it'll chew up the gear.

 

[Stumper]

Got it - so the vertical hatch mark (not the clamp grooves) that each gear range has is what you line up to the dot?

 

[ply64post]

speedo

Got it - so the vertical hatch mark (not the clamp grooves) that each gear range has is what you line up to the dot?

Yes

 

[ply64post]

speedo

Got it - so the vertical hatch mark (not the clamp grooves) that each gear range has is what you line up to the dot?

Yes

 

[Stumper]

Super, thanks alot guys. I think I'll tackle this tomorrow.

 

[tpodwdog]

theres only 4 positions it can go. the clamp will pretty much go in the little slots and bolt with a single bolt. kinda hard to get it wrong just make sure the corresponding numbers on your gear.... and the adapter are at 6 o clock

 

[Stumper]

just make sure the corresponding numbers on your gear.... and the adapter are at 6 o clock

What numbers on the gear???? These are the only markings on my gear:

And this black mark on a tooth - which is about 90 degrees to the number and letters.

 

[Joe Mopar]

Hey Stumper.........Where did you buy that speed gear ?

 

[ply64post]

speedo

What numbers on the gear???? These are the only markings on my gear:

And this black mark on a tooth - which is about 90 degrees to the number and letters.

Stumper
I see 43 on the gear the no. of teeth.
Just line mark on the adapter 39-45 to 6o'clock and you got it.


Jeff

 

[Stumper]

I bought the gear from PATC Transmission - online. It was like $44 dollars wtih shipping - way better than the other rip offs (so far at least - assuming it works and lasts )
So other than making sure the adapter is lined properly to the 6 o'clock position, is there any particular position to put the gear itself in???

 

[Cranky]

Put the gear into the adapter and then align the adapter with the small notch or mark that's in the 39-45 range at 6 o'clock...and make sure the o-ring is good or it'll leak.

 

[anmracing]

Out of curiosity, what is the formula to figure out what gear you need if:

A. The trans you had has a broken out of recognition gear.
B. The tires have been changed
C. The gears have been changed

I'm using a gear from an auto in our 4 speed just so it is sealed but it is showing a much faster speed than what I am actually going.

A~

 

[ply64post]

Gear selection

Out of curiosity, what is the formula to figure out what gear you need if:

A. The trans you had has a broken out of recognition gear.
B. The tires have been changed
C. The gears have been changed

I'm using a gear from an auto in our 4 speed just so it is sealed but it is showing a much faster speed than what I am actually going.

A~

anmracing

This is the formula I use, works for an auto or a 4-speed.
Hope this helps
Merry Christmas
Jeff

The numbers shown are original numbers, some are superceded to 52xxxx numbers, the dealer can do that.
1966-1989 727 & 904 Automatics Transmissions
AXLE
RATIO
-------24"------26"------28"-----30"
2.76 2538930 2538928 2538926 2538924
2.94 2538932 2538930 2538928 2538926
3.21 2538935 2538933 2838931 2838929
3.55 2538939 2538936 2538933 2538931
3.91 2538943 2538940 2538937 2538935
4.10 2538945 2538942 2538939 2538936
4.30 2538944 2538941 2538938
4.56 2538945 2538943 2538940

Please note: These numbers are for the standard style pinion gear, also last two numbers are the number of teeth, 2538945 = 45 teeth

Teeth color
24 White, 25 Blue, 26 Red, 27 White, 28 Blue, 29 Black, 30 Yellow, 31 Green
32 Black, 33 Yellow, 34 Green, 35 Orange, 36 Red, 37 White, 38 Blue
39 Green, 40 Orange, 41 Red, 42 White, 43 Blue, 44 Black, 45 Yellow

How to Calculate tire diameter: Example 265/60/15

265mm/25.4mm = 10.43 Inches Section Width
10.43 in. X 60% = 6.25 in. Side Wall thickness
6.25 in X 2 = 12.5 in Total Side wall height
12.5 " + 15" (rim Size) = 27.5" Diameter

With this tire size and 3.55 Gears, would use 34 Tooth Speedometer gear

Also make sure that the correct number of teeth installed corresponds to the settings on the outside of the retainer.

 

[anmracing]

anmracing

This is the formula I use, works for an auto or a 4-speed.
Hope this helps
Merry Christmas
Jeff

The numbers shown are original numbers, some are superceded to 52xxxx numbers, the dealer can do that.
1966-1989 727 & 904 Automatics Transmissions
AXLE
RATIO
-------24"------26"------28"-----30"
2.76 2538930 2538928 2538926 2538924
2.94 2538932 2538930 2538928 2538926
3.21 2538935 2538933 2838931 2838929
3.55 2538939 2538936 2538933 2538931
3.91 2538943 2538940 2538937 2538935
4.10 2538945 2538942 2538939 2538936
4.30 2538944 2538941 2538938
4.56 2538945 2538943 2538940

Please note: These numbers are for the standard style pinion gear, also last two numbers are the number of teeth, 2538945 = 45 teeth

Teeth color
24 White, 25 Blue, 26 Red, 27 White, 28 Blue, 29 Black, 30 Yellow, 31 Green
32 Black, 33 Yellow, 34 Green, 35 Orange, 36 Red, 37 White, 38 Blue
39 Green, 40 Orange, 41 Red, 42 White, 43 Blue, 44 Black, 45 Yellow

How to Calculate tire diameter: Example 265/60/15

265mm/25.4mm = 10.43 Inches Section Width
10.43 in. X 60% = 6.25 in. Side Wall thickness
6.25 in X 2 = 12.5 in Total Side wall height
12.5 " + 15" (rim Size) = 27.5" Diameter

With this tire size and 3.55 Gears, would use 34 Tooth Speedometer gear

Also make sure that the correct number of teeth installed corresponds to the settings on the outside of the retainer.

Cool! Thanks for the info!!!
A~