I have a 1967 D100 318 3 speed. I switched out the rear end from a 355 to a 272 and need to swap the speedometer gear to accommodate this change.
I think it has an A745 tranny but you can see my discussion about that here...
viewtopic.php?f=19&t=43386
Can I swap the gear? Do you know what size I need and where to get it?
Jeff, not a mechanic
Speedometer gear to adapt to rear end change
- 67D100Pickup
- Sweptline.ORG Member
- Posts: 126
- Joined: Wed Sep 23, 2020 12:44 pm
- City: Noble
- State: OK
- martincom
- Sweptline.ORG Member
- Posts: 448
- Joined: Thu Jul 30, 2020 10:04 am
- City: Five Points
- State: AL
Re: Speedometer gear to adapt to rear end change
The transmission type will not make a difference.
In addition to rear axle ratio, you'll need to know tire size. The factory service manual will have a chart which will indicate the number of teeth required, for the speedometer pinion, for a given rear axle ratio and tire size. There are also a number of online charts. Search for Mopar speedometer pinion chart or Chrysler speedometer pinion chart.
The housing the speedometer pinion is inserted to will have tooth number range marks. Be sure to align the appropriate range index mark with the index mark on the tail shaft housing.
Also, lift the vehicle from the rear only when changing. This causes the fluid to pool at the front of the transmission and you will not get a bath of it when removing the speedometer pinion housing.
Ebay and a number of online suppliers offer speedometer pinions.
In addition to rear axle ratio, you'll need to know tire size. The factory service manual will have a chart which will indicate the number of teeth required, for the speedometer pinion, for a given rear axle ratio and tire size. There are also a number of online charts. Search for Mopar speedometer pinion chart or Chrysler speedometer pinion chart.
The housing the speedometer pinion is inserted to will have tooth number range marks. Be sure to align the appropriate range index mark with the index mark on the tail shaft housing.
Also, lift the vehicle from the rear only when changing. This causes the fluid to pool at the front of the transmission and you will not get a bath of it when removing the speedometer pinion housing.
Ebay and a number of online suppliers offer speedometer pinions.
1*1971 D100 318 A/T
1*1970 Charger R/T 440-6PK A/T
2*1969 Daytona Charger 440 A/T
1*1969 Coronet R/T awaiting restoration
1*1969 Torino Talladega awaiting restoration
1*1970 Charger R/T 440-6PK A/T
2*1969 Daytona Charger 440 A/T
1*1969 Coronet R/T awaiting restoration
1*1969 Torino Talladega awaiting restoration
Re: Speedometer gear to adapt to rear end change
Do these older truck transmissions use the same speedometer pinions as cars of the same era?
If so, some list the tooth count on the gear while newer versions list the last two digits of the part number.
If so, some list the tooth count on the gear while newer versions list the last two digits of the part number.
- martincom
- Sweptline.ORG Member
- Posts: 448
- Joined: Thu Jul 30, 2020 10:04 am
- City: Five Points
- State: AL
Re: Speedometer gear to adapt to rear end change
I would speculate it depends on your definition of "old" and the size of the truck.
I haven't seen that before. All I've encountered have the tooth count molded into them. I wonder if the other is a repop?
1*1971 D100 318 A/T
1*1970 Charger R/T 440-6PK A/T
2*1969 Daytona Charger 440 A/T
1*1969 Coronet R/T awaiting restoration
1*1969 Torino Talladega awaiting restoration
1*1970 Charger R/T 440-6PK A/T
2*1969 Daytona Charger 440 A/T
1*1969 Coronet R/T awaiting restoration
1*1969 Torino Talladega awaiting restoration
Re: Speedometer gear to adapt to rear end change
Not a reproduction, same part from a newer OE application.