66-67 Dodge Charger Source Guide


Speedometer

Cable

Posted by Wes on 04/01/08

NAPA #615-1605

Posted by Ron Bianchi on 12/5/07

I purchased a new inner and outter spodo cable with lube from Advance Auto Parts, part number 03152 measured against my old cable at 62 inches.
 
Cost $ 11.00 plus tax.
 
Advance computer called out for a 81 1/2 inch inner and outer cable for a 1967 Dodge Charger, and 1967 Coronet, at $ 15.00.


Posted by Steven Drake on 09/10/03

Jim's Auto Parts catalog: a speedometer cable for 67 down, all A,B & E bodies is $19.00 Black casing( as original) and $24.00 gray casing. This price also includes the firewall grommet.

Jim's Auto part number :TR-1463B black TR-1463G gray
Jim's is out of N.H. and are open M-F 10am to 6pm and of course 24hrs on-line.
(603)-898-0535 or jimsautoparts.com


Pinion Gear Location

Posted by Ken Scobel on 03/20/06

The speedometer gear is located in the extension housing on the rear of the transmission. Its easily located by the speedometer cable that connects to it. Clean any dirt off the adaptor so you can see the adjustment marks and how it is lined up. Unscrew the cable and remove the bolt that attaches the hold-down clamp. Make sure you have a pan ready to collect the trans fluid that will come pouring out when you pull the adaptor/gear out. Based on your tire size and the 3.23 axle you have, you need a 34 tooth gear which is green in color. The tooth number is actually cast into the gear for easy identification. Reinstall by reversing the procedure. The numbers on the outside of the adaptor correspond to the tooth count on the gear. Line this up with the small mark at the bottom of the hole and reinstall the hold-down, bolt, and cable. If you don't have a 34 tooth gear, they can usually be found at your Dodge Dealer.



Posted by  Musicman on 05/07/09

There's about a million speedometer gear calculators available on line. Here have yourself a ball...

http://www.tciauto.com/Products/TechInfo/speedo_gears.asp

Posted by Musicman (again) on 7/26/09

You can remove the speedometer from the cluster and oil the shaft. You will have to carefully remove the brass plug using a knife or razor to get under the lip and raise it enough to grab it. Under that is a cloth plug which can be removed with a pair of tweezers or a pin,etc. Spray some cleaner in there to remove any old sludge, and then oil it up with some lightweight machine oil. Soak the cloth plug in the oil and put it back in. Reinstall the brass cap and your done. The assembly should be fine after that, assuming it wasn't damaged already.


Posted by Duane Pankhurst on 08/24/05

Scanned from Stewart Warner Factory Design Drawing

Readings and Function

Posted by Greg Rose on 12/07/03 and updated on 02/16/04

The cable turns a magnet that in turn moves the speedo needle. The clock spring holds the correct amount of tension to cause the magnet to "slip" enough to read the right MPH. The cable (and pinion) turns at 1000 revs per mile

I'm gonna assume the MPH thing you measured is gospel (i.e., clock spring adjustment is spot on). I'd rather you drove a know distance, say between 10 mile markers, and record your odometer reading - then decide what that difference is.

First - count the teeth in the gear you now have (forget the colors for now) .Your speedo is off by 12 MPH or 21.8%. You need 21.8% MORE teeth (in the future remember fast=MORE, slow=LESS). Assuming your current pinion gear has 34 teeth you need 34 X 0.218 = 7.4 more teeth or 41 teeth. By the way, that's P/N 2538941 (red). Seems like an awful lot?! Read further.

HOW TO TRUE-UP YOUR SPEEDO

A little background on the Chrysler speedo. The pinion gear in the tranny case is correct when it turns the speedo cable 1,000 revolutions per mile. So the other end of the cable in the speedo spins a magnetized bar at 1,000 revolutions per mile. The magnet causes the speedo needle to move as it spins. A clock spring applies the correct tension on the needle to assure accuracy and prevent it from bouncing wildly, thus smooth operation. The speedo also steps the cable down by 1000:1 so it turns the tenths odometer wheel one full revolution per mile. The tenths wheel then moves the next wheel (miles) one tenth of a revolution, and so on, and so on. The key is to match the pinion gearing to achieve 1000 revs per mile. In order to do this we need a standard to match the speedo against. It can be done on a bench with a known motor RPM driving the speedo - but that won't account for your "in-car" set-up of wheel height, rear gear ratio, etc. The following method will account for these variables and result in a very accurate gauge. One last thing - I've heard many discussions on using wheel height, rear gear, tranny final gear ratio, etc. and doing the pure math based calculation. You can get close, maybe right on it - but I believe the following method to be the easiest and absolutely most accurate. Okay, here we go:

1. Record your beginning odometer reading to the nearest tenth of a mile (if you'd like to estimate between tenths- even better!)

2. Drive a known distance. Mile marker are great for this. Drive at least 2 or 3 miles. 10 is better and the math is easy, too!

3. Record your ending odometer reading as in Step #1 above.

4. Pull the pinion gear from the tranny by removing the speedo cable and the adapter clamp bolt. Slips right out. Watch for the red flood - tranny fluid. I like to put the rear end on jack stands to move the fluid to the front and spill less. Anyway - count the teeth of the pinion gear.

5. We now have all the data we need to "get accurate"! Here's the example:

Current Pinion Gear Teeth = 33



88436.25 miles - ending reading from odometer (I've estimated 5 or about a half turn of the tenths)
- 88424.65 miles - beginning reading from odometer (ditto estimate)

___________

11.60 miles - miles driven according to odometer
- 10.00 miles - actual miles driven (10 mile markers)

___________

1.60 miles TOO FAR!

6. 1.60 miles too far divided by the actual distance of 10 miles = 0.16 OR 16% ; our speedo is reading 16% HIGH - OR TOO FAST. We need 16% more teeth!

7.

33 teeth as tested
x 0.16

_______

5.28 additional teeth needed

33 + 5 = 38 teeth.

The pinion gear with 38 teeth is P/N 52068060 (blue)

8. Change out the 33 tooth pinion gear for a new 38 tooth gear and BINGO - we are spot on. Do the test over to confirm and happy motoring!!

This doesn't promise an absolutely accurate speedo, as the clock spring tension is the adjustment for that. If the clock spring is okay and the main reason for the inaccuracy was a tire size change or rear gear change - bet you're in fine shape. The speedo clock spring tension can be adjusted (more tension = slower reading, less = faster) but it's a delicate process that might be best left to a speedo shop.