66-67 Dodge Charger Source Guide


Axles, Differential and Rear End


Useful Links


Posted by Big Sugar on 09/23/09

These links pretty much cover everything you'll need to know about Mopar rear ends.


http://www.mopar1.us/875.html

http://www.mopar1.us/875rear.html

http://www.mopar1.us/setuprear.html

http://www.moparts.org/Tech/Archive/axle/1.html

http://www.moparts.org/Tech/Archive/axle/11.html

http://www.moparts.org/Tech/Archive/axle/13.html Sure Grip info
Posted by: Curt on 01/16/04

Most Chargers came with 2.94 to 1 or 3.23 to 1. A/C cars would more likely have 2.94s, Non A/C four barrell cars would be more likey to have 3.23s. Cars ordered with towing trailers in mind would likely have 3.23s or lower. If the warranty "Certicard" is in its holder under the hood it might say what axle ratio was original.

Posted by: Gordon on 01/16/04
With 2.76 gears a pedestrian will accelerate faster than you. Had a 3.23, but thought it wasn't good enough for acceleration, but was nice for the highway (70-80mph). I put 3.55 posi on and get real nice acceleration but its about 3200 rpm at 70 mph. Depends on how you want to use the car. When the money is right, I'm going to look in to a Gearvendors overdrive unit and get the best of both worlds.

Posted by: Bryan 0n 11/22/05

Math for your Rear End

MPH = (RPM x TD) / (GR x 336)

RPM = (MPH x GR x 336) / TD

TD   =  (MPH x GR x 336) / RPM

MPH = MILES PER HOUR
RPM = REVS PER MINUTE ON TACH
GR = REAR GEAR RATIO
TD = TIRE DIAMETER (IN INCHES)
Posted by Dan McCormack

A good source for information on rear ends is: www.autohobbydigest.com.

Axle Ratios

Engine
Size 		Transmission
Standard
Optional
Optional SureGrip
Additional SureGrip Option
318 Manual
3-Speed		 2.94 3.23 & 3.55 2.94 & 3.23 -
318 Automatic 2.94 3.23 2.94 & 3.23 -
361 Manual
4-Speed		 3.23
(N.A. w/AC)		 3.55
(N.A. w/AC)		 3.23
(N.A. w/AC)		 -
361 Automatic 3.23
(N.A. w/AC)		 2.94
(Std. w/AC)		 3.23
(N.A. w/AC)		 2.94
383 Manual
4-Speed		 3.23
(N.A. w/AC)		 none 3.23
(N.A. w/AC)		 -
383 Automatic 3.23
(N.A. w/AC)		 2.94
(Std. w/AC)		 3.23
(N.A. w/AC)		 2.94
426 Hemi Manual
4-Speed		 3.54 Std.
w/Sure Grip		 none - -
426 Hemi Automatic 3.23 none 3.23 -

Lower Gear Sets

Posted by: Duane on 03/18/08

This is a spreadsheet that I made to help decide what rear end gear to run with lower gear set and a Gearvendors overdrive. (The best of both worlds IMHO). The top row (yellow) is the rear end gear your want to use.

With the 2.94 rear end and the low gear set, 1st gear will launch like you had a 3.32 rear end (blue row). At the bottom is your RPM's at different speeds for both the factory and the Gearvendors for a 25.85" tall tire (the ones on my car currently). If you have a taller tire the RPM's will be less - shorter tire will be more.

I bought the A&A low gear set as well as some other transmission goodies from different sources (6-pinion output planetary, etc.) Talk to Torqueflite Patty in Washington State and on eBay. He's the man!  I'd highly recommend the low gear set and although I'm still saving my pennies I'd strongly recommend the Gearvendors overdrive.

The OD is a bolt-in and contrary to popular opinion it doesn't split gears like a truck but can be engaged if you desire. When in auto mode, it'll engage when in 3rd and over 40 MPH - just like your OD in newer cars.

TTI makes their cross-over and 'h' pipes to fit with the Gearvendors.

The 727 low gear setup with the OD is the ultimate!  Use my chart to decide what rear end gear works for you.  I bought the hard to find 3.73. With that gear, the 1st launch will be like having a 4.22 and in OD it'll be like having 2.91!!

For all you guys spending $$$ for high horsepower, you may want to consider diverting some of that money for some smart gearing.

 

Rear Axle Removal

Posted by: Andy in OZ on 04/13/06

To get the axles out easily, just remove the retaining bolts behind the axle flanges in the brake area, and refit the wheel to the axle flange with 2 nuts, but refit the wheel backwards or use an old stock wheel.

Just do up the nuts a few turns so the wheel is flopping around still and use the wheel as a slide hammer. Ive done this for 30 years and never had an axle not come out, you have to be a man about how you pull on the wheel though , as there will be corrosion in the housing stopping the bearing from moving. Be careful that the wheel doesn't smack you in the face when the axle lets go ! Also i found that these 8 3/4 housings have an inner and outer seal on the axles. I replaced the inner seal in the housing and refitted everything and two days later the brakes were full of oil. In all my years as a mechanic I've never seen this . Just call your local bearing supplier and they will supply you with bearing kits and inner and outer seals and these have to be (installed). Note that the outer seal must be replaced while you are replacing the wheel bearing and cant be done after without pressing all the bearings off again.

P.S. I've never had to loosen or remove a diff centre or tailshaft to get axles out

Rear Axle Installation

Posted by: Jack Wands on 02/03/04
To reinstall the rear axle assembly:

(1)Install garter seal into axle tube until seated, about 3" into tube. This seal keeps the rear end lube in the pumpkin and away from the axle bearing.

(2) Install dust seal, bearing, and lock collar onto axle shaft, the adjustable dust seal retainer go's on the right side of the car. I don't think it would make a difference which side it was installed on.

(3) Pack the axle bearing with grease. The bearings sit in there own cavity, this will be the only lubrication they will have.

(4) Install paper gasket (silicone) over axle tube studs. Install brake backing plate.

(5) Install foam gasket (silicone) over axle tube studs. Install axle assembly and adjust bearing preload to be .010-.015.

I did not have any luck locating the gaskets at my local NAPA. They can be made or I decided to use a gasket forming silicone product.

Rear Axle Bearings

Posted by: Ron Smith on 02/28/04
Rear Axle Bearings are available thru Mopar Parts &/or the Performance Catalog. It's a sealed bearing kit that is pressed on the axle as are the originals, but once installed, need no further adjustment.

Questions & Answers

Q

 03/01/04
S.C. Adkins: I have been told that the open rear ends gets power to both wheels. If this is true what would be the advantages of having a sure grip differential?

A

 03/01/04
Charger George: The open diff. does transmit power equally to both wheels, but only under ideal conditions. The torque reaction of the rear end housing tends to lift the right rear wheel under hard acceleration. This is why open diff. cars usually will spin the right rear wheel very easily going forward and the left rear wheel in reverse. Also, you have to take into account the fact that both rear wheels do not always rest on the same surface during initial acceleration. If one wheel is on wet leaves or snow it will spin hopelessly with an open diff., while a Sure-Grip T.M. diff. senses the low torque condition and transmits power to the wheel with the best traction. Sure-Grip T.M., Positive Traction T.M., Traction-Lok T.M. and etc. differentials cost more for a reason, because they ARE better, hands down than open diff's.

Q

 08/25/04
Christopher Kruegel - Looking for a new set of heavy duty rear axels for 66 Charger 8 3/4 or info that has worked for you that will be able to hold 600 hp 440.

A

 08/25/04
Bob in Pittsburg : For street use you can get by with a set of 30 spline Moser axles.

A warning is needed. If your going to race this car with 600HP behind it……change to a Dana and then use dana 35 spline axles. An 8 ¾ with 600HP and a heavy car, being raced, is a time bomb. I know that from experience. Four years racing now, 2 years with 575 or more horses, and two 8 ¾ rear ends in the trash. Got a Dana mid last year and no breakage since; I had a violent yoke breakage this year…checked the Dana and it was fine. The 35 spline Dana axles are guaranteed from Moser for life.

Either way, moser axles are reasonably priced, but the stock spline 8 ¾ do not have a lifetime guarantee.