‘69 Mustang Mach 1 rear axle ID?

[Vanspeed]

Have a Mach 1 in the shop. From all I have read they came with a 3.91 or 4.30. This car has the tag on the door which indicates it truly is a 428, ‘69 Mach 1 but the axle letter is an R that indicates a 3.25. Were axle ratios beside the 3.91 and 4.30 put into these? According to the tag I say yes but not from info I read.

[Randy in ca]

From a reliable source:

For 1969 Mach 1:

An open 3.00 axle (code 6) was standard; with Traction-Lok, it's code O (that's letter O, not "zero"). An open 3.25:1 was code 9, while a Traction-Lok 3.25:1 wore code R. Open 3.50s were stamped with code A, while Traction-Lok 3.50:1 models wore code S. Code V signifies 3.91 with Traction-Lok, while a "W" means 4.30 with Traction-Lok.

[rotorwrench]

Most young owners of these cars wanted them to launch well so highway gearing was a fly in the ointment. The big FE will pull well enough with 3.25:1 but it won't be a rocket ship off the line. It'll work damn good on the highway though. It just depends on what the owner wants it to do and whether originality is important.

[packrat5]

If this is an automatic car, it is the best all around gear for it.

[KULTULZ]

Originally Posted by Vanspeed

Have a Mach 1 in the shop. From all I have read they came with a 3.91 or 4.30. This car has the tag on the door which indicates it truly is a 428, ‘69 Mach 1 but the axle letter is an R that indicates a 3.25. Were axle ratios beside the 3.91 and 4.30 put into these? According to the tag I say yes but not from info I read.

‘Drag Pack - 428CI SCJ’

Ford described the option’s content as, “Includes Traction-Lok differential, 3.91 or 4.30 high ratio axle, and the following 428 CID engine modifications: engine oil cooler, cap screw connecting rods and modified crankshaft, flywheel and damper. Available only with 428 CID 4V Non-Ram or Ram air engines. Not available with other optional ratio axles or air conditioning.”

SOURCE- https://www.stangtv.com/features/car...scj-drag-pack/

MACH 1 was a high trim level. One had to be ordered with the 428CJ option above to have a 3.91 or 4.30 rear gear.

[scicala]

Sponsored Links (Register now to hide all advertisements)

Somebody please clear the confusion for me. Only answer if you are sure. I always thought a CJ was a 428 and a SCJ was a 429 (different engine family) ?


Anyone know if I am right or wrong ?


Sal

[KULTULZ]

Do I qualify?


Both the FE 428 AND 385 429 came through either CJ or SCJ.


Depended on how much insurance money you had at that time period.

[rotorwrench]

The SCJ had a drag pack oil cooler installation so it was an extra added option configuration over and above the CJ. There are also crankshaft set up differences. Here is a link. https://www.428cobrajet.org/cj-vs-scj

This doen't mention much about the 429 though but I don't know if they were available in 1969 in CJ configuration. Another link. http://www.hcdmag.com/429-cobra-jet-engine/

[scicala]

Thanks KULTULZ and rotorwrench,


Sal

[KULTULZ]

Just to add more confusion, there was also a 351 CJ (72-74)

[scicala]

Yes, I've heard about the 351 CJ on the later Mustangs. I was reading the links that rotorwrench sullied, and the power output on the 428 CJ and the 428 SCJ was the same. The difference was stronger parts in the SCJ.


Sal

[24ruxstel1339]

I believe the only 429 engine Mustang option in 69 was the BOSS 429...

[5851a]

I believe AC would limit rear axel ratios also sometimes.

[rotorwrench]

The Boss types are extremely rare. The whole front end was modified to fit the engine and Kar Kraft put them in under contract. Ford had to put out 500 engines to qualify it for NASCAR. 859 units were produced so there aren't too many out there. They didn't have all the fancy frills of the Mach 1 so they weren't in that category. They were all business with that motor and all had the 3.91:1 axle with 4-speed transmission. They also put the engines in the Mercury Cougar but those two are really rare.

[scicala]

According to the 429 link above from rotorwrench, the new 385 series 429 came out in '68. The 429Cobra Jet was available in '69 and the SCJ 429 in '71. I guess the 351 CJ took it's place in '72.


Sal

[scicala]

Also can't forget about the '71 only Boss 351 Mustangs.


Sal

[KULTULZ]

Originally Posted by scicala

According to the 429 link above from rotorwrench, the new 385 series 429 came out in '68. The 429Cobra Jet was available in '69 and the SCJ 429 in '71. I guess the 351 CJ took it's place in '72.

Sal

The 385 Series was introduced in the 1968 model run, the 429 going to FORD/MERC and the 460 to LINC.

The 429CJ was introduced to the FAIRLANE/TORINO body in 1970 as there was a sheet metal redesign to accept the larger engine. The 1970 MUST still offered the 428CJ as it's sheet metal platform was not enlarged until the 1971 model run.

The 429CJ was introduced in 1970, the 429SCJ 1971.

The 1971 351C BOSS was 1971, the de-tuned 351C HO in 1972 and the 351CJ (lowered CR - emissions compliant) also in 1972.

[scicala]

Your right, I mis-read the link above. The 429 CJ was first available in '70, not '69.


Sal

[craig]

There were no 429's in any factory Mustangs until the body change in '71, EXCEPT, the Boss 429. There were 859 produced in 1969 and 499 produced in1970. These engines used a hemi type head, nothing on the top end is the same as a conventional 385 series engine and the front suspension was heavily modified to make it fit. In '71 the engine compartment grew and an original design 385 series 429 would fit. By then the Boss version was gone