Topic: 68 Driveline Discussion - Big Block Auto and 4 speed Discussion

[Bob Gaines]

Does anyone think that there is a difference between the auto vs 4 speed 68 BB driveshaft other then the front slip yoke ?

[Coralsnake]

Yes

[Bob Gaines]

Yes

Would you please elaborate.

[Coralsnake]

Shirley, Mr. Gaines!

The 390, 428 cars and the Cobra Jet driveshafts are different.  Maybe Mr. Speegle has a build sheet for a 390/4spd ? All information below is specific for 1968:

390  / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
390  / 4spd trans / P. No. C7ZZ-4602-C / ID markings ? ? ?

428 Police Interceptor / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
428 Police Interceptor / 4spd trans / P. No. C8ZW-4602-E / ID markings White / Orange / Yellow

428 Cobra Jet / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
428 Cobra Jet / 4spd trans / P. No. C8ZZ-4602-B / ID markings Azure / Orange / Yellow

Information comes from MPC and build sheets.

[Bob Gaines]

Shirley, Mr. Gaines!

The 390, 428 cars and the Cobra Jet driveshafts are different.  Maybe Mr. Speegle has a build sheet for a 390/4spd ? All information below is specific for 1968:

390  / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
390  / 4spd trans / P. No. C7ZZ-4602-C / ID markings ? ? ?

428 Police Interceptor / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
428 Police Interceptor / 4spd trans / P. No. C8ZW-4602-E / ID markings White / Orange / Yellow

428 Cobra Jet / Auto trans / P. No. C8ZZ-4602-C / ID markings Lt. Blue / Dark Blue / Red
428 Cobra Jet / 4spd trans / P. No. C8ZZ-4602-B / ID markings Azure / Orange / Yellow

Information comes from MPC and build sheets.

I was expecting to hear a answer to my question "difference between the auto vs 4 speed 68 BB driveshaft other then the front slip yoke" . Paint marks are all good and fine but I would like to know the difference beyond the paint marks. 

[TLea]

I was expecting to hear a answer to my question "difference between the auto vs 4 speed 68 BB driveshaft other then the front slip yoke" . Paint marks are all good and fine but I would like to know the difference beyond the paint marks.

OK I'll do it. Different slip yoke, different lengths

[Bob Gaines]

OK I'll do it. Different slip yoke, different lengths

Different slip yokes is a given since that was in my original question . So you are saying that the only other thing is the main body length is different between 4 speed and auto disregarding the slip yoke? 

[Coralsnake]

Each driveshaft has different dimensions and weights. I suspect a 4 spd toploader is not the same dimensions as the C-6.

Different colors = different driveshafts

Different part numbers = different driveshafts

Different driveshafts = different dimensions (length and diameter)

Its why you dont take the 6 cylinder driveshaft and try to run it on a Cobra Jet car.

[Bob Gaines]

Each driveshaft has different dimensions and weights. I suspect a 4 spd toploader is not the same dimensions as the C-6.

Different colors = different driveshafts

Different part numbers = different driveshafts

Different driveshafts = different dimensions (length and diameter)

Its why you dont take the 6 cylinder driveshaft and try to run it on a Cobra Jet car.

Pete , I get the distinct impression I am getting chastised for even asking the question given the sarcasm. Of course we know different colors ,different part numbers . There is no reason for the six cylinder sarcasm because the length ,u joints and I think diameter are all noticeably different toward the weaker end of the spectrum. My question was in the context of since because of the constants (dimensional any why) which are the transmissions, the rear end and I have always thought the U joints  and driveshaft tube on 428 68 Mustang for instance . Why so many different driveshafts . I think it would be considered a reasonable thing to ask a question about given those constants. You would think one would fit all with C6 auto and one would fit both big output 4 speed. I know there has to be a engineering difference hence the 3 different auto and 2 different big output 4 speed numbers . I am not 100% for sure if the 390 C6 uses the same 31 spine slip yoke. If the 390 uses the smaller 28 spline version that would skew the results. As far as balance I would be surprised if you could get two of the same part number driveshaft to balance exactly the same way with the same weights in exactly the same position on the tube.  If someone has some insight I would like to hear about it.

[J_Speegle]

Not sure if we've move far enough off of the original question that we're discussing only 68 big block drivelines, all 68 drivelines or .......

Depending on the time period we do have different diameters (tapered or untapered), different ends and if we move out of the BB range tube in tube or one tube styles.

If I've lost the core focus - let me know and I'll delete

[Bob Gaines]

Not sure if we've move far enough off of the original question that we're discussing only 68 big block drivelines, all 68 drivelines or .......

Depending on the time period we do have different diameters (tapered or untapered), different ends and if we move out of the BB range tube in tube or one tube styles.

If I've lost the core focus - let me know and I'll delete

I thought the tapered automatic BB tube started in 69 model year.

[Coralsnake]

I am not sure why you perceived sarcasm as none was intended. You implied that while the paint markings were
different there was little or no difference in the actual parts.

I am only reporting information based on what I have seen and researched.

I am sure if Ford thought they could consolidate the driveshafts they would have. They paid engineers a lot smarter than me to figure those things out.  I was merely answering your question...was there a difference between auto vs 4spd driveshafts?  The answer is “yes” as demonstrated by the multiple part numbers, color codes and dimensions.

I also suspect that just like the differences between the 6 cylinder and a CJ, there are differences in horse power and torque, gear ratios, etc., between the other engines. As new engine/ trans combinations were developed, the driveshafts were changed accordingly.

I guess you could make the arguement a 4spd driveshaft is like an automatic driveshaft, but it would be factually incorrect in my opinion.

[Bob Gaines]

I am not sure why you percieved sarcasm as none was intended.

I am only reporting information based on what I have seen and researched.

I am sure if Ford thought they could consolidate the driveshafts they would have. I was merely answering your question.

And good research it is. I suppose the sentence   "Its why you dont take the 6 cylinder driveshaft and try to run it on a Cobra Jet car" statement is what I mistook as sarcasm.   You must have missed where I said  "I know there has to be a engineering difference hence the 3 different auto and 2 different big output 4 speed numbers ."  I was not questioning Fords engineering wisdom but was trying to have identified the things that makes them different for my own understanding.

[Bob Gaines]

I am not sure why you perceived sarcasm as none was intended. You implied that while the paint markings were
different there was little or no difference in the actual parts.

I am only reporting information based on what I have seen and researched.

I am sure if Ford thought they could consolidate the driveshafts they would have. They paid engineers a lot smarter than me to figure those things out.  I was merely answering your question...was there a difference between auto vs 4spd driveshafts?  The answer is “yes” as demonstrated by the multiple part numbers, color codes and dimensions.

I also suspect that just like the differences between the 6 cylinder and a CJ, there are differences in horse power and torque, gear ratios, etc., between the other engines. As new engine/ trans combinations were developed, the driveshafts were changed accordingly.

I guess you could make the arguement a 4spd driveshaft is like an automatic driveshaft, but it would be factually incorrect in my opinion.

Pete, you mis interpreted my question "Does anyone think that there is a difference between the auto vs 4 speed 68 BB driveshaft other then the front slip yoke " . I wasn't asking to compare one to the other but given the auto slip yoke is different then the manual slip yoke the question was for example what was different between the 428 PI auto drive shaft compared to the 428 CJ auto drive shaft ? The same question was for the Manual CJ vs PI drive shaft. This is course beyond paint markings and part numbers. I suppose I could have been more clear if I would have used the example to begin with.

[Coralsnake]

I thought that extreme difference would illustrated the differences to the reader. As you so wisely pointed out, there are many factors as to why each has its own application.  The difference between the driveshafts may not be significant, but it does exist.