Original 67-69 Camaro driveshafts - information requested about your car

[bcmiller]

If you could...please measure from the center of one u joint to the center of the other.

Another way of saying that is "the center of each cap or cup that holds the needle bearings for the u joint".

[bcmiller]

Still soaking but I am starting to see the paint stripes better and better.. 

Looks good!  Thanks for the pic! 

[bcmiller]

Would really like to have more data on any late 68 or 69 cars with the TH350 transmission.

[bcmiller]

Bump

[cam69aro]

i can offer some info on my `69z, needs all the rubber replaced on the brake system so i`ll have all the wheels off it soon and will take some pics for you if needed. i can see the stripes on the driveshaft just looking under it so i know there is at least one visible.

[bcmiller]

That would be great Eldon. It most likely has one orange and one white stripe, but if you could confirm, I would appreciate it.

[cam69aro]

will do, I`m bringing it to the Street machine nationals this weekend in St.Paul Mn. so when the show is done sunday it`s time for the brake restoration.

[bcmiller]

Eldon, did you have time to check your driveshaft? 

[bcmiller]

Bump.

[19674KCamaro]

Does anyone have any info on the driveshaft for a 1967 L78 4K Camaro?  Trying to verify mine.

[Everett#2390]

The question is why are the U-joints out-of-phase?

The answer is for reducing vibrations.
Graph the power through a single U-joint and a sine wave is drawn. The joint speeds up, positive arc, and slows down, negative arc.
Add another U-joint and its power graph will have the same sine wave.
Add the two sine waves, if they are in-phase on the same shaft, and amplitude doubles, meaning the resultant twist is noticeable.
By offsetting one joint by 30°, decreases the amplitude of the associated twist, less vibration.
Now, driveshaft's having been built forever, and 1st Gen driveshaft's are different from typical design, may be due to the extreme angularity of drivetrain design on Camaro, i.e., wheelbase, length of shaft, OD and wall thickness, and critical speed of driveshaft.

Critical speed is important - it is rocket science. JMT's

[bcmiller]

Does anyone have any info on the driveshaft for a 1967 L78 4K Camaro?  Trying to verify mine.

What are the specs on the one you have?

[bcmiller]

The question is why are the U-joints out-of-phase?

The answer is for reducing vibrations.
Graph the power through a single U-joint and a sine wave is drawn. The joint speeds up, positive arc, and slows down, negative arc.
Add another U-joint and its power graph will have the same sine wave.
Add the two sine waves, if they are in-phase on the same shaft, and amplitude doubles, meaning the resultant twist is noticeable.
By offsetting one joint by 30°, decreases the amplitude of the associated twist, less vibration.
Now, driveshaft's having been built forever, and 1st Gen driveshaft's are different from typical design, may be due to the extreme angularity of drivetrain design on Camaro, i.e., wheelbase, length of shaft, OD and wall thickness, and critical speed of driveshaft.

Critical speed is important - it is rocket science. JMT's

The aren’t all “clocked” or out if phase.

[Everett#2390]

The aren’'t all “clocked” or out if phase.

True, I would think it depended upon application/options.

[rich69rs]

The question is why are the U-joints out-of-phase?

The answer is for reducing vibrations.
Graph the power through a single U-joint and a sine wave is drawn. The joint speeds up, positive arc, and slows down, negative arc.
Add another U-joint and its power graph will have the same sine wave.
Add the two sine waves, if they are in-phase on the same shaft, and amplitude doubles, meaning the resultant twist is noticeable.
By offsetting one joint by 30°, decreases the amplitude of the associated twist, less vibration.
Now, driveshaft's having been built forever, and 1st Gen driveshaft's are different from typical design, may be due to the extreme angularity of drivetrain design on Camaro, i.e., wheelbase, length of shaft, OD and wall thickness, and critical speed of driveshaft.

Critical speed is important - it is rocket science.

I have to disagree - that’s not how a double Cardan joint (U-joint) works.  Refer to page 3, 3rd post of this thread and search : driveshaft, rich69rs for other posts where this has been discussed previously.

I have my theory as to why Chevy did this - but since the forum hasn’t pursued the question seriously,  I haven’t either.  Of all the driveshafts built by all the auto makers, over all the years, ‘69 Camaro, SB, TH350, manual, and Powerglide got offset yokes, yet, as I recall BB w/TH400 transmissions didn’t???

As far as critical speeed (resonance) goes, offsetting the yokes will definitely stiffen the driveshaft and shift a natural frequency(cies) up - but at the expense of proper operation of a double u-joint system which is designed to keep the included angles of the driveshaft equal at all times.

With offset yokes, the included angle between the differential and the driveshaft will be different at all times from the included angle between the driveshaft and the transmission.  Stiffer driveshaft system? Undoubtedly.  Ideal for loading on either the diff or tans?  Not so much.  I modified my driveshaft to in line yokes back in 1991.