1969 z/28 driveshaft

[asm69]

How can you ID the driveshaft on a 1969 z/28. Is the diameter different? Is the lenght different? Are
their any identifying marks or paint dabs on it to ID it?

Thanks

[RamAirDave]

I dont know the physical dimensions, or if there was much/any difference between one that went on a Z or another type.  Obviously, BB/SB, trans type, and maybe rear axle type would determine which driveshaft.

Heres an 69 Z M20 driveshaft, with markings.  It seems to be pretty consistent with others:

[william]

For 1969 the driveshaft was common to all 1969 Camaros built with a Muncie 4-speed according to the P & A manual. 67 & 68 driveshafts are longer and do not interchange.

What they did in production may have been another issue. Z/28 driveshafts often have offset yokes while most others did not. They may have been balanced to a higher rpm.

[rich69rs]

I disagree with the statement that Z/28 driveshafts often have offset yokes while most others did not. To date, through this forum, for 1969 (and 1st Generation in general), it appears that only BB cars with TH400 transmissions had "normal" driveshafts with the yokes in line. 

As discussed recently, offsetting the yokes in a driveshaft is very unusual, and is not how one normally would build a driveshaft.  Matter of fact, just the opposite is true.  You want the yokes in line to cancel out the normal torque and rpm variations (especially problematic at 2X rpm) that exist between the driving and driven ends of a "cardan type"  mechanical coupling (driveshaft).

See posts at this link: http://www.camaros.org/forum/index.php?topic=914.0

Best "guess" that I've heard to date was that offsetting the driveshaft yokes was done in order to help stiffen the rear end without, hopefully, causing driveline problems.  It is well documented in various souces, including Untold Secrets that the higher horsepower cars had handling and rear suspension issues (axle wrap and wheel hop) - especially in 1967.  Some of GM's cures beginning with the 1968 model year included:  staggered rear shocks and  multi-leaf/multi-rate rear springs.

GM had a reason - hopefully it will be one of those things that we all will want to fully understand.

[william]

We had a Camaro parts business for 15 years and always kept driveshafts from parts cars for resale. In line yokes are the norm. When my 69 Z/28 driveshaft [offset yokes] needed to be replaced due to previous abuse my good friend Stevie at D & R provided me with the 'shaft out a L35 parts car-in line yokes.

[rich69rs]

I know nothing about BB cars, but isn't L35 a 396?  As I stated above, as well as what has been stated from those that have contributed at the referenced link above, in line yokes appears to have been the norm for the BB (396) cars with TH400.  What you have stated dovetails perfectly with those observations, i.e. the small block Z28 had offset yokes, the big block L35 had in line yokes. 

The other posts at the above link also report that the SB cars had driveshafts with offset yokes (including one for a 307 which also had a torsional damper on it - the addition of a damper for certain applications is shown in the '69 service manual.)   For example, why does VIN 124379N581767 (01C build) and 124379N551248 (late Nov '68 build), both base coupes, one with powerglide and one with 3 spd manual have original driveshafts with offset yokes?  First car is mine, second car was being scrapped and is the car that I pulled the 327 engine from that currently is in my car.  I also kept the driveshaft - still have it. Up to that time, I had assumed that the driveshaft in my car was a manufacturing error.  Then lo and behold a second base coupe with the same offset yoke driveshaft.

This has been my question all along - why did GM/Chevy do this in the first place and why did they apply it to a wide variety of SB V8 - far beyond Z28 only.

Based on the contributions of all who have commented on this topic, I would agree that in line yokes seems to have been the norm for 396 with TH400.  However, it also appears that the majority (if not all) other applications had offset yokes - a much wider useage than for Z28 only - why?   Can't ignore the fact that several base Camaros came with these driveshafts as well.

[william]

I'm not nagging but there were almost 700,000 1st gen Camaros built and conclusions are being drawn based on a couple dozen datapoints.

I've been involved with the cars for over 30 years and the Z/28 driveshaft issue has been out there for as long as I can remember. It became an issue because most driveshafts at the time had in-line yokes. 30 years later we still do not know why some were different.

[RJ_RS_SS_350]

this one appears to be offset as well  http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330006745349

[rich69rs]

William -

Thanks for your insight.   

May not have all of the data points we'd like - but sure seems to be a trend - of some sort.

This is so "out in left field" from the norm that it seems almost a no brainer that this should be a CRG research topic - just my two cents worth. 

Based on my own experience, I still contend that offset yokes will, at the very least, lead to premature failue of the u-joint cross /  bearings and in the worst case possible tranny or rear end damage - depends on mileage, how hard the car was driven, etc. 

Do you know what caused the damage to your original driveshaft?

[william]

Yup; car had bars and big rubber on a "BO" code 3.73 open.

Something broke, probably the rear U-joint, and when the driveshaft got loose it acquired a dent. The blacksmiths that repaired it re-installed the now-unbalanced driveshaft, trashing the pinion bearing. When I acquired the car everything in the housing went in the dumpster.

In all my years I have never heard of a driveshaft failure on a more or less stock 1st gen. 2nd gens are another issue. A friend twisted one into a knot on a '70 Z28.

[RamAirDave]

Another example I looked at today, if it matters:

09A (of 69), base 307/TH350.  Original driveshaft, offset yokes.


dave

[asm69]

my drive shaft may be original. It has two yellow stripes towards the center of the shaft. How can I
identify if the yoke is offset. What do I look for?

[rich69rs]

In line yokes would be as shown in this diagram - in the same plane end to end - no angular offset

[nuch_ss396]

Yes, an L/35 is a 396 ( 325hp ).  The bigger question there is if the car had a THM400.  That would tell us more.

All of my research over the years has indicated that only THM400 ( big blocks ) used the in-line yoke driveshaft.
There has NEVER been as explaination as to why this is the case.  I have looked into it many times myself.

I also agree that this should be a research topic.  We should poll all the members here to go look under their cars
and report back with their findings.  That in itself will not be conclusive proof, unless you know for sure you have
the original driveshaft.  I might suggest that this topic be posted on yenko.net since some members there have
original cars as well.


In my case, I am positive I have the original driveshaft on my car and I will go look today and report back.

Steve

[nuch_ss396]

Hey guys!

I just conversed with the owner of a low mileage L/34 '69 Camaro that has a 4-speed in it.  I'm sure he will chime in at some point.
His original driveshaft is offset as we've discussed here.  Additionally, he recently verified an original L/48 Camaro at the Camaro Nationals
and it too has the offset driveshaft.  Stay tuned.....  More to come......