[leeklm]

Originally Posted by FrankieT/A

The rear bushing in the tranny is the shaft support, so with no yoke you will have a lot of play. It must be checked with the yoke installed.

Correct. With the shaft installed, I can get about 3/16" maybe just shy of 1/4" of total play by moving the shaft firmly, but not "torqueing" on it either. I would like to measure the OD of a new yoke to see how it compares to the 1.5" measured on mine.

More testing today... I had been through this last year, but decided to break it all down again. wheels up supported by diff, I did the following:

--Normal
--No wheels
--No drums.
--with no drums, moved the pinion angle up & down a few degrees.

With all of the scenarios, I can get the pitch of the vibration to change, but it never goes away. Always comes on around 60-65, and real steady and more noticeable from 70-100.

Next step I think is "Proven Force", which is our local driveline shop where the shaft was balanced last year. I may just go through the whole drive shaft with new yoke, etc, that way I can get the correct ujoint on the differential side, instead of the Pontiac-to-chevy style, and I will know what I have, instead of the PO's mess.

[428GTO70]

Originally Posted by FrankieT/A

The rear bushing in the tranny is the shaft support, so with no yoke you will have a lot of play. It must be checked with the yoke installed.

I know and that was my point, he said he is moving it around installed.

[428GTO70]

Originally Posted by leeklm

Correct. With the shaft installed, I can get about 3/16" maybe just shy of 1/4" of total play by moving the shaft firmly, but not "torqueing" on it either.

Yeah to me that sounds like way too much play

[leeklm]

Quick update... Brought the driveshaft in. Showed the tech a video of me moving the driveshaft while installed. He brought out a trans shaft, and then noticed my yoke splines had a twist about 3/4 of the way back.

Sales desk just called me back to say the shaft was way out of balance, needed the new yoke (which I planned on) and two new ujoints. About $200.

I suggested I had no issues with this at all, but why was it delivered to me in this condition last year from their shop after a standard balance? His comment was "no way did this shaft leave our facility in this condition". As I mentioned, my company does a great job as well 99% of the time, but there is always a case when someone having a bad day screws it up. He agreed and of course we moved forward with repairs. If what he says is true, I can only assume the previous guy spun it up and balanced as-is, similar to balancing a bad tire mounted on a bent wheel. you can balance it, but the end result is still messed up. (only guessing here)

As mentioned earlier in this thread, I have always had the vibration, even after the last balance. BUT, I will be very happy if this takes care of the problem!!

Wish me luck!

[428GTO70]

Good Luck! I hope you got it all worked out.

[grandville455]

Awesome Lee!!, Sounds like u found it!

[1969GTO]

just listining in

[Qball]

Originally Posted by 1969GTO

just listining in

Same here. Hope you have your solution.

[leeklm]

... and 3 amen's! Put the newly fixed drive shaft in and could immediately feel a difference in how tight the yoke fit in the trans. Spun it up on jack stands and while not as smooth as a modern car, much better (did have my drag slicks on, with not so perfect rims).

Took a test drive and wow, what a difference! Nice smooth ride, even at slower speeds where I did not think I was feeling the vibration.

I wonder, as it relates to my recent chassis dyno results, would a driveshaft this out of whack impact my HP numbers to any noticeable difference?

It is frustrating that the first guy to balance the drive shaft last year gave me a POS. I have spent hours tracking this issue down but on the bright side, I am sure I learned a few things along the way. I am just happy that it is fixed!!

Thank you everyone for the feedback and advice!

[Blued and Painted]

Now im thinking I need a new drive shaft.

[428GTO70]

Grats! I knew that sounded like too much movement, glad it worked out for you! You going to have the car at Car Craft?

[leeklm]

Crossed my mind, but that event always looked like a pita to have your car at... Have you done it? I do hope to get out to Rock Falls this wknd for a couple of runs.

[428GTO70]

Yeah I plan on bringing my GTO. As long as your car can handle idling through the fair for an extended amount of time in potentially hot conditions to find a place to park you should be fine. There's a lot of nice cars to see, its fun to bring a car in....pack a cooler make a day out of it.

[PMD1969]

Originally Posted by leeklm

... and 3 amen's! Put the newly fixed drive shaft in and could immediately feel a difference in how tight the yoke fit in the trans. Spun it up on jack stands and while not as smooth as a modern car, much better (did have my drag slicks on, with not so perfect rims).

Took a test drive and wow, what a difference! Nice smooth ride, even at slower speeds where I did not think I was feeling the vibration.

I wonder, as it relates to my recent chassis dyno results, would a driveshaft this out of whack impact my HP numbers to any noticeable difference?

It is frustrating that the first guy to balance the drive shaft last year gave me a POS. I have spent hours tracking this issue down but on the bright side, I am sure I learned a few things along the way. I am just happy that it is fixed!!

Thank you everyone for the feedback and advice!

Did you drive it up to 65-70mph and note any change?

[leeklm]

Originally Posted by PMD1969

Did you drive it up to 65-70mph and note any change?

Got up to about 80 and yes, noticed a BIG change for the better.