Drive Line Angle will drive you crazy

[Sixpactogo]

All the different angles will drive you nuts. Cass at Dr Diff. told me the easiest way was to forget about the driveshaft angle. Put a digital angle finder on the flywheel pulley. Write down that angle. Drop the drive shaft and put a 5/8" long barrel socket in the U cups of the Pinion and write down that angle. If you have leaf springs you have to consider 2-4 degrees of axle windup. That said, if you have your pinion angle down a couple degrees from the front pulley angle, you should be in the ballpark. Driveshaft angle does not even need to be considered. IMO, your first angle measurement are in the ballpark. Your issue (as others have mentioned) is in your drive shaft itself. That dent in post #9 concerns me the most. I would have it re-tubed and balanced by a reputable shop. Bet that takes care of your tremble @ 80.

 

[70bigblockdodge]

What are you calling me a gorilla?
The yokes being tweaked could be part of the cause of failing a U- joint around 2,000 miles. (well creating more radial play than I was comfortable with.)

Thanks for the input

I was speaking of nice work with the measurements.
Always good get the details right, they are not always that way from the factory.

 

[HWYCRZR]

I was speaking of nice work with the measurements.
Always good get the details right, they are not always that way from the factory.

Thank you.
I had to laugh at the gorilla comment as that would have been the high school way.

 

[HWYCRZR]

Anyway I did some more runout work to see if I can isolate a bent or tweaked yoke. I think I can rule out the yokes. They are pretty true. I measured the center of the cap of each leg from a fixed point with the dial indicator.
On the front u-joint on the transmission input it is .004” differential from each side. On the front drive shaft yoke there was .002” difference.
Measurement 1 Transmission zero. 2- drive shaft .002”. 3 - transmission .004”. 4- drive shaft .004”. Likely within the manufacturing tolerance of a NAPA u-joint.
The rear was within .010” all around wit opposing sides only .005” difference. Probably could center the pinion yoke straps and get it around .007”. Remember points are gapped around .014 - .018. So maybe a gorilla didn’t get after it too bad.
I also marked up my drive shaft. Measured the front right behind the weld seam, the middle and rear right in front of the weld seam. Yes know it is dented. But I have to know.
Front has .030” middle .030” and rear .030” all in line with each other and opposite of the balancing weight. So maybe welded a little offset? Or the tube is a little oblong? At least there isn’t a big loop in it. If it didn’t have the dent. I could probably just have it re- balanced at 5,000 rpm? I need to do the speed calculation. I want it vibration free to at least 95 mph. I don’t want to feel any when I am cruising on the 80 Mph interstates.

 

[70bigblockdodge]

Thank you.
I had to laugh at the gorilla comment as that would have been the high school way.

I can relate to that.

 

[HWYCRZR]

I took my driveshaft to a local transmission guy that I had talked to last fall. He took one look at it said with a ding it will vibrate no amount of balancing will work plus as said before messes with the structural integrity. He printed out a sheet with his driveshaft guys address and even gave me a long box to ship it in. He says the guy does great work and usually has about a 2 day turnaround. I will call tomorrow for details.

 

[Polara_500]

Hey Marty, when you talk to the guy in SD ask him if he does the old Detroit style (ball and trunnion) shafts.

 

[HWYCRZR]

If may, what’s an old Detroit style shaft?

 

[HWYCRZR]

Driveline Service, Inc

This is the place it looks like they do all kinds.

 

[Polara_500]

I don't have a photo off the top, but Ma last used them on 65 manual trans cars. Ball and Trunnion is the more common or proper term, I usually default to Detroit Style which is a real old skool term as I understand. I fixed my previous post.

 

[HWYCRZR]

I will ask them Mike.

 

[3175375]

Driveline Service, Inc

This is the place it looks like they do all kinds.

They are about 1 mile from me. I had seen their shop and thought about running several drive shafts through them. Good to know!

 

[HWYCRZR]

I sent down the drive shaft today. Should be there tomorrow. Only $17 to ship via Spee dee delivery ( Midwest local delivery company that covers about 5 states). If I would have had a corporate account it would have only been $10. Anyway they will call tomorrow and discuss what they can do. The problem for re build is they cannot get the necked down tube. I think it is 2-1/2” at the ends and 3-1/4” in the middle. They didn’t seem too concerned about the integrity with the dent and may try to balance it. They want to look at it first. If it is not salvageable I may have to get a straight replacement shaft. If that is the case I will have to keep a good look out for the correct used one for the future. ( Sorry I do have a small list of things that I want either NOS or gently used to replace a couple of items.)

Mike, I forgot to ask them about your Detroit style shaft. I will try to ask when he calls tomorrow.

 

[78Brougham]

Drums could be out of balance also.

 

[HWYCRZR]

Drums could be out of balance also.

One piece of perfection at a time.
I am almost wanting to take my pinion wedges and transmission shims out to put it back to the original angles. Then if I have a new or balanced drive shaft I can see if that takes care of it alone. Then I may refine my angles for maybe even better smoothness. I want to determine if it is drive shaft, angle, or both. Then I will move to the next item in the vibration chase If needed.
This thing tops out at about 105 - 110 mph, so don’t need to balance for 200.

 

[HWYCRZR]

My Drive shaft is on the way back to me. They said one of the U-joint ears was bent in, so they straightened that and then straightened the whole shaft and balanced it out. He said with the ding it is a little ugly watching it spin, but no concern for integrity, plus they were able to balance it out with no issues.
Their total bill? $62, this included their work and shipping back to me. So with my $18 shipping charge $80 total. Quick turn around. They received it Friday Morning, and I should get back today. Can't wait to get it back on and try it out.
Now I need to get after the radiator guy. Hopefully it is done being re- cored and I can install that tonight as well.

 

[HWYCRZR]

Radiator installed, balanced drive shaft installed. Drive line angles in spec. Angle1 engine to drive shaft .8 degrees (well within the 0-2 degrees recommended) Pinion to drive shaft .5 degrees so total drive angle difference is .3 degrees.
Took it out on the road. Yay!!! no vibration up to 100 mph. I will have to be careful as I no longer get the speed warning (vibration) at 80 mph.
Got it home and had fuel dripping out of my new fuel pump. . After many years of over tightening I think my flare has flattened out. Either need to replace the line or see if I can't re-flare it to get me som compression back.

Otherwise I am happy with the drive shaft straightening and balancing results.
It looks like they used heat in 3 spots to straighten. We used to straighten combine header augers that way as well after running rocks through them. Heat the high spot and then cold water quench. It shrinks the metal pulling the tube back inline.

 

[70bigblockdodge]

Makes me more confident with the dent I have in my driveshaft.

 

[HWYCRZR]

Makes me more confident with the dent I have in my driveshaft.

With the straightening and balancing it was also much quieter driving down the road. For around $60 it was worth every penny.

If I was a drag racer I would be more concerned with the dent. The drive line guys weren't concerned at all. They were more concerned that if they re-built it, it wouldn't look stock as they cannot get the spun / formed tubes with the small ends and larger middle. Would have to find a longer drive shaft of the same dimensions and cut the tube. But with C-bodies having some of the longest drive shafts, there probably isn't that much hope of finding a donor shaft.

 

[Ross Wooldridge]

Glad you got those issues sorted out! Your attention to these details is something I really admire.