Driveshaft alignment.

[dirkbalter]

All,
I just rebuild and installed my driveshaft. All new components including the motor/transition mount in the rear.
I understand the concept of aligning the shaft (spacers). What I have a hard time with, is checking the alignment.
I searched a bit but didn't find an answer. The majority of the shaft is buried within the body. Are there any tricks, procedures or gages available to do this? (Driveshaft alignment verification).
Thank you

[Pawel66]

I was asking this several years ago here. Some good soul (do not remember who) told me to use a piece of string. That is what i did. Today I would consider also a laser level,  but not tried it.

I assume you are aware of the tightening procedure.

[dirkbalter]

Thanks Pawel. What do you mean by tightening procedure?
 

[Pawel66]

Tighten the main 47mm (?) nut lightly, roll the car back and forth, rock it a bit, or a bit more than a bit, and tighten the main nut with the car standing on wheels.

I can look it up in BBB to check how accurate my description was, but i will be home Friday...

[dirkbalter]

Ohh, I know what you mean. Mine doesn't have the nut. (Earlier). My 108 has the nut you mentioned.
Still working on the string theory, lol.
Thanks

[Cees Klumper]

I did this many years ago (40 to be precise) on my Triumph Spitfire MK III that had a vibration coming from the driveshaft.

I simply held a piece of chalk to the (slowly!) spinning drivershaft, with up the car on stands, engine running in gear. Holding the chalk closer and closer and closer until it touched the driveshaft revealed where it was slightly un-centered. By shimming the U-joint circlips I was able to get it centered and eliminate the vibration.

With the Spitfire it could be done from inside the cabin. With the Pagoda you would be lying underneath the car, unless you can make a contraption to remotely raise the chalk/marker up to the spinning shaft. You would do this at the attachment points, not in the center or another area of the shaft.

(Of course balancing the shaft itself is another issue, that's probably best done by a specialized shop that can attach weights in the right spots.)

Coincidentally just yesterday I replaced a U-joint on my son's 240Z. The fit inside the yolks is so precise and tight that I think the design is that there is almost no way it is not 'automatically' centered once the U-joint is installed. I don't know how that is with our Pagoda, i.e. if the shaft is out of alignment perhaps there is some other root cause.

[Pawel66]

I think   Cees was helping in my request for help years ago! i remember the chalk story!

With the string - the bearing in the middle is in the way. I think I found the way to lead the string alongside the drive shaft with something as a measure of its equal distance from the shaft along the way, or rather in the front, in the middle and in the rear.

[dirkbalter]

Thanks guys. The driveshaft is (professionally ) balanced. The u-joints shouldn’t be an issue.
It’s strictly about the motor to rear end alignment /drive shaft. I will try with a string going across and see what it looks like. As You said, tricky to get in there especially with the center bearing in the way.
Thanks

[Cees Klumper]

OK but that should not really matter, should it? Meaning that the u-joints together with the slide function should compensate for any off-center positioning? Not sure about that though.

[cfm65@me.com]

Hi Guys,
Down load ‘angle pro’ on your phone or ipad for an inclinometer in order to measure any angle. The phone could then be used to measure the angles of the prop shaft sections in sito.

[Tomnistuff]

I used the concept that to make two shaft centerlines colinear, make their perpendiculars parallel.  The two flange mating surfaces are the perpendiculars. I just installed the front drive shaft with the front flange about 1/4 inch from the engine output flange.  I then raised and lowered the rear of the engine until the flanges were perfectly parallel (by eyesight) when I raised the front driveshaft by hand to make it colinear with the engine output shaft.  If the shafts are not colinear, there will be a wedge-shaped gap between the two flanges.  When the flanges were parallel, by eyesight, I knew that the shafts were aligned.  Then I loosened the slip nut and joined the engine output flange to the driveshaft input flange, and tightened everything. It has never caused me a problem.

Tom Kizer

[dirkbalter]

Thanks again. I have some good ideas to work with now.

[Tomnistuff]

Good luck.  Let us know how you did it and how it worked.
Tom Kizer

[Pawel66]

The early BBB just. Says that you must not tighten the nut at the intermediate bearing until the car is rolled back and forth several times. Must stand on its wheels while tightening.

[dirkbalter]

The early BBB just. Says that you must not tighten the nut at the intermediate bearing until the car is rolled back and forth several times. Must stand on its wheels while tightening.

Thanks Pawel. I am surprised you found that in the earlier BBB. As mentioned, mine (66 sl) doesn't have the nut. The shafts "floats" on the spline. There is only a "seal cap" at the end. My u-joints are also held with retaining rings were as the later ones are pressed and peened in place.

[Pawel66]

My bad! I saw in the early BBB a shaft drawing that is different than mine, so I thought this is it. Now I saw it is as of August 65, you probably have an earlier one.

The nut you do not have is No. 3 on the drawing.