Driveshaft play at transmission end. Normal? (see video)

[Tomzern]

Hi!

 

I have a nasty vibration in my 1970 240z when driving in highway speeds. While going over everything in the drivetrain I noticed some play in the transmission end of the driveshaft. Is this normal or should there be no play at all?

 

Here's a video I shot today:

http://www.youtube.com/watch?v=ZLmEMtkO3M8

 

My driveshaft has been spliced and I am also wondering if it might be too short. Does it look like it should be further into the transmission when looking at the video?

 

 

Thanks,

 

Tomzern

Edited April 17, 2015 by Tomzern

[Kurbycar32]

I would check out the balance of the driveshaft, and put that at the top of my list since you said the shaft has been spliced

[Tomzern]

I have thought of that myself, but the job was done here in Norway by a well known driveshaft shop so it is unlikely that the shaft is out of balance. 

 

I found two worn out U-joints on the half shafts as well. I changed them today, but have not tried the car after that. I also suspect that the wheels might be the cause so I will try with a different set in the coming week. If this doesn't help on the vibration, I will take out the driveshaft and get it checked again

 

Anyway, Is there anyone here that knows if what I am showing in the video is normal? I would imagine that this type of play can cause vibration.

[Zed Head]

It does look like it might be short.  I think that the two dust/dirt shields usually overlap almost completely.  

 

Did the shop measure or did you, or did they use a factory specification?  If they cut it to the early 1970 spec. it might be for the set-forward differential.  Do you have the modification to move the diff back?  Need more info.  If you take a measurement, someone here can verify length.  I have one of each style, short and long.  Measure from the center of the u-joint caps.

 

In the meantime, you could unbolt the shaft from the differential and push it in to the transmission to get an idea of how much engagement you're not getting.  If you raise the back end high enough you might be able to remove it without losing your fluid.

[Tomzern]

Well, the story is that the car was imported from the US in 2013 and when it arrived, there were a couple of signs that the car had been messed around with during transport. One of the things that had happened, was that the driveshaft U-joint was torn apart in the transmission end. The dockworkers probably tried to do a burnout with it or something.   That is why the shaft had to be cut and spliced with a new end. It was the guy I bought the car from who imported it and got the driveshaft fixed.

He delivered the broken driveshaft and a spare driveshaft he had to the shop and I guess they measured the length of the broken one to make a new, but I can't guarantee that.

 

My rear end is a completely stock early 1970 one, with the straight mustache bar. My transmission is a 5-speed from a 280Z (I believe), but the 4-speed and 5-speed use the same driveshaft length don't they?

 

I will measure the length during the weekend 

 

Thanks so far!

Edited April 18, 2015 by Tomzern

[Zed Head]

While you're under there you might as well unbolt the flange from the diff and see how much room there is to push in the trans.  I'm pretty sure the factory only left about 3/4 - 1".  Pretty full engagement.  No need for more play because the diff and trans are both locked in to place.  The slip yoke barely slips.

 

Actually, it may be that the u-joint got torn up because the propeller shaft tried to come out of the transmission, got cocked and broke the u-joint.  The shop might have just reproduced a too-short propeller shaft.

 

Also, it might be too short because you have the later diff location, but the early shaft length.  

 

Just throwing out some possibilities.

[Zed Head]

Went out and looked at an early 70 shaft and a 76 4 speed trans. with a dust shield and I'd guess that you have 2 1/2 - 3" of engagement, when you could have about 4 - 4 1/2".  So, not fully engaged, but not so loose that it would pop out.

 

There is a bushing/bearing inside the transmission though that helps locate the slip yoke.  You may or may not be engaged with that.  One member here had a worn bearing, different style of transmission though, and it allowed some looseness.

Edited April 18, 2015 by Zed Head

[EuroDat]

Just watched your video. +1 on Zed heads comments. It looks like it not going far enough into the transmission. That could be what is causing that extra movement you are seeing. Mine goes in a lot further and almost zero movement, you can't see it anyway.

Your tail shaft looks too short to me.

Is your diff in the forward position or has it been set back inline with the rear wheels (Half shafts in line)? Someone could have shortened it incorrectly. Since it has been cut and spliced together it may be too short. Can you measure the tailshaft? Centre unicap to centre unicap.

You said the shop makes tailshafts. Does he make them for cars or pto's for tractors and such. Just asking because you can get away with a lot in a pto shaft, but that will be a big problem in a car drivetrain.

I don't think it is causing your vibration. The splines should keep it straight when its under load and at highway speeds it should be under enough load. It would cause vibrations when you coast.

Here is a link over transmissions. You can see my yoke in post 10 5th photo. Its a through the floor shot but gives you an idea of how far it goes in.

http://www.classiczcars.com/topic/46126-transmission-idquiz/

Chas

[Tomzern]

Thanks for helping me guys☺

I have just measured the shaft center to center between the u-joints and it is exactly 21" long.

Here's a video showing how much further into the transmission the shaft can go:

https://youtu.be/LzmrVwc8s6A

The diff is in stock 1970 position with the straight mustache bar.

Does the shaft have to be lengthened when swapping from 4-speed to 5-speed?

[madkaw]

I just went thru a similiar situation, but different trans. It looks like the diff could be a 1/2" longer. For some reason 21.5" sticks in my head. It could also be a worn tailshaft bushing that is allowing the play. Or it's a combination of both.

[Zed Head]

I get 21 1/4" from cap center to cap center on my early, diff-forward shaft.  It's not clear what "stock" means, and I don't know what shape the mustache bar was on the diff-forward setup, but it looks like you have the short shaft, when the long one would work.  MY 280Z long shaft is a hair over 22 1/4".  Looks like you have the short shaft when you could use the long one.  I look at the angle of the halfshafts to determine if the diff is forward or not.  In the improved vibration resistant setup (the factory modification and what they changed to for later cars) the shafts are perpendicular to the wheels when looking through the wheel well.  In the early cars you can see that the shafts are angled forward.

 

Did you try wiggling the yoke around like in your first video?  That would answer part of the question.  If the play goes away, then a longer shaft might be more stable.

 

EuroDat mentioned tailshaft in his post.  I don't know if he meant your transmission, but there are shorter versions of the 71B transmission. from trucks.  Maybe you have one of those.

 

Obligatory edit - to be clear, you do have the R180 diff?  It hasn't been swapped to the R200.

Edited April 19, 2015 by Zed Head

[EuroDat]

It looks far too short going by your video. I can't remeber the exact amount, but it shouldn't have that much. Did you note how far it was in the transmission? Im wondering how far its engaged. That could explain how it got damaged.

Did it still have the up and down movement when you pushed it in? Your rear extension sleeve or tailshaft yoke could be worn.

 

The standard (late) 240Z tailshaft is 22,5" (570mm). You could have the Series I tailshaft which is a little over an 1" shorter (30mm), but it is now a little bit shorter again due to the repairs. The series I should be a little under 21.5" like Steve mentioned in his post.

And for the info the 280Z, fitted with non servicable uni-joints, is 565mm (5mm shorter than the late 240Z).

 

I don't think you will be able to fit a late 240Z shaft in your situation. The shaft doesn't move around much (forward & backwards), but you still need 15 - 20mm to be able to mount it and allow some movement.

You could check if you have more than 50mm between the diff flange and tailshaft flange when the tailshaft is pushed all the way in the transmission.

33mm (22.5" - 21") + 15 - 20mm = 48 to 53mm.

 

A straight mustache bar doesn't say much. To move the diff back you simply turn it around (backwards). The way you can tell is by looking at the transverse bar connecting the lower control arms. If its straight than your diff is forward (early series I). if its curved around the diff than its been modified to the later position and the centerline is inline with the wheels.

If you are running with a 21" tailshaft I would suspect the diff in in the original position.

 

Here are some photos of one of my spares tailshafts. I thinks its from a 73 240Z.