Tbird IRS CV play - question from Australia

[PhilistineAu]

Hi,

My Dad has a Mk IV in Australia and sent across a video of the play in his rear CV. I've read some forum posts and wondered if this is a result of the nut not being tight enough or perhaps some of the early shaft problems they were having? Any suggestions? Dad is sure he torqued the nut down per the specifications (which we think was ~250 ft lbs). I believe this was an early Mk IV, sometime around 2011.

Link to the video: https://www.youtube.com/watch?v=cFuGmnT8fts

Questions:
Anyone have a suggested cause and solution?

We are assuming it isn't safe to drive... unless this amount of play is normal?


Thanks!

Phil

[mike223]

Phil,

Your father needs to examine this as four or more individual assemblies.


#1 is the outer stub - the nut captures + tensions the inner races of the wheel bearing - if the nut gets loose you have sloppy wheel bearing symptoms (250ftlbs is correct).

#2 is the stub to half shaft - this is called a Rzeppa joint (I think), and should have no rotational play.

#3 is the half shaft.

#4 is a tri-bearing plunge joint - around 2010~2011 FFR was sending out CV assemblies that were slightly short - if you assembled the rear control arms "long" (heim joints) you could get in a situation where the tri-bearing is pulling out of the plunge joint - otherwise you should have very little play here, but slightly more than a Rzeppa joint.


The possible answers for that are:

1- Shorten the heim joints (and narrow the rear track).

2- FFR sent out washers to go between the stub and the hub (effectively shortening the length the CV shaft has to cover).

3- FFR offered replacement half shafts (longer) at additional cost (probably no longer available from FFR - but try other suppliers, you'll have to know how long you want them).


And then #5 is the plunge joint moving rotationally in the differential - I have more play than shown in your dad's video there, but he specifically says the CV shaft is not moving - my question is what specific part of the CV shaft?

My best guess is that the tri-bearing is close to pulling out of the plunge joint - and no, that's not a safe way to run.


Hope that helps,

Mike

[michael everson]

Jack the rear suspension up to ride height and see if it goes away.
Mike

[PhilistineAu]

Thanks Mike for the detailed overview. That's really helpful. I've relayed the information to him and he's going to take a look this weekend. I also have a call to FFR to see if they have any of those half shafts left. Fingers crossed. I'll report back!

Best regards,

Phil

[rich grsc]

It looks about like mine, I don't see a real concern. The tri-lobs are not available new, so some wear in used parts are to be expected.