Tailsfhat: 3 prong options...

[wilbo666]

As the tailshaft for my jzz12 is soon on the list of things to do, I've been doing some thinking about the best way to make this happen...

As I see it, the options are pretty well as follows...

My main questions I guess are,

>How much does the engine move back->forward under operating conditions? OK to run with no slip join in the system? This will determine if I need a slip joint or not! The next thing is, if I do need one what is the best way and what is the cheapest

>Should I use a uni on the front of the front half of the tailshaft:
My thoughts are that this will depend on how straight the front half of the tailshaft can be made (via gearbox position via xmember), a uni needs 1deg+ (to roll the rollers) so if I manage to setup the front shaft so that it has less than 1deg of angle then I won't need a uni on the front of the tailshaft...



1) Use 3 prong, with no uni at gearbox end, no slip joint in tailshaft
>Pros:
-Cheapest, easy
>Cons:
-No stress relief in the system, all play must be taken up in rubber 3 prong connection
-If the front half of the tailshaft isn't directly parallel with the gearbox output shaft the play must be taken up in the rubber 3 prong connection

2) Use 3 prong, with uni at gearbox most end of front half of tailshaft, no slip joint in tailshaft
>Pros:
-Cheap, easy
>Cons:
-No stress relief in the system, all play must be taken up in rubber 3 prong connection

3) Remove 3 prong from gearbox (30mm socket) and convert the gearbox to 'normal type slip yoke'
>Pros:
-Cheap, easy
-Stress relief via normal slip yoke
>Cons:
-Length of spline on the gearbox is much shorter than normal gearbox (due to 3 prong yoke) -> ~30mm total spline length available
-Not much in movement desired due to short length of gearbox spline
-Need to find a different oil seal to seal on yoke shaft as opposed to 3 prong bit (3 prong has larger OD for seal)
-Need to shorten the part of the output shaft that provides the spigot for 3 pronged yoke section

4) Option 1 with a slip joint in the front half of the tailshaft
>Pros:
-Stress relief
>Cons:
-Cost

5) Option 2 with a slip joint in the front half of the tailshaft
>Pros:
-Stress relief
>Cons:
-Cost

6) Option 1 with a slip joint in the rear half of the tailshaft
>Pros:
-Stress relief
>Cons:
-Stress on centre bearing over slip joint in front half of tailshaft
-Cost

7) Option 2 with a slip joint in the rear half of the tailshaft
>Pros:
-Stress relief
>Cons:
-Stress on centre bearing over slip joint in front half of tailshaft
-Cost

8) Option 1, but undo the large nut that holds the 3 pronged section secured to the auto gbox output shaft -> the flange can slid on the gbox output shaft
>Pros:
-Cheap, easy
-Stress relief
>Cons:
-Oil seal for gearbox face on 3 pronged section that can now slide is quite short
-No real benefit and more complex than option 3?

9) Option 2, but undo the large nut that holds the 3 pronged section secured to the auto gbox output shaft -> the flange can slid on the gbox output shaft
>Pros:
-Cheap, easy
-Stress relief
>Cons:
-Oil seal for gearbox face on 3 pronged section that can now slide is quite short
-No real benefit and more complex than option 3?

10) Weld on a cut down normal auto output shaft after the 3pronged connection (with rubber bit), then use a normal slip yoke on this...i.e. make a 3 prong to normal connector...
>Pros:
-Cheapish, easyish
-Stress relief
>Cons:
-More place for the shaft to fail...

Cheers
Wilbo

[brett_celicacoupe]

as ive said before,

id be suprised if a slip yoke on a spline can actually move while the car is under hard acceleration. bear in mind that the engine would move the most under hard accel.

similar to a socket on a bolt i guess, while your exerting torque its hard to slide the socket over the nut head.


FYI im running a tailshaft with a fixed length and no slip yoke

[madmont]

What about adapting a Commodore cv joint to the 3 prong part. Gives a bit of movement and no alignment problems. I use a custom made driveshaft (made by me) with 3 of these in my Lexus powered Hilux

[wilbo666]

as ive said before,

id be suprised if a slip yoke on a spline can actually move while the car is under hard acceleration. bear in mind that the engine would move the most under hard accel.

similar to a socket on a bolt i guess, while your exerting torque its hard to slide the socket over the nut head.

I'm fine with that (and can understand your reasoning ), but it still doesn't tell me how much movement there is and hence how much possible stress that places on the rubber section of the 3 pronged part if there is not slip joint!

FYI im running a tailshaft with a fixed length and no slip yoke

Yah I know this, and seeing as you aren't having any issues; and that this is without a doubt the easiest and cheapest route I'd like to follow it unless I come across info that suggests it isn't the best for longevity of the tailshaft

madmont-> That looks like an interesting option... but I don't know how easy it would be to adapt at first glance.... hmm might not be too hard...

Cheers
Wilbo

[brett_celicacoupe]

with the aristo, isnt the slide-section in the rear half of the shaft? therefore the front section has no allowable movement anyway (besides compliance in the centre bearing rubber)???

were the engineers concerned with the diff moving or the engine moving?

[cambelt]

The only way to do it properly is use a landcruiser 60 series late tailshaft slip yoke and use the JZA 80 TT auto flange instead of the 3 prong aristo thing. Finding the flange is the hard part , there $250 new from toyota . To do it properly it needs a slip joint no if,s or buts.
Of course the rubber donut will allow some movment but it will wreck the rubber over time .
Dave

[blaze86vic]

were the engineers concerned with the diff moving or the engine moving?

*edit* for solid axle cars *edit*
The diff changes its position relative to the output of the trans as it travels through it suspension range. In cars with tight suspension not having a slip yoke is a lot less problematic than stock suspension cars. On the other hand having tired old stock rear suspension bushings and tired engine/trans mounts makes for a lot of available flex in the system.

[cambelt]

With IRS cars the diff moves less than the engine .
Dave

[blaze86vic]

Whoops, excuse my noobyness, I didn't realize we were talking about an IRSs. That changes everything.... to a realm I've never dealt with.

[wilbo666]

with the aristo, isnt the slide-section in the rear half of the shaft? therefore the front section has no allowable movement anyway (besides compliance in the center bearing rubber)???

were the engineers concerned with the diff moving or the engine moving?

The center bearing is able to transmit the compliance...

Look at a live axle two piece shaft setup... we know that the live axle will cause the center bearing to be forced in-out a fair bit (giving resulting movement at the gearbox yoke), so we know that center bearings have a fair bit of play in them and are fine to cope with that!

And in an IRS setup I think the engineers would be more concerned with engine movement primarily... but there will be slight diff movement as they aren't solid mounted (They are quite close solid mounted when compared to the engine tho in my thoughts)...

I might head around to some tailshaft places and get their thoughts...




Hmm! Looking the EPC pic, something springs to mind... there is only one uni in the system! That means that the rubber connector on the gearbox flange must be designed to handle at least the misalignment that comes from the gearbox angle moving up and down

Assuming that it all lines up perfectly flat from factory...

When the front of the engine tilts up
-> the back of the gbox will tilt down ( \ )
-> the front half of the tailshaft will rise ( / ) and as the center bearing height is fixed this will cause the following
-> center bearing will be forced towards front of car and downwards
-> rubber Y prong connector will compress at top ( /_\ ) due to angle of front driveshaft and fact that the height of the center bearing is fixed

->The reverse must happen at the diff flange end...


Cheers
Wilbo

[The Real Roadrunner]

in crystals we put a commodore CV just behind the centre bearing (which was replaced also) which allows for some back and fourth movement aswell as angle change.

just make sure you do your best to line the Gbox and the first half of the tailshaft up properly, i just used a bevel and a level on the pan where it bolts to the gbox and the shaft. then space the gearbox/centre bearing accordingly.

cheers
linden

[wilbo666]

in crystals we put a commodore CV just behind the centre bearing (which was replaced also) which allows for some back and fourth movement aswell as angle change.

just make sure you do your best to line the Gbox and the first half of the tailshaft up properly, i just used a bevel and a level on the pan where it bolts to the gbox and the shaft. then space the gearbox/centre bearing accordingly.

cheers
linden

Kinda what I'm going to do after talking to a few driveline shops today

The plan is to use a commodore cv and center bearing, i'll have to make something up to mount the commodore center bearing into the z12...

Yeah I've got a groovy little digital angle thing so I'll use that to make sure I get the front half of the tailshaft lined up straight!

Thanks for the help all

Cheers
Wilbo

[The Real Roadrunner]

you should be able to mod the centre bearing shell to suit the commonwhore centre bearing to make it more of a bolty bolty affair.

cheers
linden

[wilbo666]

you should be able to mod the centre bearing shell to suit the commonwhore centre bearing to make it more of a bolty bolty affair.

cheers
linden

That would be great, I'll def look into that when I get the commodore shaft and its center bearing bracket thing,

Thanks again

Cheers
Wilbo

[The Real Roadrunner]

crystals cost $90 for the centre bearing mod including the new centre bearing so i would assume it was a 30min job tops.

im sure you will figure it out.

cheers
linden