DIY tailshaft

[mullett]

As in a new uni joint to fit into a standard tailshaft without modification?

[thechuckster]

The yoke is only missing the circlip groove that holds in replaceable bearings?

[Shifty]

Truck shops are the go, kids. They do tailshafts all the time and in my experience are quite cheap.

Do *not* do your own tailshaft.

[convertableTA23]

Hehe, seen a do it yourself tailshaft in the front of a hilux once, standard double carden joint welded to a piece of box, double carden welded to another piece of box that was a snugish fit over the other and bang it in. I kid you not that thing was dangerous even at walking pace. It was only in a comp truck and the whole thing acted as a slip joint. Whenever it was driven people would stop to look at it cause of the noise. Moral of the story, pay a driveline shop to do it just to stop people looking at your shit tin as you drive past them

[1JZ-Rolla]

Do *not* do your own tailshaft.

Fair call for the general masses perhaps, but if you are a machinist for example, but just don't just build tailshafts for a living, why not use your skillz, which are surely equal or better than the average gearbox/diff shop worker? Not every tailshaft on the road is made by a specialist driveshaft fabricator/workshop, that is for sure.

Selection of materials is critical. Setup knowledge is important also. Welding skills must of course be spot on, so backyarders need not apply.........


The good thing about tailshafts is that almost everyone shys away from attempting to fabricate/modify their own. If only we could say the same for brakes, which are just as safety-critical Yet nobody seems to complain about the average monkey having a crack at a brake upgrade will all sorts of unknown parts.

[Toy77]

hehehh

nice call on the brakes phil....

mind you - on the tail shaft front - anyone who genuinely has the skills to make their own perhaps shouldn't have to ask on here how to make one????

i have replaced unis as described above - cut out the non serviceable ones and replaced them with servicable / removeable ones - was a celica tailshaft though from w57 to t series / volvo rear end...

Cheers
Stew

[machschnell]

anyone ever tried or thought of making one in aircraft grade alloy ? would be as good as lightening the flywheel wouldnt it ?

[Toy77]

yup they make them in all kinds of cool things.... including carbon fibre....

basically the more revs you want and the longer the shaft.... the lighter it needs to be, and or larger in diameter...

there was a cool table i ffound somewhere recently.... ill see if i can find it...

found it - http://www.markwilliams.com/driveshafttech.aspx

Cheers
Stew

[mullett]

anyone ever tried or thought of making one in aircraft grade alloy ? would be as good as lightening the flywheel wouldnt it ?

It will have an effect, for sure, but since it has quite a small radius, and what you're referring to is inertial force (IE the engine has to supply torque to accelerate the shaft), then it's contribution to the total mass moment of inertia is quite small. The flywheel makes a much larger difference, as it has a much larger radius.

Mass moment of inertia for a disk of constant thickness/density is

(1/2)*(Mass)*((outside radius)^2)

(mass)*((radius)^2))
for a hoop such as a driveshaft.

So increasing the radius makes a dramatic difference, much more so than the mass. Also there's other factors, such as the driveshaft accelerating much slower than the engine in most gears...and also the other contributing factors, such as the wheels, tyres, brakes etc which all have a substantial contribution.

[allencr]

http://rockforddriveline.com/Staked_Instructions.htm
http://rockforddriveline.com/Staked-In_U-Joints.pdf

http://theujointstore.com/staked-in-...t-ujoints.html

[mullett]

Awesome info, rep added.

Only thing that strikes me as odd; does the new joint not require a circlip groove? (which I assume they didn't bother cutting in if they were going to stake it anyway)

[allencr]

No groove in the yoke, just on the cup of these type U-joints where it protrudes on the inside of the yoke's flange.
Only potential problem is that some yokes don't have their inside surface machined at all and/or flat & perpendicular to the cup hole.
Also, bending the yoke because of improper support when pressing/beating out the cup when it's staked AND rusted in.

[alexlegault]

good luck man