915 Output flange wear ?

[MikeB]

Both output flanges on my 81 SC can be wobbled back and forth on the splined output drives. I have tightened the central bolt that hold the flange to the output shafts, but I assume due to the slight movement as the power is applied and then backed off on the overrun, they come loose. Is it normal for there to be some free play between the male and female splines?

[911hillclimber]

I have never known the drive flanges to be loose at all.
Are they tight when the centre bolts are tightened?

If so, maybe a quick call to Mike Bainbridge is in order.
IMHO all the parts should be dead tight, the only play being a little radial play due to clearances in the diff gears in a non lsd box.

[Mike911scrs]

HI Mike

is the movment in the out-put shaft rotational or when you pull them in--out, if it is rotational there is a few things,

the planet/sun gears in the diff could be worn, ( if the inside wheel has been spinning, round corners/setting off, Std diff)

the small plate that the center bolt is threaded into, is not located in the sun gear correctly on the inner splines, pulls tight ONTO the splines and not INTO them and then bolt comes loose?.

the back lash on the diff is to large/more than the setting No' on the side of the crown wheel

poss' the pinion is loose in the diff case, as in the roller bearing is loose in the diff case?

Poss' linked to the back lash, is that the outer diff bearing on the diff is loose and the diff shims are worn, also making the pinion to crown wheel back lash out of the correct setting

I have never seen the splines on the out-put shaft or the sun gear worn/have play in them, allways a slide fit, on the SC box, the early box with the corse spline could have some movement

regards mike

[MikeB]

Thanks Mike will investigate further and report back.

[MikeB]

Mike

Checked the bolts and they are tight, so the flanges are snug in the diff. There is no up and down movement and they move in and out by approx 1mm, which is the movement I was detecting and mistaking it as loose flanges

When I jack up one wheel and put the car in gear, I can rotate the raised wheel and the flange rotates 6mm (42mm measured on the tyre (630mm dia)

How does that sound re back lash/diff wear?