Pivot ball thread fouling hub?

[AndyT]

Hi,

I've just serviced my front diff for the 1st time. When it came to fitting the hubs back I had to back off the pivot ball screw quite a lot more than I remember when I built it, to stop it from rubbing against the driveshaft. Now there is some play as the pivot ball moves up and down in it's socket. Is this normal?, or do I need new wishbones and pivot balls?

[dhamblin]

The hole where the ball end of the screw is fitted has obviously got bigger with use. I wouldn't worry about it unless you race seriously. ;)

[AndyT]

ah ok, guess that makes sense with the battering I gave it last weekend ;D.

[Rick]

The threads on the pivot ball are too long, it is a design fault. What you need to do it shorten it slightly. You will need to place a nut on first, 3mm if I remember rightly, then file or dremmel a couple of mm off the end. Then when you remove the nut it will correct the threads.

Well thats what I did when I ran the plastic hubs.

The only problem i had with the plastic hubs is the thread in the bottom kept stripping!

[AndyT]

Well I got them out and cut them down following Ricks recommendations. Only had some good side cutters so used them, worked a treat, their done up so as not to cause steering bind, but also dont bind with the driveshaft, which is nice ;D

[Rick]

Glad to be of help ;)

[AndyT]

More problems now ::), the both the front pivot balls are really loose in their threads and get looser as I use it, i.e after each run I have to tighten em back up. Is there anything I can do, or should I just bite the bullet and get some new hubs, maybe alloy and wishbones?

[dhamblin]

If you don't want to get a new set of hubs put some super glue down the hole and leave for an hour or two to dry. Then simply re-thread the hole. Works perfectly.
If there is a lot of material missing though it is probably worth getting a new set of hubs...

[MattW]

I often build the plastic hubs with a little superglue on the thread.

[MarkB]

Don't remember having a problem - but then I've run alloy hubs for at least a year now. These come with the "long" and "short" ball, than as Jason has pointe out previously gurantees the same length every time for consistent set up.

Superglue would do the trick Matt ;)

If anyone has problems bending these pivot balls, a mention for the TiR replacements. Much stronger and virtually impossible to bend! [btw want a quikc of telling if the ball is bent - unscrew the ball a couple of turns at watch if the hub moves. It if does then the ball is bent]

The movement in in the outer wishbone hole seems to happen as the wishbone got older. I've seen other team drivers run either small springs or o-rings to space this out. Me I think this must cause some problem as it compresses, so leave well alone.

Of course the Mi2 will not have this problem :P

Cheers
MarkB

[dhamblin]

I was having a chat with a mate of mine who runs a Mission and we both agreed that we'd rather have the pivot bend than use Titanium replacements.
This is because the steel has a lower Young's modulus which means although it does bend in impacts it will aborb a lot of the impact energy by deforming. We thought this preferable to having it not deform and the hub or wishbone breaking.
For large circuits where you have no barriers then it is probably less of a problem but at a club meeting with solid wood track markers this becomes a significant factor!

Apologies for being technical.... ;)

[MattW]

I have used TiR pivot screws for quite a while - Think i probably had one of the first sets, as i asked them about doing them ;)

I have still bent the odd one of them, but not as badly as i bent some std ones.