Technical Brake disk wheel locator pins sheared off?

[Krikkit]

Pardon the not-so-technical term, but I don't know their proper name.

I swapped a front wheel for rear yesterday on my Mk.1 punto, and much to my horror once the front wheel came off I discovered that the locator pins which sit on the brake disk have sheared off, leaving nothing to aid in getting the front wheel back on properly.

I suspect it was done (or at least set in motion) when the disks and pads were changed in January for its MOT, although I can't be sure as I've not had the wheels off before now.

After putting the wheel back on I've ended up with a bit of wheel wobble, and was wondering if anyone had heard of it before, a recommended cure, or if it's just a case of taking extra time on replacing the front wheel?

Anyway, a picture from the excellent guide on changing disk, pads and master cylinder to show you what I mean:

The pins on the disk have broken off below the face of the disk, leaving nothing above it.

It's also worth pointing out that the disk has considerable play in its alignment before the wheel goes on, which concerns me a bit. The wheel is fine once the tyre is mounted, there's no play after that, but before it's terrible.

 

[rallycinq]

Shouldn't make a difference, as long as you get the discs back on in the right place.

You'll need to get the remains of the bolts lined up with the holes in the disc. You could grind them smooth, or drill them out if you fancy.

There should be no wobble factor, the discs should be tight against the hub when the wheel is fitted.

Cheers

SPD

 

[Ffoxy]

Shouldn't make a difference, as long as you get the discs back on in the right place.

You'll need to get the remains of the bolts lined up with the holes in the disc. You could grind them smooth, or drill them out if you fancy.

There should be no wobble factor, the discs should be tight against the hub when the wheel is fitted.

Cheers

SPD

:yeahthat: had the same happen on a Seat Ibiza & all is fine with no locator dowel.

 

[DaveMcT]

:yeahthat: had the same happen on a Seat Ibiza & all is fine with no locator dowel.

DONT LEAVE THE WHEEL WOBBLING !! THE CAR IS DANGEROUS LIKE THAT. The pins help to locate the wheel making it easier to get the wheel bolts in. When I went from a steel wheel that had small locator holes to alloys with large slots, the pins were no longer doing anything useful. It made it very slightly more awkward to fit a wheel but nothing to worry about. The wheel bolts hold the disk and the wheel so its all solid when the wheel is on However, if the pins have snapped off short, the disc can end up sat on the stubs and this is probably what caused the wobble. Its dangerous because when it settles down the wheel bolts will be loose. You need to take off the discs and extract the remnants of the locators or grind them off flush, then they cant cause problems.

 

[Ffoxy]

Or just fit new discs, pads and dowels to be sure...

 

[DaveMcT]

Or just fit new discs, pads and dowels to be sure...

Unless the discs and pads are worn there's no need to replace them, but whatever you do the disc must be settled properly when a wheel is fitted. Much better to remove or grind off the stubs . It's not always obvious on the jack if a wheel has only a slight wobble.

 

[rallycinq]

Or just fit new discs, pads and dowels to be sure...

Providing the OP can get the remains of the old pins out the hub.

Cheers

SPD

 

[Ffoxy]

Providing the OP can get the remains of the old pins out the hub.

Cheers

SPD

Lol... the game I had but the fact was the blo*dy things HAD to come out! By hook or by crook!

 

[MikeSalt]

This should not be causing wheel wobble, there is something else at play here. However, if you really do want to sort it out, Fiat can supply the part. Remove the caliper from the hub and use a cable-tie to secure it out of the way (careful not to twist the brake hose). Remove the good location pin and then pull the brake disc off over the broken pin. With a bit of luck, enough of the sheared pin should sit proud of the hub to grab with some mole grips and remove. Replace the brake disc, screw the new locator and the old good locator pin back in, put the caliper back on and then you're sorted.

However, if there is no part of the pin sitting proud, you may have to drill it out. If you are careful and do it with incrementally increasing drill sizes, you may be able to remove it without thread damage. If the threads do get damaged, you'll need a thread insert kit, or a new hub and bearing.

 

[Krikkit]

Thanks for the advice guys - once the weather fines up again I'll remount the wheel a bit more carefully, if there's still no joy I'll have to try and replace the dowells, maybe take one from the other side hub (if it's still there). I'm reluctant to spend anything though, the car's getting scrapped in a few weeks; having said that I won't risk a long journey with any wheel wobble.

 

[DaveMcT]

My issue was that the disc could have turned 90 degs and be sitting on the broken stud end. This would make it wobble side ways. If the disc is lined up properly over the broken stud it wont be a problem as the wheel bolts do all the real work.

 

[Anfield]

For my alloys ive had to take my locator bolts out, never had a problem

 

[DaveMcT]

That's my point no bolts - no problem, but broken bolt sitting proud by 2 mm could be a problem

 

[elastoplastscavenger]

as folk have said, it shouldnt be a problem. on mine the dowels are missing and i have a little brake wobble due to dirt getting behind the disk as it rattles loose when the wheel is off then the disk goes back on a little squint due to the dirt behind it.

if the brake wobble (only wobbling when you apply the brake, especially in the 25-40mph range) is bad then take the disk off, clean the faces (file etc.), grind the stubs back as previously described. While you are there you could turn the disk 90 degrees and drill and tap two new holes for the locator dowels.

 

[Krikkit]

Well I managed to remount the wheel yesterday afternoon, with no real improvement. I don't think there's any way to mount a wheel more carefully than that without a jig, so I think we can rule the mounting out.

I might try swapping the wheels back again to see if it's a wheel balancing problem - the wobble comes and goes at varying speeds, although gets quite bad above 70mph; it's also got some crazy brake wobble above 50mph which is quite disconcerting, so there might not be a simple cure.

The most annoying thing is that it only started once I changed the wheels... Bugger!

 

[rallycinq]

Well I managed to remount the wheel yesterday afternoon, with no real improvement. I don't think there's any way to mount a wheel more carefully than that without a jig, so I think we can rule the mounting out.

I might try swapping the wheels back again to see if it's a wheel balancing problem - the wobble comes and goes at varying speeds, although gets quite bad above 70mph; it's also got some crazy brake wobble above 50mph which is quite disconcerting, so there might not be a simple cure.

The most annoying thing is that it only started once I changed the wheels... Bugger!

Sounds like something isn't seating right. There is no jig, as such.

Cheers

SPD

 

[DaveMcT]

Sounds like something isn't seating right. There is no jig, as such.

Cheers

SPD

Assuming you have wheels that are meant to fit Fiat hubs... If the disc is not running true, remounting the wheels wont make any difference. Take off the wheel and the disc. Clean the disc and hub mounting faces and either remove the broken stud(s) or grind them flush. Replace the disc and fit the wheel as normal. The wheel should run true.