L Series - Front hub runout

[ratters]

Hi guys,

Recently replaced front brakes on my L Series wagon, and I discovered a slight noise coming from the drivers side brake shortly after, like a kind of wob wob wob under light braking. Put the front up on jack stands and ran the car at idle speed in 1st gear and discovered I had some serious runout on that disc. Initially I thought I had a badly produced disc but further testing swapping the discs and hubs around has led me to believe the disc hubs themselves are actually worn on the surface that contacts the outer wheel bearing, and this is causing the runout. It actually occurs to a degree on both sides but one of them was bad enough to make noise under brakes.

Does anyone know if its acceptable to machine that surface? I assume a light skim, enough to return the surface true again will resolve it but it would also have the effect of bringing the disc slightly inward. Not sure if that will cause any issues itself? Thoughts?

 

[El_Freddo]

You could do that. I’ve not had this issue but have swapped my hubs due to one being bent. I have no ide how that happened, I found it by chance.

Rather than the mounting face being the issue, have you looked into worn bearings? They may still turn and work ok, but some play in them and this allows the disc and wheel to run at different angles to the knuckle that the caliper mounts on, thus producing what you’re experiencing - but not always so check it out thoroughly.

How many km on those bearings, if known?

Cheers

Bennie

 

[ratters]

Hey Bennie,

Brand new bearings actually, and I am absolutely confident that I seated them properly in the hubs. I think Koyo bearings are reputable enough to rule them out? I did end up taking the hubs in for machining, funnily enough it did help but not 100% so I believe there is possibly some runout in the hub itself, like you found on yours. The runout is still visible but fairly minimal and enough to call it good. I put it all back together and it drives and brakes fine now but I will be having a look at the hubs on my parts car, if they are in better shape I might swap them over later down the track.

Here is a what the hubs looked like prior to machining. There is a deep groove where the old bearing sat against the hub.

 

[El_Freddo]

Hey Ratters, at least it’s done something!

What are your cone washers like, and what torque are you putting on the 36mm castle nut?

Cheers

Bennie

 

[ratters]

The cone washers are OK I suppose, didnt see anything which worried me but I guess I wouldn't know for sure if they are worn out. Regarding torque on the 36mm nut, no idea, a LOT with my long breaker bar and my foot! Not enough to strip the threads but I know these puppies need to be tight so I put a fair amount on them.

I have also just ordered a set of new strut top hats with the integrated bearing, one of mine is knocking a little bit and the bearing feels nasty so I figure might aswell do those too, every other bloody thing has been replaced recently!

 

[El_Freddo]

Done the front struts? That knocking noise could be them.

They will make the noise most when drive over slightly undulating surfaces or small bumps/knocks in the road. Typical of the Subaru strut to do this, from the MYs up to the current models I dare say.

Other thought was your caliper slide pins. Have you cleaned them up and lubed them? I’ll be doing mine on my brumby shortly.

Also a good idea to put a new seal kit in the calipers if you’ve got a torn dust boot. It’s amazing what kind of crap ends up in there! Not hard and worth the effort. A few old members might remember me doing mine on a picnic bench at a campground before we headed bush for the day...

Cheers

Bennie

 

[ratters]

I really hope its not a strut. I did KYB's and King Springs about 20,000km ago, but i do believe its an issue with the top hat. If the top hats don't resolve it I guess I will see what's around, I don't believe there are many options now though?

When I did the brakes I did completely clean the calipers and lubed up the slide pins with new grease, and thankfully no torn dust boots anywhere.

 

[ratters]

UPDATE. The new strut tops arrived on Friday and I put them in.. What a disaster. They are literally the worst chinese crap imaginable. They have MORE play in the bearings than my old slogged out ones!! Could not understand why I now had a new kind of knocking noise, pulled them back out and found massive play in the strut tops. Also discovered that I have a slightly dodgy shock, it still works and rebounds pretty normally but it makes a fair grunting noise on the compression stroke.

 

[Kevin]

What a PIA!

 

[El_Freddo]

Ah, for some reason I thought you were getting genuine units...

That’s painful.

Cheers

Bennie