Wednesday, August 20, 2014

Front Passenger Wheel Studs

About a month ago during the Drivetrain Overhaul Project (the very last job in fact) I was attaching the road wheel and managed to snap one of the studs. It was a bit annoying at the time but looking back just over a year ago when I last snapped a stud it was pretty easy to replace.

But as I tried to remove the old stud, it quickly became obvious that the newly fitted brake discs were not going to co-operate and would need to come out again in order to replace the stud. This was something of a bitter blow and I couldn't face doing the job at the time so I put it off until after I'd been on holiday.

Well now I'm back, refreshed and ready to get cracking...


Problems, Problems...
The last time I replaced a stud, I was able to get it in and out quite easily as the head of the stud could get past the centre part of the break disc. Unfortunately though the new discs I fitted recently have a slightly larger diameter on the centre part and as a consequence doesn't allow the head of the stud any clearance. So looking at the job this time: I need to take the break caliper off, remove the hub nut (all 270Nm of it), remove the break disc and separate it from the drive flange. Then and only then could the remainder of the old stud be removed.

Stud head fouling the brake disc centre.

If that wasn't bad enough the other half of the snapped stud is stuck inside the nut. Usually it can be teased out with a drift and hammer, but this one had sheared awkwardly leaving very little to play with.



Solutions, Solutions (some better that others!)
The 'some better than others!' part will become apparent as you read on, but for now lets start with one of the better solutions: getting the stud shaft out of the nut. As I am too stingy to buy a new nut, I was determined to solve this problem. I tried mounting the nut in a vice and tapping with a drift and hammer, then a nail and hammer and also a small screwdriver, but nothing seemed to want to turn the stud.

After much time wasting trying to knock it out, I decided to try drilling it out. Knowing how hard the metal is though I thought I'd better start small and work my way up. So finding my smallest drill bit I made my first hole, which turned out to be a lot easier than I had anticipated.



With no real idea what I was doing, I was planning just to make the hole bigger and bigger and see what happened, but I had another idea. Picking up a small nail I bashed it into the hole.



Now I was able to use a pair of pliers to grip the head of the nail and turn the broken shaft. I was as surprised as I was pleased as it started to make its way out.



It worked, it actually worked!



So with that victory under my belt, I ploughed on to the next problem of getting the head of the stud out of the drive flange. The first thing of course is to jack the car up and remove the road wheel. When it comes to jacking and securing the car, it always takes me far longer than it should. I have three types of jack and they all have their problems.

Then there's selecting a jacking point and where to put the axle stands. This is something I'm going to have to work on and get better at. This time I used a combination of scissor jack and a hydraulic jack on the front subframe near the bottom arm. Once up, it was secured with a number of bricks (I find my axle stands too high), some planks of wood to spread the weight and some carpet to avoid marking the underside of the car floor.



With that done, I almost started to remove the brake caliper, but stopped myself as I realised I needed it in place to remove the castle nut. After removing the split pin and asking my long-suffering wife to press hard on the brake peddal, I loosened the castle nut with a breaker bar and the big socket.



Once that bad boy was off, now it was time to remove the caliper. I rested it on top of the tie bar so it didn't dangle down



With a little persuasion, the brake disc was off



With the brake disc now free, I was able to remove the four bolts that secure the drive flange in place. Now that tiny little stud head that caused so much trouble can finally be removed.



So far, so good. However this is where I made a tactical mistake. It ran through my mind to change all the studs at this point, but looking through my spares I only had three left. I could have used up an hour going to Huddersfield Mini Spares to buy some more, but I decided to press on and just replace the broken one.

Using a small hammer I tapped the new stud into the drive flange. As it's a very tight fit I felt it was better to leave it sticking out a bit rather than bashing it fully home. It will get pulled into place by the nut when the road wheel is torqued up anyway.



Now the reassembly can begin, firstly reattach the drive flange torquing to 54Nm with a little lock thread.



Sliding the disc/drive flange assembly back on the splines, I hand tightened the castle nut with the special washer to hold it in place while I reattached the break caliper.



Once the caliper was back in place, the castle nut could be torqued up to its 270Nm. Firstly with the special washer, then the tapered washer as per the instructions in Haynes. Not forgetting of course the all important split pin.



The last job now is to bolt the road wheel in place and we are good to go. Or maybe not! That tactical error I spoke of earlier came and bit me well and truly in the backside! You guessed it, I snapped another stud. With two and a half hours wasted, I uttered words to the effect of 'Oh dear, I've snapped another one' as I threw the nearest available thing into the adjacent field. Good job I can't lift the Mini!



When it comes to tightening the wheel nuts, I'm just using the standard cross type spanner and I didn't think I was overdoing it, so I guess it's just down to rotten luck.

After a time away from the car to calm down and rethink, I decided to make the trip to Huddersfield Mini Spares to buy more studs so I could replace them all. Something I should have done the the first time around.

This time though there was nobody to press the brake so I cracked out my amazing wheel bracing tool I made in this post. It might just be a bit of wood with holes in it, but it works.



Taking everything to bits again, I replaced all the studs this time.

Thankfully this time when I tightened the wheel nuts there were no nasty surprises waiting to happen.


Conclusion
It's obvious really, I should have changed all the studs when I had the chance first time around. To be honest, if I had done it when I overhauled the drivetrain, I could have avoided the first one snapping. The second one snapping just added insult to injury.

What I'll be taking from this whole experience mostly is that if there's a niggling doubt in my mind that I should do something while I have the chance, I really should slow down and spend that little extra time in order to do a proper job.

Also, stop guessing and use the proper torque setting in Haynes, chapter 10 of 63Nm for the wheel nuts.





<Next Post> - 'Exhaust Leak Fixed'
<This Post> - 'Front Passenger Wheel Studs'
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