Brake disc bolts

[Grahamm]

I need to replace the rear brake disc on my FZ6, but, despite using a heat gun and then a blow torch, I can't get the bolts that hold the disc on the wheel to move (probably because they haven't been undone since the bike was made) and now the allen heads are starting to strip out.

I don't want to use a dremel to cut slots in them until that's the only option, so I've ordered an impact driver and I've had people on Facebook suggest hammering in a torx bit, but I want to keep the brute force options until I've exhausted all the others.

Earlier today I squirted them with a load of brake cleaner (which is supposed to dissolve threadlock) and now I've left them soaking with Plusgas, so tomorrow I'm going to give them another go with the blowtorch, but does anyone else have any useful suggestions?

[Grahamm]

A follow up to this...

I've bought an impact driver and had another go, but still had no luck, so I tried using a blow torch for a couple of minutes and discovered that the bolts had been put on with Red Threadlock, ie the one that needs to be heated up to soften it before it will release.

Unfortunately, although I managed to get one of the stripped heads out by cutting a slot with a Dremel, the other has been an absolute nightmare and the head is pretty knackered.

I tried drilling it out, but the drill bit made absolutely no impression on it and now I'm probably going to have to cut the old brake disc off around it and grind some flats on the sides of the bolt so I can heat it again and then unscrew with with mole grips.

Anyone got any other helpful suggestions?

[robbo]

If you know someone who could weld a nut to the head of the disc bolt, this would give a new surface for a six sided impact socket . It would also do a good job of melting the thread lock. Another option that could work is using a left handed drill bit, but the first suggestion is best. Thought I was going to have a problem removing my rear wheel disc the other week. Fortunately perseverance with the heat gun got the job done. Good luck

[Grahamm]

Unfortunately I don't know anyone with a welder :-(

I've sprayed a load more Plusgas over it, so maybe that will get into the bolt hole and tomorrow I'm going to try using the Dremel to make a deeper slot in the bolt as there's 5mm thickness of the disc which I can use, then try the blowtorch, impact driver and breaker bar once more.

If that doesn't work, I will try a hammer and drift or maybe get a spot weld cutting drill bit.

The main issue is that I need this sorted by Thursday as I'm supposed to be going surfing over the Easter weekend...

[robbo]

As time is not maybe on your side, a trip to an engineering workshop might be your best bet. If you progress with the Dremel Route an impact(black in colour) slotted screwdriver bit, will stand abuse a lot better than a normal chrome vanadium one. Expect Halfords will sell them. Also there’s a freeze spray I’ve had success in the past with. I know Loctite and Sealey do a freeze, shock and release spray. Another thought would be a mobile welding guy, if you got some 13mm nuts he could weld on for you.

[Grahamm]

I tried Toolstation, Screwfix and B&Q, but none had a bit big enough.

However I did find an 8mm cold chisel at B&Q which fitted into a socket on the impact driver and breaker bar and was big enough to get into what was left of the bolt head, but even after giving it 5 minutes with the blow torch, it still wouldn't shift, so I've now cut the disc off.

Unfortunately the head is almost completely destroyed, so it's going to need to be drilled out.

I'm wondering if I can get by with only 4 bolts until then as it's only the rear brake...

[Grahamm]

Well Huzzah! (in relieved tones...)

After various failed attempts to remove the stuck bolt, I finally resorted to cutting the disc and managed to get it free.

Underneath I found the sort of corrosion you usually get on electrical parts, so, for the hell of it, I used some WD40 Contact Cleaner on it and then grabbed what was left of the bolt with a pair of mole grips...

... and the bloody thing moved!!!

So very carefully, with lots more cleaner and regular WD40 I slowly unwound it and it finally came out.

Now I just need to wait for the new bolts to arrive on Tuesday and I'll be sorted.

Thanks to everyone who offered help and advice.

[darrsi]

Personally, when I've put a new disc on I just use a dot of thread lock which is all you need. As you have found out the manufacturers probably dip the bolts in the hard stuff, but it's really not necessary, it just safeguards them from any issues.

[Grahamm]

If you look at the bolt in the pic, it's only around a couple of turns of thread, but I had to heat all the bolts, even the ones that didn't get mangled.

I'm going to put the new ones in with blue threadlock!

[midden]

As I understand, the problem is the corrosion between mixed metals and not the loctite.

[darrsi]

As I understand, the problem is the corrosion between mixed metals and not the loctite.

Exactly that, it's because it is a non floating disc and gets very hot when braking then the two different metals of the bolt and wheel hub end up fusing themselves together over time, but a good blob of strong threadlock certainly adds to the pain of removal of the bolts.

[robbo]

Well Huzzah! (in relieved tones...)

After various failed attempts to remove the stuck bolt, I finally resorted to cutting the disc and managed to get it free.

Underneath I found the sort of corrosion you usually get on electrical parts, so, for the hell of it, I used some WD40 Contact Cleaner on it and then grabbed what was left of the bolt with a pair of mole grips...

... and the bloody thing moved!!!

So very carefully, with lots more cleaner and regular WD40 I slowly unwound it and it finally came out.

Now I just need to wait for the new bolts to arrive on Tuesday and I'll be sorted.

Thanks to everyone who offered help and advice.

Glad you’re all sorted. Hope the surfs up for you next weekend.

[Grahamm]

Glad you’re all sorted. Hope the surfs up for you next weekend.

Thanks, the forecast is looking good