Argh! That bolt.

[redfox]

So, I've spend 2 days trying to loosen the brakelight switch bolt on top of the rear brake master. Likewise on the rear caliper itself. No visible corrosion, but not moving it certainly is.
I tried to spray them with anticorrosion/screw loosener spray every 4- hours, combined with a bit of heat (not too much) from a heatgun on the low setting, and I've done this for 48 hours now. Not giving in at all.
I'm a bit afraid of breaking something.
Any good suggestions?

Reason for doing this is the 32 year old rear brake hose needs to be changed, as it's beginning to free some nice Black rubber material on the inside.

I have always changed the brake fluid every year for the last 12 years, but this time, it's stuck. Bleed screw too.

Kind regards,
Jacques

 

[Simonr501]

Sounds like galvanic corrosion to me!
Especially if any salt spray and moisture has got in there.

The aluminium has perhaps corroded in preference to the steel, although it is only slightly more anodic.
I don't know what brand of penetrating oil you are using but WD40 and suchlike is not the real deal!

It looks like you are going to have to go to 'defcon 2' and be a bit more brutal with the heat and perhaps man up with the right arm.
From my experience as a clanky fitter it pays to get a lot of heat in fast without melting anything to get really tight stuff undone!

 

[Haggis]

Look for a 'freezing' penetrating oil and use it generously. Don't bother with the cheaper ones. Very highly recommended.

 

[redfox]

Ok, done.

Using more special penetrating anti freeze bolt loosener (no wd40 here, please), more heatgon and larger toold and another Tool to hold opposite direction not to break anything, and dit all came loose. Then more fluid and go a little forth and back and it came off freely, not thread damaged.
It seems that the antifreeeze screw loosener spray is some graophite plus something mix and it does not ignite easity, contrary to say wd40
Now off to have a braided hose for the rearbrake made

Thanks all!!!!

Kind regards,
jacques

 

[Laverdalothar]

Jacques,

I got bored by the fact that you can not bleed this system easily and did some - I feel - nice modification. I used an adapter to take the brake-light-switch and a brake-line screw for two rings with a bleeder already installed (see pics). Seems to work... I put the adapter first on top of the brake master, then the brake-line that goes down to the caliper, both pointing into the same direction (to the battery tray). All separated by alloy washers (not the copper ones like on the photo) and all installed with the 2-ring bleeder-brakeline-screw. Now this bleeder is the highest point in the system and bleeding seems to be question of seconds.

Total cost was around 25 ? due to high shipping cost from Italy for the adapter (could not source it cheaper locally, even with the shipping costs), but well worth it! I need to check clearance to the seat unit but don't expect big issues there.

HTH