Front brake master cylinder mounting pin (5mm allen key bolt - or whatever the correct name is) is refusing to come out.

Any tips?

• Have soaked overnight in WD. Waste of time as it was probably sealed.
  
• Tried impact driver and 5mm allen key. Nothing
  
• Used 5mm in socket - and it's about to strip.
  

Have held off using blow torch for fear of melting the rubbers. Would like to clean out and reuse MC brake piston - as could have been the case on the K100 after I spent $193. 

MC piston and spring are seized, fluid crystalised, handle doing nothing. Have it all off and on the bench. This is the last step in the dismantling....

Am expecting to have to drill it out and use ezy out.

Before I do this, any thoughts, top tips or experiences that will help guide the way. Can't believe it is this stubborn.


thanks

Guy

Hi,
I've had this problem on 2 16 valve master cylinders and I ended up Getting a Torx socket and knocking it down the hex key. The pivot pin you mention is thread locked in and is very stubborn to move. You have to be quite firm with the method I mention but was the only way I could move the bolt after I stripped the hex drive out.

Good luck.

WD40 is probably not the best for that application. You need a decent release agent. We have things like Plus Gas, and Shock & Unlock here in the UK.

Mike

50/50 acetone/ATF. In every test ever done it's beaten every single commercially available penetrating fluid. If you don't want to steal your wife/girlfriend's nail polish remover then a gallon of acetone on ebay is about fifteen quid. It makes a good degreaser too; just DON'T get it on the centre (windshield) section of an RS fairing. DAMHIK. It eats some types of plastic before breakfast.

Unfortunately using some type of penetrating fluid will not work as the pivot pin is retained by thread lock.

I think you are refering to the bolts that hold the MC to the footpeg plate. Put a 5mm allen socket in the bolt and give it a good firm hit with a large hammer 20oz that will probably break the hold the corrosion has. Do it a few times or use a pin punch to do it. The seals are shagged anyway so a bit of heat will also help but heat the plate not the MC.

RicK G wrote:I think you are refering to the bolts that hold the MC to the footpeg plate. Put a 5mm allen socket in the bolt and give it a good firm hit with a large hammer 20oz that will probably break the hold the corrosion has. Do it a few times or use a pin punch to do it. The seals are shagged anyway so a bit of heat will also help but heat the plate not the MC.

Guy has issues with the front brake. Normally, there aren't any footpegs on the 'bars.

GF Wollongong wrote:Front brake master cylinder mounting pin (5mm allen key bolt - or whatever the correct name is) is refusing to come out.

Any tips?

• Have soaked overnight in WD. Waste of time as it was probably sealed.
  
• Tried impact driver and 5mm allen key. Nothing
  
• Used 5mm in socket - and it's about to strip.
  

Have held off using blow torch for fear of melting the rubbers. Would like to clean out and reuse MC brake piston - as could have been the case on the K100 after I spent $193. 

MC piston and spring are seized, fluid crystalised, handle doing nothing. Have it all off and on the bench. This is the last step in the dismantling....

Am expecting to have to drill it out and use ezy out.

Before I do this, any thoughts, top tips or experiences that will help guide the way. Can't believe it is this stubborn.


thanks

Guy

Guy,
Just to make your problems a little clearer, is it the front brake lever pivot pin that stuck?
Perhaps some images would help.

Mike.

Motorbike Mike wrote:

RicK G wrote:I think you are refering to the bolts that hold the MC to the footpeg plate. Put a 5mm allen socket in the bolt and give it a good firm hit with a large hammer 20oz that will probably break the hold the corrosion has. Do it a few times or use a pin punch to do it. The seals are shagged anyway so a bit of heat will also help but heat the plate not the MC.

Guy has issues with the front brake. Normally, there aren't any footpegs on the 'bars.

Yep you're right Just testing you

I was worried for a moment there because I thought I was going to have to move my footrests!

Was about to post pic but attachment wont work.

Attachment file size limit showing: "0.049Mb" (next to submit button on RHS)

According to my calculations that amounts to a pixel.

How do I adjust this?

Guy

Bolt has given into reason.

I resumed "negotiations" with impact driver and soft hammer. Then upped it to allen key head in socket with bigger (metal) hammer - figuring that the soft one might not jar it enough.

Gave the surrounding (aluminium) body an extended dose of hair drier (didn't want to melt the piston rubbers if they were savable). 

The allen key had bedded itself in quite well - previously thought it was about to strip. Then with a spanner to the end of it, gave it a quick jerk and it began to turn.

On removal, there was a lot of blue loctite on the thread at the base - where WD-40 was unlikely to get to or more importantly penetrate (though jarring with a hammer might have created a hairline fracture between the threads).

A lot of crystalised brake fluid in the area.

And one seized brake piston...

Am soaking it over night in WD-40 and will apply heat tomorrow and maybe compressed air.

Still can't get a pic(s) to attach. Any ideas?

Hope this is of use to some of you

Guy

Brake Piston removal failed

Heaps of WD-40 and oil and heat (hair dryer and blow torch) and time and tapping and compressed air ... repeat repeat. Hasn't moved. Dead dog

Wonder if anyone has a K1100LT 1993 or suitable brake master cylinder for sale?

Must have working piston and spring, bore not worn, brake handle mounting pin not threaded. Seals need to be good enough to use (not replace - subjective I know)

Might try the vinegar soak just for the hell of it.

Any other suggestions?

Guy

Try a soak in nitric acid that will destroy the rubbery components and should leave the alloy alone. It's sort of a last ditch effort but I have had some success with it. If there are any steel components it will destroy them.

Reminds me of the American pacification program in Vietnam... aka WHAMO

"Destroying villages to save them"

Might see if I can get a working second hand one beforehand.

Thanks again 

Guy