Air in SMC Query

[Igofar]

I agree 100%!
I already posted this somewhere on the forum a couple years back....
But while at a local Honda shop, was watching a mechanic working on a bike, and I noticed he was using a IR 1/2 drive impact like I have, so I commented on his tool. It appeared he was not removing stuff, but putting a clutch on a dirt bike back together etc.
I noticed his PSI was set around 100 or so. I couldn't help myself, but I asked about the torque setting...He said something to the effect, that's what folks don't understand about torque settings, they are the MINIMUM settings, and as long as your above them, your good.
He went on to say that ALL the mechanics in his shop set their tools at the same PSI so they don't have to worry about different torque specs, or not being tight enough etc.
I'm all for REMOVING stuff with impacts, but I never try STARTING or running a bolt back in with an impact. It only takes a few seconds to grab a ratchet and a torque wrench.

 

[Andrew Shadow]

As I wrote Larry- the problem is with the person using the tools not the tools themselves. Your story is stark evidence of that fact and the fact that that guy shouldn't be working on anything mechanical.

 

[Fawlty]

Here are some photos of my rear brake. I would appreciate any comments. Thanks in anticipation.

 

[Igofar]

OK.... Referring to the pictures by #number....
#1 Pads appear to be aftermarket pads, no Honda OEM (this may be part of the problem)
#2 The pad hanger pin is so RUSTED that the pads are unable to float/move as they were designed (this may also be a problem)
#3 Picture(s) 1,2,3, the piston does not appear to be touching the rotor, unable to see if more than one piston is in this state.
This could be caused by the rust on the hanger pin, dirt on the pistons, incorrect brake pads, etc.
#6 Pistons appear to be corroded/dirty and may be sticking, and unable to retract or move (this may be a problem)
#7 The rubber grommet that the guide pin goes in to appears to be either under suction from too much grease, or the pin is bent, tilting the grommet, or is dirty (unable to tell from photo, would investigate this more)

With all due respect, there is so much rust damage on all the banjo fittings, bolts, axle nut, and lines, it would be anyone's guess as to what is causing your issues.
Is the rear axle rusted?
Are the Flange bearings shot?
Are the Wheel bearings shot?
After seeing that much rust on the rear of the bike, the first thing I would do is pull both front calipers and see if the guide pins are rusted also!
This could cause the front calipers to go out of alignment and drag the rear brake. (the front wheel spinning would not reveal this)
In just my opinion, I would say that ALL the brake lines and fittings should be replaced, the calipers should be rebuilt with all new parts, (including bleeding nipples) etc.
good luck, let us know what you find.
Remember, I'm just the messenger.

 

[Upt' North]

+1, what Larry said, doesn't look like it's been properly cleaned/serviced in some time.
And re picture 7, something just doesn't look right.
It needs stripping and rebuilding. New pins, pads, rubbers and piston clean up. If the fronts are no better, likewise.
Upt'North.

 

[jfheath]

A useful set of pics, Fawlty.

Some more observations.

Photo 7 showing the upper (forward) boot on the slide pin is wrong as Upt'North suggested. The boot is not as it should be - there is a very obvious lip on the proper boot (see my photo in post#97 showing both boots). The one in question is the one on the right in that photo and the obvious lip is on the left hand side of the boot. That lip should fit inside the lip of the caliper bracket - and it is extremely difficult to get it back into place if the rubber has expanded - having been exposed to normal lubricating grease (mineral oil). So much so, that it might be very tempting to get a pair of scissors to it and cut it off - which (I may be wrong) but it looks as though someone has done just that. whatever - that boot is damaged, or is the wrong size or is not fitted properly, and it is not keeping out the elements. I suspect that your slider pin and the bore are corroded inside as a result.

As Larry stated, the pad pin which threads through the rear of the pads (eg in photo 1) is rusted up and will prevent the pads from moving as they should and/or prevent the caliper from moving laterally as it should.

Your pistons do not have any rubber grease applied to them and are open to the elements - which possibly means that some of them may be corroded.

The rear pads should have a white heat shield and a metal anti-squeal plate. Again - see my photo post#97. (Antisqueal grease is also normally applied very thinly to the back of the squeal plate - eg ceratec, or, dare I say it, M77)

From some shots, the left hand side seems to have worn more than the right - which suggests caliper movement is restricted. And, - difficult to be certain on this because of that odd rubber boot - that top slider pin seems to be sitting further into the socket than does the lower slider pin - which it would be if the top pin was locked solid.

As already stated, there is a lot of rust around that rear caliper. It really needs to be taken off, investigated, repaired as appropriate and re-assembled. Those banjo hose connectors need to be cleaned up and investigated for serious rust damage.

I would also be suspicious of the spring in the roof of the caliper - and it would be good to see a photo taken from the right hand side of the bike, looking at the inside pad through the spokes of the wheel.

I'm surprised at the bone dry bleed valves and brake couplings - given that the SMC has been fitted new and the entire system has been bled. Unless it was all detergent washed and what we see is the surface rust that appears within a couple of hours on bare, grease free metal surfaces.

 

[Igofar]

Good info as always John, thanks for jumping in.
The grommet may not have had the lip cut off, however, it may have been put on backwards?
What do you think?

 

[MidLife]

I do not yet know if my mechanic followed the correct bleeding procedure.

Is it a coincidence there is a Playa Honda in your area by Mar Menor? Your bike looks like having spent good part of its life by the salt marches maybe on the way to this Playa?

Looking at the pics, probably didn't really matter very much what procedure the mechanic might have followed or not....

Would be interesting to see pics of what's under your SMC boot as well!

If there is air trapped in the SMC, could the heat in the system and the bike, expand the air causing the SMC to lock up?

Can only repeat earlier suggestions: Heat will try to expand more than just air, and if parts that are supposed to float are frozen, then no good.

And it may sound contre-intuitive, but in your case of static locking with temp increase, air in the system would most likely work towards less pressure than if the lines were filled solid with oil. So plenty of reasons for not rushing to blame air in the lines on this one. But blaming the mechanic is definitely OK.

 

[jfheath]

The grommet may not have had the lip cut off, however, it may have been put on backwards?
What do you think?

Well that was my first thought to try to explain that surplus of rubber which is masquerading as a boot.
But the position of the moulding line on the segment with the largest circumference, compared with my photo of a new one, suggested that it might be the right way round - if indeed it is the correct boot - it might be a substitute. But it is all intelligent guesswork and the 'for-certain' info is that the boot fitting isn't as it should be, and is probably letting in the elements.

Regarding the behaviour of the brakes - there is enough in the photos to warrant getting the caliper off and fixing what is obviously wrong as a priority. You can separate the caliper body from the caliper bracket by retracting the rear axle enough, removing the stopper bolt and taking out the pads. Watch out for the pad spring in the roof. I'd be wanting to know which way round that is fitted and the state of that little tag on the spring.

But Fawlty doesn't feel able to do this sort of work, and is relying on finding a mechanic who probably isn't familiar with the ST1300. Certainly his last mechanic did not advise on any of the stuff that we have seen from the photos.

 

[Fawlty]

First of all thanks again to you all for your input. I cannot tell you how much I appreciate it. There is plenty of food for thought here, which I am going to put together and translate into Spanish, so that I can try and explain what needs to be done, when I find someone who is competent.

John, I am going to take a photo later from the right hand side, as you suggested, and will upload it. What do you think about photo 10 which shows that there is no head to the hanger pin bolt? Looking into the hole it appears to have sheared off!

Lots to do, but I am determined to get it done!

 

[jfheath]

What do you think about photo 10 which shows that there is no head to the hanger pin bolt? Looking into the hole it appears to have sheared off!

The head should be recessed, but it should have an allen socket (hexagon socket) in it. I stopped using these 'cos the metal seems to be very soft and the torque of 18Nm seems rather high. I frequently found that on the 3rd removal, the hex socket would start to round off - so I always kept a few new spares, used them twice and then threw them away. But with my adaptation, its a long time since I have seen one - I assumed the hex head was further into the hole - but now you point it out, I cannot see the hex socket head at all.

But in the process, I had two that I could not remove. For one, I let the dealer get it off. They welded a bar end onto the exposed length of pad pin and used that to get the pin moving in the thread. They had to replace the seals as the weld heat would have damaged them.

For the other, I took the caliper off and ground a deep 'flat' onto the round shaft of the pad pin. I used an adjustable spanner that was set just too tight - so that I had to hammer it onto the shaft, and that gave me enough grip to get it turning. I do not remember how I got the caliper off without being able to take the pads out. It must have been possible though - my notes say that was what I did 6 years ago !

Its not something that you would want to try to drill out and risk damaging the threads.

 

[Fawlty]

Ah. I understand. I have taken a very close look now and I can see the allen socket. Keep you posted. Cheers!

 

[Fawlty]

Is it a coincidence there is a Playa Honda in your area by Mar Menor? Your bike looks like having spent good part of its life by the salt marches maybe on the way to this Playa?

Looking at the pics, probably didn't really matter very much what procedure the mechanic might have followed or not....

Would be interesting to see pics of what's under your SMC boot as well!



Can only repeat earlier suggestions: Heat will try to expand more than just air, and if parts that are supposed to float are frozen, then no good.

And it may sound contre-intuitive, but in your case of static locking with temp increase, air in the system would most likely work towards less pressure than if the lines were filled solid with oil. So plenty of reasons for not rushing to blame air in the lines on this one. But blaming the mechanic is definitely OK.

Well spotted about Playa Honda! This bike has only been in Spain for 2 years. All its life prior to that was spent in the UK. I am not able to speak to the previous owner, but he imported the bike into Spain in 2016. I do have a lot of the UK service history, which shows regular maintenance at UK Honda dealers. Going on the mileages recorded on the service papers and the mileage on the odometer when I purchased it in October 2017, it has not been used much whilst in Spain, until I had it.

Yes, I am fairly sure that on the last bleed the air was purged, however, in one way that is now irrelevant as it's back to square one!

Many thanks for your input.

 

[Fawlty]

OK here are the photos of the rear caliper taken from the right hand side through the wheel as requested John. I have also taken some more photos of the front calipers and closer shots of the rear caliper.

 

[Igofar]

Thanks for posting more pictures.
Photo number 4 and 5 show incorrect bolts attaching the lines to the caliper. Just because they screw in, does not mean the are correct, or may work properly!
More importantly, photo number 10 clearly appears that the rear guide pin is bent (at least it looks like that from the photo).
The last couple pictures show a really filthy pad hanger pin, which again, would prevent the pads from floating and working as they should.
You've got way too much neglected stuff going on here.
It does look like someone had replaced the secondary master cylinder though, judging by how clean it is compared to everything else that is dirty or rusted.
You look like you have a long winter season ahead of you, cleaning and replacing rusted items, if your going to get your bike road worthy again.

 

[MidLife]

You look like you have a long winter season ahead of you.....

Not sure they know what winter is in our friend's part of the world.

Here is what biking looks like there.

https://www.youtube.com/watch?v=M0OSkDtg8Ls

Shouldn't the post title be changed to "Air in Mechanic's head query"?

 

[Fawlty]

Thanks for posting more pictures.
Photo number 4 and 5 show incorrect bolts attaching the lines to the caliper. Just because they screw in, does not mean the are correct, or may work properly!
More importantly, photo number 10 clearly appears that the rear guide pin is bent (at least it looks like that from the photo).
The last couple pictures show a really filthy pad hanger pin, which again, would prevent the pads from floating and working as they should.
You've got way too much neglected stuff going on here.
It does look like someone had replaced the secondary master cylinder though, judging by how clean it is compared to everything else that is dirty or rusted.
You look like you have a long winter season ahead of you, cleaning and replacing rusted items, if your going to get your bike road worthy again.

Thanks again Larry. Forgive my ignorance but is the rear guide pin attached to the bracket or the caliper? Don't worry, one way or another I am going to get this sorted log before winter!

 

[Fawlty]

I have another question. Is a smear of silicon grease required on the brake pad hanger pins?

 

[Upt' North]

It would have been the sort of thing copper grease would have gone on years ago, but that's gone out of fashion, have you got Honda M77 or Moly grease handy the sort of thing you put on the back of the pads?
Upt'North.
And yes, just a light coating.

 

[Al Gully]

Your pins look in really rough shape, I'd go ahead and buy 3 new pins (one for the rear and 2 for the front) along with the new o-rings and rubber caps that I didn't see in your pictures you posted.
New pins look semi chromed, then apply a smear of grease of your choice to them.