How much rear brake drag is normal?

[Sadlsor]

Sadly, @Tommo you have correctly identified the early stages of the rifling phenomenon.
Don't feel bad; when fumbling around in there shortly after getting my '08 1300 with an eerily similar problem, I managed to cross-thread the brake stopper bolt almost 3 years ago. And being the obnoxious ass that I am, I actually argued with @Igofar that this was not my issue... so now here's a tip:
Don't bother arguing with Larry The Bike Whisperer, because you're only going to be proven wrong (just about 100%), waste your time and others', and the only outcome will be unnecessary drama, and your ultimate embarrassment. At least that's what happened to me, and now that I know these forum-dwellers better than I did back then, including Larry, I acknowledge my errors due to my ignorance.
Insofar as how to maintain and enjoy these fine motorcycles, the nice folks here can - and will - cure anyone who is ignorant.
This assumes one is teachable.
I'm frequently wrong, and never in doubt. But I AM teachable.

 

[jfheath]

I thought I'd collect together some images and thoughts which may help.

First an extract from your photo.



The gap is a good warning sign that something is going wrong. You can see this developing - the retaining clip has a wing which springs onto a raised moulding. You can see the relative position of this through the spokes of the rear wheel. The gap is caused by the repeated vibration of the clip against the softer metal alloy of the brake caliper bracket. It wears away.

This is shown remarkably well in @Igofar's photo below.



With the clip in this position, the brake pads are going to be applied unevenly and the pads and bracket are going to try to oscillate.


Below is a photo taken from my previous ST1300 - probably about 70,000 miles. No signs of rifling in the bracket, but far too much wear here. Note the position of the clip relative to the raised rectangle on the caliper bracket.



So can't anything be done to prevent this wear ? I started hunting through the manuals and found that there is a glue specified for that retaining clip.
Threebond 1521 is recommended by Honda in the service manual and is described by Threebond as a multipurpose bonding agent made with synthetic rubber and synthetic resi, capable of withstanding temperatures upt o 100 deg C.
UHU Max Repair Extreme seems to be similar and is described as a Polymer adhesive which is an extremely strong, water resistant, temperature resistant and extremely flexible.
My belief is that although this clip doesn't need gluing in place, either of these two adhesives will provide a strong flexible layer between the clip and the bracket that will prevent them from rubbing against each other in the first place. Using this as prescribed, is something that could well prevent the rear calipe rbracket problems from occurring.




And again from Larry's crypt of horror stories, is this bracket where the oscillations have just started to occur. On it's way to a small part in the opening credits of a Bond film.



The hole in the bracket is not round. It is made to be elongated. The bracket is subject to large tempearture changes from the exhaust and from the brakes - which do not affect the swing arm nearly as much. There has to be room for contraction and expansion along the length of the bracket. The stopper bolt is a sloppy fit inside that hole - its purpose is to stop the bracket rotating at the same time as thee rear wheel as soon as you apply the brakes.

It doesn't say that you should in any of my manuals, but I always rub the smooth part of the stopper bolt with Moly Paste. Just a burnishing - the end of the bolt sits very close to the read brake disc surface. This bolt must be fully secured before the rear axle is torqued. If it isn't bracket will rotate clockwise and the stopper bolt will be lifted on the bit of slack that is available on the threads. The bolt will remain at a slight angle and the it will not be properly tightened against its flange.

Which is another thing that could cause the rear brake caliper issues.

Back to the question.

Do you need a new caliper bracket ? Not for me to say. But I would buy one at this stage, before they stop making them. Along with a new stopper bolt and some Threebond or UHU and some OEM brake pads.

Actually, I've just thought of what I could do with my 'Covid savings' - ie pocket money that I haven't spent during Covid for the last two years. Pity that I thought of buying a new guitar first.

 

[jfheath]

Insofar as how to maintain and enjoy these fine motorcycles

Is that Larry's brother ?

 

[Sadlsor]

Is that Larry's brother ?

Or second cousin-in-law on his mother's side, twice removed.
Thank you for pointing out another in the ever-growing list of things I despise about this iPhone.
I mean, I never had any typos on my Galaxy.
NEVER!
Except for 17 times per day...

 

[Tommo]

I do listen, and hopefully continue to learn.

Already purchased the UHU glue, having seen John Heath's recommendation. Appears it will be of use when I buy the news bits.

Brake assembly 43290MCSG01 ( £150 )
Brake stop pin 90158MZ0000 ( £20 )
Retainer brkt 43112MAJG41 ( £8 )
Pad spring 43108MAJG41 ( £5 )
Genuine OEM brake pads ( Question - do I need just the rears, or do I need a full set ? )


Anything else I'm going to regret not buying?

 

[Sadlsor]

I haven't seen your front pads; they seldom wear at the same rate as the rears, in my experience.
Others will opine; I'll just say use your best judgment. Not your everyday, casual judgment, but your BEST judgment.
May not need the fronts now, but the wise folks around here (not that I are one) know to keep spare consumables on hand, to prevent unnecessary downtime and loss of riding due to foreseeable and preventable parts needs.
That includes brake pads.

 

[jfheath]

Ditto. I replace my brake pads when I reckon that they will not last twice as long as the next trip.
I take the old ones out. Look at how much there is left on them and if I reckon they are worth keeping, clean them, wrap them, label them and put them somewhere.
Don't ask me where. I haven't got a clue where I put them. I just know that they are never where I thought that I had put them.
I fit the new ones from my spares drawer and then order a complete new set ready for the next time the game is played.

For me, the rear pads tends to wear down faster than the front. They are thicker and I hardly ever use the rear pedal when riding. That is the stopping assistance that the SMC gives you.
No. No - they are not dragging. Tut tut. How dare you ....

 

[SMSW]

Eventually found time to work on the bike again. Think Igofar is correct when you look at the elongation of the stopper plug hole.

As said, the hole is cast elongated and then probably cnc machined to final dimensions. If you look at the rim of the hole, you will see the chamfer machined into the face of the casting. No part would ever wear with such an even bevel around the perimeter of the hole. Had the hole been round when manufactured, and had it worn to an oval or elongated shape, the edge would be a sharp 90º at the elongated end.

As far as replacing parts, I've noticed that whenever I'm in doubt about a part being worn to the point of replacement, it is indeed time for a new one. The fact that I am unsure is the give away - something I am not conscious of is sending off alarm bells. I also cheerfully admit to replacing parts like brake pads and tires before they are fully worn away. I do my own maintenance and prefer to do it on my schedule during the off season (winter). I do not want avoidable mechanical downtime during the riding season, so I tend to do more during winter layup than I might if I rode year 'round.

 

[Tommo]

I accept the assembly is worn, the definitive moment was realising that the internal's had worn to a sharp lip or edge. when pushing my finger , in to out. It almost resulted in a slice injury to said finger.
My question about replacing all the brake pads, was based on the reality that the previous owner had fitted EBC ( with heat shields ) brake pads, all with lots of life left. Can I replace just the rears or do I need to invest £150 + on OEM's, and replace the fronts as well ?

 

[Sadlsor]

If the front pads are OEM and still serviceable then just replace the rear.
With OEM.

 

[Slydynbye]

I accept the assembly is worn, the definitive moment was realising that the internal's had worn to a sharp lip or edge. when pushing my finger , in to out. It almost resulted in a slice injury to said finger.
My question about replacing all the brake pads, was based on the reality that the previous owner had fitted EBC ( with heat shields ) brake pads, all with lots of life left. Can I replace just the rears or do I need to invest £150 + on OEM's, and replace the fronts as well ?

If your Bike still stops well with the front EBC, ride it till they need replacement, no need to waste gas money.
Most everyone will want the OEM but it's not their money it's yours.

 

[core-aggie]

As said, the hole is cast elongated and then probably cnc machined to final dimensions. If you look at the rim of the hole, you will see the chamfer machined into the face of the casting.

Agreed. And because my memory is pretty well shot, I even did a search for the part to double check ... all photos of new part ... designed as such for a reason

 

[Igofar]

I accept the assembly is worn, the definitive moment was realising that the internal's had worn to a sharp lip or edge. when pushing my finger , in to out. It almost resulted in a slice injury to said finger.
My question about replacing all the brake pads, was based on the reality that the previous owner had fitted EBC ( with heat shields ) brake pads, all with lots of life left. Can I replace just the rears or do I need to invest £150 + on OEM's, and replace the fronts as well ?

I would remove ALL the EBC pads, and use OEM ones.
Whoever added the OEM heat shields to the EBC pads, changed the thickness of the pads and fitment, and in my humble opinion, that was not a good idea.

 

[ST1100Y]

I replace my brake pads when I reckon that they will not last twice as long as the next trip.
I take the old ones out. Look at how much there is left on them and if I reckon they are worth keeping, clean them, wrap them, label them and put them somewhere.

I drop rear pads once they're <50% thickness... heat dissipation + exposed caliper piston surface...

 

[jfheath]

Whoever added the OEM heat shields to the EBC pads, changed the thickness of the pads and fitment, and in my humble opinion, that was not a good idea.

EBC pads are generally slightly thinner than OEM, but if you have heat shields on the front and they are newish pads, then your front pads will be dragging - which will activate the SMC and cause the rear to drag. You do not need the white heat shields on the front. They cool off very quickly. (The metal chromed plates are not heat shields, they are anti-squeal plates.)

Phone contact made.

I've added the following bit for the benefit of anyone new looking in on this thread.

The photos below show a pair of OEM pads from the rear caliper of the ST1300. OEM rear pads have the small rectangular notch in the tab end of the backing plate. Fromt OEM pads do not have a notch. EBC pads make no distinction between front and rear and supply all pads with a notch. The corresponding rear retaining clip in the caliper bracket has a ridge. The front one does not have a ridge. This may result in a bike whos owner has only ever used EBC pads placing the retaining clips in the wrong caliper. Check the clips are in the correct location when you fit OEM pads for the first time.

The 4 segments of friction material help to clear debris off the disc surface more efficiently than two segments (among other advantages).

The photos show the brake pads (top of photo); The thin white heat insulation pad (middle); the chromed metal anti-squeal plate with holes in it (bottom).
The white heat insulation pad is fitted only to rear pads. In this photo, it looks trasnlucent - but isn't The round marks are the result of discolouration caused by being pressed hard agains the anti-squeal plate.

Rear OEM pads have significantly more friction material then the front OEM pads. This is because they tend to wear down faster.

 

[Tommo]

Ok its been a while, but the bike is now running properly as it should. I have chased this issue and am very grateful to all that offered valuable advice. In particular John Health ( jfhealth ) who took time out to speak with me on the phone.
I have serviced the front brakes, and rubber greased pistons and sliders. checked the SMC and regreased under the boot, and checking proper movement. Replaced rear brake seals and pistons, using brake fluid to install and rubber grease on the external piston and also sliders. Numerous bleeds of the entire system.

What solved it without doubt was fitting genuine OEM pads all round.

Expensive a £160'ish but that was my problem having had EBC fitted by the PO, caused the rear brake to drag.

Thanks again

 

[core-aggie]

What solved it without doubt was fitting genuine OEM pads all round.

Expensive a £160'ish but that was my problem having had EBC fitted by the PO, caused the rear brake to drag.

Thanks for follow-up .... and a well known issue!

 

[jfheath]

Glad it is all sorted, and that it helped. Nothing 'Healthy' about me though !