Waterproofing the SMC

Reginald

cyclepoke
Joined
Jan 5, 2008
Messages
727
Location
Georgetown, Tx
Bike
ST1300
STOC #
8898
People suggest using the grease in order to prevent water from getting into and behind the rubber boot on the SMC. There is a little hole or pathway down which any trapped water should be able to escape, but Honda have brought out 3 variations on the original that I am aware of, and the post 2008 bikes have yet another design. The grease isn't essential for correct operation. People put it there as a precaution against future water ingress.
In the service manual, Honda states that brake grease be applied to the washer under the boot and at the top under the boot. It's a service requirement few perform, including shops. Every year when I flush the brakes I clean out the old and apply fresh brake grease.
 

Reginald

cyclepoke
Joined
Jan 5, 2008
Messages
727
Location
Georgetown, Tx
Bike
ST1300
STOC #
8898
Hi, bleed the system as per recommendations but now have noticed that with the bike on the centre stand turn the rear wheel by hand apply the rear brake, the wheel stops but stays on for a second or two before releasing. I assume that there is possibly air still in the system, driving me nuts.
Air will not cause the rear brake to seize, it'll be squishy. Make sure the SMC is cleaned up and check the pivot bearing the SMC swings forward on. My bearing actually delaminated and seized causing the symptoms you describe. I cleaned the bearing up repacked it with bearing grease and am still using it over 40,000 miles later. I don't think it was installed correctly by mother Honda or the hole the bearing was put in was drilled a micron to small so a new bearing wouldn't necessarily work. It may be your's only needs cleaning and repacking. Once the SMC assembly is removed the bearings inner race comes out easily enough to see what's going on with the bearing. I don't think shops service these either, mine didn't.
 

Reginald

cyclepoke
Joined
Jan 5, 2008
Messages
727
Location
Georgetown, Tx
Bike
ST1300
STOC #
8898
although when I tried to get under the rubber boot to do mine, I thought the risk of puncturing the boot when trying to lift it, was too great and resorted to sealing around the outside of the boot.
I pinch the boot with a pair of needle nose pliers to release it from the ledge of the SMC housing and then use my fingers to gently pull the boot up until the lip of the boot is just clear of the SMC housing ledge and repeat at a different angle until it's up. Don't pull up with the needle nose pliers which can tear the boot; the fingers can tell if the boot is stretching.
 

Kev

Joined
Aug 28, 2013
Messages
15
Location
England
Bike
ST1300
Make sure the SMC is cleaned up and check the pivot bearing the SMC swings forward on.


The lower bearing inner race was no problem at all just greased and replaced, the upper bearing by the SMC just will not budge, so possibly this is where the issue is. Mind you having said that l can remove the calliper and assembly fairly easily so wonder whether this is the issue. I shall persevere this weekend, try and have a peek under the SMC boot but not looking forward to that as the bike is my trusty stead to get to work.


Like the idea about the paper between pads and disc, definitely going to try that one.


Once again many thanks everyone.
 
Joined
Jan 28, 2017
Messages
15
Location
UK
I know its a bit late but I wouldn't seal it, have a look inside the lid of either brake reservoir, its usually wet, the same would happen there but never be able to dry, I treat it as a serviceable part and clean it regularly making sure the drain hole is clean.
I have rebuilt mine twice, Its not that hard when you have done it, same as bleeding the system, cock it up a couple of times and you soon get the hang of it.
 
Joined
Oct 9, 2014
Messages
32
Location
Isle of Man
Bike
ST1300
Hi, bleed the system as per recommendations but now have noticed that with the bike on the centre stand turn the rear wheel by hand apply the rear brake, the wheel stops but stays on for a second or two before releasing. I assume that there is possibly air still in the system, driving me nuts.
Kev, mine is the same, delayed release when the bike is on the stand. I've used jfheath's idea of using paper (or a feeler gauge) to discover its the outer 2 pistons which are the culprits. These are actuated via the delay valve and SMC. How about this for a theory....the delay valve introduces a delay in allowing the hydraulic pressure created in the rear master cylinder to pass down the line. When the pedal is released, might that valve also be doing the same in reverse?
it would be interesting if we got everyone to do the same test on theirs and report back.
It's driven me nuts too, but I'm beginning to wonder if this is an inherent characteristic of the linked system, and quite normal...
 
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