Perplexing Front Brakes

[jfheath]

My brakes often groan when I back it out of the garage. I don't ride it as frequently as I used to. But they never do this when I put it away after even a short ride.

Yes, my brakes always sssshhhhhh when new pads are fitted until everything settles down.


I haven't seen mention of your pad springs - it is possible to put them in the wrong way round. Also whether your slider pins are properly fitted into their mating hole or rubber bush. It is very difficult to separate the two halves of the left caliper, because of the SMC brake hoses, but the right hand side separates easily, so that is a possibility.

Have you checked the clearance as the disc rotates through the caliper bracket ? You'd hear it if it was catching, but if one of the clearances is tight, it might point to the real problem. Check it on both sides of the disc. You are checking the point where the disc rotor passes through the bracket where the chrome retainer clip is fitted. Clean the feeler gauge, hold it against the top of the disc rotor and rotate the wheel backwards . both sides of the rotor, both discs.

 

[Andrew Shadow]

@oilspot are the new brake pads OEM?

Rear pads were nearly new, so just cleaned everything and inspected the rear wheel bearings while I was in the vicinity. The front pads were maybe 50% worn, but the SMC side had a slight angle; so I put new Honda pads (06455-MCS-G02) on both sides.

 

[jfheath]

Even with the old pads, the wheel started to bind when the right caliper was installed so I will reevaluate that caliper.

Are you sure about that ? You also mentioned that it was binding when you fitted old pads.

A difference between the photo of my front wheel installation - posted by @Obo in post #10 and your photos in post #14 made me think of something else. The 'difference' may not be a difference at all - just different shadows on different photographs - but your spacers seem to be seated further out than mine. That may not be the case, but it made me think of bearing installation.

You could check this out. Spin front wheel. Is the wheel still binding ? Remove pads. Spin wheel. Is it the same or different ?

Slacken right (brake lever) side fork pinch bolts. Slacken Axle bolt. Tighten pinch bolts. Now spin the wheel. Is that better ?

You may be able to answer these questions without doing anything - you may have noticed the results before and not mentioned it. In the quote at the top - could it be that it started binding after you had fitted the caliper, after you had tightened the axle and you just assumed that it was immediately after fitting the caliper ?

I'm wondering whether the bearings are worn or they have not been fitted correctly at some time and that tightening the front axle is putting a side load on them.

If you do this check, don't forget that the pads are out - so don't go absentmindedly squeezing the brake lever ! Popping the pistons out and covering the front tyre with brake fluid is not going to score too highly in the 'Home garage mechanic of the year' awards.

 

[oilspot]

@oilspot are the new brake pads OEM?

Yup, 100% Honda.

 

[oilspot]

My brakes often groan when I back it out of the garage. I don't ride it as frequently as I used to. But they never do this when I put it away after even a short ride.

Yes, my brakes always sssshhhhhh when new pads are fitted until everything settles down.


I haven't seen mention of your pad springs - it is possible to put them in the wrong way round. Also whether your slider pins are properly fitted into their mating hole or rubber bush. It is very difficult to separate the two halves of the left caliper, because of the SMC brake hoses, but the right hand side separates easily, so that is a possibility.

Have you checked the clearance as the disc rotates through the caliper bracket ? You'd hear it if it was catching, but if one of the clearances is tight, it might point to the real problem. Check it on both sides of the disc. You are checking the point where the disc rotor passes through the bracket where the chrome retainer clip is fitted. Clean the feeler gauge, hold it against the top of the disc rotor and rotate the wheel backwards . both sides of the rotor, both discs.

I got a bit more air out of the smc this afternoon. Got everything back together and ready for a test ride.
I all honesty, checking the clearances makes sense and worth a try. I’ll try to look at that on Sunday to confirm it’s okay. The wheel rotates smoothly without the pads on the discs.
Although this bike is new to me, it appears pretty well cared for and smc aside, in decent shape.

 

[DannoXYZ]

I all honesty, checking the clearances makes sense and worth a try. I’ll try to look at that on Sunday to confirm it’s okay. The wheel rotates smoothly without the pads on the discs.

OK good! You’ve confirmed it’s brake-rubbing that’s causing drag and not bearings. However, fork & axle alignment being off may cause brakes to rub as well. Let’s see how your measurements go.

I fought front-end chattering/stuttering problem on my race CBR600RR for while. I had replaced steering bearings, wheel bearings, tyre, axle, rotors, pads, calipers, MC & lines, fork innards, nope. Was about to replace wheel and fork next when Dave Moss showed me a specific brake installation procedure. Similar to axle procedure shown earlier where order-of-operations make big difference.

Depending on your measurements, we may look into more detail of brake installation & tightening next.

 

[jfheath]

Ok now you have it pinned down, just re-emphasising something I mentioned earlier. The pad springs.

It is possible to put these in the wrong way round at the front and the rear on pre 2008 ST1300s. The wider strip is nearer the pistons is to cater for the movement of the pistons - as the pads wear down the pistons stick out further and the outboard pad is pushed closer to the joint.

The two circled tags are to keep the inboard pad in position, against the caliper body (on the right of this photo). If they are bent over, the pads will be out of position and will probably not sit square in the caliper. If you don't make an effort to keep the pad to the right (in the photo) of the tag - the same applies.

@DannoXYZ's comment of the order of doing things may be related to this. I put the outer (piston side , left in this photo) pad in first and hold it in place with a partially inserted pad pin.
I then offer the inner pad to the gap between the caliper and the brake disc, and rotate the wheel and the pad so that they move together, keeping the caliper pulled so that it gently squeezes the pad against the disc. There is no way then that the pad get get on the wrong side of that tag.



Easy to see with the two caliper halves separated.

 

[oilspot]

Just an update and a summary of what's been checked or completed so far:

Back in October I had my first conversation with Larry about aligning the front forks AND my SMC had a rattle when I jiggled the brake line. As far as I could tell the SMC was functional, but I had just replaced the rear brakes (probably a bit prematurely). My average mpg back then was about 48, which I thought was okay.

Aligning the front forks took about an hour and resolved my handling issue. The bike rides rock solid even on the interstate with buffeting from cars or trucks. I feel the buffeting, but the ST no longer gets pushed around!

After replacing the SMC, my mpg went down. Quite possibly from dragging rear brakes or front brakes. Another call to the white courtesy phone and I discover a pinched boot on the SMC caliper and a missing grommet/washer on the rear pad retaining pin. I patiently waited for my parts delivery and meanwhile cleaned up the brakes and bled the system again with the extra step of activating the SMC when bleeding that circuit (compress the piston all the way, pump it back up with brake pedal, then repeat till one pump easily extends the SMC). Brakes felt rock hard, so I was confident the air was eliminated. I left the brakes compressed overnight, to help chase away any remaining gremlins.

When the parts arrived I reassembled the brakes, there was still a bit of resistance on the front wheel. Slight pressure on the L & R calipers and the wheel spun freely. The pressure was brief and minute so I thought bedding the pads might do the trick. I went on a "test ride" of about 100 miles on Sunday and when I returned home the drag on the wheel was no better. I pulled everything apart again and recleaned the pistons to make sure they were sliding smoothly. Still no improvement! Another update on the white courtesy phone and I checked the front wheel bearings. The bearings looked good, no binding or poor installation was observed. As a hail Mary, I replaced the pad springs on all three calipers and at Larry's urging cleaned all exposed surfaces to remove any grease that might attract dirt/dust. At this point there was still no major change in the drag - although the rear was dragging slightly as well. Each time a reassembled the calipers and pads, I would wiggle it back and forth to confirm it was sliding okay on the pins with no binding. I don't feel any binding in the slide pins.

I decided to bleed the system again using all the tricks Larry had relayed over the past few months. Oddly, it seemed like I was getting some tiny bubbles from the rear center bleeder. It took about a pint of fluid before the bubbles disappeared. I put at least a master cylinder full through each point, with more through the SMC and rear center bleeder. All told it was about a quart of fluid. Unfortunately there was no improvement.

Someone earlier suggested measuring gaps between rotor and caliper on front brakes. That was trickier than I thought; but SMC side was about 0.1 in on each side of disc, and right side was about 0.06 inch left and right. According to the manual 0.06 is a bit less than spec - but I'm not going to place money on that measurement it was not easy to measure.

Summary:
1. New SMC
2. New front pads (L&R)
3. Nearly new rear pads
4. new pad springs
5. new grommets on each pad retaining pin
6. new boot (the larger one) on the new SMC
7. rear bearings seem good and smooth
8. front fork alignment good
9. front bearings seem good and smooth
10. There is probably something else I replaced but forgot...

So what else can I try? The most likely thing is probably keep bleeding the system, but I imagine there COULD be something I'm missing.

 

[jfheath]

Someone earlier suggested measuring gaps between rotor and caliper on front brakes. That was trickier than I thought; but SMC side was about 0.1 in on each side of disc, and right side was about 0.06 inch left and right. According to the manual 0.06 is a bit less than spec - but I'm not going to place money on that measurement it was not easy to measure.

You don't have to measure it. You have to check that it is at least the specified measurement. 0.7mm rings a bell, but you had better confirm that in your manual. Supposing it is 0.7mm, you get that size feeler gauge, and slide it along the outer edge of the disc surface to make sure there is enough clearance to let it pass through the slot in the caliper bracket. Both sides. If the feeler gauge passes through the slot, then you are Ok. It's difficult to see, but possible with a bright light peering between the brake disc and the fork leg, and one eye closed - before you put the feeler gauge in the way.

If the axle end is flush with the fork leg then the clearance should be ok. But you still need to check because if the clearance isn't there, then something is wrong with:

1. The wheel installation
2. The bearing installation
3. The caliper bracket installation
4. The caliper bracket itself is damaged
5. The chrome retainer clip where the top end of the pad seats is out of position.
6. Possibly - brake pads are incorrectly installed.

You can move the left fork leg on the axle to obtain the clearance, but if the axle end isn't flush and the clearance isn't there then it may be a sign that one of the above is wrong. Odds are that it is the wheel installation. I hate to guess, but it is the cheapest of the above to fix, and only requires you to watch and understand that animation in post #16.

Did you know that if you don't follow the tightening sequence for the front wheel exactly, then you can have a nice tight axle, but the wheel is able to slide left-right on the axle itself. That would mess up the clearance - first on one side, then the other. I doubt that it would improve the handling much either.

 

[oilspot]

I had to stack feeler gages to check the clearance. I think I’m okay, and the wheel has been uninstalled and installed a few times to confirm it was kosher.

for fun and curiosity, I tried moving the left fork in/out to see if it changed the brake behavior (better or worse) and there really wasn’t much change.

 

[MidLife]

Surprised the front brakes aren't hot after a ride, if you say the front tire turns hard?
If both front rotors are cool after a ride, then it would seem to be ok.

As said here, it doesn't look like really binding if not heating up.

Did you get to look at the square cut seals in the piston housings? They help the pistons retract.

 

[oilspot]

As said here, it doesn't look like really binding if not heating up.

Did you get to look at the square cut seals in the piston housings? They help the pistons retract.

I've checked the discs a few times and they seem to not be getting very hot - which is good. I'm judging based on the loss of fuel economy and also input from Igofar - who sent me videos of his wheels spinning many revolutions after a good kick. I am lucky to get one full rotation from front and maybe 1.5 revolutions on the rear. I'm out of brake fluid at the moment but may bleed one more time to see if there is anymore air lurking somewhere.

When I cleaned the pistons, I didn't really look carefully at the seals. You are correct, they help retract the piston slightly and could contribute to the issue. I was just hoping I could avoid opening up the system again to replace seals. I guess it's an option at some point... I was banking on "they were fine a month ago" mentality. Obviously, that is somewhat lazy and/or maybe naïve.

 

[jfheath]

I'm out of brake fluid at the moment but may bleed one more time to see if there is anymore air lurking somewhere.

Larry will correct me if I am wrong, but although air in the system is not wanted, it isn't going to cause the brakes to drag. But new pads, reseated pads are both going to take a little settling in. In my case, it is surface rust on the brake disks that nearly always cause the brakes to groan a bit when I back it out of the garage. They are as good as new in a few miles. The brakes are very exciting for the first few uses. Loads of friction. Close inspection of the windshield time.

 

[MidLife]

I've checked the discs a few times and they seem to not be getting very hot - which is good. I'm judging based on the loss of fuel economy......

Are you worried about not getting 48 mpg?

It is mainly the "Whispered" bikes that get up to over 50 mpg.

For the rest of us, commoners, it's a slightly different reality.

Original bike specs https://motorcycleinfo.calsci.com/ST1300_f.html





Road testing https://ridermagazine.com/2002/08/28/2003-honda-st1300-abs-road-test/




Fuelly https://www.fuelly.com/motorcycle/honda/st1300






As an aside here, interesting to see the spike at 37 mpg....which is typical for code 25/26 STs......

I had days with strong headwind where I could barely break 30 mpg.

MPG may not be the best gauge.

You may want to just ride it for a while as hinted here:

...... the brakes to groan a bit when I back it out of the garage. They are as good as new in a few miles. ....

 

[Igofar]

Here we go with Stats again….
More people die in hospitals, than Starbucks, but I must have beat the stats and made it back home again last night after being rushed to the hospital.
Mileage per gallons is about what you’re willing to accept and live with, just like anything else.
A stock Glock will punch holes in a paper target all day long, while a hand tuned 1911 will punch cloverleaf’s at 50 yards.
I don’t buy into the apps like fuley because everyone thinks their bike is normal, perfect, and runs fantastic, until they are shown how much better it can be
Like Reacher says, details matter.

 

[MidLife]

.......everyone thinks their bike is normal, perfect, and runs fantastic, until they are shown how much better it can be....

Can you share data on "how much better it can be", of the same thoroughness as this:

......74 fillups averaging 43.6 mpg tracked about 15,000 miles.

Comment at the time was:

....thanks for sharing......

And then....

I don’t buy into apps like fuley......

What happened to this?

 

[Igofar]

Can you share data on "how much better it can be", of the same thoroughness as this:




Comment at the time was:




And then....




What happened to this?

To sick to hold phone, no desire to debate subject,
Covid sucks and my bike gets better mpg’s than yours….

 

[MidLife]

........my bike gets better mpg’s than yours….

Hearsay, no statistical relevance.

..... no desire to debate.....

Not asking for debate, just substantiated records, as provided by @dduelin.

To sick ....

All the best for a speedy recovery!

 

[Igofar]

Hearsay, no statistical relevance.





Not asking for debate, just substantiated records, as provided by @dduelin.





All the best for a speedy recovery!

So if my bike runs like crap, and I fill it up 40 times, and getting records of it getting poor gas mileage, that makes it certain?
Why don’t you ask members who’ve had me tune their bikes how their mileage changed.
Again, no desire to defend myself in this instance.

 

[Slydynbye]

When I cleaned the pistons, I didn't really look carefully at the seals. You are correct, they help retract the piston slightly and could contribute to the issue. I was just hoping I could avoid opening up the system again to replace seals. I guess it's an option at some point... I was banking on "they were fine a month ago" mentality. Obviously, that is somewhat lazy and/or maybe naïve.

This is worth checking. At minimum pull the Piston seals out and clean the grooves. You could possibly replace all the Brake piston seals as well.
You mentioned cleaning the pistons, did you by any chance get cleaner or solvent on the rubber seals?