Brake drag

Hello,
I recently installed a brand new MC, SS lines, and I rebuilt my caliper.

My brakes are squealing, albeit very softly, and are getting worm after a short (1mile) ride where I don't use the front brakes. When I say warm I mean luke warm water warm. If I had to guess I'd say ~120deg F. Also, when I backup (while leaving a parking space for example) my brakes chatter and vibrate.

My first thought is that I need to loosen the bolt that holds the caliper to the forks. It has some play, but I'm not sure how much is enough.

When I rebuilt the caliper I did a few tests with compressed air to make sure the piston moved freely. I was able to push it back in by hand. I see mention of the small hole in the OE MC being clogged and causing symptoms similar to this, but as I said, this is a new MC.

Thoughts?

 

You probably need to pull the caliper and its "holding block" apart and ensure the caliper is free to "float" sideways in relation to the block. Pay close attention to the "sliding pin" make sure it's clean and lubed. The "block" is what gets bolted to the fork leg, and those bolts HAVE TO BE torqued to the proper torque, "loosening" them is not a viable fix. Both of my Secas had issues when I got them with the caliper not moving freely in the block, and giving symptoms similar to what you describe.

 

I agree with bigfitz.. all the bolts on the caliper assembly should be tightened to spec, and light coat of synthetic high-temp grease should be applied to the pins.

a couple of things to check though... you did put the shims back on, right?

also, if you look at the caliper from the front, the gap between the pads and the rotor should be equal on both sides. If it's not, loosen the pinch bolt on the wheel axle and adjust it (move the fork leg in or out) until the rotor is dead center between the pads (the clearance will be tight, so you might have to use feeler gauges). Don't forget to tighten the pinch bolt.

Chattering of the caliper assembly can be caused by either loose bolts or a weak/missing spring that goes behind the pads. In a pinch, you can take the spring back out and bend it gently to give it some more resistance... although a new one would be better.

 

my front wheel bearings have some play and are the cause of the same symptoms on my bike.

 

bigfitz:
Its been about two weeks since I took the caliper apart, so my memory may be a little fuzzy, but if memory serves my caliper is basicly one solid piece. The only bolt is the vertical bolt that holds it to the bike. That one bolt could allow the caliper to spin, on the bolts axis, but not 'float' side to side. Its not like the auto caliper on my truck, where the entire caliper can auto-center on the rotor.

Now that I think about it, I don't really remember what the bit attached to the fork that the caliper bolts to looks like.
Big pictures...
http://parts.tsl.ecen.okstate.edu/danie ... MG0501.JPG
http://parts.tsl.ecen.okstate.edu/danie ... MG0503.JPG

The bolt I'm talking about is shown in the last picture; when installed that bolt is vertical. Maybe I missunderstand.

I have never had shims on my brake pads, they are cut at an angle, such that the caliper isn't perfectly in line with the rotor (its off about 20deg), and the pads compinsate.

Bearings...very plausible...

Looks like I'm going to spend time with my manual...

 

Yeah, on the 650 Maxim the caliper pivots on that pin.

In your picture you have the nut on the mounting bolt above the plate washer. I assume that's just to hold your pieces together? When installed that nut goes on the end of the bolt as a lock - not between the washer and the fork.

They will rub a bit, I'm not sure 120 deg would be abnormal. Mine always sang just a bit when I pushed it backward. If your chatter is similar I wouldn't worry about it.

 

d'oh! it would have to be the one weird caliper.. I never seen a 650 so I assumed it was similar to 550/750/1100 bikes..

it looks just like a rear caliper off a XJ1100..

 

Whoa; my apologies. I made the same assumption, that it was like the other bikes in the series. Carl's advice has more experience behind it...

 

First of all, that bolt looks way too long. The mounting/pivot bolt should be as follows:

m8 x 92mm x 1.25 thread pitch
12mm flanged hex-head; flange is 17.25mm OD
un-threaded portion: 63mm, 7.85mm OD
threaded portion: 29mm
rainbow zinc/cad plated

That un-threaded portion is critical, because that is what the sleeve inside the caliper body "rides" and pivots upon; thus the 7.85mm OD of that unthreaded portion must be observed. If the bolt you are using has a much different unthreaded (shoulder) OD, or is completely threaded, that could be a cause of your problems, at it will tend to hang or "jam" the caliper so that it is out-of-line with the rotor disc, and that is sure to cause a squeal......especially when moving the bike backwards.

Also, make sure that both the sleeve and sleeve bore in the caliper body is clean-clean-clean and is lightly but WELL LUBRICATED (waterproof, high-temp grease mixed with some graphite powder is a good bet) as again, the pivoting ability of the caliper is critical to both proper caliper performance and to its silence.

The XJ1100 rear caliper looks identical to the XJ650 Maxim front one, but it is actually a mirror opposite. The internal guts (piston, etc.) are the same though.

 

Chamfer the edges of the Brake Pads; too.
Remove the hard, sharp leading edges.
Round them off with some sandpaper or a file.

The hard leading edges, when pressed hard to the Rotor, won't vibrate if you Chamfer them.

Simply remove the sharp 90-degree angle from the Pad.
Sand it uniformly dull all around the Pad.
That should put an end to the squealing!

 

Thanks guys.
I'm pretty sure the bolt is OE. It isn't all thread. I am amazed at your ability to give such exact descriptions Chacal.
I put some axial grease on it when I installed it. I may have put too much, as now I have a bit of a 'puddle' of it coming from the top of the caliper. And it seems to be collecting trash. Will this grease do the job? I didn't think of the graphite. I like the thought of sanding the edges.

I've got a bit of work to do to her tonight, I'll clean the grease up, and do a bit of sanding when I do.

 

Puddle: bad.

There's supposed to be a large o-ring that goes at the top of the caliper bolt bore hole recess......do you still have that?

 

The caliper pivots on a sleeve that the bolt holds to the fork. The length/threaded portion of the bolt aren't critical as the caliper pivots on the sleeve.

The lube needs to be on the outside of the sleeve, that's the part that's sealed. The bolt itself isn't sealed off and hot grease could leak. I'd suggest a light coat of anti-seize on the bolt rather than grease.

If you didn't know about the sleeve that is probably where you have a problem. It could be sticking in there.

 

Chamfering Brake Pads isn't a "Thought" ... it's a Technique used to prevent Brakes from squealing thats been used on Brake Pads and Shoes for a long, long time.

Like, since every car made by Ford only came in Black!

 

And today's trivia question is:

WHY were Model T's available in "any color you want, as long as it's black."?

 

I've got the sleeve in there, but I greased the inside of it, not the out side. I don't remember an o-ring, but I do have what looks like a very thick steel washer. It is the exact (or nearly so) same diameter as the rise of the caliper (where the caliper is (well, was) painted, and is milled flat to meet the fork mount).

I looked closer at the 'puddle', it wasn't so much as a puddle as a blob on one side. I cleaned it off. I guess I should go back in and grease the outside of the sleeve.

The caliper does have more rotational play then I remember. Looking at it now I'm pretty sure it has too much.

The fact that the caliper rotates on the sleeve instead of the sleeve acting as a grease bearing makes sense (smooth on smooth, instead of threaded on smooth).

 

Because Ford's "Moving Assembly Line" depended on total interchangeability of all Parts being used on-the-line, in order to keep the assembly line moving.

Ford didn't make 15,000,000 different cars.
He made 1 Car; 15,000,000 times.

 

my trivia answer:
all were painted black because black paint dried MUCH faster than other colors back then. in efforts to keep the assembly line moving as fast as possible, all cars were black. an introduction of colored "slow drying" paint would have seriously screwed up the flow of the assembly line.

 

kd5uzz: Just curious about your bike....
How many miles do you have on it? Did it "sit" long before you acquired it?
I'm running a little behind you on getting mine going.

'82 XJ650J Maxim

 

There should be an o-ring on top of the caliper, it seals against that plate washer.

Rotational play is good. Just make sure it doesn't slide up and down. You did torque the bolt and put locktite on the nut and torque it too?

 

MiCarl-
No locktight, or torque on the nut (although I did turn it pretty good..). I do remember an oring on the lower side of the caliper. I'll check the top tomorrow (didn't get to caliper work today). There is no vertical play.

Maxim82-
It sat for about two years. I had a great PO. He spent an entire summer a few years back rebuilding the carbs and most of the engine. She runs great. I did have to rebuild the front brake system. And I have some other things to do (suspension is the big deal). I'm unsure of the miles, the odometer has been broke for years. At least 60k, if not twice that. The PO had it for about 5 years as his only-driver, including many long road trips.

 

The o-ring goes into the recessed area at the TOP of the caliper, under the large, thick flat washer.

There is no o-ring at the bottom, only a smaller, thick flat washer.

 

I'm sure you're already aware of this site but I thought I'd help a brutha out if not....
The "Zoom In" feature is especially nice.

http://www.yamaha-motor.com/sport/parts/home.aspx

'82 XJ650J Maxim

 

How about because Henry Ford was the most frugal SOB ever to walk the planet? He started and popularized Kingsford Charcoal so he would have a market for the maple scraps from his automotive body construction... and yes, the Yamaha parts fiche is the best way to check the orientation of most parts although an occasional diagram can be confusing...

 

Ah, well then. I must be thinking about the top o-ring then. I do remember there being one. I'll double check tonight.