Front Brake "drag" - How much is normal/acceptable?

Hello again,

I ordered new stainless brake lines today from Len. I'm about to take the calipers off and inspect the pads, but before I do that, I am wondering how these brake systems really work!

I'm told they are hydraulically pushed, and that the pads will 'ride' on the rotors when the brakes are not applied, meaning there is no vacuum to pull the pads off the rotors.

Well, when I rotate my front tire by hand, it comes to a stop without even going a full revolution even with a 'good strong spin' (like the Price is Right)

Is this OK? I don't hear any excessive scraping noises or anything.

Just curious. Thanks!

 

No, you should be able to spin it farther than that. Something is not releasing enough pressure. If you're doing all that work, while you have stuff apart, pull the caliper apart and clean it well, rebuild if needed.....AND pull the master cylinder apart and clean that, rebuild if needed. I'd personally suggest doing it all ANYWAY, that way you KNOW when it was done, and you know WHO did it.

Dave Fox

 

+1 on Dave's advice.

The drag could be caused by a number of things. But the easiest fix is to be like the Nike commercial, and Just Do It.

When doing the MC make sure you get a strand of electrical wire and get the "back valve" cleaned.

 

Nearly ZERO, in answer to your question. The front wheel should spin as free as free can be; you should be able to hear the pads gently caressing the rotors, but that's IT. NO drag.

The above advice is spot on; no sense replacing lines without rebuilding the calipers and master cylinder.

If you don't, the bike's gonna make you anyway, trust me.

 

Thanks again guys,

Now I need to learn how to do this

Fitz, you don't have a guide like the valve clearance one, do you?

BTW, I NEVER would have attempted adjusting my clearances had it not been for your incredible attention to detail.

OK, more new parts maybe!

 

Caliper rebuild is pretty straight-forward.

Pull off dust seal
Pull out the piston either by air or use of a grease gun
pull the seal from inside
pull bleeder screw
meticulously clean EVERY crack and crevice
install seal, piston, and dust seal in reverse order

There is a metal ring around the outside of the dust seal that holds the seal in place

Use brake fluid as a cleaning agent on the inside of the calipers, along with lots of q-tips.

 

So, I pulled one caliper somewhat apart, looked at my Haynes manual and apparantly im missing the dust seal! No wonder the piston is rusty on the inside and probably why it sticks. Looks like more money for Chacal, lol. I am going to order kits for both calipers.

Oh, theres a gummy residue all over the "shim" that the pads are secured onto... Should I grease.this? I should post a.picture tomorrow

 

Hmmmm, that gummy substance could be an application of "Anti-rattle" or "Anti-squeal", if I'm reading your post correctly.

 

That's what I would think it is.

No, you shouldn't really use grease on the back of the pads.

Instead, you should use Disc Brake Quiet or some other anti-squeal compound.

And DON"T lose those pads shims, you will want to put them back where you found them when done.

 

You shouldn't need to use anything on the back of the pads; you DO use a brake lubricant to grease the pins the caliper slides on.

If you're working on a 750 Maxim, your dust seals aren't the "boot" type; it will appear until you take it apart that there aren't any dust seals. In that style caliper, the dust seal is just a second piston seal "outboard" of the main one.

Definitely talk to chacal; there's something odd about that particular caliper but I don't remember what.

A note to my fellow contributors: keep in mind that the brake calipers on the 750 Seca, 750 Maxim, 650 Seca, 650 Maxim and 550s are ALL VERY DIFFERENT except the 750 Seca uses the same style as the 550s and 1100s.

 

Ahhh, its brake lubricant.

Calipers on the 750 have different fluid seals. Chacal and I had a discussion about it, it's a safety concern.

 

Hey Timmay, I'm just about to tear apart my 83 Maxim 750 front brake and replace everything that ain't metal. I'd be curious to hear what you took away from your discussion with Chacal. I'm sure I'll get to the same question pretty quick here from what you and Fitz have said about the calipers being different. He is surely where I will be going for parts. And they say that, one day, it will warm up and stop raining here in the Great Northwet and maybe, just maybe, I'll be able to go for a ride. And then be able to stop.

 

Hey Hamster,

Basically, if you got deep pockets and want to do it right, you'll need special kits for the 750... Yours being an '83, you might be lucky...

Bottom line is there is one particular seal that is 'nearly' the same as a Seca, but on the Maxim, it's thicker, so replacing with anything other could be dangerous.

I opted to take a risk, and use the thinner seal. Lord knows thecondition of my old one. Given that I know I will be rebuilding again next winter.

I am going on the fact that my piston was already missing a dust seal and was in poor shape when I rode it last season, there were numerous safety issues with the machine and im getting them back to spec, thankfully. I certainly don't condone shaving a few bucks, As our lives are worth more I think, but like I said, I will be rebuilding again soon enough.

Please ask Chacal, hes a great guy and awealth of knowledge. Were lucky to have him on this forum.

Hope your weather improves, ive been out in WA and OR in September... Stunning scenery and we had a month of sweet weather