Forums
 FAQHelp  LinksLinks    SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

How much front brake drag is proper?

 
Post new topic   Reply to topic    Forums » General Discussion Previous topic :: Next topic  
Author Message
eggsalad
Member


Joined: 14 Mar 2020
Posts: 11
Location: Las Vegas
Buddy 150 International St. Tropez

PostPosted: Tue Mar 17, 2020 4:35 am    Post subject: How much front brake drag is proper? Reply with quote

Sorry if this is a repeat question, but the search function isn't being very helpful.

This is my first 2-wheeler with a front disc brake, and it feels like the front tire/wheel has a LOT of drag. But I'm not sure if it's supposed to be that way.

On the center stand, front wheel in the air, it takes what I would consider an unreasonable amount of force to spin the wheel by hand.

Is that okay? Nothing looks abnormal, and I didn't notice any issues on my ride home from purchase. Advice greatly appreciated, thank you.
Back to top
View user's profile Send private message  
babblefish
Member


Joined: 04 Dec 2007
Posts: 3032
Location: San Francisco
2006 Blur 180, 2008 Buddy St. Tropez

PostPosted: Tue Mar 17, 2020 8:58 am    Post subject: Reply with quote

Are the brake pads new?

If new, who makes them or where did they come from?

Is the amount of drag the same 360 degrees around the brake disk or is it just on certain parts of the disk?

_________________
Some people can break a crowbar in a sandbox.
Back to top
View user's profile Send private message  
dan v.
Member


Joined: 06 Nov 2011
Posts: 9


PostPosted: Tue Mar 17, 2020 1:05 pm    Post subject: Reply with quote

Shouldn't really notice much drag at all,

A couple of things could be going on. Axle and spacers, or brake could be installed incorrectly.

Remove the axle nut. Does wheel turn freely? If not, then the problem is in the brake installation. If it does, then problem is the speedo drive or the axle spacer are installed incorrectly.

This should help point you towards the issue.
Back to top
View user's profile Send private message  
eggsalad
Member


Joined: 14 Mar 2020
Posts: 11
Location: Las Vegas
Buddy 150 International St. Tropez

PostPosted: Tue Mar 17, 2020 5:34 pm    Post subject: What I've learned so far Reply with quote

Based on the replies and further troubleshooting, here's the update...

(And please bear with me, my knowledge of hydraulic disc brakes comes entirely from 4-wheeled vehicles)

My current belief is that EITHER the caliper piston is not retracting fully when the brake is released OR the pads are sticky in the slides.

How I came to these two possiblites...

1) I unbolted the caliper from the fork leg. I gave it a wiggle to force either the pads away from the rotor or the piston back into the bore.

2) I reattached the caliper to the fork. Wheel spins with a whole lot less drag than when I originally observed the issue. Probably an appropriate level.

3) Applied the brake lever. Brakes grab normally.

4) Released the brake lever. Wheel spins with not as much drag as initially observed but WAY more drag than before the brake was applied.

I can repeat steps 1-4 over and over, with the same observations.

(Side note: I'm not sure if the pads are original, but they both uniformly have 6-7mm of thickness)

Thoughts on where I go from here will be greatly appreciated.
Back to top
View user's profile Send private message  
eggsalad
Member


Joined: 14 Mar 2020
Posts: 11
Location: Las Vegas
Buddy 150 International St. Tropez

PostPosted: Tue Mar 17, 2020 7:00 pm    Post subject: Reply with quote

More thoughts and observations, since I'm stuck at home and bored...

First of all, I failed to realize that since this is a single-piston caliper, the inner bad is in an effectively fixed position. Rule that out.

Second, there are no sliding pins. The only (potential) sticking point I see on the outer pad is a friction fit between the backing plate of the pad and the caliper at the top of the pad. Rust or other gunk could be in there, preventing the pad from moving freely.

And tell me if I'm crazy, but it *appears* the only way to fully remove the caliper involves removing the rotor from the hub??
Back to top
View user's profile Send private message  
350kmi
Member


Joined: 22 May 2007
Posts: 101
Location: Madison, WI
'12 Buddy 170, '07 Buddy 125, '03 Vino 2T, '10 Elite 110, '83 Aero 80, '19 C125

PostPosted: Tue Mar 17, 2020 7:30 pm    Post subject: Reply with quote

At the beginning of the riding season last year I noticed a fair amount of front brake drag on my '12 Buddy.

There are caliper does have slide pins - its been a little while but I believe the pins are what the caliper mounting bolts tread into and they should have rubber boots where they fit into the caliper. Its a tight fit, but after removing the 2 caliper mounting bolts you should be able to slide the caliper off the back of the rotor. The clearance with the tire is tight and it might help wiggling the caliper a bit try to loosen the pads fit against the rotor to allow more clearance.

In my case removed the caliper and noticed that the pins were not allowing the caliper to slide side to side (seized) such that pressure was not releasing fully when the brake was not in use - particularly on the size opposite the piston. I was able to remove the pins, cleaned and re-greased them and they have been working great since.

I'm not sure this is your problem, but its pretty easy to check.

This isn't particular to the Buddy, but have also heard of scooter master cylinder sticking and not allowing the caliper to release. You can do a quick check of this by watching at the plunger that the base of the brake lever - it is pressed in when you apply the brake and it should slide back out as you let go of the brake lever.
Back to top
View user's profile Send private message  
GregsBuddy
Member


Joined: 11 Jan 2015
Posts: 500
Location: North SF Bay
Buddy 170i Vespa GTS 250ie Piaggio BV350

PostPosted: Tue Mar 17, 2020 8:06 pm    Post subject: Reply with quote

+1
And check that the rotor is straight. When we don't change our brake fluid enough, and when our bikes are old, the caliper pistons tend to not go back into the cylinders and create more than usual drag.

_________________
'15 170i Small sport scoot'
'06 Vespa 250ie GTS Medium smooth cruiser
'16 Piaggio BV350 Medium sport scoot'
'09 Yamaha TMAX Large sport scoot.
Back to top
View user's profile Send private message  
eggsalad
Member


Joined: 14 Mar 2020
Posts: 11
Location: Las Vegas
Buddy 150 International St. Tropez

PostPosted: Tue Mar 17, 2020 8:49 pm    Post subject: Reply with quote

GregsBuddy and 350kmi:

Yes, yes, yes. Your insights have been most useful!

First of all, mea culpa on getting the caliper off. I really thought it was dumb to have to remove the rotor to get the caliper off. Because you indeed do not have to!

And the overall problem seems to be a combination of ALL the ideas mentioned.

a) one of the pistons was reluctant to retract into its bore. Gentle persuasion with multi-groove pliers seems to have helped that, but only time will tell if that's a temporary or permanent fix.

b) there was indeed friction between the outer pad backing plate and the caliper frame. A few gentle passes with a file on the backing plate has fixed that issue.

c) the slider pins do need to be re-greased. I have to dig around; maybe I have some here. Otherwise, given the prevailing conditions, this will have to wait.

There's a backstory on this scoot, which makes all of these problems make sense. Per the sellers, a fine and apparently wealthy older couple, they bought the bike secondhand from a friend in Washington state, and used it there. Then, they moved to Hawaii. (In fact, I bought it with a Hawaiian title.) Then they moved to Las Vegas, and brought the scoot with them, but didn't use it much, as they'd bought a Burgman 650.

So given a few years of island use, followed by a sea voyage, followed by disuse, all the corrosion makes perfect sense. I hope I don't have too many more problems like this!
Back to top
View user's profile Send private message  
babblefish
Member


Joined: 04 Dec 2007
Posts: 3032
Location: San Francisco
2006 Blur 180, 2008 Buddy St. Tropez

PostPosted: Wed Mar 18, 2020 10:20 pm    Post subject: Reply with quote

Maybe a complete brake fluid flush would help. Otherwise, you may have to disassemble the caliper to remove any corrosion and crud from the piston and piston bore. For that chore I would use Scotchbrite or fine wet/dry sandpaper with brake fluid as lubrication. Don't use steelwool as it might leave metal particles behind.
_________________
Some people can break a crowbar in a sandbox.
Back to top
View user's profile Send private message  
Stanza
Member


Joined: 29 Jan 2018
Posts: 535
Location: Chicago
Puch Maxi, Honda C70

PostPosted: Thu Mar 26, 2020 2:47 pm    Post subject: Reply with quote

Based on your findings, and the history of the bike, it's likely that the caliper is partially seizing. It is supposed to retract smoothly, just enough that there is no real drag on the rotor. OEM replacement calipers are not terribly expensive, and there are aftermarket options available. You can certainly take the caliper apart and clean out the bore if you have the appropriate tools to hone it out and reassemble, so it's a case of what your time is worth vs the cost of putting a new one on.
Back to top
View user's profile Send private message  
Display posts from previous:   
Post new topic   Reply to topic    Forums » General Discussion Previous topic :: Next topic  Time: GMT

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

  Scootergear designed by riders for riders


Powered by phpBB © 2001, 2005 phpBB Group
All Content Copyright 2007-2011 by Modern Buddy. All Rights Reserved.