Vespa GTS 300 rear brake rotor might be warped
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Addicted
2010 Vespa 300 Super
Joined: 04 Oct 2015
Posts: 699
Location: NYC
Wed May 31, 2017 1:05 pm quote
Seems like the rotor which was replaced last year (at Vespa Brooklyn) maybe warped.What makes me say that is that I was hearing a noise that felt like the rear wheel was touching something. So while going downhill on one of the streets I shut the engine off and let it just roll, the noise came at regular intervals like the rotor was touching the brake pads at a certain part of the rotor.
Not sure it could be anything else, feels like when you have a bicycle wheel out of balance and the rim touches the brake pads. Generally in that situation you can true the wheel tightening/loosening the spokes around where it is touching.

Seems to me I don't have any options besides replacing the rotor. Could I use a hammer or a plier and pull the rotor to kinda true it?
If I have to replace the rotor then what all else should I take care of, the brake pads are fine. I could replace the gear oil since Ill have to get the wheel out.
Any guidance will be greatly appreciated.
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 2804
Location: East Anglia, The power house of the UK
Wed May 31, 2017 11:40 pm quote
baba, have you hit any large potholes lately? Is the rear wheel rim itself warped? If the rotor was replaced last year I wonder why it would be warped. Do you just use the rear brake only for stopping? Do you hold the brake firmly on after stopping (don't as this can warp the disc due to heat transferring from the brake pad into the disc)? How long has it been like this? Best to put the bike on it's centre stand and turn the wheel (engine off) by hand. Use a fixed point against the brake rotor and carefully watch to see if the rotor is definitely warped. Then do the same with the wheel rim. Check for play in the rear wheel by pulling and pushing the wheel at the top and bottom to detect sideways movement. Don't confuse rotational play in the drive shaft splines with sideways movement. It's easy to do that. There should be rotational play but no sideways play.

Yes, change the rear hub oil if it's due to be done, or it you want to do that anyway. Never a bad thing.

Never use a hammer or pliers to try to alter the disc. It won't work and you may do lots of damage to gearbox bearings if the disc is not removed from the bike when you hit it.

Report back please.
Addicted
2010 Vespa 300 Super
Joined: 04 Oct 2015
Posts: 699
Location: NYC
Thu Jun 01, 2017 3:07 am quote
Quote:
baba, have you hit any large potholes lately?
I live in NYC, I hit small pot holes all the time and larger ones on occasion if I am on a new road and it is night time don't often see it till it is too late..
I checked for any issues with the wheel itself and there is no sideways movement, a slight rotational movement that is normal.
The rotor seems to touch the brake pads at specific spots or I would call it a region as it is probably about an inch long area which is touching the pad ever so slightly, you dont hear the noise when you hand rotate the wheel, but when it is spinning and the throttle is cut the engine goes into idle mode and in the hum of the engine you can hear the grinding as the rotor touches the brake pads at that spot at faster intervals. I can continue to ride this way if I cared to but I don't see it benefitting the bike at all.
This has been happening in the last 10 days or so. I replaced it last year after hitting a fairly large pot hole at the base of Manhattan bridge while coming back into Brooklyn and I was doing around 60 mph when that happened and in that situation the rotor's warp was significantly noticeable that it had to be replaced or else it wasn't going to be a smooth ride.
I wont use no hammer, will just order parts and work on it when I have a sunny saturday/sunday.
Thanks for your input Senor
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 2804
Location: East Anglia, The power house of the UK
Thu Jun 01, 2017 11:23 pm quote
Yes, it does sound as though you have pothole damage. Changing the disc may be the best option. I'm assuming your brake pads are not worn out?
Addicted
2010 Vespa 300 Super
Joined: 04 Oct 2015
Posts: 699
Location: NYC
Fri Jun 02, 2017 4:20 am quote
Brake pads are fine...
Any recommendations on rotors, right now it has the OEM rotor that was replaced with a new one last year.
I am not sure there are any better ones unless one modifies them to fit in the GTS.
Veni, Vidi, Posti
Neutrino MP3 492.7 AK, 2013 Moto Guzzi Norge
Joined: 29 Mar 2008
Posts: 21611
Location: Harriman, Tennessee, Tn
Fri Jun 02, 2017 4:40 am quote
baba12 wrote:
Brake pads are fine...
Any recommendations on rotors, right now it has the OEM rotor that was replaced with a new one last year.
I am not sure there are any better ones unless one modifies them to fit in the GTS.
scooterpartsco.com for oem or aftermarket they have REALLY good pricing
Addicted
1979 P200E, 2006 Piaggio Fly 150, 2010 GTS 300 Super
Joined: 03 Oct 2013
Posts: 616
Location: Atlanta
Fri Jun 02, 2017 5:49 am quote
Jettin Rotors
I put these on my GTS and have been very happy with my brake system.

http://www.jettin.com/brakes.html
Hooked
GTS300ie Super
Joined: 14 Dec 2007
Posts: 384
Location: Sauk Rapids, MN & Sanibel Island, FL
Fri Jun 02, 2017 6:42 pm quote
Last year I replaced the rear rotor on my Wife's GTS 300 which had only 6000 miles. I could smell a hot rotor and it was extremely, skin burning hot to touch. The rear wheel would not spin freely either when I spun the rear wheel by hand. I put on a new rotor and all is well. Not sure why the rotor warped as my GTS 300 has over 17000 mile on original rotor and still going.
Member
GTS 300
Joined: 11 May 2019
Posts: 40
Location: UK
Sat Jun 15, 2019 11:56 am quote
I seem to be experiencing the same thing as the above posts.
I cleaned and carried out a minor servicing on the front and rear Calipers today and after the brief test ride to calibrate the ASR I have a 1 -2 inch rubbing and squeal of disc to pads at the rear wheel on each revolution.
Everything else on the bike is fine though.
Is a replacement disc and pads the answer??

Last edited by Matt748 on Sun Jun 16, 2019 2:06 am; edited 1 time in total
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Granturismo 218
Joined: 04 Feb 2013
Posts: 6150
Location: NWAOK
Sat Jun 15, 2019 9:59 pm quote
The rotors Piaggio uses are extremely cheap, especially the new ones. There are a number of better brands out there. I have the Malossi Whoop disks on my bike, and they seem to cool better. I have lost the brakes with a couple of OEM setups, mainly because scooter brake systems tend to be fairly rudimentary and not meant for long days of riding hard corners, but I haven't with the Malossi brake disks and pads.
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