OP
UTC

Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
 
Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
UTC quote
My front brake (Stella 2T) recently seized up on me; luckily I didn't fall, and was able to make it home.

I've got a new rotor and new Piaggio caliper; I also have a used SiP caliper on hand. (I threw out the old LML/Grimeca caliper because the bleed port was stripped).

Problem: both of the replacement calipers are dragging quite a bit on the right-hand side (outside, not the disc side). When I mount they calipers they are off-center, and the disc is rubbing against the caliper body. (The pistons are fully retracted). When I loosen the hub nut a bit and pull the hub back a light distance, the rubbing goes away (because the disc becomes centered between the pads).

Is there some sort of spacer washer between the hub and the back plate that I lost when I was changing stuff out?

Edit: I found the SIP exploded parts diagram for the LML/PX Disc front end, and I see that there is no spacer washer between the hub and the disc carrier. So if I am not missing a part, could something have worn out somewhere in the front end that would make the hub shift slightly to the right, causing the rubbing? Maybe something in the disc carrier assembly/"back plate" (which I have never taken apart--it's stock).
@subetherbass avatar
UTC

Ossessionato
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: UTC
Posts: 4829
Location: Australa, Mate
 
Ossessionato
@subetherbass avatar
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: UTC
Posts: 4829
Location: Australa, Mate
UTC quote
Photos will for sure help with diagnosis on this
OP
UTC

Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
 
Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
UTC quote
I'll post some pics. But a preliminary question -- on a Stella or PX with a disc brake, is the caliper supposed to be centered around the disc, or is it offset? I found some fragmentary info on BGM's website that suggested that the disc carrier is such that the caliper can't be centered?
@xantufrog avatar
UTC

Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: UTC
Posts: 8892
Location: Atlanta, GA
 
Moderibbit
@xantufrog avatar
1980 P200E - "Old Rusty", 1976 ET3 Primavera
Joined: UTC
Posts: 8892
Location: Atlanta, GA
UTC quote
If you don't have a resolution by this evening send me a pm to remind me and I can take a pic - my memory is poor but I'm pretty sure it IS centered on my px setup
@swiss1939 avatar
UTC

Ossessionato
P208, Stella VMC Stelvio 187, Stella 150, VNX1T, V9A1T, V9B1T, 02 Sportster XLH1208
Joined: UTC
Posts: 4110
Location: Staten Island, NY
 
Ossessionato
@swiss1939 avatar
P208, Stella VMC Stelvio 187, Stella 150, VNX1T, V9A1T, V9B1T, 02 Sportster XLH1208
Joined: UTC
Posts: 4110
Location: Staten Island, NY
UTC quote
I believe my LML one is not centered. It always seems to favor one side. I noticed it when I rebuilt mine and made a mental note of it wondering why it was like that.. but never had any problems with it so I left it alone. But this is still on the stock LML/Grimeca caliper.
@kowalski avatar
UTC

Addicted
2005 Stellalossi 177 Fe
Joined: UTC
Posts: 522
Location: MA
 
Addicted
@kowalski avatar
2005 Stellalossi 177 Fe
Joined: UTC
Posts: 522
Location: MA
UTC quote
Relevant pages from Genuine parts manual attached. It shows spacers on either side of the caliper carrier.
pdf
522kb
OP
UTC

Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
 
Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
UTC quote
Here are some photos of the caliper installed with the hub nut finger-tightened. You can see that if the caliper were centered would be aligned with the split in the caliper (third photo). Note too the substantial free space between the one side of the disc and the pad (note all of the daylight visible, second photo). The first photo shows the shock-absorber other side, notice, no daylight.

Ideally the hub would seat a few mm further to the non-caliper side of the bike; or the caliper bracket would be a few mm thinner where the caliper bolts on, shifting the caliper slightly to the right.

Thoughts will be much appreciated (i.e. is this normal or not normal)?

I've never had the caliper bracket off the bike, so presumably it has all of the normal spacers. I can see the "D spacer" is installed when the hub is off.
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
@swiss1939 avatar
UTC

Ossessionato
P208, Stella VMC Stelvio 187, Stella 150, VNX1T, V9A1T, V9B1T, 02 Sportster XLH1208
Joined: UTC
Posts: 4110
Location: Staten Island, NY
 
Ossessionato
@swiss1939 avatar
P208, Stella VMC Stelvio 187, Stella 150, VNX1T, V9A1T, V9B1T, 02 Sportster XLH1208
Joined: UTC
Posts: 4110
Location: Staten Island, NY
UTC quote
Last resort.. grind caliper side that is rubbing, down so that it stops rubbing.
OP
UTC

Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
 
Hooked
Rat 2003 Stella 2T; 1979 P125x (in pieces, out for paint)
Joined: UTC
Posts: 384
Location: Madtown
UTC quote
swiss1939 wrote:
Last resort.. grind caliper side that is rubbing, down so that it stops rubbing.
That's what I was thinking, I could have the local machine shop guy grind down the area of the caliper in the green circle, which would have the effect of moving the caliper a bit more to the right when the bolts draw it tight.

But before I do that I want to make sure that there's not some other issue going on. Both of my calipers have this problem of rubbing. I can't see how the caliper carrier, which is a pretty heavy casting, would have gotten bent somehow. A new Grimeca carrier from SIP is 130 bucks + shipping, I'd like to avoid ordering one on a hunch.

Anyway, someone else with a PX disc or Stella--take a look at your caliper and let me know what you find...
Forum member supplied image with no explanatory text
DoubleGood Design banner

Modern Vespa is the premier site for modern Vespa and Piaggio scooters. Vespa GTS300, GTS250, GTV, GT200, LX150, LXS, ET4, ET2, MP3, Fuoco, Elettrica and more.

Buy Me A Coffee
 

Shop on Amazon with Modern Vespa

Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com


All Content Copyright 2005-2024 by Modern Vespa.
All Rights Reserved.


[ Time: 0.0110s ][ Queries: 4 (0.0026s) ][ live ][ 313 ][ ThingOne ]