Brake Bluew II....still a drag

Joined
Jul 18, 2014
Messages
14
Location
virginia
Bike
Moto Guzzi SPII 1987
Thank you one and all for the previous posts and advice. Especially Johns "pitfalls of Pad replacement". Finally got time to attack the problem, but still dragging front left and rear.

But first, a little background on the first attempt:
-Rear Pads replaced by shop 2.5k miles ago (unfortunately, pistons not cleaned)
-I replaced front left pads, but didn't clean pistons properly (use of brake cleaner)
-System not properly bled (bypassed the proportion valve and the 15degree tilt

Did not break down fronts or rear, but did the following.
*Got the Mityvac (MV).....great product! Did not exceed 10 lbs pressure while bleeding and for the most part was under 5 LBS.
1. pulled all pads out, cleaned all pistons with tooth brush & cloth with new/used brake fluid...calipers left attached to bike....
2. all pistons moved in and out smoothly with no hang ups
3. Bleed by the book:
a)Left Top: clear with MV
b)Right Top: Clear with MV (toped off and closed up MC)
c)SMC at 15* / proportion valve>>>>would not bleed from MV....rear peddle only=clear
d)Rear center: clear
e)Right center: clear
f)Left center: clear
g)Rear top; would not bleed from MV...rear peddle (didn't try front lever)=clear

-Replace buggered Pad Clip on front right, but even wear on both old pads
-New pads for front LFT and RT and semi new for the rear

Results:
Pad slide in clean and easy with pistons fully retracted, Fluid clear and clean throughout system

But front left and rear drag after first pump of either front hand or peddle

Test ride:
3 blocks and coast stop: warm left front and rear (could lay hand on)....cold right front
3 blocks low speed and rear peddle stop: left and rear hot, but not flesh searing...right cool
2 mile 50 mph and cost stop: left and rear warm...right cool.....2 short rides, one with twists......no discernible pressure on rotors.....heat on stopping not excessive.....
Side road for 40-10 stops with all combos, and all fine....brake releases, seems like the pistons are releasing (backing off) but the front LFT and Rear pads are not moving away from the rotor
causing light drag

Have re-bled the system since and all is as it should be.......but front LFT and rear continue to drag....not grip, but you can hear the rub when spun, and yes.....there is enough drag that the wheels are not spinning free and easy.

SO, any advice? Something hanging?.....dead SMC? buggered seals? its all in my mind and its time to move away from the beltway and DCs toxic politically correct Preis system is tight with no leaks. Fluid is fresh all around. Problem is in the link system. A piston problem.....
Thank goodness the old 87 Guzzi is still thumping along! DC traffic is bad enough, but to be stuck in a sea of cages during the summer.......I'd have to eat a Bump exhaust or quit work! But man oh man I sure miss the ST...........got to get her back on the road!!!
Thanks for any and all advice!
Ian
 

woodybelle

Site Supporter
Joined
May 10, 2006
Messages
539
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72
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Sonora, California
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2006 ST1300
When you say left and rear drag after first pump of either front hand or pedal is the bike moving or sitting still? I would think you would have to be moving to activate the rear brake through the SMC. If that is the case then I think it could be that the left and rear calipers need rebuilding. The pistons retract due to the design of the piston seal. If there has been crud pushed into the seal area it could cause the problem.
 
Last edited:
OP
OP
Joined
Jul 18, 2014
Messages
14
Location
virginia
Bike
Moto Guzzi SPII 1987
Thanks Jerry: Bike was on center stand...in both lft and rear, pistons were pushed in without proper cleaning originally.
 

Blrfl

Natural Rider Enhancement
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Fast Blue One
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I live in NoVA; if you want, I can swing by with an extra set of eyeballs and a pyrometer.

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