u/GoryTv

Hello everyone.

I have a 2008 Moto Guzzi 1200 that sat idle for a few years. A few months ago, I started performing maintenance to get it running again.

This included changing the engine oil, transmission oil, cardan shaft oil, and, of course, the braking system.

Only my father used this bike; he bought it new when it was released, and now it's in my hands. Unfortunately, he passed away not long ago.

When I got the bike back in my hands, I noticed that when I braked with the front brake, the bike shook. Having old pads and discs, I figured they must be bent, so I bought new ones for both the front and rear (they were also quite worn and scored).

I have absolutely no problems at all at the rear; the bike brakes smoothly, and I was pleasantly surprised at how well it brakes even using just the rear brake. With the front wheel, however, despite having replaced the pads and discs on both calipers (I also bled the brakes, which after six years of sitting, the DOT4 was really crap), the bike shakes terribly when braking at any speed.

At first, I thought it was the ABS failing, but even after turning it off, I realized it was still doing so. To be 100% sure, I accelerated all the way to first gear, then put it in neutral, turned off the bike while it was moving and realized that even while turned off (and therefore with the absolute certainty that the ABS wasn't kicking in), it shakes like crazy.

So I'd rule out any pressure surges in the system, so I thought it might be helpful to isolate the fault to one of the two calipers.

I removed just one of the two calipers (leaving it attached to the system, of course) and tied it to the handlebars with a rope.

I did this first with one caliper and then the other.

The first one I removed was the left one, and only with the right one attached did the bike brake like a charm; it was wonderful to see it brake normally.

When I reversed the calipers, attaching the left one and detaching the right one, the shaking returned and was as frighteningly severe as ever.

The first thing I did was bleed the left caliper, just to clear up any doubts, but it didn't solve anything.

I then reassembled the left caliper, pushing in the pistons with a screwdriver (using the pad, of course), and it seems that all four pistons move freely and without any particular resistance.

I don't think there's anything else I can say. I can only add that tomorrow I'll remove the front wheel again, rotate the rotor 90/180° on the rim, and try to reassemble everything. If I remember correctly, I've read about similar cases resolved with this simple action in other threads here.

I hope you have any suggestions you can offer, because honestly, I'm running out of ideas.

Thanks everyone in advance ♥️