The front brake master cylinder as found had a M6 bolt with washer sat on the upper surface, but beneath the washer is a recess the size of the bolt head.
I have refitted the lever with a bolt with an un-threaded section that sits right into the recess, omitting the upper washer entirely as this seems a stronger arrangement. A have used a new nyloc nut to lock the thread end of the bolt against the base of the fitting, and trimmed off the bolt to suit.
Is this the correct original arrangement ?
Separately the lever bush was very sloppy on the bolt so I have machined a new brass bush and the lever operation is now very snug, free but without any slop or excessive free play.
I expect to see if the clutch lever is the same set up and expect another new bush will be necessary.
Hello there, I figured Iâd throw my two cents worth in.
Yes, youâre pretty much back to the way it was supposed to be with your revised arrangement.
Hereâs a link to a picture of the actual brake lever screw kit.
Firstly, itâs not quite a standard bolt; that unthreaded bit should be slightly greater diameter and better finished than a normal M6 cap head, so that it has a bearing surface in the lever. But having rebushed the lever, youâve taken care of that. Also the cap itself is finished properly so that it forms the bearing in the top lug of the lever housing. You can see that in the SD picture. Your normal cap head may not be and so it all might be bending a bit as the pivot is cantilevered off the bottom lug thread. Probably not the end of the world, and I think most of these old Brembo master cylinders have regular M6 bolts in by now.
Now, itâs been a while since Iâve had mine apart, but I think the wavy spring washer went under the cap head to sit in the recess in the lever, with the plain washer underneath the nyloc lock nut. Lock nut, because the pivot bolt should thread into the lower lug on the housing first. You then adjust the pivot bolt until when locked up there is no play in the lever but it still moves freely.
I think I have a spare pivot kit in my âstoresâ for another photo if you need. The parts book isnât much help because the pivot kit is just drawn as a separate little packet off to the side with a description of âScrews kitâ. But the part number for the kit is 1765 9450.
As for the clutch, no thatâs completely different; I believe that was made by Tommaselli. Much more like a conventional clutch lever set-up.
Part numbers I have for the complete assembly are Guzzi 1460 5550 and Tommaselli 0343.04. This may help you track down the components, or parts diagrams. I just use a conventional bolt in there, I think.
The new bolt I used was marine grade A4 (316) with a highly polished surface where it sits in the bush. I selected one with a long enough non threaded section then timed the otherwise over length bolt to suit one thread past the nyloc.
I also made the new bush to sit proud each side of the small recess in the lever, and certainly no wave washer was present when I dismantled.
I tightened gently until the bolt nipped the bush then backed off ~ 1/8 of a turn and locked it with the nyloc. I could likely find a wave washer, but not sure it will do very much, but easiest enough to mill the bush back flush with the base of the recess. I did finish the bush ID very close to the bolt using a reamer rather than a drill, I also applied some penetrating wax chain lube to the pivot (not needed for the Guzzi, but my Bandit drinks the stuff !).
I noted in the manual that there should be a distance gap of ~0.2 - 0.4mm between the end of the master piston and the bearing surface of the brake lever and this adjusts using the small screw in the opposite part of the lever in line with the handle, but even with this fully back home there is no clearance, but virtually nil piston movement either.
Should I hone back the material around the adjuster bolt to allow the lever a small clearance as per the manual ?
Something doesnât sound quite right here.
Virtually no piston movement isnât right.
There should be the clearance between the lever and the master cyl piston.
Only things I can think of are that the lever blade might not be the correct one ( prob unlikely ) or perhaps the master cylinder piston isnât all the way home ? That doesnât explain the lack of piston movement, though, unless itâs somehow hung up outside the working part of its bore.
I wouldnât start removing metal from the lever until you work out whatâs going on.
If you can measure the position of the bearing face of the piston vs the master cylinder housing Iâm sure someone can compare that with their one.
I think you are getting confused with the brake pedal master cylinder. The front lever doesnât have any adjustment. Iâve just checked mine and there is no gap between the lever and the piston, As soon as I pull the lever, it is working the piston. This could be caused by the piston retaining ring not being locked in place? Iâm not sure, itâs a long time since I last rebuilt it. What is important is that the piston can travel back far enough to allow fluid from the reservoir into pipe system. My front brake doesnât have much lever movement, probably about 20mm from nothing to fully on, measured at the end of the lever.
The linked master cylinder should have a tiny bit of clearance between the actuating lever and the end of the piston for the same reason. I spent ages trying to bleed my cali brakes, finding the pedal adjustor was holding the piston in very slightly and so fluid wouldât flow from the pipe back into the reservoir. There is an eccentric adjustor on the body to adjust the clearance.
On the subject of the clutch lever, this does have the same set up as the front brake.
The brake lever is in gentle contact only with the end of the servo piston. In its rest position it is not displacing the piston by more than a couple of thou, and there is plenty of free piston travel. I checked the WM and it states 0.05 to 0.15mm (0.002 to 0.006") lever to piston clearance, but heyho. So the suggested gap is tiny but as mentioned as long as the cylinder port opens when the lever is relaxed all should be fine. since I re-bushed the pivot the whole mechanism feels just right.
Thanks for the note about the clutch lever pivot bolt set up.
