“Crabbing the frame” – 7 Jul 2016.

A couple of days ago I said how, while synchronising the carbs on my V7Sport, I noticed what appeared to be gearbox oil dripping from the bikes’ clutch housing. I had considered using an oil additive that claims to soften and swell oil seals to stop leaks but decided the gearbox would have to come off for the job to be done properly.

The engines and gearboxes of Tonti-framed Guzzis cannot be removed from a rolling bike. Instead the frame has removable lower rails so the main part of the frame can come off the power unit. Moto Guzzi tell you to do this by removing the frame and everything else from the engine/gearbox unit and then wheeling it away on the front wheel. Then the gearbox is then separated from the engine. I’m not sure who came up with the idea (possibly Pete Roper) but there is another way to access the clutch and gearbox without as much dismantling and with fewer bits ending up littered around the workshop. This has been termed “crabbing the frame” (although I always thought crabs moved sideways). It involves hinging the main frame upwards around the front engine bolt. I’ve used both methods in the past and find the “crabbing” method easiest when it comes to putting things back together and working alone. There’s still a lot of dismantling to do though.

I got the bike up on my lifting bench. The wooden platform is for me to stand on when putting the bike on the centre stand. Today I couldn’t do it! The bike kept sliding back instead of coming up on the stand. The wooden platform also allows me to put the bike on the side stand while I think about what to do next. I held the front wheel in the clamp, tied the front of the bike down then jacked under the sump until I could deploy the centre stand by hand. Then I let it down onto the stand and slackened off the wheel clamp. I need the bike on the main stand so I can get the rear wheel off later.


I drained the gearbox oil and left it for ages as it was cold. I measured how much came out. 670cc of the original 750cc. That’s over 10% lost in a very short period of time. I’ve still only done 540-odd miles and it hasn’t been leaking all the time!

To crab the frame;

    • Remove the fuel tank.
    • Battery out.
    • Remove the four front screws from the plate under the battery to the top of the gearbox.


    • Disconnect the front brakes. I slacken the cables at the lever and disconnect them from the dual pull adapter. This gives enough slack to remove them from the brake hub plates without altering the adjustment of the cables relative to each other.


    • Remove the front wheel. This needs to be done so the forks can move down when the rear of the frame is raised. I have to remove part of the bench wheel clamp (only two bolts) and jack the bike up a little higher to get the wheel out. I count how many turns of the jack screw it takes so I can lower it by the same amount after.
    • Remove the silencers.
    • Remove the exhaust crossover. I’m pleased to say that the silicone sealant I put on the joints worked and allowed them to come apart OK.
    • Remove the nuts, bolts and spacers from the exhaust header to frame P-clamps.


    • Remove the starter motor.
    • Remove the starter motor relay with its bracket.
    • Disconnect the rear brake cable from the brake back plate.
    • Disconnect the brake light switch wiring.
    • Remove the brake torque arm.
    • Remove the rear wheel.
    • Remove the right hand suspension unit. I remove it completely although this isn’t strictly necessary.
    • Remove the rear drive box from the swing arm – four nuts. I leave the driveshaft and connecting sleeve inside the swing arm if possible. If you don’t want to change the bevel box oil store it so the pinion is at the top so the oil won’t leak out. I also use some large nuts as spacers to secure the pinion when the box is off the bike.


    • Remove the brake and gearchange pedals.
    • Disconnect the gear linkage from the spline on the back of the gearbox and remove the gearchange cross shaft. I’m talking about the one that had the pedals at either end.
    • Support the wing arm and remove the left hand suspension unit. Again it could just be disconnected at the swing arm end.


At this point I like to reassure myself that what is left of the bike is good and stable on the bench. There’s not much weight on the centre stand and this will be folded up soon. I tie my bike down with ratchet straps on each side. They are made to sit down between the fins of the cylinder barrels so they can’t move. At the same time I make sure that they aren’t squashing any cables etc.


Back to the dismantling;

    • The swing arm has to come off now. I undo the clip holding the rubber gaiter to the gearbox and try to pull it off the ‘box as much as I can. Then remove the lock-nuts from the pivot pins. Before taking the pins out I like to measure how far out they are (left – 7.12mm and right – 7.16mm). I also remove the rearmost nuts and bolts from the footrest bracket/frame joints. With the pivot pins out the swing arm should come off with the universal joint held by the support bearing inside.
    • I had to remove my K&N air filters.
    • Crashbar lower mounting where the frame joint is.


    • Now it’s time to disconnect all the cables , wires etc that might be pulled when the rear of the frame is lifted. The ones I found were;
        • Speedo cable at gearbox end.
        • Tacho cable at timing chest end.
        • Clutch cable at lever on gear box.
        • Engine and gearbox breather hoses.
        • Throttle cables at carbs. Don’t touch the adjusters!
        • Wire to oil pressure sender.
        • Disconnect both plug leads and push them back through the brackets holding them under the manifolds.


    • Loosen but do not remove the front engine mounting bolt.This is the one that holds the side stand bracket and will act as a hinge when the frame is lifted from the engine.


    • Remove the remaining bolts holding the footrest brackets on and joining the lower frame rails to the main frame.


You should now be able to pivot the frame around the front engine bolt. Have a piece of wood handy to put across the rocker boxes to keep it in position. I also put some wood under the back of the gearbox just in case although everything would have been fine without.


I found the frame wouldn’t move because the lower crashbar mountings were still blocking the holes. I had to remove the crashbars completely. I had hoped I wouldn’t have to do this as the nuts and bolts at the top are fiddly to get out and even harder to refit later. It all moved after the second attempt. I was still watching carefully to make sure nothing got snagged or pulled.



Once the frame was up I secured the front forks to the bench as a belt and braces measure.


More dismantling;

    • Now the rear engine/gearbox mounting bolt can come out.It’s the front one here.


    • Then pop in a couple of bolts, one each side to keep the centre stand mountings together.


    • Carefully fold the centre stand up by hand.
    • The lower frame rails complete with main stand can then be lowered out of the way.


I now had the necessary access to remove the gearbox and everything was steady on the bench.


With all the removed parts stored safely.


It took me about 4 hours to get to this stage including stopping to write notes and take photos. It could be quicker if you’re less worried about chipping the odd bit of paint!


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