Tonti clutch replacement

Had to replace the clutch on my 850T, one of the plates had lost it’s rivets and vaporised to toffee in the flywheel. Still got me home though!
I have new plates, intermediate and springs, along with a new deep splined input boss and I have taken the gearbox off using the ‘crab’ method.
Question is: can I fit the new clutch with the engine in the frame? It looks like I’m going to need a centering / compressing tool to get the teeth on the intermediate engaged, but do I need to buy an expensive item that I may only need once or is there a work around?
Or should I get the engine out and upright and line 'em up by eye?
Can a centering tool be rented if I have to have one?


Yes to the engine in the frame.
Make sure that the dots are lined up to ensure that the spings go in straight.
A wee bit of glue on the end of the springs to keep them in place.
Centre boss compressing tool is the best way to go.
You can pull it in with longer bolts as you have a new centre boss in your hand to keep everything lined up .
Or seeing as it is not attached to the gearbox you could convert it to a compression tool.
Anyone with one may post a photo/ drawing of it .
or send me the photo/ photo of drawing and I will post it up.
Thoughts people???


A bit like this…


I did mine using some temporary long bolts and nuts to compress the springs in three of the holes. Once it was wound in enough you can put the other standard bolts in to take the pressure.If you peer down the small holes you should be able to see the outer splines lining up with their slots and just nudge them into place with a small screwdriver until they engage. DO NOT PUT MUCH PRESSURE ON THE SPRINGS UNTIL THESE ARE IN PLACE. or you will bend the plain plates.Also look out for the position of the flywheel and starter ring so it goes back in the same holes it came out of or you will loose your timing marks on the outer edge. I believe there is a mark you need to line up. Normally use the gearbox shaft to line up the inner splines as in the top picture, could someone local lend you one if yours is still attached to the gearbox? Are you anywhere near Keith Guzzi (Chattham)

Don-Spada2013-01-12 12:44:58

That’s the way to do it!You will also need to arrange a way to lock the motor when torquing up the bolts.Best of luckSteve

Piece of 4 x 2 timber cut down and wedged in the starter slot worked well for me! You can also put a good ring spanner on the clutch bolt head and turn the engine until it locks against one of the protruding studs

I use a ring spanner to a bolt to hold it, I always take off the gearbox spline, worst you need to buy then is a new sprag washer and maybe a nut, BUT not only will it centre the clutch BUT also it is then set up to work with the actual splined shaft. the rest as Don says, there is an article in the club magazine re “crabbing the frame” to be honest i have always took the frame off and at the same time done a check, repaint and such of the whole thing I can get this done …on my own in under 8 hrs now.

The Haynes manual is ok for a first time go at it you do find short cuts with experience. Crabbing the frame will save a couple of hours easy.

Make very sure you have the engine set TDC as per the manual and add a tippex mark to the dot on the flywheel that lines up with the mark on the crankcase it is at about the 11 o clock position a small arrow on the casting.

It is easier to realign the gearbox shaft to the clutch on reassembly with everything horizontal. I tend to line it by eye and slide it up a screwdriver thro the timing hole can make the minute adjustments and a rubber mallett to tap the gearbox it goes on with a very satifying sllluck sound

The clutch replacement is one of the most demanding jobs to do on a Guzzi , but take time read the Haynes and go at it bit by bit.

Nick, I have a spare splined gearbox centre that I use to centre the plates, you can borrow it any time.

Regards Chris

Many thanks all! The top photo from Min is really helpful - I have the splined boss already (changing to the deeper 4mm splines) so it looks like I may just need a long bolt and some washers to finish the job.
Right, back out into the cold rain and snow…


And don’t forget to put the clutch thrust washer back in place (The one the push rod works against)

and the rod …guess how I know??? demolished a fence I did
fence 0 Guzzi 10

not a mark on the bike Annie reconed the look on my face was priceless, she was rolling about. I had started the bike banged it into gear …pulled in the clutch and rode right through a fence panel, looked like something out of a Roadrunner cartoon hit the kill switch in utter bewilderment …

David (cylvabirch) wrote this when I asked about fitting my clutch. “In the end of the crankshaft you will find there is an M10 thread. Although it is a metric fine thread an ordinary M10 thread will go in for a couple of threads.I used an M10 long coach bolt from B&Q with a nut threaded on plus 2 penny washers and an old gearbox inlet splined shaft with a 19/32” socket (1/2" square drive) pushed up through the middle to keep the coach bolt central in the splined shaft.Put the springs on the flywheel then the spring backplate making sure all the springs pop into their respective little pockets.Now screw the end of the coach bolt into the female thread in the end of the flywheel until it stops after a couple of turns (no need to force it).Now slowly tighten down the running nut on the coach bolt allowing the end of the dummy splined shaft to push the spring backplate down towards the flywheel thereby compressing the small springs evenly. Once it has bottomed you can very easily thread on the first friction plate, steel intermediate plate and second friction plate onto the old splined shaft. Finally you can place the big plate with the ring-gear on it and tighten down all the screws. You can then release the pressure on the spring plate by undoing the running nut on the coach bolt and take out the alignment tool by unscrewing the coach bolt from the end of the crankshaft.It takes longer to type this than to do the job! No damaged teeth on the clutch intermediate plate or dishing of it." I used this method and found it easy and foolproof.

ReggieV2013-01-13 18:21:06

Thanks for this. by the way, I found that it’s an M12 rather than M10. Clutch back together now with no miss-haps and no need for an expensive tool! Gear box will go on when my fingers defrost.

Good job before you mate the 2 halves, if you took the frame off completely make sure the engine is supported at the same height as the frame is with the centre stand on it. This makes getting the box back on easier and the subsequent mating up of the frame.

I found over a fair few goes that the box mates best in the horizontal I wrongly tried doing it vertically with the engine down thinking that gravity would pull it all together. Nooooooooo.

I found by far the easiest way is to line up the gearbox spline visually and sit behind sliding the box onto the engine… a tap with big rubber mallet helps it but it will only need a gentle tapping NOT a massive thwack.

Most times it goes straight in, now and again you have to withdraw …( Oi STOP that chuckling at the back!)

Just take a beep breath and jiggle it in… when id slides together …pop a couple of nuts/bolts onto it, THIS is a good time to replace the casing nuts with acorn stainless ones, bit o’ copper grease and presto… By the way it is the same size nuts for the bevel box - shaft cover

NOW go get a beverage and stand back with a big smile…Jobs a gud un