The following information and best practices were developed by various Garelli dudes. For stock setups its very simple: keep it clean, keep the right oil level, use the right oil, and adjust that clutch engagement. For other setups, there are a few things that may need to be considered.
All Garelli Rubber Clutch Bikes
- Age Issues - You will get a few issues from aged clutch parts. Keep in mind, there are 6 (VIP\Gulp\2spdNOI) or 7 (NOI\1spdAVANTI\1spdMonza) total pieces of rubber not including the oil seals inside the transmission case.
- When they're old, they tend to get hard or even crumbly if it is left with water or some kind of solvent. Sometimes you will get lucky and find a clutch sitting in its original oil and everything works just fine.
- The small pieces of rubber are meant to absorb certain stresses. If they are not in good condition, they may fall apart and the moped may do damage to itself if it goes untreated.
- The clutch rubbers may lose some of their elasticity and "swell up" as to engage themselves faster or even engage all the time causing idle issues. This usually happens because of a breakdown in bonds within the rubber from water or the wrong oil in the case.
- Oil Condition Issues
- You will want to always go the safe route: use 30 weight non-detergent. Don't get hasty and just put something else in there. Grab the non-detergent from the store 10 miles away and you won't have to think about it again. Otherwise, it'll only take a week or two before your clutches are pretty much ruined. Any reports on other certain oils with some documented success would be welcome.
- Water can tend to break down rubber. Oil that is milky has usually been exposed to excessive water.
- The right amount of oil is important.
- Too much oil will cause clutch slippage. Clutch slippage, while not always a bad thing, can tend to wear out clutches much faster.
- Too little oil will cause abrupt shifting which wears out the metal parts inside.
- Shifting stages
- Fluid Friction - The clutch rubber and bell move through a viscous fluid.
- Kinetic friction, lubricated -Rubber expanding toward the bell with a thin oil film between them.
- Kinetic friction, not lubricated - Rubber pushes some oil out of the way, now rubs directly against the bell - coefficient of friction is much higher, generates great heat on the surfaces, wears rubber down
- Static friction - Oil is mostly pushed out of the way and the rubber and bell are touching while moving together, fully in gear.
- Cutting down stage  by keeping a proper oil level will ensure that the clutch does engage well and will often cause the bike to stall out from slowing down on a steep hill, meaning your gearing is appropriate. You are much better off stalling than slipping clutches.
- High torque situations such as adding a performance cylinder or pipe may extend stage  on a steep hill since it can power through the high friction. Given the right situation, stage  can be extended to many seconds causing the clutch rubber to melt from the high heat. When going all out, be sure not to make this mistake often. If you hear high RPMs and feel no apparent difference in acceleration, its time to start pedaling or stop and push.
== 1 SPEED SECTION == A recent find by myself was that Garelli actually made a shoed clutch for the horizontal style engines! Its from a Garelli Gary uno, looks very similar to puch e50 and pretty much works same way with pedals and starter plate. They also have a kickstart version but theyre thin on the ground. The Garelli bells for these are non existent so I used a puch bell with garelli gear pressed into the middle, this is a direct swap.chuck the clutch in and hey presto it works! Ive have slso seen Gary due 2 speed clutches which have two sets of shoed clutches sandwiched in the bell, im sure they could be made to fit?
2 SPEED SECTION
- The Rubber Guys
The 4 little rubber guys can get old and split in half. This will enable the starter plate and clutch bell to hit each other without much resistance. A tight rubber guy is good for absorbing some forces within the transmission. The bigger issue is when they fall out and get chewed up. They tend to clog oiler holes within the teeth of the clutches that sits on the crankshaft. These parts tend to seize if not properly oiled. Another issue is when they get within the clutch bells and get smeared all around within. The bike will try to engage almost constantly and idle issues abound. Parts of rubber can also roll between the main rubber and the bell causing much more stress to many parts not only because of the force of squishing rubber around in a tight space, but the imbalance it causes.
- The Engagement Plate ([Fig 1])
This plate uses the cork to push against the outer rubber. The bike essentially starts in 2nd speed, but the back wheel must turn in order for the bike to start. Often n00bs don't left off the clutch when trying to start and that's the time to laugh at them. If you take you clutch apart and you find that you have almost no cork left and the side of the disc is glazed over, you may flip the disc and use the cork on the other side.
- The rubber "guys" to pop-rivet conversion. - Martin Bandit
See this thread.
Often abrupt shifting will cause the engagement plate to slap around within the outer clutch bell. You may experience this more often with a swelled clutch. This will cause the clutch engagement red area ([Fig 1]) to get mushroomed which increases the distance between them and intensifies the clanking between the parts when accelerating or abruptly downshifting to 1st on a hill. Instead of letting the engagement plate slide around independent of the cross piece, you can tighten it up with pop-rivets and transfer some of the force to that cross piece that is also contacting the outer bell. Not only do you spread out the force over the green area ([Fig 1]), but you also push the faces of these parts together. Be sure that you maintain proper cable tension on the clutch engagement. A dragging clutch engagement will cause idle issues and will intensify the mushrooming the effect on one side dramatically.
The pop-rivets ([Fig 2]) are ground down on a single side so that the plates can be flush. There are usually stainless steel pop-rivets available which may not be better for dis assembly, but could hold up better. I have run a set of 4 aluminum pop-rivets for a year and have not replaced them or any other parts
- Special note on cleaning: If you have chunks of rubber in the transmission case, be sure to check your oil holes on the clutch between the teeth.