Planning for the layshaft rebuild

I contacted my mentor Tom G. and I asked him if there is anything special I need to consider when riveting and rebuilding the layshaft (cush drive aka Christmas Tree). I do not have a proper work bench nor vice yet, so I will head over to Paul S.'s house to borrow his late next week. Here is Tom's response:

Rebuilding a layshaft is not technically complicated, but in practice is not exactly child's play. Aside from the obvious (put the plate with the bulge in it on the correct side), you need to keep the plates firmly seated against the primary and cluster gears. To do this, assemble the whole unit with machine screws and bolts, and then remove one bolt at a time, substituting the rivet. You have to mash the rivet heads flat and firmly to hold the plates in place firmly. There are rivet presses that do this very nicely (but I don't have one). It is possible to just mash with a hammer, but this requires alot of care. I use a modified pneumatic brad driver (I put a bolt in the brad driver slot where the nails usually go, and drill a small locating dimple in the bolt head. The rivet tail seats nicely in the dimple. Then you just puch down on the brad driver, which is pressure activated, and the tool delivers hundreds of hammer blows in seconds, firmly collapsing the rivet. Just an idea. Good luck, Tom

I plan to buy an Air Palm Nailer and modify it for driving rivets and a vice.

Layshaft Disassembly

Quite over due and finally . . . I am back to working on the VSC and getting that clutch grind sound solved. The two prospective culprits for the sound are the layshaft or the clutch. Therefore, I will rebuild both since the engine is open and they are both out.

Prior to this project, I got both my wife's and my Bajaj Chetaks running again and then sold via Craigslist. Both bikes had been sitting for quite a while. My wife's bike's flywheel rivets sheared off and I replaced the flywheel, while my bike required a lot more trouble shooting to determine the problem from rebuilding the carb to installing a new spark plug resistor cap and spark plug. You can read about those repairs here. Now we are looking to buy a Vespa P200 for my daily rider.

I also had my 1962 Lambretta TV175's front fender repaired. You can read about that here.

Furthermore, if you are or know a teacher in public education, like myself, then you know how it feels to interview mid-summer for work every summer, because the economy is crap.

The layshaft disassembly went well and at close inspection, without surprise, Christopher M. did a great job rebuilding it when he rebuilt the engine only 15 miles ago. I felt bad tearing it down, but better safe than sorry. I bought a layshaft rebuild kit I will install.

You will note that the top plate is warped looking. According to Gene M. the only way to avoid that is to have a machine that installs all the rivets at once at the same time for even distribution. The small warping does not hurt the function.



The only pain in the butt was removing the rivets once I got the top and bottom plates off. It required a lot of drilling and Dremel grinding and patience. I was stressed I would grind the "seat" where the plate rests or the lip the plate rests against and twice, by accident, I hit it extremely lightly. I wish I had the attachment for the circular blade for my Dremel. That would have been best I think. I rarely need it and it costs quite a bit for the limited use I would give it.

Tomorrow I hope to rebuild the layshaft with new parts. Christopher M. did install a sealed bearing into the layshaft and I will remove one seal so the oil can get in there the way Vespa intended it to. In the mean time I am soaking my new corks for the clutch.

Gonna rebuild the clutch and cush drive

Here are the following parts I am ordering:

Part # / Description / Qty

**** Clutch ****

- 110633 / Clutch Springs / qty: 6 (uprated if available)

- Clutch steels and corks

- 18975 / Clutch Rollers (needle bearings) / qty: 40

- Tool to open the brass nut to replace needle bearings (no more screw
driver -- not safe to use to open)

Am I missing anything else for a full rebuild?

**** Cush Drive ****

77372 / Internal Spring / qty: 6

77373 / External Spring / qty: 6

S.5765 / Rivets / qty: 6

77371 / Internal Spring Retainer Plate / 1

77370 / Outer Ring Retainer Plate / 1

Am I missing anything else for a full rebuild? I have a brand new
bearing there.

**** Seals ****

Engine Gasket

Gear Selector Gasket

Rear hub seal

Cush drive is okay

Chris B. inspected the cush drive today and gave it a clean bill of health, because he said "it's already been rebuilt. See the rivets that's not the manufacturer and the little bit of warping on the plate between the rivets is normal on a rebuild". He also dismantled the gears from the axle and inspected how it all fit together and confirmed the gears were installed correctly and were not rubbing. Everything looked good. Crap! At that point Chris recommended installing a new or tester clutch even though my clutch looks just great.

When Chris inspected the clutch and again today when he inspected the cush drive he commented, "it looks brand new." That combined with a rebuilt cush drive prompted me to call Christopher Markley and ask him if he rebuilt it. He has rebuilt so many of these and could not remember. He told me to check the parts invoices he gave me to be sure.

So I found a Scooter Works invoice he ordered back on 7/2006 and among the many items ordered I found:

1 Comp Clutch Kit -- VSX Surflex (item #CK4)

6 Spring, Cush Drive Inner (item #77372)

1 Plate, Spring Gear, Inner VSX (item #77371)

1 Plate, Spring Gear Outer VSX (item #77370)

6 Rivet, Spring Gear Assembly (item #S 05765)

1 Bearing, Spring Gear VSB, VSC (item #S 07153)

1 Lock Washer, Spring Gear NOS VSB,VSC (item # 58636)

From Scooter Parts Direct I placed an order on 11/2006 that included:

6 Spring, Spring Gear Outer (item #78853)

It seems all items for the cush drive were ordered on my dollar. So I regret not checking my paperwork to verify before I cracked the cases.

Besides Chris being right that everything looks brand new, I am not exactly sure what this could mean. Maybe after market products resulted in this sound. Research time.

I will post detailed photos before I put her back together.

Suggestions?

Dry test trouble shooting

I seeked help from Hiro and he gave me some good advice in terms of how to identify the grinding sound between neutral & 1st gear. Here are Hiro's suggestions:

"It is a good time to see if the gears mesh perfectly and how the noise can be generated by turning the motor by hand, shifting the gear through 1st to 4th from neutral. I am doubting the gears on the selecting rod installed with improper alignment. In case, the noise comes from the grind between the gears and shift cross. Assuming the noise can be heard during the acceleration with fully engaged clutch.

Once again, I will doubt the clutch unit if the half engaged clutch generates the noise.

I doubt the improper alignment between 1st and 2nd gear (which should have room for the neutral) or worn gears(both gears on the cush drive and the gear shift)/shift cross. I need to check if the gear cable adjustment and the condition of the waved (which align the gear location) dishes in the gear cable adjustment unit. There is a possibility that the peak(s) between the neutral position and the 1st position was worn badly and can not stay in the 1st position to grind inside the gear on shift unit."

Thank you Hiro!