Rebuilding your Vespa variated gearbox with a overhaul kit from Treats.

I found out the worst thing you can do to your variated gearbox is to strike the input shaft with a hammer when trying to remove a stubborn rusted variator. The result is it drives the inside bearing cup out of the gearbox creating a ton of end play slack, or in my case cracked out the back of the cup so gear oil could flow onto the brake lining and rendering the rear brake useless.
This tutorial is my method for installing the Treats rebuild kit. It is long and boring but has some important points to watch out for so you don't wind up damaging the new bearings or not properly adjusting the "end play" of the gear shafts of the transmission.

cracked bearing cup

Here is the cracked bearing cup of the input shaft that I had beat on with a hammer. Chasing this oil leak proved to be a bitch and I went as far as replacing the input shaft seal as that's where the fluid appeared to be coming from.

slow drain

In anticipation of shipping time from Treats of my new build kit I set the gearbox aside on a waxed paper plate and just let gravity drain as much fluid as possible from the cracked bearing cup.

stuff for teardown

Lay out some clean rags or a towel to line up the innereds of the transmission. I like to use this 5 gal bucket cut off and diesel fuel to clean my greasy builds.

four bolts

Start out by removing the four 10mm bolts of the gearbox cover.

light pry

It may take a slight pry with a flat blade screwdriver to get the cover started up off the alignment pins. From the factory the cover gasket is not set with any glue or sealant, you will not need to use any when reassembling. I have included a small bowl to keep the box level in the bucket during the disassembly and cleaning.

lift off top

When lifting off the top cover, I keep pressure on the input shaft to keep it in place.

note shims

Keep track of all the parts at this point and lay them out on your towel in order as you remove them. Two of the shims attempted an escape by sticking to the top cover.

add diesel

I use my parts cleaning brush with diesel fuel to scrub the old 90wt oil off. Gasoline cuts better and faster but can be dangerous. I was always taught never to use gas in a cleaning bath. Anything could set that shit off.

clean as you remove

Clean and wipe dry, set aside as you go.

output shaft

The output shaft has the most parts with the spring and all.

lay out in order

This is the total of the contents.

Zippys parts sheet

This might help if you get lost.

clean cases

I like to go ahead and get the cases clean as I can while I have the diesel bath going on.

Treats rebuild kit

Here is the super duper rebuild kit from Treats. This treasure box was About 39.00 and seems to come with more than enough bearings and shims to do this job, even a new keyway. It comes with five extra shims that I will not be using. I have opened two gearboxes over time and these shims were not in either of them. They also don't show on the factory schematic picture. These shims would only fit on the short intermediate shafts and if used would not allow you to close up the case. I believe they are included in the instance where a gear box had heavy damage and the case itself had been milled away by the steel gears. These shims would then be used to make up the missing case material. The only thing the kit did not have was a new gasket for the fill bung. What a rip.
Get yours at
Also comes in non variated.

move to assembly jig

For the old bearing removal you need a solid surface to rest the case against to drive out the old bearings. I move my work to my trusty engine building jig. Its simple design lets me turn and position all kinds of cases for hammering and torching. Evan allows for motors with pokey cranks.

19mm socket

First I go after the biggest bearing of the output shaft A 19mm deep socket fits nice so I start whacking.

bearing moving out

As shown the bearing moves right on out.

Dont drive on this side

Next I used a 8mm nut driver that fit nice on the small bearings. It was at this time I discovered my first mistake. You do not want to drive on the small bearings from the open end. Doing this causes the bearing cup to collapse and the nut driver just punches the needles right through, leaving behind the outer shell which must then be dealt with.
Always drive on the closed end of these cupped bearings.

stuck bearing cup


torch the case

I figured that if I heat up the case with a torch it my help in the broken cup extraction

driveing out broken cup

I can just barely catch the lip of the bearing cup shell to give it some whacks.

broke cup out, hooray

Hooray I got the hot fuck out of there

proper cup driving direction

I then position the case with the closed end of the cups looking up and drove them out easily in one piece.

last one driven out

Input shaft bearing knockout

A small length of aluminum tubing knocks the last bearing out.

measure new against old cups

A quick check with my calipers tells me the old and new cups are nearly identical in size.

Permanet sealant just in case

Before I start to install the bearing cups I give them a light coating of hucky spooge just in case the metal on metal fit wants to seep a little oil.

These next steps I feel are important as it has to do with the "end play" or side to side movement of the intermediate gears. This "end play' is adjusted by how far in you drive in the bearing cups toward the gear shafts.

Mock up intermediate gears

First install the two opposite side intermediate bearing cups but leave them standing out of the case about 1mm on one side and flush installed on the other. Then lay in the first gear and dry install the gasket and lay on the cover all the way flush down.

shaking the case

Then grasp the case in both hands and shake it lightly. You will naturally hear the side to side movement of the gear going "cloppy cloppy" What you want to do is reduce that movement and sound to a "tinka tinka". Do this by lightly driving in the bearing you left standing out till the cloppy sound is reduced to a tinka sound and feel. Imagine the sound that Bewitch's Samantha Steven's nose makes when she casts a spell, "tinka tinka".
I am not that educated and that's the best way I can describe what you want. Its not that big a deal but you need to have some end play or the gears will fit too tight and slowly carve through the end of the bearing cups and leak oil.
When you a happy with the end play of this gear then reopen the case and do the same for the other short intermediate gear.

mock up input shaft

The adjustment for the input shaft goes the same as the others. Install the small bearing cup partway then mock up the input shaft with its net top shim from the kit.

cheak for "tinka tinka"

Mock on the gasket and cover and then feel the ply and adjust the bearing cup till you have the "Tinka" play feel.

love taps

Light taps on the bearing cup is all it takes to get your shaft end play feeling right.

Installing the open ended large bearings takes special attention as well. These two bearings have a thick side and a thin side. You do not want to drive on the thin side of the bearing. It could crack and the needles escape. Inspect your bearings from the kit to determine which side is the hammer side.

thin side of bearing

Thin side. Don't hit this end.

thick side of bearing

Thick side. Hit me.

drive from outside to inside

Drive these bearing from the seal side in so that you can see when you have driven the bearing down flush with the seal bed. If you leave it too high the seal might not get a good footing down in and drop loose later.

bearing even with seals seat

This looks good.

mock up output shaft with shims

Setting the output shaft end play you can do last. I am not sure but I believe that the output shaft is pre adjusted using the shims that ride on the top and bottom of the shaft. Anyhow I treated it the same as the others.

close cover and adjust bearing

You can see as I close the cover on the mocked up shaft that I have left the bearing cup sitting out a bit. On this adjustment I could reach under with my fingers and bump the shaft up and down as I drove the big bearing cup down till I found the feel I wanted.

break in grease

All bearings are now set and I feel comfortable about doing the final assembly. I like to poke some break in grease in on the bearing cups so they don't run dry before the oil can get splashed on to them. Stand in all the gears and get ready with the cover.

This side up toward throwout forks

This top driving gear has a distinction and can accidently ne set in upside down. You will want the side with the flats that line up with the throwout forks to face the forks. Hold it up to the forks to be sure of the right fit.

last shims in place

Three, two, one, Zero parts left. You may have noticed that I reused my OEM shims. They were not grooved or worn so , yeah. Now to the cover and gasket.

cover on for keeps

Lowering the cover down for the last time is a little tricky to find the holes. When it drops on run in a couple of bolts finger tight and check the movement by turning either shaft with your hands. If it spins stiff but freely, then put a few more turns on the bolts and check again. If it binds up something could be wrong. Tap the edge of the whole mess lightly on the concrete and check again. If it is still bound up then you need to open up and find out what is out. But if you pre set all the end play of the gears correctly nothing will be wrong.

seal goes last

Grease the shafts and slide the seals on and force them into their seats. Now you can install the gearbox back on the bike. Last you will want to remove the fill bung and fill the unit with your favorite gear lube. I use 80-90wt. You can also calculate what your gear ratio is by looking here:

I am now finished with this Wiki page. If you have any questions about the tips I suggested, or are having trouble with the process or can suggest how I can correct a mistake I have made or to make the page better, contact Cheetahchrome,26847