LCGB Forums

Hi all
can anyone let me know causes for xmas tree gear rubbing casing please?
as I go through the gears manually on the bench side casing off the gears make a whirring noise getting worse in 1st gear.
I marked the casing with permanent marker behind the xmas gear last time it made a noise. now found a big circular score mark which cuts through the marker pen too. but why?
any advice would be great. I did do up the clutch nut as much as poss to draw the gear out but not made any difference.
cheers

There should be a shim behind the Christmas tree, have you missed it out?

no infact I put a slightly larger one in. made no difference.

Maybe try replacing the gear cluster casing bush & roller bearing to see if that makes a difference, good luck

mmmm
rather not try and change the bush if i can help it. not an easy job. dont have a drift exactly the right size to use as a hydraulic drift.
may have to go there though.

Try stripping the gearbox completely out then put the Christmas tree back in and twirl with your fingers, does it rub? If so keep adding shims until it doesn’t.

Is it a poorly made aftermarket Christmas tree I wonder? Can you borrow another to try?

Scooterdude wrote:Try stripping the gearbox completely out then put the Christmas tree back in and twirl with your fingers, does it rub? If so keep adding shims until it doesn’t.

Is it a poorly made aftermarket Christmas tree I wonder? Can you borrow another to try?

Hi
thanks for the reply.
the xmas tree will rub anyway when fitted on its own until the endplate has been fitted and clutch nut pulls it outwards to allow clearance between the bottom of the gear and casing.
the xmas tree is genuine original Li s3 and has performed with no probs since 2004. I have got an SX one and will try that to see if thats the same but will sant to keep my Li 150 gearing.
cheers

lam1962brettagg wrote:

Scooterdude wrote:Try stripping the gearbox completely out then put the Christmas tree back in and twirl with your fingers, does it rub? If so keep adding shims until it doesn’t.

Is it a poorly made aftermarket Christmas tree I wonder? Can you borrow another to try?

Hi
thanks for the reply.
the xmas tree will rub anyway when fitted on its own

No it shoulden't do.

lam1962brettagg wrote:I marked the casing with permanent marker behind the xmas gear last time it made a noise. now found a big circular score mark which cuts through the marker pen too.

Is it a perfectly circular complete score or just a partial circular score?

Hi
circular score, seems deeper toward the front of the score as you look into casing score is deepest toward the right.
hope that make sense.

Correctly fitted with parts that are 'proven' there should be no interference.

I suggest you fit just the cluster with it's bearing, with just the end plate (no gears) & torque up the cluster nut with spacers/sockets etc. As previously mentioned, that process takes up the axial play all toward the chain case cover side.

If there is still an issue, suspect either the cluster or endplate/bearing.

(The cluster shim should be fitted in the event of sorting out the problem, but is only there to avoid excessive float of the bearing & often needs to be omitted in the case of DIY CR gearboxes where there is a weld in the corner near the journal)

+1

+2

thanks for your replies and help.
I'll try that, but if the cluster gear still rubs without the gears should I suspect the casing needle roller bearing aswell as the endplate bearing tolerance? too tight. not allowing the cluster gear to be pulled into place enough?
if the race is to be changed in the casing for the needle roller am I right thinking its a 22mm solid bar drift with hydraulic action to remove it? or smaller? to fit into the base of the race directly onto the casing at the back of the race?

disregard just the question about the casing race, just had one delivered and can see what it is clearly now. so 22mm drift.
cheers

If you have decided to hydraulic out the cluster outer race then I would advise that you provide adequate support directly underneath to ensure that you don't accidentally smash through the back of the casing. Without this support they are a devil to remove anyway and so people use unnecessary force making damage more likely. (I get an assistant to hold the case over a dowell of hard wood leaving me free to use the hammer and drift)
I find thick waterpump grease works very well.
Never tried the sodden bread method, but hear it works rather well.

Some of these races are badly made and out of tolerance. Some are hardened incorrectly. So, buy your new race from a reputable source and make sure the bearing face on the cluster is perfect. (these can be restored by certain specialists if necessary). It goes without saying that a new bearing will be necessary. If it doesn't come in a sealed bag with manufacturers markings or packaging then it's probably best left on the shelf! All too often I am told by these so called reputable Lambretta dealers that "Oh yes its definitely an INA bearing" only to discover its just a piece of Indian crap.

Get some heat into the outer casing first and use bread, insert it into the track and use a 22mm bar, a 22mm Yam crank pin works well

thanks for the advice scotty.
brown white or wholemeal? only jokin
I'll give it a go with both grease and bread obviously not at the same time though.
I got a couple of casings to do anyway.
cheers

I wonder if the heat generated by the hydraulic action is sufficient to toast the bread?

Lifted my low mileage cluster bearing and a roller fell out. Had to change race as it had shiny marks on it. I used a 16mm socket packed with grease, and packed race as well. Came out in seconds. Tapped a good old one in cold. Took about 5 mins. Changed my bearing supplier afterwards.