Scooterotica

I'm just about to fit the drive plate washer before I fit the plate and I notice that the new washer provided in a gasket set is a lot thinner than the original gasket I removed.
I measure the depth to the drive side bearing to be 3.5mm from the plate flange and the drive plate projection that inserts into the casing measures 2.5mm which leaves a gap of 1mm.
The original gasket is 1mm thick but the new gasket is less than 0.5mm thick which by my reckoning would leave a gap for potential oil leaks.

i hope I haven't got a thin bearing and missed out a spacing shim washer under the bearing

Would it be ok to fit the new washer on the bearing followed by the old washer to make up the thickness ? I intended to use a little Neo 1104 Threebond between the new gasket and the casing as a belt and braces

There are no spacing shims between the bearing and the case.

If you got a "thin" bearing then you got the wrong one or you went cheap and ended up with a counterfeit bearing.

.5mm is nothing. Just grease the halite washer and run it as Innocenti/god/your belief system of choice intended. Make sure you use nice new screws and run them down evenly.

Do not double up the HW. It won't work and you'll be back wondering why your crank shaft rubs against the main seal plate.

As grumpy says add a bit of loctite to the screws and check it's level

thanks for the replies guys.
So you wouldn't be concerned that the original gasket is nearly 3x times as thick as the new one supplied by a major UK Lambretta dealer ?mmm...all sounds a bit 'gung ho' to me

I'm thinking....... yeah I could also just ignore the difference in thickness and hope for the best......... but then I think of the consequences of having a drive side leak into the mag housing when the engine is fitted . The amount of work and time involved in refitting a new gasket would be too bitter to contemplate.

I really don't think that the crank webs are likely to rub on the plate due to 0.5mm difference but if they do.....then that also would be disasterous but I should be able to check that crank float and clearance is within recommended tolerance etc before closing up and fitting.

This is a key oil joint so i think i might order up a couple of gaskets from other suppliers and see if there is any difference in thickness. Most of these gaskets sets come from india these days and we all know what poor quality stuff it is the majority of the time.

Perhaps it wouldn't be a bad idea to fit the existing gasket then remove the plate again and see if the gasket is getting compressed between the plate and case flange

I would greese it up and fit it and see and I usually get around 0.7 gap between plate and crank web

I would use the new washer,but instead of grease I would cover both sides of the washer in silicone gasket sealant,that way when its compressed it will seal and prevent oil from the gearbox entering the cylinder.

HxPaul wrote: ↑Fri Sep 08, 2017 2:00 pm I would use the new washer,but instead of grease I would cover both sides of the washer in silicone gasket sealant,that way when its compressed it will seal and prevent oil from the gearbox entering the cylinder.

yes thats definitely preferable to grease. I always use Threebond on all my bikes and scoots . I once used a silicon gasket Blue Hylomar and a tiny blob broke off and blocked the oilway to the head and wrecked the top end of a new built engine....never again.

I'm surprised that so many engine builders advise against the use of a liquid gasket due to the aggro of removing old gaskets .. I don't know whether they are planning on rebuilding their engines several times a year like a race engine . I'm expecting this engine to run for at least 20 years without any need for rebuilding.

I've just flatted the gasket face of the drive plate and found considerable distortion . If I were to have fited this as it came off it would never have sealed properly.
The crankcase flange that the gasket seals against is only 3.5mm wide and both the flange and the drive plate mating surfaces need to be flat to seal effectively given that the gasket is only 1mm thick .
[fbvid=]drive plate face LiS200 by John, on Flickr[/fbvid]
[fbvid=]DSCF4956 by John, on Flickr[/fbvid]

[fbvid=]https://flic.kr/p/YgAbiw[/fbvid]
[fbvid=]https://flic.kr/p/XVDdZ5[/fbvid]

Have you considered the RLC x260 seal plate with the viton ring? I've not used one myself but they look good, if a little expensive.

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If you use the aluminium type of seal plate,they distort on tightening.

HxPaul wrote: ↑Fri Sep 08, 2017 2:58 pm If you use the aluminium type of seal plate,they distort on tightening.

Yeah I read that in Sticky , fortunately all the plates I have are all original Innocenti steel but the one I chose to use I fitted a Viton Oil Seal before checking the gasket surface for flatness and it looks like its slightly distorted plus a little surface rust has made it slightly uneven in places. Nothing a little rubbing on a wetNdry block won't cure though.