Crownwheels

[neily03]

Am i correct in thinking it's not wise to use the older crownwheels with the internal springs on a tuned engine?

[al pushpak]

Yes, not advisable, solid later type much better

[neily03]

Great, thanks

[Knowledge]

The solid ones need to use a bronze bush rather than two needle rollers, as the centre is not hardened like the old ones with the internal cush-drive.

[neily03]

Yes I've been reading about the bushes in solid ones, MB do a solid crown wheel that uses needle bearings but are the bushes really problematic?

[Knowledge]

No. There are some very good quality after market bronze bushes now, with a clever oil-groove cut into them. The OEM ones are not the best.

I sometimes wonder if MB seek solutions to problems that don't seem to exist. Still, they build a lot more machines than me so they must find more problems than me.

[foremanbob]

I had a bronze bush last year on route to Whitby... but that's the first I've ever heard of...

[neily03]

Great, thanks guys

[HxPaul]

Do the riveted solid type(without springs) still require bushes,or can they be run on bearings ?

[Knowledge]

Is there such a thing as a riveted solid crown wheel? Why would it need rivets if it is solid?

I suspect you have one with a spring cush-drive hidden within.

Anything old with a cush-drive has a hardened centre and can use needle rollers.

[HxPaul]

https://www.ebay.co.uk/itm/Lambretta-cr ... :rk:3:pf:0

[Steve J]

Is there such a thing as a riveted solid crown wheel? Why would it need rivets if it is solid?

I suspect you have one with a spring cush-drive hidden within.

Anything old with a cush-drive has a hardened centre and can use needle rollers.

Yup, there is such a thing - probably late Series 2 or early Series 3. It's 'solid' in that there is no movement between the inner clutch bell and the chainwheel part, due to the six rivets holding them together. I've got one, but I drilled out the old rivets and fitted M6 screws, with a drop or two of loctite. The main reason for using it was that I wanted to keep the needle roller bearings.

[neily03]

Out of curiosity is it possible to convert a sprung crown wheel to solid so needle bearings can be used?

[rossclark]

It's not the springs or the solidness that matters, it's whether the race in the centre is hardened suitably.

[Warkton Tornado No.1]

The real beauty of the two part, non sprung, rivetted crownwheels is the fact that they are dismantleable.

Once apart, the slots can be deepened to allow for five plates or more. The task is far easier than pocketing the one piece crownwheels.

Then, as previously said, high tensile fasteners such as button heads can be used to assemble, but check nothing fouls.

I personally like the needle bearings in preference to plain because the assembly will run truer. That said, only 46T are readily available in that format.

However, think about when the bearing is put into action for a moment. It only gets to be used in a dynamic capacity when the clutch is pulled in, that is, it is disengaged. The majority of the time, the bearing is in a static capacity & only there to support & centralise the whole clutch assembly when it is engaged, which is the majority of the time.