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Half Moon Seal
https://www.ausmini.com/forums/viewtopic.php?f=2&t=82212		 Page 1 of 1
Author:  Mick [ Fri Jul 26, 2013 12:48 pm ]
Post subject:  Half Moon Seal
I'm just fixing up a half moon seal on my 998. I'm wanting to do it as a precaution as I have a leaking timing cover seal, and while I'm there with the gaskets...

Now, I am sure I have covered this before, but can I change out a half moon seal without splitting the gearbox from the engine?

And I'll be buggered if the timing chain hasn't eaten into the oil slinger again! :x
Author:  drmini in aust [ Fri Jul 26, 2013 1:16 pm ]
Post subject: 
Nope I think the seal needs the engine off the box, it is a crush fit in there.
I would just take the timing cover front plate off and gun some sealer in there where it's leaking (probably at one end).
If the duplex chain is eating the oil slinger you need to fit the later one.
Early ones had 2.4mm offset, duplex late ones as used on S were 1.0mm offset.

PM sent.
Author:  Mick [ Fri Jul 26, 2013 1:57 pm ]
Post subject: 
drmini in aust wrote:
Nope I think the seal needs the engine off the box, it is a crush fit in there.
I would just take the timing cover front plate off and gun some sealer in there where it's leaking (probably at one end).
If the duplex chain is eating the oil slinger you need to fit the later one.
Early ones had 2.4mm offset, duplex late ones as used on S were 1.0mm offset.

PM sent.


Thanks Kev.

I can't see any oil from the half moon seal, so I may leave it alone. the oil slinger bugs me, I was certain it cleared when I fit it up...

I see Minisport (SA) have them new to suit duplex, so I'll pick up a new one and make sure.

cheers

Mick
Author:  MattE [ Fri Jul 26, 2013 9:19 pm ]
Post subject: 
I was interested to find that the original half moon seal fitted to my Metro engine/box (which I believe hadn't been split before) had a kind of metal support built in - it couldn't be bent/twisted etc.
The replacment seal supplied in the kit was quite different - just floppy rubber.

Are the original seals known to be a superior quality with this metal support built in?

I recall that one of the suppliers was offering a standard and a "high quality" half moon seal - would this be the difference?

Matt
Author:  drmini in aust [ Fri Jul 26, 2013 9:22 pm ]
Post subject: 
Originals way back were cork.
Then came the rubber one.
The rubber one with metal in came much later, I am not sure when. It may be aftermarket supply.
I find the common rubber ones work fine... if you drop the gearbox onto the motor.
Author:  MattE [ Fri Jul 26, 2013 9:29 pm ]
Post subject: 
Thanks Doc.
Any idea why box onto donk works better than donk onto box?
(Apart from the engine being heavier)
Author:  drmini in aust [ Fri Jul 26, 2013 9:41 pm ]
Post subject: 
MattE wrote:
Thanks Doc.
Any idea why box onto donk works better than donk onto box?
(Apart from the engine being heavier)

Because the seal is sitting firm on the motor with the gaskets, and when you guide the box straight down onto the 2 dowels (which you can easily see) it doesn't get displaced.
The only other thing you have to watch is the oil pickup O ring is sitting firm in the gearbox flange, I put a bit of Loctite 315 in the groove.
Author:  TheMiniMan [ Fri Jul 26, 2013 9:43 pm ]
Post subject:  Re: Half Moon Seal
Mick wrote:

And I'll be buggered if the timing chain hasn't eaten into the oil slinger again! :x


probly cause you cam & crank gears not aligneded properbly

:-)
Author:  drmini in aust [ Fri Jul 26, 2013 9:59 pm ]
Post subject:  Re: Half Moon Seal
TheMiniMan wrote:
Mick wrote:

And I'll be buggered if the timing chain hasn't eaten into the oil slinger again! :x


probly cause you cam & crank gears not aligneded properbly

:-)

Nope he had the early simplex slinger and a duplex chain... they rub. :lol:
Author:  Mick [ Fri Jul 26, 2013 10:19 pm ]
Post subject: 
Uh huh!

I have been bitten twice I am afraid...I thought I had the right slinger last time, and there was plenty of clearance. Obviously not!

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Author:  TheMiniMan [ Sat Jul 27, 2013 10:18 am ]
Post subject: 
yep,,, there we have it ,,, gears not aligneded properbly :-)

sorry but i can`t help typimngb funndy whenm things arented aligneded properbly :-)

so,,, to remedy this problem,,, i`m going to guess you have no shims under the crank-gear yeah???,,, so,,, if that`s the case then get the cam gear off & have the abuttment-shelf & the thrust shoulder machined (in a lathe will do, but make sure you clock it true before machining it) enough so that the cam gear aligns with the crank gear.

most mini engines rely on the shims under the crank gear to align the crank gear to the cam gear

but what we do is machine the cam gear till it sitts square/straight... inline with the crank gear

2x skims,,, one from the most inner edge of the gear ,,,to align the gear with the crank gear,,, then skim some off the next shoulder in to allow for the cam thrust clearance

got it?

this way you will have no more dramas shredding slingers & you`ll even have a tiny weeny bit more power because you are not trying to pull shafts sideways into thrusts.

edit--> oh sorry,,, i may need to explain something here

std issue minis , with the shims under the crank gear to align the gears,,, is fine & dandy in a perfect world,,, but we are not all living in a perfect world now are we??? just like the balancing an engine thread of a little while ago--> not everything is how it was from the factory & even if it was , that was 30 or 40 or 50 years ago & no one knows who`s stuffed with it since then,,, or how many times it`s been stuffed with the wrong way r, right??? so,,, they (the shims) often they give trouble,,, especially if the crank has been hardened with the shims still sitting on the crank ,,, they then become very brittle & break & fall out & get all munched up in the gears/chain/cover,,, & then your front pulley comes loose & starts hitting the cooling fan while you`re driving along etc etc etc

so,,, to help avoid all that ,,, instead of shimming up the crank gear,,, we find it best to skim down the cam gear to align things yeah? -->But don`t forget you need to skim things so there`s the right clearance for the cam thrust washer yeah???

anyways,,, that`s enough for the day,,, typing fingers going numb (again) :-)
Author:  drmini in aust [ Sat Jul 27, 2013 12:07 pm ]
Post subject: 
Matt,
As I said before that is the WRONG slinger for a duplex chain.
You can shim it all you like, the chain will still move out with the sprocket and hit that slinger, it is all an assembly on the crank and will move out with the shims.

The right slinger only has 1.0mm offset (like the 2 you sent me, Matt) and will miss the chain fine, shims or no shims.
Author:  Mick [ Sat Jul 27, 2013 2:22 pm ]
Post subject: 
Hi Matt,

Thanks for the detailed reply. I've got a number of shims here removed from the crank. I used a ruler across the gears to make sure each was flat relative to the other when I put it together last time. The slinger was pushing up against the chain once it was torqued up.

I'll take a closer look at it again and recheck the alignment once I put it back together. I've got the plate off to look at the half moon at the moment.
Author:  Mick [ Mon Jul 29, 2013 11:53 am ]
Post subject: 
I reassembled the timing gear end of the engine once I got the seals and gaskets I was missing. Sorry Doc, I led you astray, but I was wrong and Miniman was right, the timing gears were out of alignment slightly afterall...

The oil slinger was the wrong one, but it wasn't out by much being a very similar offset.

I was missing a single thick shim to kick them back into alignment. The geometry of it all means a slight misalignment eats up the entire gap between the timing gear and the oil slinger entirely.

Thanks Doc and Matt.
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