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 Post Posted: Sat Nov 30, 2019 3:11 pm 
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True Horneteer
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Hello,

I'm gonna be changing shims soon and I've been informed that I need to coat the new shims in a 50/50 mix of molybdenum disulfide grease and engine oil.

I've got a tub of Moly grease for CV joints which has a very low percentage of molybdenum disulfide (3%) so I'm assuming that this is the wrong stuff for the job and I need a tube of 100% molybdenum disulfide grease instead?

I've heard some people don't bother with it and just use a coating of assembly lube or engine oil - but I saw a video of a mechanic re-shimming a Yamaha R1 engine and he very specifically made a point of mixing up a paste of molybdenum disulfide grease and engine oil to coat the new shims in.

Does anyone know where I can get some legit molybdenum disulfide grease for shims? There is a lot of stuff on the market with molybdenum disulfide in the title for various applications but nothing specifically for shims - any info would be appreciated, thanks.


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 Post Posted: Sat Nov 30, 2019 3:17 pm 
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True Horneteer
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P.S. This Millers Oils Competition Car Engine / Engine Assembly Lube / Lubricant - 30ml
looks like it should do the job?

https://tinyurl.com/sueajju


Competition assembly lube has been specially formulated for competition engine and transmission builders to protect mechanical components during initial start up of new components. The lubricant features a high concentration of anti wear additives and once added to the components at the assembly stage it will stay on there.
Unlike engine assembly pastes competition assembly lube is fully miscible and compatible with all engine oils. It will dissipate once the engine is running reducing the need for an extra oil change.

Ideal for use on components subject to high stresses such as camshafts, followers and crank bearings.


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 Post Posted: Sat Nov 30, 2019 5:21 pm 
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Knob Magnet
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ITS OVERKILL, you only need to coat the parts in fresh engine oil on reassembly,
i always turn the engine over on the starter until the oil pressure light goes out,
that way the oil gets where it should be and the engine isnt under any running forces.

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 Post Posted: Sun Dec 01, 2019 12:45 pm 
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True Horneteer
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Cheers Steve, yeah - sounds like overkill just for shims - thanks for your opinion. :D


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 Post Posted: Tue Dec 03, 2019 11:49 am 
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Hornet Lord

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I just put a tiny smear of Moly CV grease, when I did mine. Don't think it matters tbh.

Engine oil should be fine like steve said.


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 Post Posted: Tue Dec 03, 2019 9:59 pm 
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True Horneteer
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Yeah agree - it's easy to get over-paranoid about stuff like this :D


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 Post Posted: Wed Dec 04, 2019 12:46 pm 
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Victor Meldrew
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I thought the special lube was for the cam lobes, not the shims. I used cv joint grease mixed with engine oil.

I installed my shims dry, any lube would probably alter measured clearances, given the advice about slackening the cam chain tension to remove pull on oil gap, as it says in FSM.

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 Post Posted: Thu Dec 05, 2019 11:41 am 
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True Horneteer
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Yeah - good point - the tolerances are so fractional that if you smear the shims in any kind of 'gloop' you are going to potentially throw your measurements out.


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 Post Posted: Mon Dec 09, 2019 3:47 pm 
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Hornet Lord

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HOON98 wrote:
Yeah - good point - the tolerances are so fractional that if you smear the shims in any kind of 'gloop' you are going to potentially throw your measurements out.


True but how are you supposed to measure it, with or without grease(can't remember the instructions)? As the people setting the tolerance window would have set them either with or without grease. Also something to consider might be that the spring tension might be enough to push out the grease to the point where it gives you the right clearance.


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 Post Posted: Tue Dec 10, 2019 10:36 am 
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Victor Meldrew
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Just had a quick read of the official FSM, which states that :.

Moly oil should be applied to the camshaft lobes and bearings (journals) on reassembly.

Also to the 'valve lifters', which I interpret as meaning the sides and tops of the cam buckets, where they bear against the cam lobes, and run in the holes in the head.

Nowhere does it say anything about lubing the actual shims, which as we know sit between the top of the valve stem and the bottom inside of the cam bucket.

I suppose on checking the clearances on an engine that has previously been run there will be a film of engine oil on all the moving bits. Probably just over thinking this ….

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 Post Posted: Tue Dec 10, 2019 6:06 pm 
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True Horneteer
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Yeah - that sounds spot on - in terms of moving parts the lobes, journals and lifters are the most obvious candidates for some kind of assembly lube after removal and re-installation - whereas the shims (which basically just sit there under the lifters) should get by with just a squirt of engine oil.

As mentioned above - it's probably over-kill but I bought a bottle of Millers Oils Assembly lube to apply to the lobes, journals and lifters - although I'm sure a decent application of engine oil will do the trick (as this is a working engine and not a rebuild etc) this is my first cams out job and I thought it would probably be best if I followed the official advice.

Granted the Millers assembly lube is not described or marketed as the 'molybdenum disulfide grease' that the manual says should be used upon re-assembly - but based on my research it is designed to do exactly the same job and has good reviews.

It's also important to note that the assembly lube should be used quite sparingly - all that is required is a thin smear to protect the moving parts on initial start up before the engine has a chance to pump some oil over the valve train components.


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