Lubing your piston?

varta330

varta330

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What is the best way to lube up your piston?
After achieving a mirror finish on the piston do you apply moly paste all over it or just on the contact points?
I was watching an old tinbum video and he left the piston running dry save for lubing the contact points with the cylinder.
In his more recent videos he still polishes the piston but then applies a thin coat of moly paste all over it.
I'm confused, how are other tuners lubing their springer pistons?
 
I use high content moly for piston. Good smear around the rear skirt as that's where cocking force is mostly exerted. There will often be a polished look to the metal here to highlight contacting with cylinder. A light smear right around the front behind seal, even lighter smear on seal sides. Finally a smear on any other suspect contact

Amount of rifles ive stripped to find a piston swamped in moly grease which is just a waste and more likely to find its way forward of seal into the chamber.

Less is more really 👍
 
varta330 said:
What is the best way to lube up your piston?
After achieving a mirror finish on the piston do you apply moly paste all over it or just on the contact points?
I was watching an old tinbum video and he left the piston running dry save for lubing the contact points with the cylinder.
In his more recent videos he still polishes the piston but then applies a thin coat of moly paste all over it.
I'm confused, how are other tuners lubing their springer pistons?
Click to expand...
~ 1/2" behind the front seal & a swipe of moly ~ that same 1/2" , from tail end to ahead of the rear skirt.👍 Polishing is a feel good thing... Boredom at work, unless you've some surface scratches to address.
 
Some guns benefit from a little moly at the top rear of the piston and very lightly around the rest of the skirt. There is very little need if any at the front of the piston
 
I only lube the rear piston bearing, with a smear of high moly paste

There shouldn't be any contact between the front of the piston (just behind the seal) and the cylinder, if the piston seal is doing it's job
Wear at the front of the piston, indicates that there's something wrong. Either the seal has lateral play, the spring is badly supported, or there's too much preload

Polishing the piston body, serves no purpose at all, apart from looks, as it's impossible for it to come into contact with the cylinder as it has a narrower OD, than the rear bearing and seal
 
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I still don't get why polish the piston to a mirror, just smooth it a bit maybe to remove any really rough sharp bits.
If it's a mirror will it not hold the grease properly and it will move?
 
I'll put a smear of high content moly around the seal, and a dab around the back of the skirt.
 
Ignoring lubing a piston seal for the minute, as I dont believe that's useful at all.....

Consider the stroke of a springer (the amount in mm) that a piston moves, on firing , from cocked to shot
Any lube applied to that stroke length, risks being shaken off the piston body, onto the cylinder walls upon firing, then scraped back by the expanding seal, on the next shot, to combust

If you're using "anti fling" type lubes, of the kind that Venom and VMach used (that stick like shyte to a blanket), the risk of shake off is far less
 
varta330 said:
What is the best way to lube up your piston?
After achieving a mirror finish on the piston do you apply moly paste all over it or just on the contact points?
Click to expand...
Polish all you like; if you were to look at a magnified image of the surface it would still resemble a relief map of mid-Wales, all hills and valleys, and the valleys can hold lubricant to lower friction and reduce wear.

I'd recommend lubricating the piston skirt, whether polished or not.
 
I wipe a tiny bit of high moly paste all over the piston just to prevent any possible corrosion but as others have said
too much risks it getting into places where you don't want it.
Overlubing can also cause drag and may lead to inconsistent output.
 
After you've added a bit of lube to areas of the piston that contact the cylinder that lube is going to get spread to all areas of the cylinder where at least that part of the piston contacts over the entire stroke length of that part of the piston... the lube will obviously get spread along all that area. The thick gun grease might be a good idea but I can't see it not being flung around to some extent during the high speed and high G movement of the spring and piston regardless of how thick it is.

While it is true that even highly polished metal has hills and valleys if looking through a microscope, there is a reason why it is usually preferred to aim for a honed finish on new engine cylinders, the honing retains the engine oil which the engine piston rings slide over. Of course engine cylinders/pistons are a different subject to gun cylinders/pistons but I wonder to what extent some of the same principals should apply. I reckon highly polished or honed would make far less difference on areas of a springer gun piston than on the engine.

In the 80's advice seemed to be to put a small amount of gun grease on the spring and on at least the rear part of the piston that contacted the cylinder, a single drop of silicone oil (that will stand high temperature before combusting) down the transfer port on a newly rebuilt gun and again every 1000 shots. I'll need to look at what modern advice for lubing the piston seal is but the old advice seemed to work just fine.

What's this high moly stuff anyway, is it the stuff also called bumslide (sorry if I got the name wrong lol) or is bumslide something else? How different is this high moly stuff to automotive moly/CV grease?
 
Lpgc said:
While it is true that even highly polished metal has hills and valleys if looking through a microscope, there is a reason why it is usually preferred to aim for a honed finish on new engine cylinders, the honing retains the engine oil which the engine piston rings slide over. Of course engine cylinders/pistons are a different subject to gun cylinders/pistons but I wonder to what extent some of the same principals should apply. I reckon highly polished or honed would make far less difference on areas of a springer gun piston than on the engine.
Click to expand...
Back in the day when IC engine cylinders were only honed, it was normal for the engine to have to be 'run-in', which meant not over revving or overloading it for the first so many miles.

Running in took the peaks off high spots, leaving plateaus and valleys. so to speak.

These days, ICE cylinders are 'plateau honed', so do not need to be run in.
 
JimPlas said:
Back in the day when IC engine cylinders were only honed, it was normal for the engine to have to be 'run-in', which meant not over revving or overloading it for the first so many miles.

Running in took the peaks off high spots, leaving plateaus and valleys. so to speak.

These days, ICE cylinders are 'plateau honed', so do not need to be run in.
Click to expand...

Yes of course engines are built to better tolerances these days, different materials too (including for things like piston rings). But I'd bet even old engines were built to better tolerances than a spring airgun. The running in isn't just for the rings/bores. It was always possible to reduce the amount of running in for the rings by taking some of the sharp edge off with an oilstone etc, no piston rings and hopefully no sharp edges on the airgun piston :) The most recent engine I honed cylinders on and fitted new pistons and rings in was my boat's SBF engine a couple of years ago but I've built loads of engines in the past. I took 2thou out out of one of the cylinders using an electric drill powered honing tool to bring it up to the correct bore size, hard work and took a long time lol. I fitted upgraded hypereutectic pistons, moly top rings, ductile middle rings and standard oil rings. The change to these components alone can mean less running in is necessary for the bores/rings etc even with my oldskool DIY cylinder honing.
 
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Lpgc said:
After you've added a bit of lube to areas of the piston that contact the cylinder that lube is going to get spread to all areas of the cylinder where at least that part of the piston contacts over the entire stroke length of that part of the piston... the lube will obviously get spread along all that area. The thick gun grease might be a good idea but I can't see it not being flung around to some extent during the high speed and high G movement of the spring and piston regardless of how thick it is.

While it is true that even highly polished metal has hills and valleys if looking through a microscope, there is a reason why it is usually preferred to aim for a honed finish on new engine cylinders, the honing retains the engine oil which the engine piston rings slide over. Of course engine cylinders/pistons are a different subject to gun cylinders/pistons but I wonder to what extent some of the same principals should apply. I reckon highly polished or honed would make far less difference on areas of a springer gun piston than on the engine.

In the 80's advice seemed to be to put a small amount of gun grease on the spring and on at least the rear part of the piston that contacted the cylinder, a single drop of silicone oil (that will stand high temperature before combusting) down the transfer port on a newly rebuilt gun and again every 1000 shots. I'll need to look at what modern advice for lubing the piston seal is but the old advice seemed to work just fine.

What's this high moly stuff anyway, is it the stuff also called bumslide (sorry if I got the name wrong lol) or is bumslide something else? How different is this high moly stuff to automotive moly/CV grease?
Click to expand...
High moly paste is just that.
A stiff paste rather than a grease. Usually moly grease with a higher content of molybdenum disulphide powder

bum slide is the name given by TBT for their specific concoction (which is very good)
 
What is the specific concotion like (if they don't spell it out) and what bits of the gun is it for (spring / outside of piston / etc)? To completely replace the moly stuff? Any links to this high moly paste stuff? Does anyone simply use moly/cv grease instead?

And what is the advice for lubing piston seals these days?
 
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