Are motorcycle suspension coatings worth it?

[Larry250]

So the question is are dlc, tin, kashima coatings worth it? Whats your experience? Did you notice a diffrence in performance?

[mog]

No honestly they are not

[GDI70]

They can work, obviously many use them. They are not however, the "magic bullet" in suspension performance. If damage occurs, they must be recoated to maintain functionality. They also wear over time, and can look worse for wear than stock tubes in time

[SteveThe Snakes]

Little difference to none. It’s more about valving and proper springs. DLC is pretty hard stuff. 

The factory coatings seem to hold up better then the aftermarket applied in some cases I’ve seen.  

[LuxonMX]

Depends on what you mean by worth it... Do you have bone stock suspension and are considering coatings? Then the answer is probably not.

Do you have well set-up suspension, various upgrades, etc. already and are considering coatings? Then the answer is maybe, it depends on what you're looking for. If you want the most performance available and cost is no object then get the coatings.

Coatings absolutely make a difference. But there are many other upgrades available that will make more of a difference for the same amount of money or less. Regardless, if you do get coatings, make sure you're getting them from someone who really knows what they're doing otherwise it may end up being eye candy that hurts performance.

[Larry250]

Depends on what you mean by worth it... Do you have bone stock suspension and are considering coatings? Then the answer is probably not.
Do you have well set-up suspension, various upgrades, etc. already and are considering coatings? Then the answer is maybe, it depends on what you're looking for. If you want the most performance available and cost is no object then get the coatings.
Coatings absolutely make a difference. But there are many other upgrades available that will make more of a difference for the same amount of money or less. Regardless, if you do get coatings, make sure you're getting them from someone who really knows what they're doing otherwise it may end up being eye candy that hurts performance.

What coatings did you have done to what bike and how they did they perform better?

[Larry250]

Ok. I searched google for luxonmx and you guys offer a coating service in california. I think you might be biased[emoji16]

[LuxonMX]

41 minutes ago, Larry250 said:

Ok. I searched google for luxonmx and you guys offer a coating service in california. I think you might be biased

Sure, but as evident by my earlier post, we're not pushing it real hard or claiming that it works wonders! In the end, though, it's just basic physics. Coatings result in a lower friction coefficient, and this allows your suspension to work better. The coating performance improvements really have little to do with seal drag as many people believe (though it does help some, it's not much).

The real advantage to coatings is the reduction of sliding friction between the tubes and bushings under a side load. Forks are rarely loaded perfectly on-axis. The attitude of the bike is different for every bump you hit and therefore the side load is different for every bump you hit. With side load comes friction, which is a form of damping. More specifically a form of damping that you can't tune and entirely dependent on the magnitude of the side load and the friction coefficient. This is a bad thing! By reducing the friction coefficient, this un-tunable variable can be reduced giving more consistent performance.

[GHILL28]

Most coatings offer no perceivable benefit in hysteresis under oil or durability over really good stock stuff.

If you feel a noticeable difference, 90% of the time it's from the added thickness reducing the heel-toe striking when the tubes bend from a tall square edge.  You'd probably feel the exact same thing by shimming your bushings by the same amount as the coating thickness.

[GDI70]

Spending the money on springs (if necessary) and a good tune ( by someone who knows WTF), far outweighs any benefits coatings alone offer. 

[n2dirt]

I guess the entire mountain bike community knows less than these guys.?

[GHILL28]

I guess the entire mountain bike community knows less than these guys.[emoji52]

Mtb community is equally as full of hype and non-engineering. Arguably worse. The friction case for a mtb fork is a whole lot different too. Lack of lubrication in most cases of modern forks, and an ever-changing sprung mass relative to springrates.

[Larry250]

Most coatings offer no perceivable benefit in hysteresis under oil or durability over really good stock stuff.
If you feel a noticeable difference, 90% of the time it's from the added thickness reducing the heel-toe striking when the tubes bend from a tall square edge.  You'd probably feel the exact same thing by shimming your bushings by the same amount as the coating thickness.

Offtopic here but. How exactly do you shim the bushings? Whats the process?

[Gustl]

4 hours ago, GHILL28 said:

Mtb community is equally as full of hype and non-engineering. Arguably worse.

True!

You also have to consider that MTB tubes are aluminium and you need to have a coating on them anyhow.

11 hours ago, LuxonMX said:

The real advantage to coatings is the reduction of sliding friction between the tubes and bushings under a side load.

The coating itself does nothing to the friction coefficient in a system with teflon coating bushings. 99% of the sliding performance is done by the finish of the surface. Its very hard to beat pure chrome tubes with the right surface finish. A lot of factory teams run this setup. Coatings are just a fancy look not more.

[LuxonMX]

In order to claim that coatings offer no benefit, you have to be willing to ignore basic physics and engineering. Which makes it ironic when people who claim this also refer to those who understand that coatings DO work as non-engineering types.

Done properly, coatings do NOT add appreciable thickness. Assuming your stock upper tubes were hard anodized (they should be), stripping that anodize and applying Kashima or Kyokote (the coating we offer) will result in no dimensional change. For the lowers, PVD coatings like TiN and DLC do add thickness, but it's on the order of 2 microns. That's 0.002 mm (0.00008 in). You're certainly not shimming your bushings with 2 micron shims!

If coatings don't work, explain why lower tubes come from the factory hard-chrome coated? It's partially for corrosion protection, but also because hard chrome increases hardness and reduces the friction coefficient. If you can further increase hardness and reduce friction coefficient with a DLC coating, you're going to increase performance. Similarly, if you can impregnate hard anodize with either molybdenum disulfide (Kashima) or Teflon (Kyokote) to further reduce friction, you're going to increase performance.

If you want to argue the cost-benefit of coatings or how much of a difference they make over stock, that's fine. Coatings certainly don't make a huge difference, but they do indeed make some difference. If cost is no object or you're looking for the absolute best suspension out there, get coatings. If you're on a budget, there are much better ways to spend your money and increase performance.

[GHILL28]

Show me test data that proves:

1)  Your coating of choice on top of hard chrome vs a PTFE lined bushing submerged in oil has a measurable and statistically significant difference.  The coating must not provide a dimensional change significant to the bushing gap which is typically around .003" on a proper build.  2um is ~.0001".

2)  Your coating of choice on a surface that has had hard anodize chemically stripped (aggressive as hell and roughs up the surface of the substrate since anodize impregnates the first few .001" of aluminum) and replaced with the coating vs a PTFE lined bushing submerged in oil has a measurable and statistically significant difference.

I'm going to spoil it for you - neither of these situations are improved with the addition of PTFE or MoS2.  Once the bushings and seals are under oil, and dimensionally correct in the diameters and cylindricity, surface finish (roughness) is the game to play.  Not coatings.  That's not ignoring basic physics and engineering - that IS the basics.

The best thing a coating can do is increase the hardness and the durability for someone who is putting a LOT of hours and heavy strike loads into the sliding surfaces.

[mog]

The hard coats I have found don't stand up to rocks etc ,they are worse as they make the high spots much sharper and harder to knock off ,to stop them ruining the next set of seals , and then they look terrible as you can see the underneath of the leg show through

I have had the coatings done ,on mine it altered the amount of play/slop so much the fork hardly moved. I would not spend the money again

[LuxonMX]

If I wasn't clear earlier, properly applied is the key here. Some random anodize shop or some random PVD company won't be able to do it correctly. It takes a rather long development process to sort out how to properly strip the old coating, how to correctly anodize the parts so the resulting dimensions do not change, how to properly impregnate the anodize, and then how to seal it. Tuning in the parameters of the DLC process is similarly complex.

If the coatings are changing the dimensions, altering the surface finish (in a negative way), quickly wearing through, or sharpening high sports, then the parts were not properly prepped and/or not properly coated. It's a rather complex process. If the coatings are not applied correctly they will be a negative in performance. But applied correctly, they are a positive.

Arguing that reducing the friction coefficient will be a negative is simply ridiculous. If you're trying to argue that the performance gain is small, then that is indeed true as I've mentioned repeatedly in this thread, but small or not, it is still present. Yes, Teflon bushings gliding on a surface coated in oil results in very little friction. But there is still friction present and reducing that as much as possible is pretty basic logic. If you can do that with coatings and surface treatments, why not?

[GHILL28]

Nobody here has argued that the effort of reducing friction is a negative.  Only that it generally doesn't turn out that way when people try to achieve it.

Arguing that reducing friction is a negative is more of a system level and dynamics issue (and there IS an argument for it), irrespective of whether the coatings are doing what is advertised.

[lukethedork]

There's a lot of talk about bushings being submerged in oil and keeping the bushes and tubes from actually touching. But if the loads exceed the oil film strength then there will be contact between the tubes and bushes.

This is all fairly elementary but first off we have to look at what sort of lubricating condition are we talking about. My opinion is the turbulence along with the low head of oil does not provide consistent or enough pressure for the bushing to work in a hydrostatic condition. This should be fairly obvious and I don't think anyone will disagree with me on that.

The next condition we would be talking about would be hydrodynamic lubrication. This is the same condition that main bearings in engines work under. We have to look at the environment and conditions that the bushes are in. These are not ideal conditions to maintain hydrodynamic lubrication. Due to the low relative velocity between the tubes and bushes every time they change direction. Also due to the orientation and direction of movement between the two surfaces. The loads are also very high at localized points due to the distortion (and again the orientation and direction of movement or force).

Fork oils are usually very light on EP additives, which is why coatings may help significantly for the times that the bush is not properly separated from the tubes by the oil film.

All the calculations I have done show that the bushes are regularly beyond the capabilities of the oil to maintain hydrodynamic lubrication.

P.S. Of course depending who you are talking to, there are other lubrication conditions. But most of these can be grouped under the main few conditions. I only mentioned the two which may be relevant and envelope some other sub categories that the oil would be working under.

 

TLDR: The fork is only lubricated by hydrodynamic conditions under ideal conditions. My calculations have shown that the fork may be in boundary lubrication thousands of times during an average motocross race.