Gold or Black Nitride Treatment

[lowmass]

Slow down there big shifter. Look I agree with yall. Once you figure in all the time, payroll, rent, expenses, etc etc  the price is more that 1K. AND without the available equipment and the limited budgets and time we always worked under from previous employer I would not have figured out a much less expensive way to do these tests. The trench is a great place to find easyer ways to get it done.

 I caution you about how you look when you make hard and fast judgments publicly about someones character. I may seem like someone who simply likes to argue on the forum. But someone who is after the truth will often sound the same.

Right now with nothing but a computer, a 500$ linear encoder, 200$ force gauge, 50 $ worth of tube and plate mild steel (none of which needs any high precision machining in my setup), and a couple days work, I can get data that will give about 90% of what ya need on this one). NO it likely will not be data that can split the hair on friction coefficients to 3 decimal places, but  if past experience is valid it will be data that gives you whats needed to make a case. 

15 years ago I would have sat in the design seat for a week or two  making overboard in-experienced judgments about what is needed here, and in the end it would cost 10K, AND it would then take another two weeks or so working out the bugs ;). 

years of having to develop inexpensive clever test setups while the Biz owner wasn't looking, have been critical in winning many of his contracts. 

 

 

 

Edited June 20, 2019 by lowmass

[lowmass]

One of issues we see with sliding structures similar to forks is the difference in performance when tolerances are high on the list. It becomes much more expensive however to get tight fits with the precision necessary to get them to move well throughout stroke. The machining processes are much more work. I suspect this is most of what goes into a tru works fork. I doubt the "A kit" forks on some new bikes are doing this?? 

Also find that its much easier to get success with tight fits on designs that are more rigid. 

Edited June 20, 2019 by lowmass

[LuxonMX]

3 hours ago, lowmass said:

Slow down there big shifter. Look I agree with yall. Once you figure in all the time, payroll, rent, expenses, etc etc  the price is more that 1K. AND without the available equipment and the limited budgets and time we always worked under from previous employer I would not have figured out a much less expensive way to do these tests. The trench is a great place to find easyer ways to get it done.

 I caution you about how you look when you make hard and fast judgments publicly about someones character. I may seem like someone who simply likes to argue on the forum. But someone who is after the truth will often sound the same.

Right now with nothing but a computer, a 500$ linear encoder, 200$ force gauge, 50 $ worth of tube and plate mild steel (none of which needs any high precision machining in my setup), and a couple days work, I can get data that will give about 90% of what ya need on this one). NO it likely will not be data that can split the hair on friction coefficients to 3 decimal places, but  if past experience is valid it will be data that gives you whats needed to make a case. 

15 years ago I would have sat in the design seat for a week or two  making overboard in-experienced judgments about what is needed here, and in the end it would cost 10K, AND it would then take another two weeks or so working out the bugs ;). 

years of having to develop inexpensive clever test setups while the Biz owner wasn't looking, have been critical in winning many of his contracts. 

 

 

 

I'm not making a judgement about you personally, I'm saying you're wrong regarding how much a test like this would take. Using your resources at work and working for free you can get this done cheaper; so what? That's not going to happen. In the real world we have to account for engineering time, design time, fabrication time, fixture costs, equipment costs, sample part costs, etc. You just gloss over all that and ignore it as if it's free. Regardless, it's clear you won't agree with me. So as it won't cost you very much, go ahead and do the test. It's cheap, right?

[LuxonMX]

4 hours ago, mog said:

I'm still very unconvinced the coatings do make a difference to feel in terms of friction

Here is an example to show that don't always do much

2006 sxs forks with all the fancy coatings , these were the best forks I have ever felt for " striction" everything moved do smooth ,on the track they were so so ,not terrible but nothing great ,they had valving I considered decent

Then in 2009 ktm altered the tube stiffness , guess what ? A STD 2009 fork was better than the fancy sxs forks

Stiffness made a huge difference,coating made imo a small to tiny difference
 

That's a pretty apples to bananas comparison though... How would the stiffer uncoated fork do against the same fork with coatings? Introducing the stiffness variable to determine if coatings work or not only muddies the waters.

[lowmass]

OK ya got me

 

 

Edited June 20, 2019 by lowmass

[lowmass]

some interesting data. Notice no change between teflon on steel with and without lube

This "proves" nothing ( many details missing) but its interesting

 

 

Edited June 20, 2019 by lowmass

[lowmass]

also interesting is teflon on teflon looks same as teflon on steel. again not to read too much into this but interesting

 

The best one is synovial joint ha. Biologic  fork fluid anyone? only 500$ and once 

Edited June 20, 2019 by lowmass

[mog]

That's a pretty apples to bananas comparison though... How would the stiffer uncoated fork do against the same fork with coatings? Introducing the stiffness variable to determine if coatings work or not only muddies the waters.

Ok that is true ,but it does say a coated tube cannot make up the shortfall of the too stiff tubes ,so that says in some way they don't do that much , bear in mind these were the smoothest moving forks I have ever felt

 

[Husabetunia]

What is your opinions and experiences about different lubricants if the opinions about the surfacing are all different?

Personally, I use mineral oil fork liquids and some lubricant behind the dust seal. I remember somebody reporting some basic testing of friction using simple method and getting interesting results. It was a few years ago and might have been Terry from Australia... 

The oil not always being present with the bushings might be the case with closed chamber forks, but with open chamber forks the bushings literally swim in the oil bath all the time and still the bushings wear out eventually. The more often one has the oil changed the longer the bushings last. 

Thanks! 

 

[lukethedork]

Husabetunia. The issue of the bushes not being lubricated with fork oil is not due to them not being 'in' oil or having oil on them in normal conditions. But rather from the shear and compression forces squeezing the oil and wiping the oil off. The shear and compression forces are too great for the oil to maintain a film between the two bush surfaces. Side loading of the fork bushes is an inherent design of telescopic fork suspension and one of its main negatives.

[Creeature]

Wp went back to hard chrome on the cones claiming less friction than the coatings lol

[LuxonMX]

6 hours ago, The Creature said:

Wp went back to hard chrome on the cones claiming less friction than the coatings lol

Yeah, it's not hard chrome, though. Pretty sure it's this: 

http://duralar.com/replacing-hard-chrome/

[rjg]

No mention of duralar disadvantages. 

[lowmass]

perhaps the surface finish is more important than hardness when we have a very soft Teflon ridding on orders of magnitude harder surfaces ? 

If I remember right from some work in past the finish seemed more important under higher loads....

[rjg]

Have you ever seen the look of a kreft micro polished fork tube? It is entirely a different color after the polish. Still has a slight mirror finished but is very dull and dark. It looks like laser etching on the whole tube.  He says diamond polish, the guy has it mastered.

[lowmass]

Interesting, we experimented a bit comparing surface finish of diamond vs other polishing  mediums. The diamond paste gave a much better result but was quite expensive. Simply could not get the same performance out of the other types . diamond produced a very uniform and repeatable result 

[Creeature]

How are guys shimming bushings? How do they take the measurements and how tight should the tubes be? I think the fit should be first priority then finish?

Edited June 27, 2019 by The Creature

[lowmass]

I second that

I could see maybe feeler gauge and by "feel" ??  I suspect make as tight as can without any added friction in feel by hand when disassembled and NO seals.

Just cut shim stock to fit under bushing?

also wonder if outer tube pump up would be less with tighter fit between tubes? Im assuming here that the pump up is due to seal lips loosing contact allowing air in? Always noticed on new bikes the pump up is much less than after forks have some time and wear.

 

Edited June 27, 2019 by lowmass

[mog]

Trouble is you need room for the flex , you take up all the tolerance and as soon as the fork flexes your going to get more friction ?

Wp did tests on the tubes and they flexed about 40mm on hard landing I seem to remember

[lowmass]

yes good point

isnt the part of tubes that backside of bushing sits against a slightly round or V shape so that bushing can angle itself a bit as geometry changes under hard flex?

 

 

Edited June 27, 2019 by lowmass