Zzz wrote:Not owning a T3 (yet) and not having the experience with tuning one, I would fall back on my motocross suspension experience and bring up the importance of preload. Preload sets the sag and initial spring rate, and is also what helps the shock rebound back in those opportunities when the tail is unloaded a little. Without proper preload, the shock can wallow in the bottom of the stroke and really feel stiff, because it's experiencing no travel.

Is that preload more important for wheels which need to be in constant contact with the ground for controlling the vehicle? Being pre-loaded may actually be unhelpful from the point of view of a tailwheel, I haven't thought about it.

I now realise spring rate is different to spring constant. Ignore that mistake in my last post.


From the point of view of a tailwheel, I don't think remaining in touch with the ground matters as much as it does in a car / bike / or the main landing gear of a plane, for that matter.

If I were to summarise my reasoning simply:
The T3 has added a shock absorber, that's the material difference.
The shock absorber reduces spring oscillations to smooth the ride, that's all.
The smoother ride benefits the fuselage and passengers, not the assembly in contact with the ground.
Therefore it seems unlikely that the T3 will considerably reduce wear on the tailwheel.
I don't see this as a bad thing, it's designed to protect the expensive bit - the fuselage - which is what it does.

Zzz wrote:I saw this video on Instagram today of them drop testing a T3: https://instagram.com/p/BIIV1lcAOnY/

Does anyone else see that shock blowing through its travel and bottoming out? Or just me?

That video is graphic - a very good illustration!

But yes.... just under it's own weight from that small height - you can see the spring completely bottoms-out.

Battson wrote:

Zzz wrote:I saw this video on Instagram today of them drop testing a T3: https://instagram.com/p/BIIV1lcAOnY/

Does anyone else see that shock blowing through its travel and bottoming out? Or just me?

That video is graphic - a very good illustration!

But yes.... just under it's own weight from that small height - you can see the spring completely bottoms-out.

It does bottom out. But, it looks like the traditional leaf spring handles the balance of the load. Not sure that is a bad thing. Just part of the system. Idk.

Crzyivan13 wrote:

Battson wrote:

Zzz wrote:I saw this video on Instagram today of them drop testing a T3: https://instagram.com/p/BIIV1lcAOnY/

Does anyone else see that shock blowing through its travel and bottoming out? Or just me?

That video is graphic - a very good illustration!

But yes.... just under it's own weight from that small height - you can see the spring completely bottoms-out.

It does bottom out. But, it looks like the traditional leaf spring handles the balance of the load. Not sure that is a bad thing. Just part of the system. Idk.

I don't think it's designed to provide traditional leaf spring action though.

When trying to absorb a given impulse through a defined travel range spring preload is not as important as compression damping. If you're blowing through your travel and bottoming hard, compression damping will help more than cranking up preload won't it? Watch the action of a storch, q400, highlander with the long air shocks, or any gear with relatively long stroke, and when on the ground they are statically almost completely compressed. Tail wheels operate in a different environment so it's not quite the same, but the idea that single large hits are dealt with more effectively via damping instead of spring preload is still valid. Does the T3 shock have externally adjustable compression and/or rebound damping?

NoCOpilot wrote:When trying to absorb a given impulse through a defined travel range spring preload is not as important as compression damping. If you're blowing through your travel and bottoming hard, compression damping will help more than cranking up preload won't it? Watch the action of a storch, q400, highlander with the long air shocks, or any gear with relatively long stroke, and when on the ground they are statically almost completely compressed. Tail wheels operate in a different environment so it's not quite the same, but the idea that single large hits are dealt with more effectively via damping instead of spring preload is still valid. Does the T3 shock have externally adjustable compression and/or rebound damping?

All true. Fluid damping is hugely important for mitigating the compression and rebound. Pre-load just establishes initial spring rate but also the ability for the shock to rebound through enough travel to be poised for another hit, like you would experience running the tailwheel across a rock field (if you were silly enough to keep it on the ground.) If rebound damping is too high and preload too low, the shock will remain compressed.

Zzz wrote:

Crzyivan13 wrote:It does bottom out. But, it looks like the traditional leaf spring handles the balance of the load. Not sure that is a bad thing. Just part of the system. Idk.

I don't think it's designed to provide traditional leaf spring action though.

It isn't designed to provide any spring action - it's got a pinned joint at the top, which offers zero resistant to movement. The spring-damper has to deal with it all.

Battson wrote:

Zzz wrote:

Crzyivan13 wrote:It does bottom out. But, it looks like the traditional leaf spring handles the balance of the load. Not sure that is a bad thing. Just part of the system. Idk.

I don't think it's designed to provide traditional leaf spring action though.

It isn't designed to provide any spring action - it's got a pinned joint at the top, which offers zero resistant to movement. The spring-damper has to deal with it all.

The swing arm bar does flex though, thankfully, with the bottom attach point of the shock acting as the fulcrum. Something has to give if you bottom out the shock, and hopefully it's not the fuselage attach points, which are interestingly not covered in the cub in the video. You can see the resonance of the system caused by the flexing swing arm (flat bar) and the compression of the tire in the video. As the suspension compresses, the shock itself pulses in compression a few times. It's really interesting to watch in slow motion, there's quite a bit going on there.

Tailwheels live a brutal life.

That's why I think an elastomeric bumper would be a good solution to limiting bottom-out stresses.

You mean like the ones inside these?



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Barnstormer wrote:You mean like the ones inside these?

Nice photo! How do you adjust compression damping?

NoCOpilot wrote:

Barnstormer wrote:You mean like the ones inside these?

Nice photo! How do you adjust compression damping?

You don't. It is what it is, whatever that is.

They are actually easy to adjust. Phil have you played with your red dials yet?

Counter clockwise to the stop then one click clockwise and they are soft and eliminate all bounce. You can increase the tension by turning the red dial clock wise to eventually create a bounce. Mine only has one red dial and one shock and there the new ones...

150 plus landing now on them. They are a game changer.

AKT

You adjust it on mine by taking the red dial counter clockwise to the stop then one click forward. On your Phil you turn the two red dials counter clockwise then one click forward. Rotating them clockwise makes them stiffer and creates a bounce



AKT


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aktahoe1 wrote:They are actually easy to adjust. Phil have you played with your red dials yet?...

Kevin, NoCOpilot was asking about compression dampening, not rebound dampening which is what the red knobs are for. And yea, I've played with rebound dampening although after watching some video Bob Breedon took of me with my iPhone I haven't added enough (a lot of tail bouncing that I didn't feel in the cockpit).

Troy Hamon where are you I need your help? (He once posted "My goodness, Phil...back slowly away from the smoking wallett...keep your hands in plain sight...") It's raining and I find myself surfing the Mountain Bike Shock websites learning more and wondering hmmm what if......

I think it's time to head to the gym and hope for better weather so I can fly instead of surfing the Internet.

Sometimes there is no cure for MOREBETTERDISEASE!! You just have to keep the master card handy until the fever passes
DENNY

Zzz wrote:I saw this video on Instagram today of them drop testing a T3: https://instagram.com/p/BIIV1lcAOnY/

Does anyone else see that shock blowing through its travel and bottoming out? Or just me?

It is not just you... anyone else who spent a fair time really setting up the suspension in their bikes or off road cars, as opposed to just buying the latest greatest and bolting it on), will see it as well.

Anyone with a reasonable amount of mechanical / engineering / suspension background will be able to identify the two logical points it will fail at. It will either fail at the fuselage attach points, or it will fail at the point where the aluminum swing arm attaches to the steel pivot point. The aluminum does flex there, it will work harden, and then it will crack...Fortunately one cancels out the other, so a double failure is not likely, but either mode will stop you in your tracks, one (the tail structure) will just cost more to fix.

The cure to that is A) a bump stop or limit strap in the design, and B) proper adjusting of the spring rates. The second part of that equation is something I can see most people just completely blowing off or being oblivious to, after all... we never adjusted our springs, but with spring rates (compression and rebound) as well as dampening, there is no such thing as 'one size fits all' which is why off road cars have multi rate springs, or multiple shocks of varying rates. If you are the guy that likes the STOL thing or spend the day on the Knik playing empty and light (not that there is anything at all wrong with that) and then decide to go camping for two weeks in Idaho, your tail weight is going to change dramatically, and you will either have rock hard suspension when light, bottom out when heavy, or learn to properly set up your suspension... Incidentally, I know of no suspension that can overcome the amount of weight change in spring rate we can be talking here (percentage wise), with the twist of a knob or spanner wrench, unless that spanner is being used to completely swap springs

Having said all that, I'm not knocking the product, or it's developer, I am of the opinion that undampened leaf springs and stingers are as archaic as magnetos, and with all the ground broken before us in the offload industry, the better mouse trap is already there, it just requires a little investment in application. Kudos to Dan for going there. Having seen a couple, I think they're very well crafted, and expect that with time they will evolve to an even better product than they already are. Totally reminds me of an old '74 YZ and hopefully just like the old mono shock changed the industry, so will the T3.
In my mind the single biggest draw to the T3, is its single biggest problem, and hurdle to overcome, and that is it's ability to fit the constraints of a stock cub / pawnee tail spring. STC'd this would be about the best thing going for a stock cub, OR the experimental guy who doesn't want to invest time or energy re-inventing the wheel, but would rather just plug and play. For the experimental guy with any welding skills, and the desire to to build a better mouse trap, getting away from the constraints of the 'piper pad' and attach points would not be all that tough, and unlike the mains, which offer steering complexities, a pivoting swing arm style suspension that surpasses what the T3 is constrained to should be a walk in the park.

Very envious of you experimental guys, and hope to join you soon...

Take care, Rob

Good post Rob. I think another thing to mention is, for anyone who was around in the early days of mountain bike rear suspension, that the number of designs on the market was staggering. I feel like people were skinning the cat in more ways than I could count, and the variations all had to do with how the swing arm compressed the shock. Weight and compactness was also a concern.

Successfully designs used a linkage to extend travel so it wasn't linear to shock travel. If you ever look closely at a (real) dirt bike, at the bottom of the shock unit, you will see that it doesn't bolt directly to the swing arm. There's a hollow area in the middle of the swing arm with a scissoring linkage that allows a ratio of swing arm travel to shock travel. This requires a much stiffer shock and beefier components but the payoff is great.

The T3 is a direct compression of the shock from the "swing arm." It is a beautiful piece of equipment but I predict before long we see the design shift to the above mentioned linkage. Even though practical travel is limited by the constraints of the rudder and 3-point AOI, I think the way the shock is compressed will see changes trending toward a linkage.

None of this discussion is meant to be overly critical of Dan's design. Without his vision to get this idea off the ground, we'd still be dreaming about such things. Instead we have a great useable foundation to test in real world situations.

I just got done landing a few of my local sites, and now am on a rocky ass trail with my e bike. I wish it wasn't a hard tail but hey, at least it folds and fits in the plane. Still happy with my 3 leaf J-3 tail spring on the 7, have VISA card handy for when I feel one of the T3's is a gotta have for me, not quite yet. I sure like my rebound damped (Fox, adjustable) main gear, but still sticking with bungees for the main "spring". New and old tech working together, cool.

I'm a fan! 3000 hours on a hard tailed 180 and a few hundred in a cub with the traditional leaf spring, the T3 removed the loud thud and hard tail feel taxiing around. How often are you really landing on your tail anywhere. We land on the mains and ride it out until we are slow enough to set the tail down. The T3 has removed the loud bang or thud feel when taxiing around. It's rated to a heck of lot more weight than that 80 lb tail in the cub or for that matter call it a 500lb tail which isn't even close. It's a very nice ride taxing around 100%.

Now having first hand experience with it, I sure wish I could get it for the 180. It's truly incredible.

Time will tell on the over all durability but I sure do like it. The cub has the new single heavy duty coil. I agree, I bet there are more changes to come but I predicte its only a matter of time before its certified.




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