Interesting

[russ17]

I was doing alittle surfing on suspensions and came across a thread that I found it quite interesting, and think most of you will also .
It was some thing I never gave a thought too, as far as springs are concerned. It is to long to type so here is the link


http://www.allthingsmoto.com/forums/showthread.php?s=&threadid=7452&forumid=157


Russ

 

[russ17]

I would like to here some thoughts on spring side loads. It is something I never gave a thought to, and was wondering how many others have taken this into consideration. I have never seen this discussed before.
From the reading of this, IMO there could be some good benefits, from the reduction of these side loads. Stiction, internal ware, a more fluid stroke especially in changes in directions of the stroke. Face it anytime we can elliminate stiction it is in our best interest to take a look at. (I think so anyway)
By the way I contacted Jeff and discussed this with him, and asked him if I could put this info up.

Russ

 

[marcusgunby]

Russ i would love to feel the difference a no friction setup has, i think it maybe underestimated by most as a small issue, we all know how bad a sticky linkage feels but dont consider internal friction much, i know the pds is bad for this(high internal friction) and maybe its a small part of the whole pds problem.Shame the Showa seems to be the hardest to hook up with the platform:(

 

[bclapham]

can we get a picture please???? :)

 

[Jeff Howe]

I cannot post pictures here. They are up on ATM in that thread. If I could get them up here I would do it for you Bruce, but unfortunately I can't. If anybody wants to copy them and put them up here go ahead.

 

[bclapham]

i think i will nominate Marcus for that task since i am supposed to be working and its snowing there so he has plenty of time on his hands;)

 

[Jeff Howe]

Speaking of weather, we hit a balmy -20 F last night. Great stuff! Just had a good snow fall Sunday too. Time to ride baby!!

 

[russ17]

Here is some more info from the creater himself.

Russ

Hyperco/ICP Hydraulic Perches
Thought I'd come in and help clear up any questions about these pieces - I am the designer/inventor. I'll state right up front that I know squat about motorcycles - my specialty is road racing formula cars - but we all deal with the same laws of physics, so I can usually grasp the different requirements pretty quick!

Some additional explanation on spring characteristics:

All coil springs produce side loads. If you look closely at a spring, you can visualise that the spring force travels up or down thru the wire to the perches. The wire force is applied primarily at the first point of contact of the wire with the perch, resulting with the load being offset some distance from the shock centerline. For the load to be centered, the end coil has to have equal loading over it's full face. But, like anything that a load is applied to, it has to be allowed to flex - sort of like walking out to the end of a diving board. All this hydraulic perch does is allow the end coil to flex until the load is evenly distributed. Once the load is distributed evenly, the tilting stops and the load is centered on the shock. Sounds simple, but it took years to get it right!

Some of our tests on Hyperco springs showed side loads that were up around 75% of the applied load. This was on springs loaded to around 80 or 90 % of their available travel. Lower applied loads showed lower side loads as a percentage of that applied load.

An example was a 378 pound load on a 500 lb/in rate, 4 inch long spring - a pretty typical spring on the front of a small formula car. The side load produced was 238 pounds. With the hydraulic perches, the side load was reduced to 10 pounds.

If you saw someone that weighed around 240 pounds jumping up and down on the sides of your shocks, you'd probably chase him away with a tire iron!

These side loads, when applied to a shock, result in greatly increased frictions internally in the shock. In a nutshell, friction kills grip.

Think of what is happening at the tire when you have to overcome this friction before the suspension moves. For a tire to produce grip, it has to have a load on it. The tire is trying to move all of the time, even on supposedly "smooth" asphalt tracks. If, for instance, you have to unload the tire by 30 pounds before the suspension will move in rebound ( a very real number - frictions can be a LOT higher), in a 1 G corner, you have just lost 30 pounds of lateral grip! For a race car that can generate 2 to 5 G's, that grip loss is proportionally higher.

For a driver/ rider, the thing he will feel is an immediate increase in grip levels, as well as a reduction of harshness. Very often, because that loss of friction is also a loss of damping, the shocks will need to be stiffened slightly in low speeds to compensate. Also, sometimes you may find a need to increase the spring rate slightly to "support" the increased grip levels.

Automobile championships we've been a part of since this perch was introduced include the IRL, CART, Formula Atlantic, Indy Lights,Trans Am, GT2, 3 & 4, Formula Ford, F2000, DIRT Modifieds, Sprint Cars, and a bunch of others. It IS a proven product, but we are new to the motorcycle end of the racing world.

If you have any further questions, I will be happy to answer them, but bear with me as I am leaving in a few minutes to fly to Atlanta to give an engineering seminar this weekend.

Richard Pare
Indianapolis Competition Products

 

[svi]

I came across these spring seats early last year when a friend of mine in England told me about them. I've used them on road race shocks and they work really well, I've found that they particularly increase grip when the bike is on it's side mid turn when the shock needs to react quickly to small inputs.
A short description and image can be found if you scroll down the page at.
http://www.reactivesuspension.com/shocks.html