Hydraulic Spring Perches

The ones I saw were made by Hyperco. They allow the spring end coils to tilt up to 4 degrees as the spring is compressed, reducing the bending loads on your shocks by as much as 96%. This reduction in side force and friction allows more force and energy to be directed to the car's mechanical grip while reducing wear on your shocks. Having a hydraulic perch at one end of the spring will reduce shock bending loads significantly; however, hydraulic perches at both ends of the spring will provide optimum performance.

My question is are these used at all in the sport of rally?

$150 per spring perch is pretty steep x 8 spring perches.

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Michael LeCompte

No, it's silly.
And the side forces on the supension comes from the fact that suspension telescopes in and out while the swinging parts the suspension is bolted to swings in arcs.
And the fact we hit stuff with side vectors.

Just silly.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

john vanlandingham Wrote:
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> No, it's silly.
> And the side forces on the supension comes from
> the fact that suspension telescopes in and out
> while the swinging parts the suspension is bolted
> to swings in arcs.
> And the fact we hit stuff with side vectors.
>
> Just silly.
>

Hmmm...let's see what the forces actually are. Lets take a YARG with a 275 lb/in spring rate and load it up about 5" into it's travel. That's 1925lb of force in the spring at a max of 4deg off concentric for those perches.

SIN(4deg) = X / 1925lb

Thats a whopping 134lb of side load.

But they are really effective at separating wealthy SCCA club racers from their money...

Regardless, they make for some riveting theater!

http://www.hypercoils.com/images/video.wmv

Yeah no Kidding Eddie!

Look at that dial go... This has got to be my favorite video of 2008...

Ok, so I'm full of shit... but seriously I was wondering what they did exactly..

Good find on that video.

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Michael LeCompte

To me, it looks like it's primary job is dampening/squaring the load created from the spring which appears to be focused where the coil ends. From the video, I think their argument is that the spring doesn't evenly apply load to the perch and hence puts some side load on the shock, causing wear and apparently "grip" problems. It's likely better than not having one but how much $$ (ie $5 or $500) better is another question.

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Andrew M
Onterrible
30ish

Ya, so it reduces the bending load in the shock by up to 96% according to the ad copy. It likely does that but 96% of very little is still a small number. I just calculated that for one of my struts those perches could potentially change the stiction by 1% at the very most.

and here for a mere $1,000 extra or half a complete set of JVAB
http://rallispec.com/prod_rssp.htm

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Gone fishing

David,
Are you referring to the hydraulic bump stop system? I think this is something else entirely... If you're talking about hydraulic spring perches I missed it on that link.

Anyone care to comment. This is new to me... I thought bumpstops were always either rubber or poly... They can be hydraulic also?

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Michael LeCompte

pikespeakgtx Wrote:
-------------------------------------------------------
> David,
> Are you referring to the hydraulic bump stop
> system? I think this is something else entirely...
> If you're talking about hydraulic spring perches I
> missed it on that link.
>
> Anyone care to comment. This is new to me... I
> thought bumpstops were always either rubber or
> poly... They can be hydraulic also?
>
>
>
>

Yes, DMS has used hydraulic bumpstops in their 60mm struts for years, the old Group A Prodrive/Bilstein units in the Subarus used it, any off road Baja truck has them, usually a seperate unit. They're really good in rough terrain and you can actually use a softer spring rate for better traction and not have to worry about bottomming.

pikespeakgtx Wrote:
-------------------------------------------------------
> David,
> Are you referring to the hydraulic bump stop
> system? I think this is something else entirely...
> If you're talking about hydraulic spring perches I
> missed it on that link.
>
> Anyone care to comment. This is new to me... I
> thought bumpstops were always either rubber or
> poly... They can be hydraulic also?
>
>
>
>

Yeah, but I think it's just different terminology acheiving the same effect. Could be wrong but either way I'd rather spend money getting really good dampers and springs that work well together and are strong. Are these solving a problem that never existed?

Edit: the OTHER dave posted at the same time as me. Regardless lotsa guys faster than you or I are somehow managing to get by without either.

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Gone fishing



Edited 1 time(s). Last edit at 01/28/2008 04:20AM by david amor.

Roger that.

I bet those Stadium trucks must use those. Anything where you can noticeably see the whole vehicle dive under braking and raise up when accelerating like it's on super squishy springs but yet hit huge jumps like no problem must have those.

I'm still learning but I do know that the softer the spring the more grip you're gonna get on a loose service like dirt. But like you said, if you can run a softer spring without bottoming out by using hydraulic bump stops then you're going to be able to slow down faster before the turns and accelerate faster out of them.

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Michael LeCompte

I have fawked with hydraulic bottom out AND top out devices. Every motorcycle fork going back to the last Ice Age had them.
The are nothing special, just a tube of tight clearances around a rod and the degree of retardation in direct correllation of the ID/OD and the oil viscosity.

Many times the hydraulic bump and top out deals DIDN't work well if the oil we used in the fork itself was correct. That's what we were doing disassembling things and boring the ID 020" or 0,5mm. Often if we didn't the tight tolerance meant that we would lose the first inch and the last inch of travel.

Simple LONG cured foam bump stops work good and are easy to mod.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

These perch things are for a series where 1/2# of air pressure is noticeable.
10 to 20# of rate could make a difference and money is no object.

pikespeakgtx Wrote:
-------------------------------------------------------
> Roger that.
>
> I bet those Stadium trucks must use those.
> Anything where you can noticeably see the whole
> vehicle dive under braking and raise up when
> accelerating like it's on super squishy springs
> but yet hit huge jumps like no problem must have
> those.

I always that that was down to the high speed/low speed damping characteristics.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.