Hydraulic Spring Perches

Pete Wrote:
-------------------------------------------------------
> 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.

That pitching that is that noticable is down to the 15"-18" 24" wheel movement.
>
>
>
> Pete Remner
> Cleveland, Ohio
>
> 1984 RX-7 reshell
> 1978

---

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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> 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.jvab.f4.ca



Yeah, but part of that could have been technology 30 years ago, vs technology now. Who say's they havent improved?

---

Welcome to the cult of JVL drink the koolaid or be banned.

Dazed_Driver Wrote:
-------------------------------------------------------
> john vanlandingham Wrote:
> --------------------------------------------------
> -----
> > 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.jvab.f4.ca
>
>
>
> Yeah, but part of that could have been technology
> 30 years ago, vs technology now. Who say's they
> havent improved?
>
>
> Feisty Peacock?


Every time I hear a 18 year old say some vague shit about "Tech fucking nology" I know they don't know sweet fuck all about shit either today or 30 years ago.
Do you really understand how these fuckin things work Tim?
Do you have any clue what they were 30 years ago? No.

Do you know what they are today? No.

Do use big words like "technology" when you just talking drivel.
Everybody recogizes that's a "marker" of somebody not know shit.

---

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.

Your right John, I'm not sure that I've got a 100% understanding of this. However, a hydraulic bump stop (so you can run softer springs for traction with out the fear of bottoming out) sounds like *might* be a mechanism hyrdaulicaly controlled that upon all the usable travel taken out of the softer coil spring, takes over as the primary spring to prevent bottoming out. I would guess it would be more of a longer, more fluid (in motion) version of a rubber progressive bumpstop.

NOW, that all may be completly wrong. It may be right. It may be half right. Or just one word. Thats not the point.

I asked a question. I asked "could the technology change in 30 years?" You took that WAY too personal. I'm too lazy to go dig up the thread on SS were I could quote you telling someone to not take offense to a question. Why are you? Technology is a very broad category. You could even classify the advances in fabrics (like the under type shirts, or nomex, or anything sort of synthetic fabric designed for a partiular application) as "advances in textile technology" Sure, it sounds goofy, but its just a word.

And the reason I asked about the 30 year difference? 30 years ago computers barely existed. We couldnt even has this little chat like we are. Today, however, they run almost eveything. Just an example.

---

Welcome to the cult of JVL drink the koolaid or be banned.

Dazed_Driver Wrote:
-------------------------------------------------------
> Your right John, I'm not sure that I've got a 100%
> understanding of this. However, a hydraulic bump
> stop (so you can run softer springs for traction
> with out the fear of bottoming out) sounds like
> *might* be a mechanism hyrdaulicaly controlled
> that upon all the usable travel taken out of the
> softer coil spring, takes over as the primary
> spring to prevent bottoming out. I would guess it
> would be more of a longer, more fluid (in motion)
> version of a rubber progressive bumpstop.
>
> NOW, that all may be completly wrong. It may be
> right. It may be half right. Or just one word.
> Thats not the point.
>

So a hydraulic bump stop or position sensitive valving on an off road truck is a fairly easy thing to accomplish with the external bypass tubes like this:

http://www.swayaway.com/siteImages/Shocks/RR6TubePiggybackBypass.jpg


More often than not people use additional air bumps that have static valving and not even a valve pack to make it velocity sensitive. That's because they are generally just as ignorant of shock tuning as the average rally car guy (there are some sophisticated guys who have bypass tubes positioned relative their dual stage spring rates etc, etc, but not many) and these make an excellent stop gap fix. They look like this.

http://www.swayaway.com/siteImages/Shocks/2_HydraulicBumpStops.jpg

Neither of these solutions work particularly well on a rally car due to the packaging constraints (like coil over springs) so some struts have internal air bump stops, the secondary valving John referred to, or just a closed cell urethane foam bumper a la Bilstein. The air bump is probably best from a pure performance standpoint but the urethane foam bump stop is a pretty damn good substitute for a fraction of the cost. They are far removed from being a rubber bump stop. I can't find a spring curve for one right now but rest assured they are not some exponential rate rubber block.




> I asked a question. I asked "could the technology
> change in 30 years?" You took that WAY too
> personal. I'm too lazy to go dig up the thread on
> SS were I could quote you telling someone to not
> take offense to a question. Why are you?

He's grumpy from having a cold...just let it go.

Dazed_Driver Wrote:
-------------------------------------------------------
> Your right John, I'm not sure that I've got a 100%
> understanding of this. However, a hydraulic bump
> stop (so you can run softer springs for traction
> with out the fear of bottoming out) sounds like
> *might* be a mechanism hyrdaulicaly controlled
> that upon all the usable travel taken out of the
> softer coil spring, takes over as the primary
> spring to prevent bottoming out. I would guess it
> would be more of a longer, more fluid (in motion)
> version of a rubber progressive bumpstop.
>
> NOW, that all may be completly wrong. It may be
> right. It may be half right. Or just one word.
> Thats not the point.
>
> I asked a question. I asked "could the technology
> change in 30 years?" You took that WAY too
> personal. I'm too lazy to go dig up the thread on
> SS were I could quote you telling someone to not
> take offense to a question. Why are you?
> Technology is a very broad category. You could
> even classify the advances in fabrics (like the
> under type shirts, or nomex, or anything sort of
> synthetic fabric designed for a partiular
> application) as "advances in textile technology"
> Sure, it sounds goofy, but its just a word.
>
> And the reason I asked about the 30 year
> difference? 30 years ago computers barely existed.
> We couldnt even has this little chat like we are.
> Today, however, they run almost eveything. Just an
> example.

Tim you have zero zilch no idea what these "hydrulic" bump stops are; you're just talking drivel, stop.

First find out what they were 30 years ago, compare what they are now and then see why drivel about technology is a sure indicator of a person who is BSing.

And I didn't take it personal, I just am fed up with kids (of all ages, there are many 39 year olds who are mental teenagers) talking vague BULLSHIT and as I said, it's a sure sign they don't when they say NOTHING aboput the design or function of whatever the subject is and say the exact words "Maybe technology has changed since....".


>
> Feisty Peacock?

---

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.

Well, actually Tim, I was thinking more like the old R/C car "dampers" They were just filled with air. It's like compressing a syringe fill no liquid, it will reboud.

Heres what I was thinking. The black is the shock body, and spring perches, the red is the "plunger" and body of the hydraulic bumpstop, and the yellow is the spring. There is an extended and compressed version.

---

Welcome to the cult of JVL drink the koolaid or be banned.

Well, now you're adding a pneumatic element which wouldn't work well at all on the a full scale vehicle.

Since air is less dense than oil, it will compress a whole lot more, which means a very low level of stiffness and inaccurate response, making it difficult to control linear position accurately.

The gist I'm getting from the whole conversation is that hydraulic bump stops are kinda similar to what you've drawn, but they use oil instead of air. They're bulky, add weight and take up space, and take proper tuning and fucking around with. Might as well go the easier cheaper route with a polyurethane bumpstop and not try and reinvent the wheel. It's good enough for bombing through the woods.

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Michael LeCompte

Dazed_Driver Wrote:
-------------------------------------------------------
> Well, actually Tim, I was thinking more like the
> old R/C car "dampers" They were just filled with
> air. It's like compressing a syringe fill no
> liquid, it will reboud.
>

Yeah, that's just an air spring which is in every way worse than a urethane bumpstop. The worst of all worlds it doesn't have the damping from the internal hysteresis of the urethane material and it has static seal stiction. You can get the same dual rate with steel springs more easily.

Hydraulic bumpstops are in the case of "air bumps" an air sprung and hydraulically dampened shock. In the case of bypass shocks the piston passes by the bypass ports at the end of the stroke causing an increase in damping force. John's motorcycle forks are yet another variation of increasing the damping rate at the end of the stroke.

Yet another would be the internal bypass shock that FOX holds the patent on. They have never produced it but it's basically a twin tube shock with the bypass architecture consisting of some drilled holes in the internal tube. Cheap to build, easy to tune, you can get velocity and position sensitive valving, and you can still run it as a coil over. There are a million variations in between.

So it would be similar to that? I didnt know what to fill the stop with, so i just choose air. But thats a pretty crude version then?

---

Welcome to the cult of JVL drink the koolaid or be banned.

Ok... so we've come to the consensus that hydraulic spring perches are probably a waste of money for a privateer rally car.

What about Torrington Bearings? I hear these make adjust the ride height 1000 times easier and helps the spring to twist as it compresses. A much cheaper solution than hydraulic spring perches at about $11.00 per spring perch.

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Michael LeCompte

Fine on a tarmac car, but dirt is not a good thing for needle bearings! They won't spin well for long.

Bob

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Opel is a 4-letter word...
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