rec.autos.simulators

GPL: Bubbump Rubbubberbbers

Aubre

GPL: Bubbump Rubbubberbbers

by Aubre » Sun, 04 Jul 1999 04:00:00

I'm sure this bores the ***out of some of you, but hey,
that's what usenet is for.

I have 2 theories:

1.  The Lotus isn't completely off the bump ***s unless
you set the rideheight to about 4".  This only applies to a
nice flat circuit like Monza, so on a track like Mosport, or
the 'Ring, it may be impossible to stay off the bump ***s
thru most of the corners.

2.  Longer bump ***s are indeed softer.  But this makes
me wonder, why not just use 2.5" bump ***s ALL the time?

And here's an interesting remark I swiped from Alison Hine's
site at http://www.racesimcentral.net/:

---snip---
"Remember that the minimum length for bump stops is one
inch.  Dave Kaemmer recently confirmed to me that when the
car is about one inch off the ground, the suspension
contacts the top of a one inch bump stop. Keep in mind that
at a length of one inch, the spring rate of the bump stops
is very, very high - many times higher than that of the
springs at their stiffest setting.

Now watch how many times the bottom of the car goes down to
one inch or less above the ground. And remember that every
time it does, the spring rate has just gone up dramatically
at whichever corner of the car that's down at one inch or
less. Notice how often the rear of the car goes down by
itself, while the front stays above one inch - and what
happens to the car's direction of travel when this occurs."
---snip---

MAKE NOTE of what Papy's physics programmer, Dave Kaemmer
says.  This isn't exactly relevant to my argument, but it's
been a hot topic of debate in the past.  Also interesting,
is that she agrees with me that longer bump ***s are
softer.

And here's where I get controversial-
Now, I think Alison may have made a mistake with her new
setups.   She's made them smoother by raising the
rideheight, but she's mistaken in thinking that the car is
off the bump ***s thru the turns.  I think all she's done
is limit how hard the bump ***s get hit.  The impact
occours closer to where the car is completing its suspension
movement, thus the impact is softer, thus the car feels
smoother.  It was a great discovery, but you can take it
even further by using longer bump ***s.

Furthermore, taller bump ***s may actually allow you to
run a LOWER rideheight, since you don't have to worry about
softening the impact by changing the point where it occours.

I've now created Lotus setups for Monza and Mosport using
tall bump ***s, and they are both more stable than any
Lotus setup I've ever tried.  I really think I'm on to
something.

I hope its obvious that this is in no way a slam against
Alison.  On the contrary, I wouldn't have even thought of
revising my own setups if it weren't for her great Ferrari
setups.

Discuss.  Heck, just TRY it!  You'll like it!

**** Posted from RemarQ - http://www.racesimcentral.net/ - Discussions Start Here (tm) ****

Stephen Barnet

GPL: Bubbump Rubbubberbbers

by Stephen Barnet » Sun, 04 Jul 1999 04:00:00

Hears a simple answer to your theory. Progressive rate bump ***s were not
available in 1967.  Modern elastomer materials allow them to be an integral
part of the shock absorber. But not then. One inch is a good height to set
them at, because all they were used for was to stop the chassis bottoming
when going 'off-road'. Alison is right.
Steve


>I'm sure this bores the ***out of some of you, but hey,
>that's what usenet is for.

>I have 2 theories:

>1.  The Lotus isn't completely off the bump ***s unless
>you set the rideheight to about 4".  This only applies to a
>nice flat circuit like Monza, so on a track like Mosport, or
>the 'Ring, it may be impossible to stay off the bump ***s
>thru most of the corners.

>2.  Longer bump ***s are indeed softer.  But this makes
>me wonder, why not just use 2.5" bump ***s ALL the time?

snip...

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