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Author Topic: Chaffey College and Sam Contino  (Read 5660 times)
Jon Mello
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« Reply #15 on: May 20, 2013, 12:42:58 PM »

Robert,

Yes, it did. I might have some pics of it on the track but I don't have a camera with a telephoto lens so they will be on the small side.
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Jon Mello
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« Reply #16 on: May 20, 2013, 02:04:46 PM »

Is there an advantage to reversing the mounting of the Watts linkage? The Firebird in another thread had the outer mounts mounted to the Axle tubes and the Center mounted to the chassis. http://www.camaros.org/forum/index.php?topic=7815.msg59952#msg59952

Is there a reason for the reversed mounting methods?
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Jon Mello
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« Reply #17 on: May 21, 2013, 09:42:35 AM »

I asked Gary Wheeler, former chassis engineer/designer for Traction Master and then Dan Gurney's AAR team and this is what he had to say on the subject...

That's a very interesting question and the answer is a kinematic subtlety. The answer is: the two methods of utilizing a Watts Linkage are effectively the same. (After all, straight-line motion between axle housing and chassis - - - is straight-line motion between axle housing and chassis no matter how it's achieved.)  As it turns out, straight-line motion is great when the car is on a straightaway.  But during cornering, straight line motion isn't as good as a LONG Panhard Rod.  Why?  Well, while cornering the chassis has a roll-angle.  For clarity, let's say it's softly sprung and has a rather large roll angle of 4 degrees.  That means any rear axle movement relative to the chassis will rise or fall along that same 4 degree angle with respect to the horizontal road surface.  THAT forceably yanks both rear tire contact patches laterally a tiny fraction of an inch - which is undesirable because any lateral motion of a tire's footprint caused by suspension geometry is immediately subtractive from rear-axle cornering power.

Yanking the rear tire footprints laterally even a tiny bit is no problem on the straights, but it's the last thing you want during cornering, simply because IF you're cornering at 10/10ths and the car is perfectly balanced, a momentary degradation of rear axle cornering power will momentarily move the car toward oversteer.  The driver will perceive the car as needlessly twitchy when encountering tiny bumps in the corners.  And there are ALWAYS tiny bumps in the corners.

Short & highly-angled Panhard Bars are obviously deadly.  Although LONG horizontal Panhard Bars aren't perfect either, a careful layout of the geometry of a long-bar, low Roll Center Panhard Bar installation will reveal that during bump or rebound travel, it will actually move the rear tires laterally during body roll slightly LESS than a perfectly straight-line travel Watts or Roberts link.  THAT, not simplicity or weight, is why I used a Panhard Bar the AAR 'Cudas. (I consulted a bit to Mark Donohue in 1968-69 and that's precisely why the Penske Camaros always used Panhard Rods.)

Parnelli and Follmer's factory Mustang engineers didn't catch this subtlety and used Watts links.  They won the 1970 TA championship because of our unreliable engines, but if memory serves me right, we ended up with more lap records.  One thing few people appreciate to this day - is that our works Cudas weighed 3200 lbs. yet Gurney broke all his own previous A-production works Cobra lap records at every track in the country - by approx. two seconds per lap!  This is stunning, considering both the Cobra & 'Cuda had Gurney as the driver, nearly identical 540 horsepower, similar tire footprints, yet the 'Cuda was exactly 1,000 lbs heavier than the Cobra! (3200 vs 2200 lbs.)  It's interesting to consider how well Dan's works 'Cuda had to be handling for him to hot lap two seconds faster than his own works Cobra lap records - in a pony car weighing nearly 50% heavier!!
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Jon Mello
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« Reply #18 on: May 21, 2013, 09:54:24 AM »

Very interesting, and he explains it excellently...   I feel smarter after reading it.  Smiley
and the AAR Cuda vs Cobra example was interesting also..
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« Reply #19 on: May 21, 2013, 11:49:53 AM »

540 HP in a 70 T/A Cuda?  Must be a typo?

Robert Barg
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« Reply #20 on: May 21, 2013, 12:40:08 PM »

540 HP in a 70 T/A Cuda?  Must be a typo?

Robert Barg

...I was thinking the same.  Maybe 480-490 hp for a late-season 'Cuda.  I wonder too if reference is being made to a 427 Cobra or the antiquated 289 Cobra running transverse leaf springs front and rear and generating maybe 390-400 hp in period.  Thanks...

Mike K.
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crazyamc
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« Reply #21 on: May 21, 2013, 03:24:29 PM »

I'm certainly no suspension guru or engineer, but as far as "differences" between an axle-mounted watts or chassis mounted, it was explained to me by Bruce Griggs this way.. ..   " The watts pivot point IS the rear roll center; so, if it's chassis mounted, it rises and falls as the chassis leaps and bounds over the racetrack. Since a lot of work goes into designing a front suspension that tries to keep the roll center at a set height to the pavement, in compression and jounce, you want the rear roll center to do the same, or the front-to-rear bias changes...... an axle-mounted watts accomplishes this....  It also eliminates the need for a rear sway bar ( when sorted correctly ).  Instead of loosening or tightening the rear (or front) bar, the pivot is adjustable vertically on the rear.....    My next car, I'm gonna try it...  Smiley
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cuda48
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« Reply #22 on: May 21, 2013, 07:58:42 PM »

In Gary Wheeler's defense the numbers are transposed.  He meant 450hp.  We had this very same conversation when I interviewed him years ago.

Camicia
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« Reply #23 on: May 21, 2013, 08:29:03 PM »

Thank you for the clarification everyone(not to say it was only for me), this first-person knowledge is invaluable! Especially the info about Panhard vs. Watts linkage....very interesting, and also making me rethink a reason to fabricate a Watts linkage system.
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Jon Mello
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« Reply #24 on: May 29, 2013, 12:01:19 AM »

The Chaffey College Camaro as seen at the Palm Spring road races back in 1992. Our own Robert Lodewyk (Sixteengrandsedan56)
hovering over the engine compartment. This was a fundraiser event for the as-yet-to-be-built National Corvette Museum and a roast
of Roger Penske was part of that weekend's events. Robert and I of course wanted to be there for that. Dick Guldstrand drove both
the Chaffey College Camaro and the red Corvette parked next to it that weekend. Can't believe that was over 20 years ago...


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Jon Mello
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« Reply #25 on: May 29, 2013, 08:48:40 AM »

interesting info

also noticed in the original article it shows two shocks mounted above the axle and parallel to the drive shaft.
In the restored pics the mounts are still there but no shocks are used

I wonder if they were used to try to control "wheel hop" in acceleration and braking which was a problem in 1967 mono spring designs?

The 67 Z/28 used a pass side traction bar from the factory and the hi po Firebird used two traction bars from the factory that were mounted similar to those shocks but I don't think they were used on race cars. The wheel hop problem was said to be mostly fixed by the 1968 multi leaf springs vs the 1967 mono spring.
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Jon Mello
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« Reply #26 on: May 29, 2013, 05:41:43 PM »

Mark Mountanos told me he has the horizontal shocks. They came with the car but he says they're worn out.

Most of the Camaros that ran in Trans-Am in '67 used the traction arms (radius rods) on both the LH and RH
side. It was legal to do that. The '67s that I have seen that didn't run in '67 but did run Trans-Am after that
year, they seem to have gone with adding the staggered shock arrangment like a '68-'69 and not using the
'67 traction arms.
« Last Edit: October 14, 2013, 11:21:46 AM by Jon Mello » Logged

Jon Mello
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« Reply #27 on: October 14, 2013, 12:07:24 AM »

I spent many days under this car with my dad Owen Hixon who helped Tom maintain the car til his passing in 2010. Many fond memories.  Was at the Palm Springs race working on both cars.
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Jon Mello
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« Reply #28 on: October 14, 2013, 12:09:32 PM »

Very cool. Thanks for checking in here. Your dad had a dyno shop down in the LA area, didn't he?
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Jon Mello
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