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#829441 - 10/11/10 05:45 PM Art Morrisson Building G-Body Frame
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
Just found this bit of info on another site, it seems the G-Body is getting some more interest from the aftermarket part suppliers.
DSE is close to marketing their front-end G-body kit, now AME is beginning a frame. Exciting times!

Here is one pic from the Facebook link:


From Pro-Touring.com:
"
Here's a link to the AME Facebook album that has some pics of the G body that Holley is building. Pretty amazing car; it was one of the GM cars that was sold at BJ - vin 00001 and 50 miles on the odometer. Another 20 miles were put onto it while at Holley and then it was taken apart and shipped out to us.

http://www.facebook.com/#!/album.php...3183796&ref=mf

We are reverse-engineering a new chassis for it right now and it is going to be Holley's track day car. Out of all the cars I have seen come through the shop over the years this has to be one of the cleanest cars we have ever started with. It's a brand new car that just happens to be 23 years old."

From:
http://www.pro-touring.com/forum/showthread.php?t=23398&page=17


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#829463 - 10/11/10 07:14 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
GuysMonteSS Offline
Member

Registered: 04/25/06
Posts: 2964
Loc: Kentville,Nova Scotia
Pretty cool,Art Morrisson builds some really nice looking chassis.
Guy
_________________________
GuysMonteSS '86 SS,468 BBC,Brodix Race Rite Heads,UDHarold Custom Solid Roller Cam,Jesel Shaft Rockers,Balanced & Blueprinted,Doug Nash 4+1 5 Speed,Hurst In-Line Shifter,Ford 9 Inch Rear,SC&C Street Comp Stage 2+ Front End Kit...

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#829485 - 10/11/10 07:49 PM Re: Art Morrisson Building G-Body Frame [Re: GuysMonteSS]
84supersport Offline
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Registered: 04/19/05
Posts: 4694
Loc: Louisville, KY
I hope they put them into production. I would definitely want one. I've seen how easy some of their others slide right under tri-five bodies.
_________________________
84 Monte SS stolen September 2012. 077 DFE Jefferson County KY plate. $2500 reward. Vortec headed 350ci, th350, 3:73 limited slip cast aluminum cover, Autometer gauges, Pro-Stick, 2.5" fiberglass hood.



Matt

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#829546 - 10/12/10 02:01 AM Re: Art Morrisson Building G-Body Frame [Re: 84supersport]
MAP Offline
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Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi Folks,

That's a CMM (coordinate-measuring machine or device,) no doubt being using to check the locations of cardinal points on the chassis against factory specifications.

This thread from a few months ago about a hypothetical DSE rolling chassis for the A/G body is perfectly appropos and dovetails here as well.

http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=817828&page=1

Best,
MAP


Edited by MAP (10/12/10 02:04 AM)

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#829698 - 10/12/10 07:10 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
JAWSS Offline
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Registered: 10/25/06
Posts: 1791
Loc: Ft. Hood, TX
Dave, I think the 84's would look great rolling on that new chassis.
_________________________

86 Monte Carlo SS T-top(His)
84 Monte Carlo SS TPI (Hers)
70 Chevelle Malibu (Second owner, grandma car)
12 Cadillac CTS-V Wagon

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#829718 - 10/12/10 07:49 PM Re: Art Morrisson Building G-Body Frame [Re: JAWSS]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
My piggy bank is fearing for his life.
I assume the G-Force frame for the Gbody will look a lot like the Tri-5 chassis.

Here is one with the optional C5 front arms, I hope the G-body frame gets this option too...

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#829741 - 10/12/10 08:26 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
JAWSS Offline
Member

Registered: 10/25/06
Posts: 1791
Loc: Ft. Hood, TX
Very nice!!!!
_________________________

86 Monte Carlo SS T-top(His)
84 Monte Carlo SS TPI (Hers)
70 Chevelle Malibu (Second owner, grandma car)
12 Cadillac CTS-V Wagon

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#829830 - 10/13/10 02:47 AM Re: Art Morrisson Building G-Body Frame [Re: JAWSS]
MAP Offline
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Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi 84,

Well, superficially it might similar, but there need to be substantial modifications to make that frame fit an A/G body. For one thing, the rails need to "kick out" to a full perimeter to fit the floor clearances in the car. Also, the rack as shown would interfere with the engine.

I also very much hope that they don't use the factory rear 4-link design.

As I wrote in the DSE thread, I feel the best way to do this is re-engineer the entire car structure for a quasi unibody configuration. A rolling chassis could add substantial stiffness to the car, but going unibody would accomplish the same thing with lower total weight.

Best,
MAP


Edited by MAP (10/13/10 02:48 AM)

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#829915 - 10/13/10 03:49 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
Originally Posted By: MAP
I also very much hope that they don't use the factory rear 4-link design.

Hi Map, AME recently had a video comparing their Quadra Link to a their own 3-link, on a 69 Camaro, the same car was used on the same day in back-to-back tests.
I am not sure if you were considering one of these over the other, or instead a torque-arm setup w/panhard rod, but here is a nice comparo of the 3-link vs 4-link triangulated. It seems that in both the LCA are parallel links.
Great food for thought.

Interestingly they both had a slight advantage in one area of testing, but both were close to the 1.0 G turning abillity. So in this case, no real need to go one design versus the other, other than preference, and packaging/fit.
I'll try to find that video, it really demonstrates how the high-tech in these 2 cases work extremely well.

Here it is:


From this thread at Pro-Touring
http://www.pro-touring.com/forum/showthread.php?t=69372&highlight=3-link


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#829922 - 10/13/10 04:32 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
MAP Offline
10+ Year
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Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi 84,

Even if both suspension setups return 1.0G on a flat skidpad, I still hope they don't use the 4-link OE design. Why?

1.) A 3-link with an independent means of anchoring roll center height ("RCH,") achieves decoupling of anti-squat with this factor.

2.) A low RCH has advantages for handling over bumpy surfaces with stiff-sidewalled tires. This has to do with behavior of the suspension in the low-frequency (compliance-controlled) versus high-frequency (mass-controlled) regions of operation, constrained by Hamilton's principle. This is a bit deep from a theoretical perspective, but AME or DSE should certainly understand and appreciate this.

A low RCH is tricky to execute with the OE 4-link, which lends itself better to a far higher (usually 13" and up,) RCH. For very low RCH's, one can "flip" the OE 4-link upside-down to create a Satchell link, but then packaging difficulties ensue.

Best,
MAP



Edited by MAP (10/13/10 04:34 PM)

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#830576 - 10/16/10 01:59 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
MAP Offline
10+ Year
Member

Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi Folks,

After reading a bit more at the pro-touring web site, I was intrigued to learn that when they set the RCH "lower" (I'm not sure how much lower, but I presume below the rear axle centerline,) that the car returned 0.96g max centripetal acceleration. When they raised the RCH, they achieved 1.0g. Watching the video of the car doing circles to attain peak acceleration, I'm struck by the car's understeering characteristics. Perhaps the lower RCH wasn't counterbalanced by an increase in rear roll stiffness, so the 0.96g figure perhaps is merely a reflection of increased understeering, and thus mostly overloading of the outer front tire.

Which leads to an interesting question: virtually all the OEM is using a rear RCH of about 12-13" with live axles. But all IRS's are using an RCH of far, far lower than this - maybe a few inches at most, like the front. Dynamically speaking, bump behavior is optimized with an RCH of zero in the mass-controlled frequency domain - this much is absolutely certain.

In sum, the best RCH for the rear is a thorough mess! What I'm reading here is that something "good" happens (inclination of roll axis and yaw stability?) with a tall rear RCH, that overwhelms the best bump performance with zero RCH? Or is it simply that it's practically hard to dial-in as much roll stiffness in the rear as at the front?

About a rolling chassis versus quasi unibody conversion, I feel strongly that going unibody is the lighter way to approach the problem. Even though the A/G body would need door-perimeter stiffening and triangulation from the base of the A pillars down to the front suspension area, the added mass here, in relation to the gain in overall chassis stiffness, would be far lower than with a beefed-up rolling chassis alone.

But it's clear that if you're not up to re-engineering the entire structure of the car, then the next best thing to do is to get a good rolling chassis like this AME piece (I'm sure) will be.

Best,
MAP


Edited by MAP (10/16/10 02:02 PM)

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#831001 - 10/18/10 02:26 AM Re: Art Morrisson Building G-Body Frame [Re: MAP]
MAP Offline
10+ Year
Member

Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi Folks,

FYI: I have a 1981 Monte Carlo up in the air without suspension, drivetrain, nor hood. The frame has all 14 OE body bushings attachment to body. In this condition, I measured a torsional stiffness in the frame between the front and rear axle locations, of 2,490 ft-lb/deg. I'd assign about a +/-5% tolerance to this measurement. If the car had all missing components installed, I suppose ths number would have been a tad higher - maybe 2,600 ft-lb/deg?

The frame, body, and even the bushings look essentially as-new (with 100% of the car's life lived in eastern San Diego, I suppose I shouldn't be surprised.)

By the way, just as I always suspected, this number is awfully low, and goes a long way toward explaining why this platform reacts so poorly to stiff springs, shocks, tires, and sway bars.

Best,
MAP

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#831037 - 10/18/10 09:48 AM Re: Art Morrisson Building G-Body Frame [Re: MAP]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
MAP, did the car have the F41 jounce bars on the front? that is a spot that would make a big variation with vs. without.
Also the later years (87 IIRC) have the rear seat brace, which adds a little more structure (and also has trunk brace on driver side inner fender).



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#831078 - 10/18/10 01:21 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
MAP Offline
10+ Year
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Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi 84ZZ,

This car came with nothing in the way of additional frame stiffeners - no triangulation behind the seats, no stiffeners to the front frame horns, no radiator opening cross-stiffeners, no fender braces - nothing. Now, I added all of these braces and more to the 1978 Malibu I had, and they made a big difference (although not nearly big enough) for sure, but I don't think that the difference I perceived was solely attributable to an increase in torsional stiffness. Of all the stiffening treatments I did to that car, the one that made by far the biggest individual impact was converting the #1 bushing to Delrin.

Now my plan is to take this car to the opposite extreme of torsional stiffness, by converting to a quasi unibody configuration.

Best,
MAP


Edited by MAP (10/18/10 01:25 PM)

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#840750 - 12/06/10 01:06 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
Well, this week there was an update on AME's facebook page.
There may still be some details or changes later, but this does look REAL tasty.
The little magic I would like to see, is if they can package the tri-link rear to still retain some form of rear seat.
Still, it's good to see something coming to the market for our cars.






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#840752 - 12/06/10 01:18 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
Monte_ExpreSS Offline
Member

Registered: 12/16/07
Posts: 3738
Loc: Oshawa, Ont. Canada
Well shoot, why'd they have to go & make that? You know how long it's gonna take to save up for one laugh
Looks like they've moved the rear rails in alot, should be plenty of room to tuck some massive meat.

Any idea on a price?
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#840778 - 12/06/10 04:48 PM Re: Art Morrisson Building G-Body Frame [Re: Monte_ExpreSS]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
Yeah, My piggy bank is living high on the hog now, knowing that he's safe for a good year or 2...
Here is a similar frame of theirs, I assume maybe similar pricing...
http://www.artmorrison.com/2006cat/18.pdf
From this webpage: http://artmorrison.com/maxg.php

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#840806 - 12/06/10 06:26 PM Re: Art Morrisson Building G-Body Frame [Re: 84 ZZ4]
Tony_SS Offline
10+ Year
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Registered: 07/24/03
Posts: 1840
Loc: Washington, MO
Wow.. I wonder how much that weighs vs a stock frame.

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#840830 - 12/06/10 07:53 PM Re: Art Morrisson Building G-Body Frame [Re: Tony_SS]
84supersport Offline
Member

Registered: 04/19/05
Posts: 4694
Loc: Louisville, KY
I meant to post some of those pics and forgot. They've been updating every day or so.
_________________________
84 Monte SS stolen September 2012. 077 DFE Jefferson County KY plate. $2500 reward. Vortec headed 350ci, th350, 3:73 limited slip cast aluminum cover, Autometer gauges, Pro-Stick, 2.5" fiberglass hood.



Matt

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#840905 - 12/07/10 02:02 AM Re: Art Morrisson Building G-Body Frame [Re: 84supersport]
JAWSS Offline
Member

Registered: 10/25/06
Posts: 1791
Loc: Ft. Hood, TX
R&R here I come....I would like to see that under the 84 SS. I will be in touch with them shortly about mass production, options, and pricing.

J
_________________________

86 Monte Carlo SS T-top(His)
84 Monte Carlo SS TPI (Hers)
70 Chevelle Malibu (Second owner, grandma car)
12 Cadillac CTS-V Wagon

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#840964 - 12/07/10 12:21 PM Re: Art Morrisson Building G-Body Frame [Re: JAWSS]
MAP Offline
10+ Year
Member

Registered: 05/11/02
Posts: 3517
Loc: Yuma, AZ
Hi Folks,

Yes, that frame's got to weigh more than stock unless they took a heap of weight out of the front-end. Again, with a body-on-frame platform, the chassis as a whole isn't get to get much more rigid without adding weight, since the structure as a whole has a huge weak link (pun intended,) in that you're coupling the body and frame with compliant bushings. Now, if someone counters, "Then replace the compliant bushings with rigid ones," then the immediate rejoinder would be, "Well, then do it with the stock frame." Since both are equally susceptible to improvement this way, it wouldn't be correct to confound the two factors.

Also, the rear seat isn't going to be compatible with that third-link mount.

Also also, I'd prefer to see the Watt's link "football" pivot made fixed with respect to the frame than with respect to the live axle, and I would have hoped for more range of adjustability in rear roll center height than the photos illustrate. While I'm on the topic: I'm curious as to why nobody I'm aware of, markets a rear live axle with an RCH (Roll Center Height) of less than about 10". To me, this ranks as one of the, "great mysteries of the universe," and especially considering that rear IRS's typically run a much lower RCH. I therefore can't accept the idea that roll-axis inclination is sacrosanct. Marcus says the rear roll stiffness required for handling neutrality reaches for the sky when the RCH drops below about 12", but the implied sharp non-linearity of this phenomenon is likewise mysterious to me. Does anyone have any thoughts on this? Norm?

But, back to Art Morrison's frame - all of these engineered assemblies represent a mixed bag of compromises between performance, weight, cost, ease-of-installation, etc, and every company will make a different call on the best set of compromises.

While I wouldn't go this route, I think many others will, and will be justifiably pleased with the results. It probably represents a good "80/20" type of solution to the problem of the OEM frame's many inadequacies for high-performance handling.

Best,
MAP


Edited by MAP (12/07/10 12:39 PM)

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#840968 - 12/07/10 12:49 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
88ss408 Offline
Member

Registered: 08/13/07
Posts: 1301
Loc: miramichi,new-brunswick
that is a nice looking frame!!
i don't like the rear suspension set-up
but it's nice to see that the G-body is finally getting some attention.
_________________________
1988 monte carlo ss 408 sbc 11:1 compression a.f.r.195cc heads accel ignition system comp cams .507/.510 air gap intake 800cfm edelbrock carb th350 trans 3000 stall torque headman headers 3" dual super 40's 3.73:1 limited slip
-----------------------------------------------------
1984 monte carlo cs 400,headers,th250c,air gap intake

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#840976 - 12/07/10 01:42 PM Re: Art Morrisson Building G-Body Frame [Re: 88ss408]
Norm Peterson Offline
10+ Year
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Registered: 03/14/01
Posts: 1578
Loc: state of confusion
Other than the lowers being a little close together and maybe the diff-mounting for the Watts link (which to fix would be relatively minor tweaks), what's not to like?

With a 3-link, you can build in more anti-squat for the dragstrip without trashing the handling in the process. The upper link carries about the same load as either lower, not somewhere around two times the load in each lower link like people sometimes think.


Norm
_________________________
mine - '08 Mustang GT/5M, slightly unstock
hers - '10 Legacy 2.5GT/6M, almost stock
auto-X, winter DD, available spare - '95 626/V6/5M, slightly unstock
other spare - '01 Maxima 20AE/5M, mostly stock
stripped & sold - '79 Malibu, I kept most of the non-GM parts

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#840980 - 12/07/10 02:28 PM Re: Art Morrisson Building G-Body Frame [Re: MAP]
Norm Peterson Offline
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Registered: 03/14/01
Posts: 1578
Loc: state of confusion
Originally Posted By: MAP
While I'm on the topic: I'm curious as to why nobody I'm aware of, markets a rear live axle with an RCH (Roll Center Height) of less than about 10". To me, this ranks as one of the, "great mysteries of the universe," and especially considering that rear IRS's typically run a much lower RCH. I therefore can't accept the idea that roll-axis inclination is sacrosanct. Marcus says the rear roll stiffness required for handling neutrality reaches for the sky when the RCH drops below about 12", but the implied sharp non-linearity of this phenomenon is likewise mysterious to me. Does anyone have any thoughts on this? Norm?

I know that at the OE level there is high corporate resistance to allowing suspension components remain visible unless you're actually laying flat on the ground practically under the bumper.

There is also the not so small matter of making it work structurally. Longer cantilevers = beefier members or more extensive bracing. A low and level PHB or WL in the vertical-transverse plane could have ground clearance issues. WL's have been done in the horizontal plane and pinned under the diff (think race cars), but then you've got two consequences that would be less than optimal for a street-driven car with decent ride quality.

I haven't thought in terms of the whole vehicle having a "roll axis" for quite some time. The car does not physically roll about the "roll centers", so assuming that the entire sprung mass rolls about a line drawn between the geo roll centers is not realistic. I look in terms of geometric lateral load transfer and lateral load transferred elastically (and unsprung mass lateral load transferred almost uniquely).

I'm far more concerned about the rear suspension's own roll axis, which defines the amount of roll steer (small-signal). In the 7% - 8% range at static ride height, the car tends to be slalom-clumsy. At 2% roll steer, the car is a lot happier about having to slalom - and you have to perhaps be a little more careful about rear roll stiffness so it doesn't go too "loose".

As OE constructed, LCA-mounted rear sta-bars are the least effective of the four elastic suspension components (front springs, front bar, rear springs). IIRC, the sprung mass CG height is around 21", maybe 22". Dropping a 17" rear RC down to 12" roughly doubles the roll moment if you're trying to hold the roll angle and LLTD balance constant. I think. Drop the RC down to 10" and it's 2.4 times M. That's a lot to be trying to make up.


I think I basically like the AME solution to the problem of chassis side 3rd link pickup. You need clearance to the driveshaft and possibly exhaust, so it can't be too narrow. I might do its bracing a little differently, though. And if you could get the diff side pivot further back over the top of the diff, you could pull the chassis side back a little, too. I'm sure there's more you can do - nobody I know of ever volunteers to sit in the back seat middle anyway.


Norm
_________________________
mine - '08 Mustang GT/5M, slightly unstock
hers - '10 Legacy 2.5GT/6M, almost stock
auto-X, winter DD, available spare - '95 626/V6/5M, slightly unstock
other spare - '01 Maxima 20AE/5M, mostly stock
stripped & sold - '79 Malibu, I kept most of the non-GM parts

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#840989 - 12/07/10 02:55 PM Re: Art Morrisson Building G-Body Frame [Re: Norm Peterson]
84 ZZ4 Offline
Member

Registered: 08/16/07
Posts: 4792
Loc: San Antonio, TX
More about that back seat.... here is a teaser:

Note the frame sectioned into the rear wheel wells, I would have to conclude that a tubbing is coming up soon....
maybe a bit more trimming to clear the UCA.

From this thread at pro-touring.com:
http://www.pro-touring.com/showthread.php?23398-G-body-Roll-Call/page19

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