AME complete chassis '77 280Z

[lifeprojectZ]

Hello all-

 

I started reading at hybridz somewhere around 20 years (+/-) ago and took a break for many years while my '77 280Z sat in storage and I traveled the world for work, all the while never losing the passion to continue with and finish the project.  Haven't had much to report until now.  I am trying to read up on some of the incredible projects posted here which have similarities to my own, and I am certainly interested in any comments / advice as I go forward with my project over the next several years, hopefully to complete within the next 5.

 

So the story starts in 2001 with buying a clean original '77 280Z from original owner in San Jose, CA, and driving it across country to Indiana with 220K on the odometer.   Fortunately I made it back without issues, but the original engine died within 3 days after arriving and suffered from random shut-downs while driving without being able to immediately restart.   As I had plans at the time to install a '95 LT1 turned 383 stroker, I just parked the car.    Fast forward 21 years through work, life, wife, kids, and the car sitting in garages / storage in Indiana, West Virginia, Ohio, and now S. Carolina with all expense paid (by me) trailer tows between these states, I finally decided to say screw it with spending gobs of money to modify the existing suspension and still be left with the original suspension geometry.

 

I just put down my deposit on a full Art Morrison custom Max G chassis with sport IFS and compact IRS, built to my specs.   Should be done and shipped in 6-8 months.     Here are the specs.    Will share more detail as it comes.

 

- 1977 280Z

- Art Morrison Max G chassis, 5.25" ride height (floor to bottom of 2x4 rect tubing).  (I chopped my OE springs in the photo attached to lower the car to the height I want for the purpose of taking measurements)

- LS376/480 crate engine + T56 Magnum

- Forgeline 18x9" fronts w/ 255/35R18, and 18x10.5" rears w/ 295/30R18.  

-13" front brake rotors w/ Wilwood calipers, 12.4" rear rotors w/ TBD calipers

-Strange Dana 60 IRS w/ Eaton Truetrac diff, 3.54:1

-Strange Ultra double adjustable coilover shocks, 350lb springs (to start)

- Woodward manual steering rack (rack gain TBD)

- Electric power assisted steering installed in column

 

I have some parts up for sale now in the Parts for sale section which I acquired over the years and am no longer going to use in my project.   Other parts will be added over the next year, including Ford 8.8 rear diff, Cobra CV axle shafts, and a lot of OE suspension etc. parts

 

Greatly appreciate all comments / advice / questions / interest.

 

Steve

[jhm]

Sounds like an insane build!  Subscribed and following!!  

 

Good luck with it.

Edited February 27, 2022 by jhm

[lifeprojectZ]

Thanks for your interest.   I have spent the past several years trying to convince myself that I am not insane (though the project may be), and my move to the AME chassis was a big decision.   It was a trade-off in spending money up front to save me time and ultimately get a car capable of handling the way I would expect after dumping tons of money into it regardless of which direction I choose.   I have followed some of the other members' projects, and I see tons of work going into reinforcing the unibody which ultimately adds a lot of weight anyway.  My goal with the AME chassis is that it, together with a minimally designed roll cage to meet NHRA / SCCA requirements, will provide all of the primary rigidity for the car, and the small remaining shell of the body I will use will just go along for the ride pretty much. 

 

I have struggled with coming to terms on a few aspects of the project.   I don't like super wide wheels that protrude far outside the original body lines of the car.   I wanted to keep that minimal, while recognizing that I would definitely need fender flares for what I have planned.  Initially I wanted 17" wheels because I though 18" wheels looked strange on the Z car and was afraid they would just transmit too much road vibration to make it enjoyable to drive on the street.   Plus, 17" tires now are relatively cheap.   However, I also wanted to stick with a max tire diameter of about 25", so I came up with limitations on the 17" wheels and tire sizes.   I finally decided on 18", and both front and back will be 25" diameter.  OE Datsun tires were 24.6 I believe, and I felt it important to stay as close as possible to that.     

 

The narrowest track width (hub to hub mounting) that AME offers is 55.5 (OE Z car is 54.5), so I went with that on the front and rear, and am using 5.5" backspacing on the front wheels (18 x 9) and 6.5 backspacing on the rear (18 x 10.5) to keep the wheels tucked in as much as possible.    I'll be picking up my wheels within the next 60-90 days and will post pics when I have them.

 

[Mayolives]

This build sounds really cool.  I have owned many z cars over past decades including one 240/350SBC that was fun. But the rest of that car was not up to all the 350's power.  Your choice of the Art Morrison chassis and all the rest sounds like the ticket and should be far better to any of the many modifications that most of us are accustomed to. I'm staying tuned!

[lifeprojectZ]

Someone interested in the Ford 8.8 IRS parts I just posted for sale in the Parts for Sale section asked me to tell more of my story of how I arrived at those parts to begin with, so I thought I would take a step back and provide some background here in the event that it may help or interest others.

 

Back around the time I bought my '77 280Z (2001), I was planning a lot of the common modifications being discussed on hybridZ at that time, including sectioned struts with coil-overs from Ground Control,  300ZXT CV shaft conversion,  5-lug hub conversion, and a Chevy V8 (that alone is a story in itself for another day).   All of the reading I had done to that point in time led me to believe that the OE R200 differential would be sufficiently strong for a 400-500 HP V8 because of the light car weight and the belief that I would never run slicks (I still don't think I will), so the diff would have a relatively low stress life.  I was planning on a torque biasing differential like Quaife, but other than that I was satisfied with the 200mm ring gear, instead focusing my mods on converting to CV shafts and eliminating the crappy U joints from the half shafts.

 

Fast forward through moving to South America in 2003 and returning to the US in 2010, I pulled the Z out of storage and started working on it again.   I started buying up core CV shafts from the 300ZXT, and bought the billet steel 5-lug stub shafts from Modern Motorsports (no longer in business I believe) because I wanted to run 5 lug wheels.  I tuned in again to hybridZ, and started to pick up on a new idea of using the Ford IRS 8.8 aluminum diff housing together with the 2003-2004 Mustang Cobra CV shafts with 31 splines.  This differential housing can be found in several Ford models including the 2001-2004 Mustang Cobra, Ford Thunderbird, Lincoln Mark VIII, etc. but only a few of these models use the dual mount on the front of the diff housing, so of course I had to get one of those, and the Lincoln Mark VIII had it.    Someone found that the rear differential cover from a Ford Explorer of the same time period had extended side mounts, so that also seemed like a good idea to me to stabilize the differential housing mounting (still seems like a good idea to me, we don't want that thing moving around). 

 

What a great way to save weight, improve gear ratio options, and have bullet proof rear axle shafts.   So like the junk yard addict (probably a poor description, but I mean one who loves to combine OE parts from different car models into one thereby making it much better!) that I was, I started accumulating those parts.   My plan was to buy original (NEW) Cobra CV shafts and then send them out to get shortened.   Reman shafts were not available at that time.  Only used and new, so I bought new.   I planned on using the Ford hubs (5 x 4.5 bolt circle) and hub bearings, and my custom fab work would be limited to the rear Z strut / knuckle assembly, which would need to house the bearing for the hub and keep all that junk from ejecting while driving.   Really not a difficult design project, the trick is to design it such that it can be fabricated easily and at the lowest possible cost, so this requires several components which would be bolted together, unless you have a milling machine at your personal disposal.   Try to keep welding to a minimum or eliminate altogether to avoid distorting parts and introducing residual stresses, unless you plan to stress relieve your parts. 

 

Of course the strut tube must be located properly on the knuckle, and you need to consider shortening that as well for coil-overs and lower ride height.   I was planning to use the same Tokico BZ3099 struts I have for sale now in the rear as in the front, because I was going to raise the strut tube up higher on the knuckle, so you would need the shorter strut.

 

.....So I got a scrap IRS aluminum knuckle from a Thunderbird (same as the Mustang), and started taking measurements and planning out the design.

 

It was at about that time (2015) that I realized the best plan for my job and my family was to pick up immediately and move to Barranquilla, Colombia, so I did that and stayed there for 4 years while the Z slept in storage again.

 

2019 and back living in the USA, I decided to say screw it with all of the custom fabrication for the rear end.   If I am ever going to finish my project and enjoy it, I needed a big jump start, and I don't really want to be disappointed with the handling after spending many $1000's throwing aftermarket parts at it.   I remembered discussions with one senior member (still on hybridz) back 20 years ago who raced his V8 Z and told me that the rear suspension was limited design-wise and needed to be replaced with something better to get to the next level.     Through Youtube and some other sources, I became aware of other Z enthusiasts who have gone to extremes to modify the rear Z suspension and even created a fancy new suspension specifically for the Z car with shocks inside the rear hatch area, but after looking closely at these designs, they looked very flawed to me.   A double-articulated swing arm seems like a very bad idea to me.   I am a mechanical engineer, and I did study mechanical linkages and automotive suspension design.  Doesn't make me an expert by any stretch of the imagination, but it helps me to consider concepts and ideas with a better understanding of the potential pitfalls.   

 

I started looking at Art Morrison and found they offered a custom chassis built to customer specifications.   Price tag is very high, and it took me a couple of years to finally come to terms with it.   But I don't see myself ever buying a sports car, and the fun is in building something yourself, getting to the end result.   I could definitely design a suspension.   But in reality, it would be a beginner level suspension, not a race proven and tuned one, as the AME suspensions are.  And it would take me forever to build.   I don't have a chassis jig.  So I decided to take the leap finally, and have settled with slicing apart the 280Z body and welding (a large piece of) it to a pre-made chassis to my specs.  A chassis already aligned and set up with a race proven front / rear suspension.  

 

So about a year ago I sold off the billet stub axles and collection of 300ZXT CV shafts.   Now I am putting up for sale the rest of the (Ford IRS) parts and some other stuff I accumulated which I will no longer use.    For someone else who has the ambition, resources, and the ability to follow through with their adaptation, they are quality parts.

[Michael]

After likewise >20 years of pondering the pros/cons, one concludes that there’s no comprehensive or optimal “right answer”.  Any compelling plan can easily be assailed by an even more compelling counter-plan.  Meanwhile, time ticks.  Merely old cars become venerable classics (or rust heaps), and our own youth spills into middle-age and beyond.  Eventually we just want to be done, to show progress and to have something definitive, even if it fails by whatever criteria to be “optimal”.

 

That said, the quandary with any of these comprehensive chassis-kits is the labor and cost of grafting them into the Datsun unibody.  A roll-cage, or more properly a tube chassis that is welded into the Datsun unibody, is more trouble to engineer, relative to a ready-engineered ladder-bar frame… but it is a more natural fit.  Also, to really get the torsional rigidity that some people desire (or some applications demand?), there are all sorts of tubes to be welded onto the ladder bar.  There are alternative ready-built tub-chassis space frames, but again, it’s unclear that this is “optimal” either.

 

The ready-built ladder frame also has the suspension and brakes worked out… not a minor thing, for those of us with radical power-increases and concerns, again over 20+ years, for how to put the power to the pavement.

 

Is the AME frame pre-welded – I mean, does it come ready-built, as on AME’s web page?  Or is there the frenetic exercise of getting all those bits aligned, tacked and welded-up?

[lifeprojectZ]

4 hours ago, Michael said:

Is the AME frame pre-welded – I mean, does it come ready-built, as on AME’s web page?  Or is there the frenetic exercise of getting all those bits aligned, tacked and welded-up?

 

The chassis I ordered three weeks ago is their "Max G" shown on page 6 of the AME 2022 catalog, except that I ordered the compact IRS instead of straight axle housing shown.   They have spec sheets where you can specify a certain number of dimensions to tailor the frame to your specific needs, and that is what I did.   They have designed frames already for a lot of cars, but not the Datsun Z.   And yes it is a fully aligned and welded assembly, so my task is to cut out what I don't need / want from the Datsun unibody and mount the rest to the AME chassis.   Imagine just the outer shell of the body but including the firewall, trans tunnel, and rocker panels.  That is about all I will use.   There is a "but".    I found that AME was not really willing to customize the chassis as much as I wanted them to, because even for the Max G customizable chassis, they still use a jig and follow certain standard designs and layouts.  So they will only let you do so much before adding on tons of additional money for custom fab work.   

 

For this reason, I decided to make a compromise in the foot well area and will have to cut out and reinforce a section of the front frame rail which passes through the firewall straight back into the foot well that would otherwise inhibit movement of my right foot to reach over to the brake pedal.    After sending them several of my design ideas and being met with resistance to doing anything different, I decided the best approach was to let them build the chassis using their standard layout, and then I will modify what I need to in that one area.   After studying this quite a bit, I don't think my modification will compromise the structural integrity to any significant degree, nor will it be too technically complicated for me to pull off with my skill level and tools on hand.   I'll provide more detail about this when I receive the chassis later this year.

 

I also decided to build a cage.  For safety, extra torsional rigidity, compliance with NHRA/SCCA rules, and just all around coolness if none of the rest matters.  But my cage will be minimalist on the inside, with extensions reaching out to the front rails.   I see many guys going far beyond what the rules require for a cage and what I think benefits them, and I don't plan on doing that.   I still want to keep weight to a minimum, so I will be removing all of the Datsun underbody reinforcements, strut towers etc. to lighten as much as I can.

 

At this time I only have a solid plan for how to weld the rocker panels to the 2 x 4 frame.   I am not sure how I will attach the other sheet metal edges to the frame, but I am sure that I will figure this out one step at a time.     I am a novice TIG welder, but I have a good machine so I am sure that with some practice I will be able to do all of the welding necessary.  

[lifeprojectZ]

Quick update.

 

Chassis and Steering:

 

I received the design for my chassis this week and have had a lot of back and forth with AME trying to pry out details to better evaluate it.   Not as forthcoming or as detailed as I was expecting, but slowly and surely have managed to get answers.   I will sign the print and turn it in next week so they can put it in line for build.    If they will allow me, I will post the diagrams here in the future so all can see for what it might be worth.    Today I called Woodward and spoke with Tony, as a few of you have who bought a rack from him.   He convinced me to locate / weld the rack bracket on myself and not leave this to AME.   The more I look at it, the more I agree, as I see the need for the rack to be set back to improve ackermann as much as possible and also get a stiffer linkage in hard turns.   When I start asking really detailed questions to AME, I get some resistance and the comment that I am their first customer ever to ask about ackermann geometry and other such details, so I can only imagine if I were to ask for a fully dimensioned suspension diagram.

 

Wheels:

 

I decided to go with Forgeline G3A wheels (https://forgeline.com/wheel/ga3).   18 x 9 on front with 5.5" backspacing, with 255/35 tires, and 18 x 10.5 on the rear with 7" backspacing, with 295/30 tires.    Both tires will be square with the tire manufacturer's design wheel widths for each, and both have diameter of 25".   Those factors weighed heavy in my decision, as I didn't want to get much larger in diameter.    The AME front and rear suspension has hub track width of 55.5" which is 1" wider than the OE Datsun.  Tire bulge side to side will be about 64.5", so I will need small flares, and am planning on welding on metal ones and blending in.    Total width of the OE Datsun fender lips is somewhere in the 63.5" range by my measurements.    For a while there I was thinking of using 6.5" BS on the rear, but then the tires would have bulged out 1/2"  more on each side than the fronts.   Probably not noticeable from a visible standpoint, but I am hoping that tucking them in more will counter the car wanting to "plow" as the president of AME said he thought it would when I spoke with him the other day.   Plan is to order the wheels and tires this month before prices jump.   Got a good price quote from Hawks Motorsports locally, significantly below the retail price on the Forgeline website.     Would love to hear any thoughts / experiences others have on wheel tire combos, wider track in rear vs front, and what effect you saw on the track. 

 

Brakes:

 

AME sent me the Wilwood front brake kit.  I will post some photos later.   Includes 12.88" rotors w/ aluminum hats, aluminum hubs, and FNSLR6 calipers, etc.   

[Michael]

13 hours ago, lifeprojectZ said:

...When I start asking really detailed questions to AME, I get some resistance and the comment that I am their first customer ever to ask about ackermann geometry and other such details, so I can only imagine if I were to ask for a fully dimensioned suspension diagram.

 

...  Would love to hear any thoughts / experiences others have on wheel tire combos, wider track in rear vs front, and what effect you saw on the track. 

Doubtless AME are knowledgeable people, but most of their market is going to be muscle car restomods, whose aim is to ride well, handle lots of power, and look good.  Road racing is probably not their market, and indeed, it is unlikely that they have any road-racing entries of note.  Thus they are probably doing a cost-benefit calculation when deciding to what extent to field abstruse questions related to handling.   Well, that, and probably some worry about trade-secrets too.

 

As to questions about track width and wheel fitment and so forth, one supposes that details on the order of 1/2" would have to be worked-out once the chassis is installed.  Such level of accuracy would be too hard to predict, if for no other reason than the variability of the Z unibody and how it would be welded to the chassis.  I would expect several iterations of wheel fitment and other such details, unfortunately likely causing revision of orders of costly parts.  This is the downside of a large leap forward in the construction saga, vs. steady (but frustrating!) incrementalism.

 

Several of us have followed the trusty JTR V8 swap-book's recommendation to move the front lower control arms ipick-up point in the K-member outboard by around 1/2" each (or was it 1/4" each?  I forget now).  That results in a slightly larger front track width.  I have driven the car with this mod casually, in brief spurts, but can not report with any rigor as to how handling-feel has changed, or whether anything has convincingly improved or gotten worse.  

[calZ]

I'd think 1/2" would be within the realm of just rolling your fenders rather than going through the work of adding in new metal and blending it. 

[lifeprojectZ]

10 hours ago, Michael said:

  Road racing is probably not their market, and indeed, it is unlikely that they have any road-racing entries of note............  

 

Agree completely.  I believe it may be a matter of cost.   They have some good endorsements backing their IRS which was a draw for me.   On turns, the inner wheel toes in and outer toes out due to the multi-link setup.   Supposed to help. 

 

10 hours ago, Michael said:

As to questions about track width and wheel fitment and so forth, one supposes that details on the order of 1/2" would have to be worked-out once the chassis is installed.  Such level of accuracy would be too hard to predict, if for no other reason than the variability of the Z unibody and how it would be welded to the chassis.  I would expect several iterations of wheel fitment and other such details, unfortunately likely causing revision of orders of costly parts.  This is the downside of a large leap forward in the construction saga, vs. steady (but frustrating!) incrementalism.

 

Yeah I am hoping not to make any major mistakes, but I am sure there will be at least small ones made and money spent on education, unexpectedly.   For me the wheels are one shot.  I will live with what I get.    AME claims my choice of fronts will provide more than adequate turn without touching, and they even encouraged me to bring them inboard more.   I wanted to keep the track width the same as OE and in fact that is what I have done considering the positive offset of 0.5" counters the increase in hub track of 0.5".   The result of using the 18 x 9 wheel is that the tires will fill out completely to the OE fender lip and perhaps a tiny bit beyond.   

 

On the rear it is a different story.  I was/ am mostly concerned about fitting a 14 x 9" Borla muffler behind the tire, between the rear chassis member and the quarter panel.   Pretty tight in there.   Exhaust routing will require mitre cuts/welds, and I may have to tear into the muffler to create a custom entry from the side (I hope not).   But I did not want tires sticking way out the sides for my project.  Just don't like the looks, and I am not convinced it is necessary to improve handling.  So I think I finally convinced myself to tuck them in so that outside-to-outside of the tires will be the same front/ rear.   But the 295's on rear will of course go in deeper.

 

 

[lifeprojectZ]

6 hours ago, calZ said:

I'd think 1/2" would be within the realm of just rolling your fenders rather than going through the work of adding in new metal and blending it. 

 

If you look closely at the OE S30 fender lip, that max body width of ~63.5" is only captured at a very short section slightly toward the front of wheel centerline.  Then the rest of the lip curves back inboard fore/aft.   The more I look at it, the more I dislike it.   Honestly the thought of adding flares has me stressed because I am not looking forward to body work of any type, and want to farm this out as much as possible after I have done the major structural / mechanical work.   So I try not to think about them too much for now, but I am sure that it will be easier overall the smaller flare that will be needed.    

[manninen]

White Z with black og steelies looks so good

[Ironhead]

Just reading over your plans, and have to say I was getting a bit annoyed just hearing about how hesitant AME has been to convey information or "work with you" on anything custom regarding your project.  It kind of gives me the impression that their chassis are intended for show car builds wherein they do little but provide the means for the completed project to roll on and off a trailer....

[lifeprojectZ]

20 hours ago, Ironhead said:

Just reading over your plans, and have to say I was getting a bit annoyed just hearing about how hesitant AME has been to convey information or "work with you" on anything custom regarding your project.  It kind of gives me the impression that their chassis are intended for show car builds wherein they do little but provide the means for the completed project to roll on and off a trailer....

 

I now believe this was more of an issue of my expectations as a mechanical engineer who has developed and/or led many designs over the years with companies having varying levels of design / engineering talent.   I am accustomed to receiving and studying dimensioned prints and the back and forth that design work entails.   So when I heard I would be receiving prints, my expectations were in line with my experience.   I always like having more dimensions vs. less, but in the end they have provided what I needed.   I also don't like communicating with someone's engineering department through a salesman, and usually don't,  but I understand the reason for their business configuration.

 

Through later conversations, I came to realize that most of their customers order their pre-designed frames, and just pick options (e.g. brakes, etc.).  So there is really no custom engineering to those.   Then, of the few who custom spec a chassis, they rely heavily on faith in Art Morrison's reputation.   I have gotten burnt too many times in life doing that with contractors of all types, and I explained it that way to the salesman at AME about a week ago when he, very politely, informed me that I was the first customer to ask about ackermann, and no customers ever go into anywhere near as much detail as I have.    Of course I thought that was odd because I don't feel I have gotten into much detail at all!    Anyway, speaking with their company president (won't mention names here, you can see his name in their catalog), I believe they do have very good engineering talent on board, and have designed their products very well.   They also have a business to run, and I respect that and understand the impact of custom fabrications in a streamlined manufacturing environment, which is what they have developed.   From what I can tell, they build about 40-50 chassis / month.

 

Today I spoke again with AME to finalize the designs and confirm that I will make my own bracket for the steering rack (which Tony Woodward convinced me to do).   When I finally understood the design of the bracket AME had proposed, it was an easy decision.   Tony has been a wealth of knowledge, as anyone who has spoken with him knows.  Throughout the conversations I felt like I was right on the limit of his patience, but fortunately I averted any disasters.    I am waiting on some additional info from AME now before I order the rack.    They gave me the pivot-to-pivot distance, but I would like to see this for myself on an overlay with the suspension pivot points.   An exercise made a little more difficult because the upper arm is on an inclined plane.   When I receive (or not receive) the info I requested, I will post a diagram of a few design elements.

[lifeprojectZ]

The wheels are supposed to arrive week of June 13th.   Specs in first post.  A direct contact at Forgeline has been very helpful.   Can't wait to see them, and will post pictures and details of how I decided on the sizing and spacing for anyone who might be interested.   I am nervous as hell about the dealer mounting the tires on them and not scratching them in the process.   

 

I am also (slowly) working on fabricating a steering rack "simulator" which will allow me to do several things:

 

1) Tie together the steering arms of the spindles when I uncrate the chassis in my driveway this fall so that I can actually steer the thing into my garage.

2) Locate it in the (baseline) position specified by Art Morrison so I can check Ackermann steering geometry and bump steer for myself.

3) Move it to other locations (namely, down and rearward) to check the same and try to improve clearance with the engine.

4) Adjust (reduce) pivot-to-pivot distance if necessary to achieve the above.

 

All of this so that I can be sure before I order the custom rack from Woodward.   

[calZ]

You maybe mentioned and I missed it, but how are you attaching the body to the frame? Completely removing the floor and making a new one? Or just cutting slots and dropping it over the tubes? 

[A to Z]

Sounds good, but PICTURES are priceless.

[clarkspeed]

First I have seen this thread. Very ambitious. Good luck and glad to see you finally got back to your dream car.

[lifeprojectZ]

15 hours ago, calZ said:

You maybe mentioned and I missed it, but how are you attaching the body to the frame? Completely removing the floor and making a new one? Or just cutting slots and dropping it over the tubes? 

 

The (incomplete) plan at this time is to cut out and disgard the floor pans and most of the deck area inside the hatch.  Will also remove the rear strut towers since I won't be needing those with the new IRS.    See in the attached photo how I will route the 2 x 4"  rect tubing along the inside of the rocker panels.   I will drill out all of the spot welds in the vertical lip below the rocker panel, and plug weld those holes directly to the tubing.    This is the only part of the body-to-frame connection I am sure of at this time.  The rest of the areas I will have to figure out as I go and will probably be bending a lot of sheet / plate metal in the interface so that my welds are either lap welds or plug welds.