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  #51  
Old 06-14-2018, 10:49 AM
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heinke heinke is offline
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Originally Posted by Kerry Pinkerton View Post
I'm a bit confused about the gears and chain? I'm involved in the GMC motorhome cult and they used the Olds Toronado (caddy Eldorodo) TH325 transmission which was basically a TH400 turned 180 degrees. They connected the engine and tranny via a chain. The chain itself is about 1 1/2 to 2" wide if I recall from having mine out. The pan in the photos doesn't look deep enough for two gears and the chain?



Of course, technology has progressed a bit since the early 70's. I was just thinking you'd need a pretty stout chain to handle that much power?


Can you elaborate on the differential? The napkin sketch just shows a chain. I'm assuming it somehow connects to a limited slip differential type of thinge that the half shaft axles bolt to?
Kerry: we decided to do gears only and NOT include a chain in the transfer case. This was because the transmission is close enough to the crankshaft that the gear size was reasonable. Using gears only is simpler and minimizes the the thickness of the transfer case. This design change is one of those things you can only work out with a mockup using real parts. If the distance between engine crank and trans was another inch or two, a chain would have been required.

The differential center section is limited slip unit used in a 2015+ Mustang IRS. Instead of using a pinion gear and hypoid ring gear, we'll be using two helical/angle cut gears. The smaller gear mounts on the transmission main/output shaft and the larger mounts on the differential where the ring gear normally mounts. I'm targeting a 3.40 final drive ratio so that will dictate the size of these gears. We'll make a case to house differential unit that will mate up and attach to the output housing on the transmission. There's stub axles that connect the differential to the CVs, etc.

I'll show this in pictures once we start building that part. We're waiting for the output housing and transmission main/output shaft to arrive in order to start on that area.
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  #52  
Old 06-21-2018, 10:33 AM
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heinke heinke is offline
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Post Miura chassis construction underway

As a reminder, I decided to use an all aluminum monocoque chassis from Strickland Racing for the Miura. Iím very excited about this chassis for the Miura as to me it represents a big technological advancement. The original Miura chassis was known to exhibit some flex and was prone to metal worm attacks over time. The Strickland chassis should be much lighter weight, more rigid, and shouldnít deteriorate over time given the use of ďmarine gradeĒ aluminum. In addition, Charleyís highly automated approach to chassis construction keeps the cost in the reasonable range.

A small part of the car sizing answer was in consideration for chassis table fixture mounting. By adding .5% on 105% giving the 105.5% this resulted in good alignment to the chassis table such that mounting holes aligned to fixture holes. The chassis was fully modeled with a CAD application and then the CNC cutting instructions are generated from the model. Chassis parts are made from 5052 aluminum and are cut from ľĒ sheet on a 3 axis CNC router. Iím told the accuracy of the CNC cut chassis parts is incredible and they fit to one another easily by hand.

Some chassis parts after cutting and removal from sheet.





Sheet on CNC cutting table after the cut pieces have been removed. With careful placement on the sheet, thereís very little waste after cutting.



The chassis is assembled on a precision chassis table. The chassis members are secured to the table during assembly to ensure alignment for a straight and true chassis. Tabs and slots are used to accurately index the chassis members to one another.





After trial fitting to ensure fitment, the chassis members are fastened together with special metal bonding epoxy glue. As you can see in these pictures, the chassis is quickly taking shape.

Iíd like to thank Charley Strickland for providing these progress photos. I know it provides much better insight for you as to how something is made when you can see it in the various stages of construction.
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  #53  
Old 06-21-2018, 11:54 AM
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Kerry Pinkerton Kerry Pinkerton is offline
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Joel, do I understand that the chassis is put together with adhesives????


If so, I'd be interested in what they use. I have some of the 3M panel bonding stuff and the special gun that mixes the two parts as it squeezes out but I don't think I'd trust that on a chassis.
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  #54  
Old 06-21-2018, 12:08 PM
bobadame bobadame is offline
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That's a beautiful system. By physically locking the pieces together instead of welding, the aluminum retains it's full strength at the joints. Welding always anneals aluminum to condition zero which is several times weaker than the original heat treated strength of the alloy.
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  #55  
Old 06-22-2018, 09:42 AM
76mx 76mx is offline
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Quote:
Originally Posted by Kerry Pinkerton View Post
Joel, do I understand that the chassis is put together with adhesives????


If so, I'd be interested in what they use. I have some of the 3M panel bonding stuff and the special gun that mixes the two parts as it squeezes out but I don't think I'd trust that on a chassis.

Kerry,
This is called structural adhesive, although there is no formal definition or specifications for any glue to be called that. They fall into three general types, this one is methacrolate (spelling?). I am using Loctite AA-H8000 Aluminum Bonder with a 15 minute open time. It is a two part bonder with a special gun. This is the same stuff that Rolls-Royce puts their aluminum chassis together with. Loctite is a Trademark of the parent company Henkel, which is based in Germany. Their engineers have been here and given help and approved the application and the project. In future picture you will be able to see how their engineers and I made sure there are no butt joints, each connection is supported in at least two planes and in shear, compression, and expansion. This assembly is quite adequate but there has been a new development within the last few months. In preparing a chassis for the Chupacabra, it has come to our attention that one Federal Requirement is that the chassis welds must be inspected. If 27 years in Nascar has taught me anything, it is to not give them an opportunity to have a problem, so we will put a few welds on it for them to inspect. While making that revision, it occurred to us that if we were going to place welds, we might as well do it to our construction advantage, but they are still more requirement oriented than necessary.
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  #56  
Old 06-22-2018, 02:46 PM
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Technical data sheet on the adhesive from the manufacturers site. Lap joint tensile strength over 2000psi. Your joints are lap joints, right?


http://tds.henkel.com/tds5/Studio/Sh...EN&plant=WERCS
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Last edited by Jacob; 06-22-2018 at 02:53 PM.
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  #57  
Old 06-22-2018, 05:57 PM
Rick Mullin Rick Mullin is offline
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When I worked at an aluminum structural repair facility, we used 3M DP490. It was required by Audi, Lamborghini and Ferrari. I believe there are variations of that number which have to do only with dry time. DP490 cured over a 6 hour period. I usually tried to do all of my bonding at the end of he day so it had the entire evening to cure. Along with the self piercing rivets, it made for a very strong and rigid body structure.

I have never compared the specs with other bonders but Audi did significant testing before they mandated DP490.

Are you riveting as well as bonding?
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  #58  
Old 06-23-2018, 09:43 AM
76mx 76mx is offline
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Jacob, yes that is what I meant by supported in two planes. Any joint that would be a butt joint was also designed with a third member that makes that same joint a lap joint as well.
Rick, The dogbones index the pieces but in many cases I also drill rivet holes while the piece is on the CNC which mainly help with indexing but cannot hurt structurally. There are several dry times, I use the 15 minute one. The trick is to find one that sets up fast enough to suit without drying fast enough to clog up the gun between fitments.
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  #59  
Old 06-24-2018, 10:24 AM
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Post Body design underway

I decided it was time to learn how to use Adobe Photoshop so I could create some visuals to prove out the look on the plus sized Miura body. I took a couple of days to go through a bunch of online tutorials and practice with throw away stuff so I could overcome some Photoshop roadblocks that had turned me away before. I also want to thank Superleggera (Mark of modenawest.com fame) for giving me some tips and tricks for using Photoshop for digital restyling of automobiles. Iím nowhere close to being in Markís league yet but Iím now able to do some basics.

One thing Iím trying to visualize is what my Miura will look like if a C4 Corvette windshield is used. So I took a stab at changing out the windshield with no other body modifications. The net result is that the windshield posts need to angle further forward as the C4 glass doesnít wrap on the sides as far as Miura windshield. It changes the look some but not dramatically.



My next step was to do a front quarter view where the windshield is more visible. For this picture, I also widened the body below the windows and raised/arched the cockpit roof some. With these multiple changes, the windshield change doesnít seem to stand out at all.



Next, I wanted to do front and rear views with objective to make sure the widening only beneath the beltline would have a good look. For the front view, the widening is proportional across the whole front clip. For the rear view, the widening is only outside of the louvers and trunk lid, so not proportional across the rear clip. I did this to accentuate the wider fenders and thus visually widen the stance.





And for the side perspective, I think Superleggera (Mark of modenawest.com) nailed it with his Miura stretch rendition. So Iíll go with that for now and want to give Mark full credit for his work. Note: This doesn't include the windshield change but as the other side view shows that change is subtle in the overall picture.



All in all, Iím satisfied with what Iím seeing. It still looks like a Miura SV but with some subtle changes. At 15 feet, Iím guessing very few people could pick out the differences if this car wasnít parked right next to an original.
So question out to you auto body design experts, what other perspectives or views do you find to be most helpful in highlighting visual design issues? Iíd really like to surface and resolve the visual design issues when theyíre just pixels versus when they are already in aluminum sheet.
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  #60  
Old 06-24-2018, 11:40 AM
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Kerry Pinkerton Kerry Pinkerton is offline
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Perfect Joel. The only person who will notice that is a Miura owner or AACA judge and probably only if it is parked next to an original. If anything, I like the lines better than the original.
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