I have collected a lot of photos and posted them throughout the previous front clip posts listed above.  If you are landing here via a search engine, I have made this post for you so that you can find what I looked at in one place.

Link to front clip gallery

I took the majority of these pictures from eBay and Google image search.  If any of these pictures belong to you and you do not want them displayed here, please accept my sincerest apologies and leave me a comment below describing the image you would like pulled.

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Now for the view from underneath the V8Mongrel.  Typical of a unibody design, the SA22C chassis has two sheet metal runners front to rear that look like the frame rails of a traditional body-on-frame car.  They are about equidistant from the transmission tunnel and the rocker panels, and do play an important role in stiffening the car, but are not frame rails in the traditional sense.  They also tie into the front frame horns, which means they will likely play a role in the upcoming alterations.

Those pictures are mainly of the transmission.  I never had a reason to take pictures of the underside of the floor panel.  As you can see, these rails are pretty beat up, and I don’t feel comfortable using them as-is for the basis of any kind of new front clip.  They simply aren’t true.  Fortunately, there is a way to reinforce them that I learned from MuscleCar TV.  The episode Comet Frame Rail & Roll Cage details how to add a lot of strength to a unibody car by adding real frame members to these unibody runners.

I am going to be taking a break from the front clip posts and discussing the fender flares I have been building.

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While the previous posts in this series have shown how other cars front clips are designed and built, the obvious question of how to apply that to the V8Mongrel has remained not only unanswered, but completely unaddressed.  After all, the root of the problem is my not having thought that question through far enough for another part of the project.  Plus, there are some significant differences between the full tube frame cars which I have posted pictures of and the unibody design of the RX-7.

A lot of attention has been given in the previous posts to the way in which the frame members in the passenger compartment area connect to the front frame horns.  Here is the reason why:

As you can see, the SA22C chassis has, like most unibodies, a rocker box that provide a significant portion of the strength.  That box runs from the front wheel opening to the rear wheel opening; thus the entire length of the passenger compartment.  Also, as the second photo in the pair above shows quite clearly, the base of the A-pillar links into the rocker box as well.  In the SA22C chassis, the A-pillar is set back quite far from the firewall, unlike most of the more upright sedan style bodies which I have worked on previously.

Since the rocker boxes have to stop at the wheel wells, there needs to be another structure above it for the factory MacPherson strut mount upper mount.  This member was also designed to serve as the anchorage point for the fenders.

Above, you can see the upper structure I spoke about.  note that it too ties into the A-pillar.  Also of note is the attachment to the upper cowl.  The triangular shape where the cowl joins the front structure indicates to me that the cowl and firewall is an important structural piece.  A shear panel that is supposed to tie together the two sides of the car.  This means hacking up the firewall must be done only after serious consideration and planning on how to put back that strength.

This picture hopefully better shows how the structure extends forward.  Of note is how much the upper structure widens where it meets the A-pillar.  Also, the panel between the rocker box and the upper structure is stamped in a way that makes me believe that it too is acting as a shear panel.

The detail on the A-pillar is curious.  The upper structure is not attached to the A-pillar with a continuous weld like is the case for the rocker boxes.  Not sure why this is, as I would think a full weld would be the strongest.

Up next, the view from underneath.

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I have found a few more pictures that show some different approaches to the challenging transition area from passenger compartment frame to front frame horns.  Here they are, with comments.

It looks like there are two frame members here, with the inner one angling in from the connection point with the front frame horns.

The round tube connection looks complex, and I don’t see any other connection in place.

The compromise versus the above setup appears to be moving the pedals higher.  I will have to consider this as I have floor mounted pedals in reserve and the option to use the stock units.

Interesting compromise.  I like the small tube that goes upward from the connection point and becomes part of the transmission tunnel.  Shear panels rock according to me friend Ed.

Same kind of brace from the connection point, but instead of upward, it goes backward.  Also, the round upper tube has a significant angle to it so it can be the width of the car.  My initial thought is that the companion tubing going to the center would be difficult to fit in my smaller application.

Same picture as before but this time  highlighted to show, the round upper tube which seems to make a longer, more gradual run to the outer width of the car than the previous car.  Also, the second, lower round tube would be very hard to package, I think.

That is a complex solution.  Not sure exactly what all those bars do, but I want to find an easier way than this.

These rails seem to have a lot less spread to them.  It is a dirt car, so perhaps that is not required.

Up next, the RX-7 side of things.

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I have posted previously about how you always have to be on the lookout for opportunities and ideas.  This weekend, I took the kids to see the America 200 at Rockingham Speedway and found another such opportunity.  The America 200 is part of the ARCA RE/MAX series, and is the final race of the season.  I have already created and posted a gallery if you are interested.  I really like all kinds of racing, and the ARCA races are great value and are setup in a way that works well for my kids.  The top level NASCAR races are expensive, require a lot of travel and the races are often four hours long or longer.  Yes, they are a lot of fun, but ARCA at the Rock is just as enjoyable and a whole lot easier.

Before the race, as the kids and I were walking to our seats, we passed a car corral with half a dozen race cars in it.  Stock cars from different eras.

Most are pretty rough as it appears they sit outside all the time, but they are still interesting.  The one pictured above appears to be about a decade old and from the NASCAR Busch Grand National series.  Notice how the front end seems high?  That is because there is no engine in the car.  That large fender gap allowed me to poke the camera in and snap a few pictures.

Nothing earth shattering, but just another data point for my own efforts.  I have collected some more eBay images as well.  At this point, I need to post them all up, organize them and continue my analysis of the different options.

Planning – Front Clip – Getting Acquainted (Part 1)

First, here are some more pictures I have found on eBay of tube frame front clips.

Second, here are some observations on the pictures posted previously.

How the front frame horns tie into the rest of the frames appears to be the most complex design element.  If you consider the car a three box layout – box one the engine bay, box two the driver compartment, box three the trunk area – the difficulty appears to stem from the fact that boxes one and three have narrower frame widths than box two.  So how bridge that gap without sacrificing strength or adding a lot of weight is a design challenge.

I will be looking for more pictures of that area and posting them up.  If you see any, leave a link in the comment box below please.

Having come to terms with the fact that I have some major work to undo and then an even greater amount of work to do, I have started looking at how others do what I need to do.  Specifically, I have been looking at the front clips of various stock cars.  Step one was to get on eBay and see what was for sale.  In the next few posts, I will breakdown the differences and how I think they apply to me, but for now, here is what I have found:

I am also going to look at professional road racing chassis to see what they are like.  The difficulty is that road racing cars are mostly either production based, therefore having things required by the rulebook instead of good design criteria, or mid-engined, therefore not applicable to the V8Mongrel.