Mid- Engine Modified Sports

[manta22]

Stainless;

Actually, you had to cross two cattle guards to get here.  

A few beers and a handful of M & Ms are good for energy-- aren't they?  

Regards, Neil  Tucson, AZ

Peanut or regular?  

Peanut, of course. Jimmy Carter needs the money now that he's unemployed.  

Regards, Neil  Tucson, AZ

[manta22]

Sometimes I get lucky but not often.

A long time ago a friend asked me if I wanted  a good-sized piece of sheet aluminum. His dad worked for the AZ Dep't of Transportation and his road maintenance crew had found it lying alongside of I-19. From a couple of cutouts, it looked like someone had used it as a pickup truck bed liner but it must have flown out of the truck before it was scratched and scarred by cargo. It was 0.063" Alclad 7075-T6 and said "sure, I'll take it", thinking that someday it would be useful.

Now I'm using that piece of free aluminum on the bottom of my chassis. Thanks, Dave!

Regards, Neil  Tucson, AZ

[manta22]

Here is a photo of that aluminum sheet clamped to the bottom of my chassis. I laid it on the chassis and marked its required outline from the underside. The next step was to turn it over so the Magic Marker lines were visible and clamp a piece of angle as a straight line guide for my little el cheapo HF plasma cutter. After the piece was cut, I dressed the edges with an abrasive flap wheel. Next I'll lay out a rivet pattern with about 250 #20 holes. That is not going to be fun but countersinking them will be even worse!

I've been looking a long time for two 5/8" bolts for the bottom of my rear uprights that would be higher quality than the grade 8 bolts that I now use. I was fortunate enough to find what I need on eBay-- two MS bolts made by SPS that are exactly the right size. Commercial bolts are not suitable for some applications where a bolt is in shear. The threads should not be in the joint between two structures; this places the threads in shear which is much weaker than the full diameter shank. Aerospace/military bolts are made in different lengths with only a short threaded section so the bolt can develop its full strength. These bolt sizes are determined by "grip length".

Regards, Neil  Tucson, AZ

[tauruck]

Neil, are you going to bond and rivet the Alclad?.

That is one expensive piece of metal. Big bucks over here.

[manta22]

Not a bad deal when it's free, Mike! Actually, I'm going to try to seal the faying surfaces and rivet holes with sealant as I assemble it to prevent-- as far as possible-- salt corrosion. My rivets are CherryMax & CherryLock 5/32" (-5)  A286 or Monel body & mandrel.

Regards, Neil  Tucson, AZ

[Milwaukee Midget]

My rivets are CherryMax & CherryLock 5/32" (-5)  A286 or Monel body & mandrel.

Regards, Neil  Tucson, AZ

I didn't know Ace Hardware had a produce aisle . . . 

[manta22]

Ya just gotta cherry- pick your groceries, Chris. 

Regards, Neil  Tucson, AZ

[tauruck]

Neil, if you bond and rivet the plate it becomes one with the chassis.

I did similar work on Trans Am projects and it eliminates any flex that might be a problem while also acting as a seal.

[manta22]

I agree, Mike-- it would be preferable to bond the aluminum to the chassis tubes but it would complicate things for me. To get a good bond, the chassis tubes would need to be bare and the aluminum would as well. I need to prime & paint both before riveting.

My saving grace is that the rivets I'm using are extraordinarily strong. They are 5/32" dia with a Monel body and 15-7PH stem. They have a shear strength of 2260 lbs-- way stronger than equivalent aluminum/aluminum CherryMax and way, way stronger than ordinary Pop rivets. In fact, the rivets are stronger than the bearing strength of the 0.063" 7075-T6. The sheet holes will tear before the rivets fail. Bonding would be better but a 1" spacing rivet pattern should be OK.

Regards, Neil  Tucson, AZ

[salt27]

Neil,
  Does the expansion/contraction of the aluminum attached to the steel chassis present an issue?
The reason I ask is I've seen what an aluminum deck on a steel trailer frame does when left in the sun.

 Thanks, Don

[manta22]

Don;

A couple of things to allay your concern-- good question, though:

Trailer aluminum skins are thinner than cheap toilet paper; there is very little rigidity in those panels. Mine is far thicker- 0.063" or 1/16".

The panel is riveted to the bottom of the chassis; hopefully it won't be exposed to direct sunlight 

Regards, Neil  Tucson, AZ

[manta22]

64 holes drilled so far but those holes aren't really "finished" so I can't check them off as done yet. I laid out a 1' spacing rivet pattern, marked the hole locations with a p_r_i_c_k punch (this is not a disabling karate blow   It's like a center punch but the tip has a sharper angle), and drilled the holes with a #30 drill. These will serve as pilot holes for a #20 drill later.

May people ask about this so I'll post a picture of two different types of Cleco clamps-- one is the ordinary spring-loaded clamp that is installed with special pliers that compress its spring. When a Cleco is inserted into a hole and the pliers relax the tension, the spring inside pulls the two sheets together by expanding its diameter (and aligning the holes in both sheets) by catching the rear of the bottom hole with small "ears" on its expandable shaft. This type of Cleco is common, easy to find, and relatively inexpensive.

The less common Cleco is the larger one. It is called a "cylindrical Cleco" and it has far greater pull-up force that the little ones. Instead of an internal spring to generate clamping force,  it has a threaded spindle and it is installed by turning the top of the spindle. There are pneumatic tools to install these but there is a little manual tool that is handy & cheap. A small circular collar with a sprag clutch lets you turn it one way to tighten and if it is turned over, to loosen the clamp.

While I'm at it, let me put in a plug for pneumatic drills in this application. The one I'm using is a 4500 RPM air drill with a 1/4" chuck. It probably dates back to the Korean War but it still works nicely. Air drills have a number of advantages-- high RPM which is what you want for drilling small holes, it doesn't get hot (in fact the drill gets cold), you can stall it without burning up the motor, and it is small and lightweight.

This stuff may be obvious & boring to you guys who've been around a long time but I thought I'd pass along a little knowledge to those who haven't.

Regards, Neil  Tucson, AZ

[manta22]

I had to put underscores to get that word to go through. The "spell check" kept substituting the phrase "penile device"        

Regards, Neil  Tucson, AZ

[Glen]

Neil, is this belly pan going to be removable, If not how you going to get the salt out of the nooks and crannies, I would dzus it so everything is easier to clean. Just a thought.

[wheelrdealer]

Neil:

I appreciate the detailed explanation. I know about the regular clecos but never heard about the large screw type. I have never seen one until your picture. I can see where that is a handy device when you need additional grip. I always learn something from your post.

I now use a little punch I have with a built in magnifier it helps the old eyes get the punch on the mark. I bought it on a machine tool site. Comes in handy when I need to be exact.

BR