[DeTomaso] Asa's installing the roll cage

Will Kooiman wkooiman at earthlink.net
Sun Jan 31 00:43:10 EST 2010


I hesitate to recount this story, especially with my recent engine mishap.
Just remember that stupidity isn't hereditary.  I'm not claiming that I
don't do stupid things.  I'm just saying I didn't inherit my stupidity.  I
learned it on my own.

This is related to the rollbar issue.  Really.

My dad has a small farm in Arkansas.  It isn't large.  It's just something
to keep him busy in his retirement.

I love my dad very much.  Remember that.  Also know that my dad is cheap.
If he can buy a $10 item for $2, he'll offer the guy 50 cents.

My dad has 4 tractors.  All of them are worn out.  If he sold them, he could
buy a very nice, brand new tractor.  To be fair, two are pretty cool.  One
is an old John Deere (A model). The other is an old Ford.  The other two are
John Deere work horses (4030/4040) - but worn out.

I was at his house on Thanksgiving.  While I was at the farm, I was helping
him move 93 hay bales (that he didn't need, but they were a good price -
remember, he's cheap).  Back to the tractor story...  I happened to notice
that the front wheel on his tractor was wobbling.  A second after I saw it
wobble, the wheel popped off.

That's when my dad hit me with a doozie (sp?).  He said that he was missing
some studs, so he went into town to replace them.  The studs were $4.50,
which he thought was too much, so he bought bolts instead - at $1.00 each.

Ding! Ding! Ding! Ding!  Does anyone see a problem with this?

These bolts weren't graded.  If I remember correctly, a Grade-5 bolt has 3
marks on the head.  These bolts didn't have any marks.  So, naturally, they
stretched, went into shear, and popped right off.

We stole some bolts from the other front wheel, put the wheel back on, and
carefully drove the tractor home - without one of those big round hay bales
loaded on the front end.

The next day, we went to a tractor supply, and bought grade-8 bolts.  We put
these on, and called it good.  I argued that we should get wheel studs, but
he argued that it didn't need the $4.50 studs.

I was going to send him some studs and maybe a new hub for x-mas, but I
didn't get around to it.  I found out later that he put red loctite on the
nuts - thinking that they were loosening.  A few weeks later, he lost the
wheel again - all 6 bolts popped off.

I'm not sure what's currently happening with his tractor.  I don't call my
dad nearly enough.  I need to, so I can rub it in.  If he had bought the
proper studs in the first place, he would have avoided a lot of headaches.

By the way, the point I was making is going into shear is a bad thing.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of MikeLDrew at aol.com
Sent: Saturday, January 30, 2010 7:59 PM
To: guson at home.se; detomaso at realbig.com
Subject: Re: [DeTomaso] Asa's installing the roll cage


In a message dated 1/30/10 17 34 37, guson at home.se writes:


> Carpet between cage and car: Big time no-no IMO.
> 

If the cage is just there for looks (as most of them are), then it's not a 
problem.   But if you're installing a roll cage with the idea that you might

actually want it to function someday, then yes, you're absolutely right.   
It's critical that you get metal-to-metal contact between the feet of the 
roll cage, and the chassis of the car, which means the carpet HAS to go.

Car crashes can be incredibly violent things.   In an impact, the carpet 
would easily crush and allow the roll cage to move around.   There is a
shear 
plane there, and the bolts could easily shear and cause the roll cage to 
come loose, rendering it useless.   That's one of the many things I learned 
(well, not about roll cages and carpet specifically, but rather more
generally) 
when I went to the Air Force's crash investigation school.  We studied 
failures that led to airplane crashes, as well as failures that took place 
during the course of crashes, and one of the important points that was
stressed 
was that when two things that are supposed to be bolted together are tight, 
they are strong, but when the bolts are loose (which is what they would be
if 
there was carpet between them), they are incredibly weak, and the weak link 
is the bolts.

It would not surprise me if a roll cage that was bolted on top of carpet 
would fail tech, if the tech inspector noticed it.

Figure out where the footprint of the cage is on the carpets, mark them, 
then cut the carpet there.   If you don't want to leave the cage in place 
permanently, you can probably glue the carpet back in place on a
semi-permanent 
basis, or come up with some other aesthetically pleasing solution.

Mike
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