Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Richard,

I think the reason for all the messages of concern you are receiving is that
most of us have seen far too many bumpers seemingly hanging on by the
strength of prayers and rust.

Bumper hitches were popular... decades ago when vehicles had substantial
bumpers.

The auto industry then went through a period where "bumpers" were little
more than chrome decoration bolted ONLY to sheet metal or fiberglass and
years where they were constructed of metal so thin that they could be
twisted by bare hands. I personally witnessed a bus driver twist, with his
bare hands, a AMC Gremlin bumper straight after a minor collision.

I don't know what the bumper attachments for your Jeep are but I know what
they look like in XJs and WJs and would personally feel uncomfortable
hauling a trailer bolted solely to the bumper.

My first concern was your use of four 3/8 inch bolts to hold the angle iron
to the bumper. When I installed a frame hitch on my XJ I used eight 1/2
inch stainless steel grade 5 bolts. I fully understand this was overkill but
I received additional reassurance by the expenditure of an additional $2.40

As an engineer you were certainly trained to design a product for it
intended use and then imagine what a complete moron might try to do with it
and calculate a sufficient safety factor.

You intent is to never tow anything more than your 1000 pound inflatable
boat/trailer. I will accept based on your education that it is properly
designed for that load. What about when your kids use it to pull the
homecoming parade float or your neighbor uses it to pull a trailer full of
gravel?


"Richard J Kinch" <kinch@truetex.com> wrote in message
news:Xns9756BCCAF677Dsomeconundrum@216.196.97.131. ..
> Mike Romain writes:
>
>> If you get pulled over by the highway patrol, you will/should get
>> busted for something as dumb as that. Not meaning to be a jerk or
>> anything but Wow...
>
> Jerk or not, your legal opinion is baloney.
>
> http://www.google.com/search?q=florida+statutes+316.530
>
> Show me where hitch ratings have any legal significance in traffic laws.
>
>> The bumper isn't rated for towing or even jacking up under so
>> technically that is an illegal hitch, let alone an unsafe one.
>
> The stock bumper is essentially a 3 x 4.5 inch 3.5-sided 13 gage steel
> box beam 50 inches long. Maybe someone can calculate the strength of
> this member.
>
> We're talking about towing a small rig under 1000 lbs, not dragging the
> universe behind.
>
> My mechanical intuition is that it is plenty strong when properly
> fitted. It doesn't visibly flex when I jump on the step.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Richard,

I think the reason for all the messages of concern you are receiving is that
most of us have seen far too many bumpers seemingly hanging on by the
strength of prayers and rust.

Bumper hitches were popular... decades ago when vehicles had substantial
bumpers.

The auto industry then went through a period where "bumpers" were little
more than chrome decoration bolted ONLY to sheet metal or fiberglass and
years where they were constructed of metal so thin that they could be
twisted by bare hands. I personally witnessed a bus driver twist, with his
bare hands, a AMC Gremlin bumper straight after a minor collision.

I don't know what the bumper attachments for your Jeep are but I know what
they look like in XJs and WJs and would personally feel uncomfortable
hauling a trailer bolted solely to the bumper.

My first concern was your use of four 3/8 inch bolts to hold the angle iron
to the bumper. When I installed a frame hitch on my XJ I used eight 1/2
inch stainless steel grade 5 bolts. I fully understand this was overkill but
I received additional reassurance by the expenditure of an additional $2.40

As an engineer you were certainly trained to design a product for it
intended use and then imagine what a complete moron might try to do with it
and calculate a sufficient safety factor.

You intent is to never tow anything more than your 1000 pound inflatable
boat/trailer. I will accept based on your education that it is properly
designed for that load. What about when your kids use it to pull the
homecoming parade float or your neighbor uses it to pull a trailer full of
gravel?


"Richard J Kinch" <kinch@truetex.com> wrote in message
news:Xns9756BCCAF677Dsomeconundrum@216.196.97.131. ..
> Mike Romain writes:
>
>> If you get pulled over by the highway patrol, you will/should get
>> busted for something as dumb as that. Not meaning to be a jerk or
>> anything but Wow...
>
> Jerk or not, your legal opinion is baloney.
>
> http://www.google.com/search?q=florida+statutes+316.530
>
> Show me where hitch ratings have any legal significance in traffic laws.
>
>> The bumper isn't rated for towing or even jacking up under so
>> technically that is an illegal hitch, let alone an unsafe one.
>
> The stock bumper is essentially a 3 x 4.5 inch 3.5-sided 13 gage steel
> box beam 50 inches long. Maybe someone can calculate the strength of
> this member.
>
> We're talking about towing a small rig under 1000 lbs, not dragging the
> universe behind.
>
> My mechanical intuition is that it is plenty strong when properly
> fitted. It doesn't visibly flex when I jump on the step.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Richard,

I think the reason for all the messages of concern you are receiving is that
most of us have seen far too many bumpers seemingly hanging on by the
strength of prayers and rust.

Bumper hitches were popular... decades ago when vehicles had substantial
bumpers.

The auto industry then went through a period where "bumpers" were little
more than chrome decoration bolted ONLY to sheet metal or fiberglass and
years where they were constructed of metal so thin that they could be
twisted by bare hands. I personally witnessed a bus driver twist, with his
bare hands, a AMC Gremlin bumper straight after a minor collision.

I don't know what the bumper attachments for your Jeep are but I know what
they look like in XJs and WJs and would personally feel uncomfortable
hauling a trailer bolted solely to the bumper.

My first concern was your use of four 3/8 inch bolts to hold the angle iron
to the bumper. When I installed a frame hitch on my XJ I used eight 1/2
inch stainless steel grade 5 bolts. I fully understand this was overkill but
I received additional reassurance by the expenditure of an additional $2.40

As an engineer you were certainly trained to design a product for it
intended use and then imagine what a complete moron might try to do with it
and calculate a sufficient safety factor.

You intent is to never tow anything more than your 1000 pound inflatable
boat/trailer. I will accept based on your education that it is properly
designed for that load. What about when your kids use it to pull the
homecoming parade float or your neighbor uses it to pull a trailer full of
gravel?


"Richard J Kinch" <kinch@truetex.com> wrote in message
news:Xns9756BCCAF677Dsomeconundrum@216.196.97.131. ..
> Mike Romain writes:
>
>> If you get pulled over by the highway patrol, you will/should get
>> busted for something as dumb as that. Not meaning to be a jerk or
>> anything but Wow...
>
> Jerk or not, your legal opinion is baloney.
>
> http://www.google.com/search?q=florida+statutes+316.530
>
> Show me where hitch ratings have any legal significance in traffic laws.
>
>> The bumper isn't rated for towing or even jacking up under so
>> technically that is an illegal hitch, let alone an unsafe one.
>
> The stock bumper is essentially a 3 x 4.5 inch 3.5-sided 13 gage steel
> box beam 50 inches long. Maybe someone can calculate the strength of
> this member.
>
> We're talking about towing a small rig under 1000 lbs, not dragging the
> universe behind.
>
> My mechanical intuition is that it is plenty strong when properly
> fitted. It doesn't visibly flex when I jump on the step.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Most of the ones distributed by the big names (Warn, ARB, etc) are designed
to work with newer vehicle crash equipment and airbags.... at least that is
what they claim..



> Richard J Kinch wrote:
>
>>
>> I wonder if people buying all those macho aftermarket bumpers understand
>> that they've *given up* a lot of their crash protection?

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Most of the ones distributed by the big names (Warn, ARB, etc) are designed
to work with newer vehicle crash equipment and airbags.... at least that is
what they claim..



> Richard J Kinch wrote:
>
>>
>> I wonder if people buying all those macho aftermarket bumpers understand
>> that they've *given up* a lot of their crash protection?

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Most of the ones distributed by the big names (Warn, ARB, etc) are designed
to work with newer vehicle crash equipment and airbags.... at least that is
what they claim..



> Richard J Kinch wrote:
>
>>
>> I wonder if people buying all those macho aftermarket bumpers understand
>> that they've *given up* a lot of their crash protection?

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

I had the 1000 lb rig out for a test drive tonight after I finally got
the wiring done. No problems that I could detect.

billy ray writes:

> I don't know what the bumper attachments for your Jeep are but I know
> what they look like in XJs and WJs and would personally feel
> uncomfortable hauling a trailer bolted solely to the bumper.

On the TJ the stock bumper mounts are substantial with nicely welded
seams to the box. They appear stronger than the rest of the bumper.

> My first concern was your use of four 3/8 inch bolts to hold the angle
> iron to the bumper.

Why a concern? The working strength of a 3/8 bolt exceeds the rest of
the components. and the applied loads.

> You intent is to never tow anything more than your 1000 pound
> inflatable boat/trailer. I will accept based on your education that
> it is properly designed for that load. What about when your kids use
> it to pull the homecoming parade float or your neighbor uses it to
> pull a trailer full of gravel?

It is first-grade towing sense that you don't hook up loads larger than
the lowest-rated component of the tow vehicle (GTWR, hitch, drawbar,
etc), which in this case is a conservative 1000 lbs for a shop-built
bracket system.

If one holds that you should not install a hitch with a lower capacity
than an ignorant or careless user might someday attempt, then there is
no such hitch.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

I had the 1000 lb rig out for a test drive tonight after I finally got
the wiring done. No problems that I could detect.

billy ray writes:

> I don't know what the bumper attachments for your Jeep are but I know
> what they look like in XJs and WJs and would personally feel
> uncomfortable hauling a trailer bolted solely to the bumper.

On the TJ the stock bumper mounts are substantial with nicely welded
seams to the box. They appear stronger than the rest of the bumper.

> My first concern was your use of four 3/8 inch bolts to hold the angle
> iron to the bumper.

Why a concern? The working strength of a 3/8 bolt exceeds the rest of
the components. and the applied loads.

> You intent is to never tow anything more than your 1000 pound
> inflatable boat/trailer. I will accept based on your education that
> it is properly designed for that load. What about when your kids use
> it to pull the homecoming parade float or your neighbor uses it to
> pull a trailer full of gravel?

It is first-grade towing sense that you don't hook up loads larger than
the lowest-rated component of the tow vehicle (GTWR, hitch, drawbar,
etc), which in this case is a conservative 1000 lbs for a shop-built
bracket system.

If one holds that you should not install a hitch with a lower capacity
than an ignorant or careless user might someday attempt, then there is
no such hitch.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

I had the 1000 lb rig out for a test drive tonight after I finally got
the wiring done. No problems that I could detect.

billy ray writes:

> I don't know what the bumper attachments for your Jeep are but I know
> what they look like in XJs and WJs and would personally feel
> uncomfortable hauling a trailer bolted solely to the bumper.

On the TJ the stock bumper mounts are substantial with nicely welded
seams to the box. They appear stronger than the rest of the bumper.

> My first concern was your use of four 3/8 inch bolts to hold the angle
> iron to the bumper.

Why a concern? The working strength of a 3/8 bolt exceeds the rest of
the components. and the applied loads.

> You intent is to never tow anything more than your 1000 pound
> inflatable boat/trailer. I will accept based on your education that
> it is properly designed for that load. What about when your kids use
> it to pull the homecoming parade float or your neighbor uses it to
> pull a trailer full of gravel?

It is first-grade towing sense that you don't hook up loads larger than
the lowest-rated component of the tow vehicle (GTWR, hitch, drawbar,
etc), which in this case is a conservative 1000 lbs for a shop-built
bracket system.

If one holds that you should not install a hitch with a lower capacity
than an ignorant or careless user might someday attempt, then there is
no such hitch.

Re: Bumper-mounted trailer hitch bracket for Jeep Wrangler TJ
 

Richard, in your article you make a point of saying "I used Grade 5 bolts
since ungraded hardware is not suitable for load-bearing applications. "
You do realize that the bumper you are attaching to is only 3/32" thick and
is not rated for load bearing applications....... This is somewhat of a
contradiction don't you think?

Tom

"Richard J Kinch" <kinch@truetex.com> wrote in message
news:Xns9756BE3F3DDE8someconundrum@216.196.97.131. ..
> Grumman-581 writes:
>
> > Perhaps his next project should be to design a real bumper for his TJ
....
>
> Bad idea. Bumpers are weaker than the frame so they absorb impact energy
> instead of bending the frame. You put a heavy bumper (or a frame hitch
for
> that matter) on the back of your car, and many collisions are going to
> result in frame damage that would have just been a simple bolt-on swap of
a
> new bumper.
>
> On a previous rear-ended TJ I was able to replace a crunched back bumper
> with a $25 OEM item from eBay (surplus to somebody's aftermarket upgrade)
> with hand tools. The other guy had $1000s in damage.
>
> I wonder if people buying all those macho aftermarket bumpers understand
> that they've *given up* a lot of their crash protection?