I made a dirt bike carrier last weeks:
http://www.wallys-speed-shop.com/projects.html#carrier
and there was concern regarding the hitch/receiver set up. I added a few
more enhancements to make it stronger. This supports a 40lb rack with a
215lb motorcycle strapped to it. The tongue extends about 15" from the jeep.
Here's a detailed pic of the hitch:
http://www.wallys-speed-shop.com/hitch_getup.jpg
Wayne Cook, what are your thoughts?

thanks folks,

walt

On Mon, 12 Sep 2005 09:03:41 -0400, "wallster"
wrote:

I made a dirt bike carrier last weeks:
http://www.wallys-speed-shop.com/projects.html#carrier
and there was concern regarding the hitch/receiver set up. I added a few
more enhancements to make it stronger. This supports a 40lb rack with a
215lb motorcycle strapped to it. The tongue extends about 15" from the jeep.
Here's a detailed pic of the hitch:
http://www.wallys-speed-shop.com/hitch_getup.jpg
Wayne Cook, what are your thoughts?


The only area of concern is at the bottom of the bumper. If you look
at it you see that the gusset stops right at the bottom of the bumper
leaving only the 3/4" thickness to hold the whole thing up. If that
gusset went to the top of the bumper I wouldn't worry to much.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.

wallster wrote:
I made a dirt bike carrier last weeks:
http://www.wallys-speed-shop.com/projects.html#carrier
and there was concern regarding the hitch/receiver set up. I added a few
more enhancements to make it stronger. This supports a 40lb rack with a
215lb motorcycle strapped to it. The tongue extends about 15" from the jeep.
Here's a detailed pic of the hitch:
http://www.wallys-speed-shop.com/hitch_getup.jpg
Wayne Cook, what are your thoughts?

thanks folks,

walt

Wayne Cook wrote:

The only area of concern is at the bottom of the bumper. If you look
at it you see that the gusset stops right at the bottom of the bumper
leaving only the 3/4" thickness to hold the whole thing up. If that
gusset went to the top of the bumper I wouldn't worry to much.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

VERY good point (i dont know how i missed that), Wayne, you're a
mechanical wiz. I have two 1/4" gussets that would fit perfect on each
side (inside the right angles, one per side) and i think that would be
much better. Thanks.

walt

RoyJ wrote:
I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.



Roy, the 1" plate (or cross member) is bolted to the backing plate on
the jeep and that is bolted to the frame. Each end of the cross member
has four 7/16" grade 8 bolts with washers and lock washers. I also
added one more through the L bracket section of the hitch because i did
not weld that (i bought the jeep with this hitch on it) and i dont know
what kind of penetration the previous welder had received (or what rod
he, or she had used) It looks good, but without x-ray or cutting it, i
just cant tell.
does this answer your concern? i'm not positive what you mean by the
outside shell.
thanks,
walt

Wayne Cook wrote:
SNIPPED
leaving only the 3/4" thickness to hold the whole thing up. If that
gusset went to the top of the bumper I wouldn't worry to much.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Hey Wayne (or anyone else here), have you ever mig welded on a bumper
while it's still attached to the vehicle? It's a major pita taking this
thing on and off but i'm not big on exploding (from the proximity of
the fuel tank)
I would be welding outdoors to allow for optimum ventilation.
It sounds like a no-brainer not to do it but i've seen a car completely
engulfed in flames and the fire fighter told me that the blowing up of
the gas tank wasn't a major concern. (although the spare tire popping
was exciting!)
thanks,
walt

On Mon, 12 Sep 2005 09:03:41 -0400, "wallster"
wrote:

I made a dirt bike carrier last weeks:
http://www.wallys-speed-shop.com/projects.html#carrier
and there was concern regarding the hitch/receiver set up. I added a few
more enhancements to make it stronger. This supports a 40lb rack with a
215lb motorcycle strapped to it. The tongue extends about 15" from the jeep.
Here's a detailed pic of the hitch:
http://www.wallys-speed-shop.com/hitch_getup.jpg
Wayne Cook, what are your thoughts?

thanks folks,

walt

My neighbor just had a brand-name class-III (6000 lb tow weight, 600
lb tongue weight) hitch professionally installed on his van at a
hitch place. Yours looks somewhat stiffer than his.

Don Foreman wrote:
My neighbor just had a brand-name class-III (6000 lb tow weight, 600
lb tongue weight) hitch professionally installed on his van at a
hitch place. Yours looks somewhat stiffer than his.

Don, I can buy a HD frame mounted hitch that simply bolts on for $150.,
maybe even less if i really looked hard enough,
(http://www.thepartsbin.com/sitemap/j...tch~parts.html) but what fun
would that be? No cutting, welding, grinding? Geez, if i cant make this
a major project, why bother?? : )

Walt

On 12 Sep 2005 08:39:04 -0700, "wallster"
wrote:


Wayne Cook wrote:
SNIPPED
leaving only the 3/4" thickness to hold the whole thing up. If that
gusset went to the top of the bumper I wouldn't worry to much.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Hey Wayne (or anyone else here), have you ever mig welded on a bumper
while it's still attached to the vehicle? It's a major pita taking this
thing on and off but i'm not big on exploding (from the proximity of
the fuel tank)
I would be welding outdoors to allow for optimum ventilation.
It sounds like a no-brainer not to do it but i've seen a car completely
engulfed in flames and the fire fighter told me that the blowing up of
the gas tank wasn't a major concern. (although the spare tire popping
was exciting!)

In this situation I wouldn't worry to much. There's plenty of metal
between you and the gas tank. When I start to get worried is when
welding above a plastic gas tank.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

On Mon, 12 Sep 2005 14:24:04 GMT, RoyJ wrote:

I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.


That looks like 1" x 4 or 5" (possibly 6") I wouldn't worry to much
about it. Ever try to bend a piece of 1" x 4"? It's pretty strong. I
admit that it's not the best piece of steel for the job but I don't
think it'll bend before he breaks his bolts.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Wayne Cook wrote:
On Mon, 12 Sep 2005 14:24:04 GMT, RoyJ wrote:

I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.


That looks like 1" x 4 or 5" (possibly 6") I wouldn't worry to much
about it. Ever try to bend a piece of 1" x 4"? It's pretty strong. I
admit that it's not the best piece of steel for the job but I don't
think it'll bend before he breaks his bolts.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm


1" x 4"... now you can sleep tonight.

walt

On 12 Sep 2005 09:26:15 -0700, "wallster"
wrote:


Don Foreman wrote:
My neighbor just had a brand-name class-III (6000 lb tow weight, 600
lb tongue weight) hitch professionally installed on his van at a
hitch place. Yours looks somewhat stiffer than his.

Don, I can buy a HD frame mounted hitch that simply bolts on for $150.,
maybe even less if i really looked hard enough,
(http://www.thepartsbin.com/sitemap/j...tch~parts.html) but what fun
would that be? No cutting, welding, grinding? Geez, if i cant make this
a major project, why bother?? : )

Walt

Absolutely! T'wouldn't be any fun at all.

I would question the ability of the "name brand" hitch I looked at to
handle your application, while yours looks very capable.

wallster wrote:
Wayne Cook wrote:
SNIPPED

leaving only the 3/4" thickness to hold the whole thing up. If that
gusset went to the top of the bumper I wouldn't worry to much.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm


Hey Wayne (or anyone else here), have you ever mig welded on a bumper
while it's still attached to the vehicle? It's a major pita taking this
thing on and off but i'm not big on exploding (from the proximity of
the fuel tank)
I would be welding outdoors to allow for optimum ventilation.
It sounds like a no-brainer not to do it but i've seen a car completely
engulfed in flames and the fire fighter told me that the blowing up of
the gas tank wasn't a major concern. (although the spare tire popping
was exciting!)
thanks,
walt


Just fill the tank with water..

Seriously, if it's not leaking and you're not putting sparks in the
filler neck you're ok. If there's any concern about sparks getting in
the filler neck or tank, making sure the tank is all the way full
eliminates the possibility of explosion. As always, keep a good
extinguisher or two handy when working on a car.

John

JohnM wrote:

Just fill the tank with water..

Seriously, if it's not leaking and you're not putting sparks in the
filler neck you're ok. If there's any concern about sparks getting in
the filler neck or tank, making sure the tank is all the way full
eliminates the possibility of explosion. As always, keep a good
extinguisher or two handy when working on a car.

John

i've decided to just take a few extra minutes and take it off first (at
least this time the bolts aren't all rusted on). Plus, I think my welds
are better when i can position the work rather than having to position
me.
thanks for the suggestion, it sounds wierd to make sure the tank is
full, but it is true that the fumes ignite, not the fuel.

walt

The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.

wallster wrote:
RoyJ wrote:

I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.



Roy, the 1" plate (or cross member) is bolted to the backing plate on
the jeep and that is bolted to the frame. Each end of the cross member
has four 7/16" grade 8 bolts with washers and lock washers. I also
added one more through the L bracket section of the hitch because i did
not weld that (i bought the jeep with this hitch on it) and i dont know
what kind of penetration the previous welder had received (or what rod
he, or she had used) It looks good, but without x-ray or cutting it, i
just cant tell.
does this answer your concern? i'm not positive what you mean by the
outside shell.
thanks,
walt

On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:

The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.

Did you figure in the fact that it was held on both ends.

wallster wrote:
RoyJ wrote:

I'm more concerned with the torque loading on the cross member than I am
with the gussets. Apparently the cross member is 1" bar stock but in
torque loading, only the outside shell actually takes much load.



Roy, the 1" plate (or cross member) is bolted to the backing plate on
the jeep and that is bolted to the frame. Each end of the cross member
has four 7/16" grade 8 bolts with washers and lock washers. I also
added one more through the L bracket section of the hitch because i did
not weld that (i bought the jeep with this hitch on it) and i dont know
what kind of penetration the previous welder had received (or what rod
he, or she had used) It looks good, but without x-ray or cutting it, i
just cant tell.
does this answer your concern? i'm not positive what you mean by the
outside shell.
thanks,
walt


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

"Wayne Cook" wrote in message
...
On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:

The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.

Did you figure in the fact that it was held on both ends.

Wayne, here's how the 1"x4" steel bar is mounted. Roy, i think it's strong
enough for my application, but i DO appreciate your input.
http://www.wallys-speed-shop.com/mounting_bolts.JPG
Also, I welded two 4'x6" 1/4" gussets to the L bracket.
http://www.wallys-speed-shop.com/new_gussets.JPG
here's the finished hitch... i 'm not taking it off anymore!!! (i smacked my
head on the jeep, left a nice cut!)
http://www.wallys-speed-shop.com/painted_gussets.jpg

thanks,
walt

On Tue, 13 Sep 2005 14:23:42 -0400, "wallster"
wrote:


"Wayne Cook" wrote in message
.. .
On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:

The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.

Did you figure in the fact that it was held on both ends.

Another thing about the above I should point out now that I've got
more time is that if you look and any of the class 5 hitches out there
now days and you'll see something like 3" x .120" square tube or even
2 1/2" x .120 round tube for the torque member (and that's on the
better built ones I've seen many have smaller tube). I've not got a
table handy but I'd bet that we're in the same ball park strength wise
here.

Wayne, here's how the 1"x4" steel bar is mounted. Roy, i think it's strong
enough for my application, but i DO appreciate your input.
http://www.wallys-speed-shop.com/mounting_bolts.JPG
Also, I welded two 4'x6" 1/4" gussets to the L bracket.
http://www.wallys-speed-shop.com/new_gussets.JPG
here's the finished hitch... i 'm not taking it off anymore!!! (i smacked my
head on the jeep, left a nice cut!)
http://www.wallys-speed-shop.com/painted_gussets.jpg


That looks much better. Of course in any system there's always a
weak link. The trick is for the weak link to be strong enough to do
the job. You've now moved the weak link up to the bolts and frame in
my opinion. Most likely strong enough but keep a eye on the frame tabs
that the bumper is bolted to for a while just to make sure that they
don't start to deform.

A proper receiver hitch would be mounted under the frame for a
distance of about 12" apart for the bolts. This longer leverage helps
compared to the closer spaced holes in the bumper.

I hate to say it at this stage but just for the record I would of
probably of made a extension of the receiver and run it up under the
Jeep for about 12" farther forward than the bumper. Then put something
like a piece of tube or channel across the frame at that point and
tied the extension to the cross piece. This would make for a better
leverage and remove most of the torque on the bumper itself turning it
into more of a downward force.

A easier fix for you at this stage if any sign of problems crop up
would be to weld some brackets under the bumper in such a way that
they go up along the bottom of the frame for a ways and bolt them.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

I actually was working with some demo programs on Matlab, ran this one
as a test. I figured support on both ends (doubles the load), length is
not a factor (but degree of twist before failure is definately related
to length!) I'll generate the full table to finish testing but the
first pass said that the flat bar was NOT very good in pure torsion. Nor
is it very good in bending mode in the flat side axis.

Wayne Cook wrote:
On Tue, 13 Sep 2005 14:23:42 -0400, "wallster"
wrote:


"Wayne Cook" wrote in message
. ..

On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:


The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.


Did you figure in the fact that it was held on both ends.


Another thing about the above I should point out now that I've got
more time is that if you look and any of the class 5 hitches out there
now days and you'll see something like 3" x .120" square tube or even
2 1/2" x .120 round tube for the torque member (and that's on the
better built ones I've seen many have smaller tube). I've not got a
table handy but I'd bet that we're in the same ball park strength wise
here.


Wayne, here's how the 1"x4" steel bar is mounted. Roy, i think it's strong
enough for my application, but i DO appreciate your input.
http://www.wallys-speed-shop.com/mounting_bolts.JPG
Also, I welded two 4'x6" 1/4" gussets to the L bracket.
http://www.wallys-speed-shop.com/new_gussets.JPG
here's the finished hitch... i 'm not taking it off anymore!!! (i smacked my
head on the jeep, left a nice cut!)
http://www.wallys-speed-shop.com/painted_gussets.jpg



That looks much better. Of course in any system there's always a
weak link. The trick is for the weak link to be strong enough to do
the job. You've now moved the weak link up to the bolts and frame in
my opinion. Most likely strong enough but keep a eye on the frame tabs
that the bumper is bolted to for a while just to make sure that they
don't start to deform.

A proper receiver hitch would be mounted under the frame for a
distance of about 12" apart for the bolts. This longer leverage helps
compared to the closer spaced holes in the bumper.

I hate to say it at this stage but just for the record I would of
probably of made a extension of the receiver and run it up under the
Jeep for about 12" farther forward than the bumper. Then put something
like a piece of tube or channel across the frame at that point and
tied the extension to the cross piece. This would make for a better
leverage and remove most of the torque on the bumper itself turning it
into more of a downward force.

A easier fix for you at this stage if any sign of problems crop up
would be to weld some brackets under the bumper in such a way that
they go up along the bottom of the frame for a ways and bolt them.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

On Fri, 16 Sep 2005 05:02:00 GMT, RoyJ wrote:

I actually was working with some demo programs on Matlab, ran this one
as a test. I figured support on both ends (doubles the load), length is
not a factor (but degree of twist before failure is definately related
to length!) I'll generate the full table to finish testing but the
first pass said that the flat bar was NOT very good in pure torsion. Nor
is it very good in bending mode in the flat side axis.

I agree that it's not very good in those directions compared to the
weight of the bar. However is it good enough for the job is the real
question. Admittedly I'm just going by experience and gut feel but I'm
no where near as worried about it as I was other parts of hitch. There
was a lot weaker portions in this hitch when he started. It's much
better now but I admit that there's still weak points. I still feel
that the bolts or what they attach to on the frame will fail before
the flat bar.

Wayne Cook wrote:
On Tue, 13 Sep 2005 14:23:42 -0400, "wallster"
wrote:


"Wayne Cook" wrote in message
...

On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:


The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.


Did you figure in the fact that it was held on both ends.


Another thing about the above I should point out now that I've got
more time is that if you look and any of the class 5 hitches out there
now days and you'll see something like 3" x .120" square tube or even
2 1/2" x .120 round tube for the torque member (and that's on the
better built ones I've seen many have smaller tube). I've not got a
table handy but I'd bet that we're in the same ball park strength wise
here.


Wayne, here's how the 1"x4" steel bar is mounted. Roy, i think it's strong
enough for my application, but i DO appreciate your input.
http://www.wallys-speed-shop.com/mounting_bolts.JPG
Also, I welded two 4'x6" 1/4" gussets to the L bracket.
http://www.wallys-speed-shop.com/new_gussets.JPG
here's the finished hitch... i 'm not taking it off anymore!!! (i smacked my
head on the jeep, left a nice cut!)
http://www.wallys-speed-shop.com/painted_gussets.jpg



That looks much better. Of course in any system there's always a
weak link. The trick is for the weak link to be strong enough to do
the job. You've now moved the weak link up to the bolts and frame in
my opinion. Most likely strong enough but keep a eye on the frame tabs
that the bumper is bolted to for a while just to make sure that they
don't start to deform.

A proper receiver hitch would be mounted under the frame for a
distance of about 12" apart for the bolts. This longer leverage helps
compared to the closer spaced holes in the bumper.

I hate to say it at this stage but just for the record I would of
probably of made a extension of the receiver and run it up under the
Jeep for about 12" farther forward than the bumper. Then put something
like a piece of tube or channel across the frame at that point and
tied the extension to the cross piece. This would make for a better
leverage and remove most of the torque on the bumper itself turning it
into more of a downward force.

A easier fix for you at this stage if any sign of problems crop up
would be to weld some brackets under the bumper in such a way that
they go up along the bottom of the frame for a ways and bolt them.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

I have a Jeep with off road bumpers and the same mounting problems with
the rear as the OP. The 8 bolts go through holes that are on either side
of where the main frame rail joins up to the rear cross member. Both
frame and cross member are relatively thin at .104" The bolt holes are
1.25" on center vertically, 8" horizontally (spaced evenly on either
side of the main rail joint. This is NOT a solid item to bolt to for
straight pull, really flimsy for the torque loading of the motorbike rack.

I used some 1/4"x2" backer plates with radiused ends to match the curve
of the cross member in an attempt to get some of the load transferred
out to the edges of the cross member. That still didn't look good enough
so I ran more 1/4"x2" strap forward on both top and bottom, then drilled
all the way through the frame to bolt the sandwich together with 2 ea 7"
grade 5 bolts per side. Spacing on the through bolts was set to allow
standard tow hooks to be added on either top or bottom.

BTW: bumpers were 2"x5" rectangular tube, tapered ends, sealed to allow
use as air tanks. Rear bumper has intergal (through the tube) 2"
reciever hitch, front has built in winch mount. People have told me they
look like factory or aftermarket parts.

Wayne Cook wrote:

On Fri, 16 Sep 2005 05:02:00 GMT, RoyJ wrote:


I actually was working with some demo programs on Matlab, ran this one
as a test. I figured support on both ends (doubles the load), length is
not a factor (but degree of twist before failure is definately related
to length!) I'll generate the full table to finish testing but the
first pass said that the flat bar was NOT very good in pure torsion. Nor
is it very good in bending mode in the flat side axis.


I agree that it's not very good in those directions compared to the
weight of the bar. However is it good enough for the job is the real
question. Admittedly I'm just going by experience and gut feel but I'm
no where near as worried about it as I was other parts of hitch. There
was a lot weaker portions in this hitch when he started. It's much
better now but I admit that there's still weak points. I still feel
that the bolts or what they attach to on the frame will fail before
the flat bar.


Wayne Cook wrote:

On Tue, 13 Sep 2005 14:23:42 -0400, "wallster"
wrote:



"Wayne Cook" wrote in message
m...


On Tue, 13 Sep 2005 03:15:06 GMT, RoyJ wrote:



The 1"x4" steel bar has about the same polar section modulus (failure by
torsion) as a piece of 2"x4"x .120. It should bend at about 1500 pounds
at the point where the bike mounts. A couple of good chuck holes should
bend it.


Did you figure in the fact that it was held on both ends.


Another thing about the above I should point out now that I've got
more time is that if you look and any of the class 5 hitches out there
now days and you'll see something like 3" x .120" square tube or even
2 1/2" x .120 round tube for the torque member (and that's on the
better built ones I've seen many have smaller tube). I've not got a
table handy but I'd bet that we're in the same ball park strength wise
here.



Wayne, here's how the 1"x4" steel bar is mounted. Roy, i think it's strong
enough for my application, but i DO appreciate your input.
http://www.wallys-speed-shop.com/mounting_bolts.JPG
Also, I welded two 4'x6" 1/4" gussets to the L bracket.
http://www.wallys-speed-shop.com/new_gussets.JPG
here's the finished hitch... i 'm not taking it off anymore!!! (i smacked my
head on the jeep, left a nice cut!)
http://www.wallys-speed-shop.com/painted_gussets.jpg



That looks much better. Of course in any system there's always a
weak link. The trick is for the weak link to be strong enough to do
the job. You've now moved the weak link up to the bolts and frame in
my opinion. Most likely strong enough but keep a eye on the frame tabs
that the bumper is bolted to for a while just to make sure that they
don't start to deform.

A proper receiver hitch would be mounted under the frame for a
distance of about 12" apart for the bolts. This longer leverage helps
compared to the closer spaced holes in the bumper.

I hate to say it at this stage but just for the record I would of
probably of made a extension of the receiver and run it up under the
Jeep for about 12" farther forward than the bumper. Then put something
like a piece of tube or channel across the frame at that point and
tied the extension to the cross piece. This would make for a better
leverage and remove most of the torque on the bumper itself turning it
into more of a downward force.

A easier fix for you at this stage if any sign of problems crop up
would be to weld some brackets under the bumper in such a way that
they go up along the bottom of the frame for a ways and bolt them.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

RoyJ wrote:
I have a Jeep with off road bumpers and the same mounting problems with
the rear as the OP. The 8 bolts go through holes that are on either side
of where the main frame rail joins up to the rear cross member. Both
frame and cross member are relatively thin at .104" The bolt holes are
1.25" on center vertically, 8" horizontally (spaced evenly on either
side of the main rail joint. This is NOT a solid item to bolt to for
straight pull, really flimsy for the torque loading of the motorbike rack.


snipped for space
Roy, your set up sounds great, nice and sturdy. I've been looking at my
rig and I'm about 95% confident in it's ability to carry the load of my
dirtbike. That being said, it's not 100%, and that does have me
concerned. I don't believe i'll actually use the carrier that often but
it only takes one incident to ruin the day. Because this is a '93 Jeep
with 145k miles on it (and it has a salvaged title to boot, seems i
just can't buy anything nice that doesn't need fixing!)I'm reluctant to
drop alot of cash on materials to reconstruct the ass-end of the
vehicle. I just found a class III FRAME mounted hitch on ebay that
would be about $114, including shipping. I'm real tempted to just go
ahead and order it, bolt it on and cut off the hitch I have now.
Here's a link:
http://cgi.ebay.com/1987-96-Jeep-Wra...temZ5616563461
Anyway, thanks for the input... who'd have thought this dopey thread
would have lasted this long??

walt

On Fri, 16 Sep 2005 14:44:36 GMT, RoyJ wrote:

I have a Jeep with off road bumpers and the same mounting problems with
the rear as the OP. The 8 bolts go through holes that are on either side
of where the main frame rail joins up to the rear cross member. Both
frame and cross member are relatively thin at .104" The bolt holes are
1.25" on center vertically, 8" horizontally (spaced evenly on either
side of the main rail joint. This is NOT a solid item to bolt to for
straight pull, really flimsy for the torque loading of the motorbike rack.


Exactly my point.

I used some 1/4"x2" backer plates with radiused ends to match the curve
of the cross member in an attempt to get some of the load transferred
out to the edges of the cross member. That still didn't look good enough
so I ran more 1/4"x2" strap forward on both top and bottom, then drilled
all the way through the frame to bolt the sandwich together with 2 ea 7"
grade 5 bolts per side. Spacing on the through bolts was set to allow
standard tow hooks to be added on either top or bottom.

Perfect fix IMHO.

BTW: bumpers were 2"x5" rectangular tube, tapered ends, sealed to allow
use as air tanks. Rear bumper has intergal (through the tube) 2"
reciever hitch, front has built in winch mount. People have told me they
look like factory or aftermarket parts.

Sounds great to me.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

On 16 Sep 2005 09:23:21 -0700, "wallster"
wrote:


RoyJ wrote:
I have a Jeep with off road bumpers and the same mounting problems with
the rear as the OP. The 8 bolts go through holes that are on either side
of where the main frame rail joins up to the rear cross member. Both
frame and cross member are relatively thin at .104" The bolt holes are
1.25" on center vertically, 8" horizontally (spaced evenly on either
side of the main rail joint. This is NOT a solid item to bolt to for
straight pull, really flimsy for the torque loading of the motorbike rack.


snipped for space
Roy, your set up sounds great, nice and sturdy. I've been looking at my
rig and I'm about 95% confident in it's ability to carry the load of my
dirtbike. That being said, it's not 100%, and that does have me
concerned. I don't believe i'll actually use the carrier that often but
it only takes one incident to ruin the day. Because this is a '93 Jeep
with 145k miles on it (and it has a salvaged title to boot, seems i
just can't buy anything nice that doesn't need fixing!)I'm reluctant to
drop alot of cash on materials to reconstruct the ass-end of the
vehicle. I just found a class III FRAME mounted hitch on ebay that
would be about $114, including shipping. I'm real tempted to just go
ahead and order it, bolt it on and cut off the hitch I have now.
Here's a link:
http://cgi.ebay.com/1987-96-Jeep-Wra...temZ5616563461
Anyway, thanks for the input... who'd have thought this dopey thread
would have lasted this long??


Looking at it I feel you'd be better off just finishing with what
you've got. The class III hitch is light for your use and would
require you to put more extension onto your carrier. It's not rated
for your load up close and I believe it would be too weak once you
extended your carrier.

Notice that it's just got a 2" square tube running across as the
torque member. It's hard to tell from the pic but I'm betting that
it's no thicker than 3/16" wall and possibly less. Your 1"x4" bumper
is as strong or stronger I believe. Next the mounting brackets are
thin on that hitch.

If you'd do like Roy did and put straps top and bottom. Or just put
something like 2"x 1/4"w tube bolted under the frame and running to
the front of the vehicle about 16" or so and attached to the bumper
with a good gusset or the like you'd go a long ways in taking care of
the worst of the weak links that are left.



Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm