Technical Assistance

Jan 22, 1999
11
0
0
Call to All:

This was not a good weekend road trip to Prescott for the "Green Worm."
First, I didn't get two miles from the house before a Blazer hit me in the
side; the damage is minor but I need materials engineering assistance. Next,
I got about halfway between Phoenix and Prescott and I rear tire separated
and tore up the wheel box; I need some fiberglass assistance.

Materials Engineering: I know the aluminum sheet is .062 thk, aerospace
quality, and can be TIG welded. Does anyone know what grade; e.g., T-6061.
I'd also like to get confirmation on my proposed method of repair.

Location: The location of the 6 - 8 inch tear is at the same water line as
the stripe, and about 28 inches behind the fuel intake box. Until I get a
chance to remove the bunk bed and panel, I can only assume no ribs were
damaged. It appears from the outside that the impact just went in like a can
opener.

Proposed method of repair: From inside the coach, flatten the aluminum sheet
and attempt to align the cut seams and set the contour. Next, from the
inside, tack weld (TIG) a backing plate the covers the damaged area. From
the outside, TIG weld the seams shut. The backing plate should not only give
the area support but will provide material for the weld to bond to. Grind
the welds and finish smooth.

Fiberglass wheel box (driver side). From what I understand a lot of GMCers
have experienced a blowout and have had to repair the wheel box. The damage
is pretty extensive, basically the tread blew away the entire front portion
of the wheel box (9 inches wide by 18 inches vertical). I've been told this
is common, has anyone built a plaster or wooden mold of the wheel box from
the top curvature down to where the box bolts to the floor? The parts manual
shows that a single wheel box is used for both driver and passenger sides.
Therefore the mold would be the same as the passenger side, rear portion of
the wheel box.

Assuming, no one has built a mold, does anyone know where I can purchase a
product that would allow me to make a mold of the passenger rear portion;
e.g., modelers clay. I can then build a form for laying-up the fiberglass. I
know gravity will be working against me, but I'm out of ideas.

I saw Bebe in Prescott on Saturday. Purchased one of his bottle jack support
brackets that fit under the rear boggie. I still need to acquire a 1/4 inch
piece of steel to fit between the boggie and torsion arms, but I can see
where I'll never need to carry a floor jack to raise the rear of the coach.
Great idea and a great weight saver!

In advance, I appreciate and thank anyone's input on either the aluminum
material and fiberglass repair.

Mike & Dolores' 77 Palm Beach michael.andrews
 
Mike & Dolores' 77 Palm Beach michael.andrews
>
>
>
That was a bummer Mike! Contact Jim Bounds on advice on rebuilding the
wheel well. He did a beutiful job on mine and I think I had more damage
than you did. (I know-small consolation)

Mike, wht kind of tire blew. Make, size, load rating, etc.

>

David Lee Greenberg
GMC Motorhome Registry
200 Macfarlane Drive PH 4
Delray Beach, FL 33483-6829
800-827-9989
 
>
> Materials Engineering: I know the aluminum sheet is .062 thk, aerospace
> quality, and can be TIG welded. Does anyone know what grade; e.g., T-6061.
> I'd also like to get confirmation on my proposed method of repair.

Mike, at first glance, 6061-T6 should be strong enough.

> Proposed method of repair: From inside the coach, flatten the aluminum sheet
> and attempt to align the cut seams and set the contour. Next, from the
> inside, tack weld (TIG) a backing plate the covers the damaged area. From
> the outside, TIG weld the seams shut. The backing plate should not only give
> the area support but will provide material for the weld to bond to. Grind
> the welds and finish smooth.

That would be a tough way to make the repair - lotsa welding and excess
weight. I'd only use welding on the ribs if they're damaged. IMO, you
need to find an aircraft shop, or at least a body shop that knows how to
work aluminum. You'd probably be better off to cut the damaged area out
and flange the hole. Be sure to match the body contour before attaching
the patch. Then you can either tak weld or flush rivet the patch in
place. The rest is standard bodywork stuff - just remember to use an
etching primer on any bare aluminum.

A quick call to Jim Bounds or Alex Sirum might be in order too. I'm
sure they've made this sort of repair many times.

Good luck.
Patrick
- --
Patrick Flowers
Mailto:patrick

The GMC Motorhome Page
http://www.gmcmotorhome.com
 
The fibergalss wheel liners can be bought from Alex Sirum. Hew advertises
them on his seb site. I am still at a loss what aluminum you are talking
about since the body from the roof rail down is fiberglass. Would like to
know what tires you have on the coach and the rating and pressure.Did you
have D rated tires?

>Call to All:
>
>This was not a good weekend road trip to Prescott for the "Green Worm."
>First, I didn't get two miles from the house before a Blazer hit me in the
>side; the damage is minor but I need materials engineering assistance. Next,
>I got about halfway between Phoenix and Prescott and I rear tire separated
>and tore up the wheel box; I need some fiberglass assistance.
>
>Materials Engineering: I know the aluminum sheet is .062 thk, aerospace
>quality, and can be TIG welded. Does anyone know what grade; e.g., T-6061.
>I'd also like to get confirmation on my proposed method of repair.
>
>Location: The location of the 6 - 8 inch tear is at the same water line as
>the stripe, and about 28 inches behind the fuel intake box. Until I get a
>chance to remove the bunk bed and panel, I can only assume no ribs were
>damaged. It appears from the outside that the impact just went in like a can
>opener.
>
>Proposed method of repair: From inside the coach, flatten the aluminum sheet
>and attempt to align the cut seams and set the contour. Next, from the
>inside, tack weld (TIG) a backing plate the covers the damaged area. From
>the outside, TIG weld the seams shut. The backing plate should not only give
>the area support but will provide material for the weld to bond to. Grind
>the welds and finish smooth.
>
>Fiberglass wheel box (driver side). From what I understand a lot of GMCers
>have experienced a blowout and have had to repair the wheel box. The damage
>is pretty extensive, basically the tread blew away the entire front portion
>of the wheel box (9 inches wide by 18 inches vertical). I've been told this
>is common, has anyone built a plaster or wooden mold of the wheel box from
>the top curvature down to where the box bolts to the floor? The parts manual
>shows that a single wheel box is used for both driver and passenger sides.
>Therefore the mold would be the same as the passenger side, rear portion of
>the wheel box.
>
>Assuming, no one has built a mold, does anyone know where I can purchase a
>product that would allow me to make a mold of the passenger rear portion;
>e.g., modelers clay. I can then build a form for laying-up the fiberglass. I
>know gravity will be working against me, but I'm out of ideas.
>
>I saw Bebe in Prescott on Saturday. Purchased one of his bottle jack support
>brackets that fit under the rear boggie. I still need to acquire a 1/4 inch
>piece of steel to fit between the boggie and torsion arms, but I can see
>where I'll never need to carry a floor jack to raise the rear of the coach.
>Great idea and a great weight saver!
>
>In advance, I appreciate and thank anyone's input on either the aluminum
>material and fiberglass repair.
>
>
>Mike & Dolores' 77 Palm Beach michael.andrews
>
>
>
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
"The beautiful Mohawk Vally"
 
Mike

Alex just bought two GMC "junkers" (I just hate calling any GMC a
junker) for parts. Bodys on both are real nice. It might be more
prudent to call Jeff or Alex and get the "section" you need. They
also have the mold for the rear wheel close-out (fiberglass
section over wheels).

Alex 941-763-1121

Mike

- -----Original Message-----
From: owner-gmcmotorhome
[mailto:owner-gmcmotorhome]On Behalf Of Andrews,
Michael (AZ15)
Sent: Sunday, May 23, 1999 5:49 PM
To: 'gmcmotorhome'
Subject: GMC: Technical Assistance

Call to All:

This was not a good weekend road trip to Prescott for the "Green
Worm."
First, I didn't get two miles from the house before a Blazer hit
me in the
side; the damage is minor but I need materials engineering
assistance. Next,
I got about halfway between Phoenix and Prescott and I rear tire
separated
and tore up the wheel box; I need some fiberglass assistance.

Materials Engineering: I know the aluminum sheet is .062 thk,
aerospace
quality, and can be TIG welded. Does anyone know what grade;
e.g., T-6061.
I'd also like to get confirmation on my proposed method of
repair.

Location: The location of the 6 - 8 inch tear is at the same
water line as
the stripe, and about 28 inches behind the fuel intake box. Until
I get a
chance to remove the bunk bed and panel, I can only assume no
ribs were
damaged. It appears from the outside that the impact just went in
like a can
opener.

Proposed method of repair: From inside the coach, flatten the
aluminum sheet
and attempt to align the cut seams and set the contour. Next,
from the
inside, tack weld (TIG) a backing plate the covers the damaged
area. From
the outside, TIG weld the seams shut. The backing plate should
not only give
the area support but will provide material for the weld to bond
to. Grind
the welds and finish smooth.

Fiberglass wheel box (driver side). From what I understand a lot
of GMCers
have experienced a blowout and have had to repair the wheel box.
The damage
is pretty extensive, basically the tread blew away the entire
front portion
of the wheel box (9 inches wide by 18 inches vertical). I've been
told this
is common, has anyone built a plaster or wooden mold of the wheel
box from
the top curvature down to where the box bolts to the floor? The
parts manual
shows that a single wheel box is used for both driver and
passenger sides.
Therefore the mold would be the same as the passenger side, rear
portion of
the wheel box.

Assuming, no one has built a mold, does anyone know where I can
purchase a
product that would allow me to make a mold of the passenger rear
portion;
e.g., modelers clay. I can then build a form for laying-up the
fiberglass. I
know gravity will be working against me, but I'm out of ideas.

I saw Bebe in Prescott on Saturday. Purchased one of his bottle
jack support
brackets that fit under the rear boggie. I still need to acquire
a 1/4 inch
piece of steel to fit between the boggie and torsion arms, but I
can see
where I'll never need to carry a floor jack to raise the rear of
the coach.
Great idea and a great weight saver!

In advance, I appreciate and thank anyone's input on either the
aluminum
material and fiberglass repair.

Mike & Dolores' 77 Palm Beach michael.andrews
 
The body is fiberglass from the beltline down and is aluminum above that. Except
the end caps which are all fiberglass.

> I am still at a loss what aluminum you are talking
> about since the body from the roof rail down is fiberglass.