Blizzard's GMC 6500 Conversion Project -RumRunner, New pictures! October 26th Options

[blizzardND]

Hey guys I finally have my ideas together enough to post a PDF file of my project. The 2 real criteria for this project was sleep/travel 4 and fit into my shop/storage Garage door is 9'-0"

What I found is a 2001 GMC 6500 100K miles, 3126 Cat 210hp 605 tq, fuller 6sp manual w/ OD 3.07 rear gears with 19.5 low pro tires 245/70R19.5
The truck has air ride rear, hyd. rear disc brakes and air ride seats. AC and Cruise is nice too!

I have a client that can laser cut and form my steel frame components and they will become the structure to weld in my floor cross members.

Conversion weight;
So far with most of the shell figured in; with the exception of the front over the cab nose piece- The interior furnishings such as flooring, dinette, bed and cabinets; as well as shower surround and sinks. Also not figured into my weight computations are the wiring lighting and plumbing (although the weight of the 50 gallons of fresh water are included). so far the weight has risen to 6211 lbs.

Without spending an entire evening running the math, I'm guessing 1/4 on the front axle and the balance on the rear. Figuring a 1/4 split this would change my rear axle weight from 3100 to around 7758lbs and my front axle from 5860 to around 7412lbs. Which as I type this, I realize that my front axle is rated for 7000 so I may want to move my batteries and generator further to the back perhaps on the drivers rear where my propane tanks are and move them forward or across to the pass side rear.

Anyway it is just a drawing at this time, the truck is in our heated attached shop, paid for and insured. I'm not in a hurry, and I still have our Roadtrek if we have the urge to travel. As a matter of fact we are leaving in the RT for Elkhart IN on Thursday to find deals on RV parts and to save on freight. We will rent a U-haul for a one way trip to haul home our treasures!

Here is the link to my PDF File, when there is something cool to post, I'll post pictures too!


Blizzards GMC 6500 Conversion pdf

blizz

This post has been edited by blizzardND: Oct 26 2009, 10:26 AM

[Bill B]

Looks like a darn cool project, please keep us up to date.

[Adios]

.

Without spending an entire evening running the math, I'm guessing 1/4 on the front axle and the balance on the rear. Figuring a 1/4 split this would change my rear axle weight from 3100 to around 7758lbs and my front axle from 5860 to around 7412lbs. Which as I type this, I realize that my front axle is rated for 7000 so I may want to move my batteries and generator further to the back perhaps on the drivers rear where my propane tanks are and move them forward or across to the pass side rear.

A
blizz

Nice design and drawings. If the drawings are to scale, I would spend the entire evening and the next day running the numbers on the front axle weight. You will find it to be much greater than what you estimate. I have built 3 different bodies on my 2004 IH4400 and front axle weight is always the problem. Run the numbers before you commit. Good luck with the project.

[blizzardND]

Nice design and drawings. If the drawings are to scale, I would spend the entire evening and the next day running the numbers on the front axle weight. You will find it to be much greater than what you estimate. I have built 3 different bodies on my 2004 IH4400 and front axle weight is always the problem. Run the numbers before you commit. Good luck with the project.

Thanks for the tip, I was thinking as I typed that hmmm, this might be a bit heavy on the ft axle.

3 bodies on the same truck? I think my finance director is giving me one shot at this, so I better make it right.

It's been a long time since I had to figure load calculations, might have to dig up some old notes.

I wonder why they would build a truck that only had 1200#s to spare on the front, that just doesn't make much sense. heck fuel and 3 guys in the cab would put you over. I supose they figure everyone will build a long rear overhang to offset the balance and take #'s off the steering axle. My design would see a lot of driveway scrapeage if I put much rear over hang; plus I need as much of my "floor space" in the dropped area as I can. We don't need a longer rear bedroom.

I'll start by moving Batteries and genny to the way back, good thing copper has dropped in price. when in Elkhart I'll look for a fiberglass over the cab extension to save weight, or I'll build that section out of aluminum, and bolt it to the steel cage.

thanks again for the advise, this is my one shot, so I have to do it correctly.
-blizz

[Stanley P. Mille...]

Folks tend to spec the front axle as light as possible for a better ride. Options to look at should include moving the rear axle forward to change the front loading.

[bstark]

As Rick and Stan have already pointed out, you should consider carefully and explore any and all avenues to keep your front axle as light as possible. I'm going to suggest you consider replacing the location for your fresh water with a fuel tank instead and delete a forward one. You will run with a full fuel load more often than with full water. Aside from the expense of cabling, considering moving batteries rearward and installing heavy items like your invertor with an eye to your weight bias rather than convenience. I cannot remember ever seeing a design with those side skirts forming an integral part of a 'coach' body' that will enhance torsional rigidity. You may want to consider what effects, if any, frame flex will have on your structure above the waistline. My theory would be that the heavier you make the rear portion of your rig the better as you need to overcome the rather rigid suspension a couple of heavy rated air bags will be providing, the more you can 'squish' the ride the less frame twist you'll have as a constant.

The HDT conversions that utilize heavier welded side skirting traditionally begin low and end low with no "superstructure" to contend with as a welded integral part of the side skirting. The ones that have added a type of Drom box, have done so in a manner of keeping it separate from the lower toter body. The two can behave in differing dynamics without causing stress on each other.

My truck at 205" w/b scales fully loaded at over 17,600lbs and with the softest bag I could get at the time (04) at 15,500lbs, with a 7 gal ping tank, and a 5/8" crossover air line between the bags and tank, I still get torsional twisting of the frame as design-allowed by 'huck bolted' crossmembers. My bike barn is a separate structure from the rear toter body and sits like a saddle over the fram rails with little internal flexing. The toter body, being much longer was designed to accept some torsional flex but the highest point at the two top corners of the light 'tiara' have consistantly been a point of concern. To attempt to build a rigidly welded cage structure incorporating the outside perimeter lower side skirts and of the height and breadth of a coach body, I would do everything possible to reduce the normal flexing of the trucks original frame by softening the response at each rear wheel to allow the wheel to rise with minimal transferring of force to the frame.

This post has been edited by bstark: Oct 22 2008, 11:02 AM

[bstark]

As an aside to my previous post, I would like to enquire what previous duty your truck was designed for with those "tight" rear gears of 3:07? When spec'ing my truck, International responded to the salesman's input of my requested 3:08 ratio inconcert with a full ten spd with O/D and 300hp, with a "what's he using this truck for?" Only after assurances that the truck was performing RV duty did their engineering dept "sign off". I would not have advised yoju to go the 19.5" route but in your case they may prove to be a "god send" with those rear gears. Your truck could very easily be spun up to a higher Hp/Tq but must be done so with an eye on that tranny as it is probably torque rated to 700Ft/Lbs. or less.

[blizzardND]

As an aside to my previous post, I would like to enquire what previous duty your truck was designed for with those "tight" rear gears of 3:07? When spec'ing my truck, International responded to the salesman's input of my requested 3:08 ratio inconcert with a full ten spd with O/D and 300hp, with a "what's he using this truck for?" Only after assurances that the truck was performing RV duty did their engineering dept "sign off". I would not have advised yoju to go the 19.5" route but in your case they may prove to be a "god send" with those rear gears. Your truck could very easily be spun up to a higher Hp/Tq but must be done so with an eye on that tranny as it is probably torque rated to 700Ft/Lbs. or less.

The truck was owned by a rural electric/telephone co-op, they had 3 the same and I was told they were used to transport spools of telephone wire. I saw a picture, it looked like a flatbed with an "A" frame to spool off the wire. They are trading them in one at a time for MDT Freightliners. It sat for a long time, I'll bet trade in values on the next 2 will be a bit harder.

As for the Engine/transmission. I asked in a previous post about the engine transmission combo and was told

The transmission is a Fuller 8406A with 6th being a .78 OD

aug 25 2008
bstark wrote:
"blizz: You're in luck on the tranny, as that is the highest torque rated manual fuller 6spd (the only 6spd with this rating) at 860Ft/Lbs. and all of the FS/FSO 6sp series are fully synchronized trannies.

You at least know that the tranny will withstand a HP boost. It has an over-all ratio spread of 9.04 with 1st being 7.05,2nd-4.13,3rd-(your favourite)is 2.52,4th - 1.59, 5th - 1.00 and the 6th is an overdrive of .78. She'll back up fairly quickly with a 6.75 reverse ratio.

You might ask them what that suspension listing refers to as it states 7,000# which is the front axle rating while the rear axle is I believe the Eaton 17,600 rated which would probably be fitted with 15,500lb air bags.

I don't plan on upgrading the engine at this time, I'll run it a while and see how she pulls (or doesn't) it's real flat around here, and if you can catch one of the 5 days a year the wind doesn't blow, you shouldn't need too much HP

About my frame design, you really have me wondering about frame flex, with my interior plates being bolted directly to the frame, and it doesn't show very well in my pdf but all of those plates have a 2" flange formed both top and bottom to form an I beam down the frame rails. will I have a problem with the frame flexing between the jointed ends of my support plates?

Also by having everything tied together will I be asking for trouble in the cab to box area. My plan was to sheet the front of the box with 1" FRB (the same fiberglass coated plywood used on Commercial Box vans), I'll bolt the cab solid to the FRP and in turn, bolt the FRP to the first set of tube uprights and roof bow. Also, if you look carefully, notice the blue inner plates that reach under the cab, I will bolt down thru the cab floor to tie the floor of the cab to the top flanges of the plate to help keep the cab from flexing on the FRP. My whole theory on this design is trying to pattern the frame structure after the bus style RV's in which every thing is bolted or attached directly to the frame structure without any that I can tell isolation. I figure the must just control Noise Harshness and Vibration (NHV) thru the use of proper springs and shocks.

This flexing concern has me wondering how all these enclosed race car trailers I've been studing lately control there flex? The certainly do not have near the frame that I would have with the use of my inner plates.

On a different thought, with my need to drop the center of the frame 11" for head room, would anyone have an idea how I would be able to mount this box in a more conventional and possible lighter/cheaper fashion?
-blizz

[hjsdds]

Blizz, congratulations, it's good to see "homegrown" activity on the MDT side. Most of it was more in evidence on the "overcharged" HDT side and it always puzzled me "why not MDTs"? After all just as many MDTs come up for sale used and become availalble for "tinkerers".
The frame twist is the fact of life for both MDTs and HDTs. The flex is allowed or "restricted" depending what is being done to the truck or what service it is likely to see. From running open rail with just a fifth wheel to carrying cement mixer on it. Depending on the "service" frame rails can be cut, extended stiffened (by insering rails inside rails) and the frame material can be purchased in different strength grades. There are companies that do that exlussively and hardened steel rails are available from distibutors who again just do that. These distributors will also fabricate and sell you cross members and assemblies to keep the frame together. You can also purchase high strength huck bolts to bolt things together and they are available in a variety that does not require $6,000 huck bolt setting tool. I can give you more details if you PM me.
You should not drill or mount anything throught the top flange, it's a "no-no". If you are going to hard mount it an L bracket bolted through the rail side wall is preferable. Avery common way of mounting things on MDTs (and HDTs) is to use long U-bolts that go down around the frame and a spanning plate on the bottom of the frame rail. Again there are supliers who will sell you these, just give them dimensions. We used this method to mount this deck on the back of the HDT.

On this project we also needed to extend the frame 7 feet. We purchased 80,000 psi hardened rails to do it. These were bent for us to fit the Volvo frame perfectly, the shop also bent and supplied an inner sleeves to strengthen the frame in the area where the two frames were joined (welded) and a cross braces to install in the added section. A common practice when using U-bolts is to separate the box from the frame with "something" which range from hard plastics to rubber to hardwood.

By the way I had a 3.07 rear end on my International MDT (4700) and that was with only a four speed Allison tranny. That sucker would go like an ass on a loco weed, had no problem getting it up to 85 mph in the fourth.

hjs

This post has been edited by hjsdds: Oct 22 2008, 06:06 PM

[bstark]

Blizz; I remember the info on the tranny now and you did score on that one! It's always nice to have a more robust trans than needed for available torque, simply adds to the reliablity factor. I sincerely hope I haven't unwittingly discouraged you in any way. My desire is simply to help foresee any potential problem areas. This project will undoubtedly inject some new life into this forum as those of us who've designed and built our own rigs are a minority but I suspect there are lurkers with that "why not" syndrom just waiting out there for stimulous.

The process of cross country assistance has already begun with Henry's post and I suspect he will also be passing the word around to others who will venture input. I will further postulate that you'd better keep a significant portion of a hard drive free for the incoming ideas. This is going to be fun for a lot of us.

[blizzardND]

Blizz; I remember the info on the tranny now and you did score on that one! It's always nice to have a more robust trans than needed for available torque, simply adds to the reliablity factor. I sincerely hope I haven't unwittingly discouraged you in any way. My desire is simply to help foresee any potential problem areas. This project will undoubtedly inject some new life into this forum as those of us who've designed and built our own rigs are a minority but I suspect there are lurkers with that "why not" syndrom just waiting out there for stimulous.

The process of cross country assistance has already begun with Henry's post and I suspect he will also be passing the word around to others who will venture input. I will further postulate that you'd better keep a significant portion of a hard drive free for the incoming ideas. This is going to be fun for a lot of us.

I am really looking forward to this project, It is taking the next step as the finance director and I will leave early tomorrow (thursday) to travel to Elkhart IN to pick up some of the heavier bulky items that are hard to ship. Once in my possession, I can design around them. So I may only be able to check in via my pocket pc over the next few days.

any suggestions or off the beaten path shops we should check out please post!

blizz

[blizzardND]

I am really looking forward to this project, It is taking the next step as the finance director and I will leave early tomorrow (thursday) to travel to Elkhart IN to pick up some of the heavier bulky items that are hard to ship. Once in my possession, I can design around them. So I may only be able to check in via my pocket pc over the next few days.

any suggestions or off the beaten path shops we should check out please post!

blizz

This is another PDF that I forgot to include with that first set, it kind of shows the progression of my frame/skirt assembly It would make more sense if it was in 3D but I have not had the time to convert all these parts into a 3D model and starting with the 2D truck from photos and tape measure it would not really be feasable for me to model it. If only GM had a website with models.

link: Truck Frame Progression

-blizz

[U Long]

Hi Blizz. It's inspireing to see that people still think outside of the normal RV on the lot. I did a Volvo 610 back in 2002, home built. Some of the things I see in your plans that you should keep in mind on the lay out. Axel weight to wheel base, load and tire are very important. Need to do home work on what you have now (load) and what you want(load). Droping the frame ..OK, What about drive line angles?? Befor you put the box on, build the tow hitch, and brake lines(air lines?), so you can pull a toy trailer. The frame flexing is a big deal. Most cab to box is done with a boot. The cab set separate of the box. Not me, I had to do it the hard way. I made a conection at the bottom and top(above the doors) , cab to box. I went back about 14" behind the doors and cut off the sleeper. So the cab is part of the box. The cab is clamped to the frame just like the box. No air ride cab. So far with 150,000 + miles on the conversion A OK. I used 60 thousand aluminum for the box(102" X26'). FRP gets wet on the cut edge and comes apart with age. Go look at the bottom edge of a older moterhome. What about heat and air conditioners??? ON top or under box?? How is the plumming going to run to get to the tanks? Propain tanks and lines ... are they near each other?? Water tank , water pump, hot water tank and water lines locations. Gray water lines and vent. Roof vents with fan and hood. Lots of things to think about. It looks like you are making this for short trips. I know storage inside and out goes fast. Don"t get side tracked and stay with it. I spent two years planing and four mounths every day and I still do modfications as I need them. I know hjow it"s put togather and how it's comes apart. Hope this helps and it's good to see a project starting. If I can be of any help, let me know. u-n-sue

Attached File(s)

 DSCN0185_2.JPG ( 10.53K ) Number of downloads: 66

 

[U Long]

Hi Blizz I'm trying to send a picture of my project. I see that I got the interior looking from the cab to the back. The picture of the HD is a little durty, had to go elk hunting. Wating for it to rain to wash it. Ha Ha. u-n-sue

Attached File(s)

 DSCN0191_2.JPG ( 10.11K ) Number of downloads: 122

 

[blizzardND]

Hi Blizz I'm trying to send a picture of my project. I see that I got the interior looking from the cab to the back. The picture of the HD is a little durty, had to go elk hunting. Wating for it to rain to wash it. Ha Ha. u-n-sue

We had a great trip to Elkhart they were practically giving things away: like hatches, windows, and upholstery. We bought new captains chairs, microwave, dinette, water and black and gray tanks. Picked up a 13' electric awning for 300 dollars. bought a rebuilt Onan 5500 genny for 1700 with warranty. Bought so much stuff that we needed to rent a u-haul trailer to bring it all home. Then they wanted $821 for a 5 day one way rental. I bought a new 6x10 enclosed trailer for little more than double the rental. its now in front of our office forsale.

I spent the last few days since we got back placing my newlly found treasures into my plans. I moved the genny,both saddle fuel tanks, and the Gasoline tank, house batteries, and propane all back behind the rear axle.

Spent the day crunching numbers. everything minus cabinets, sinks dinette set and Electical appliances I calculate, unit weight 5528# on rear axle and 989# on the front axle. That puts my rear axle near 8000# and my front near 6500# for a total fueled and water, propane at 14,500. adding another 1000# in misc and the above I should be right in my 15-16000# target .

If you have been following a thread on the HDT forum I have found Michelin Tires XDE 2+ 265/70 R 19.5's that I may run with only the outer dual, but I will finish the unit completly, then scale it. Dropping those inner 2 steel wheels and 95# tires would knock nearly 300# off my truck. We'll see.

enough rambling, I just thought I'd give a breif update.
Blizz (still married even after our shopping spree)

[bstark]

Good stuff Blizz. Especially like the prices you paid for some of those goodies! Wow!

[blizzardND]

End of the year report;

Progress has been made!
My individual steel parts drawings may go out tonight so they can be cut and formed for delivery right after the 1ST. To me that is the 1st real step as I need those plates and channels before I can cut the frame to stretch it.

I have relocated most of the heavy stuff to the rearest of the truck, behind the rear axle, this sadly made the unit longer than I wished, but it needed to be done in order to balance the load to the rear and take weight off the front axle. With this setup, I am around 10,009 on the rear and 6838 on the steering axle.

The steering axle is close to my limit of 7K but the base wieght of 5860 was measured with the 35 gallon saddle tanks and their mounts and ??fuel still located directly behind the front tires. With the tanks moved to the rear, I should have room for at least another 200lbs of misc. on the ft axle and still bring me back to the 6800.

The rear axle is rated for 19000, I will have fully loaded with water & fuel & gasoline roughly 10,500 total on that axle.

I read with interest a thread on running the outside duals on the HDT page yesterday, I noticed a chart for axle de-rating mentioned and I found that chart for my Eaton 19060S rear axle. It is listed as "not approved" so I'm not sure what that means for me, I really didn't expect them to warranty it. No where did their charts allow for my 3:08 gears either.

I noticed that Motorhome applications get uprated a bunch more 41000 lbs, than school bus 31000 or constuction 31000 max gross wight, but I don't understand the Max gross wt of City delivery at 60K / 50K /45K depending on Operational Road Grades. Perhaps it is because those trucks stop frequently to allow bearings and such time to cool?

I am still of the persuasion that with 2000 lbs of my 10500, being the axle itself, and my limited milage (less than 5000/year) this axle will last forever with a set of single 285R19.5 Michelin XDE 2+ Tires rated at 6385lbs each mounted outboard by themselves. But having said that, the mention of more tire to cushion the load, and the ability to carry across potholes as mentioned in that thread has me looking back more conventionally, perhaps to a pair of narrower lighter rated tires.

I have raised my roof to 8'10.5" to clear the 9'-0" garage door, in doing so I have dropped the fantastic fans down into the roof with the front one draining rainwater forward when the rig is standing still. The rear one will be forward of the A/C unit which is allready dropped 8" the crankup TV antennea will lay next to the offset A/C unit to protect it from trees, and cut down on drag as it would scrape the garage door opening.

I have attached links for both my weight spreadsheet and my drawings, both are rather incomplete and scattered, much like my mind but I have a good ieda what this is going to look like and wanted to share what I have so far with you guys.
-merry Christmas,
-blizz

Spreadsheet PDF file
Drawings PDF File

[blizzardND]

Update, Jan 11 2009,

Well I did it, I took a saz-all to my 6500 frame rails, took about the length of a song on the radio for each of the 4 cuts. I went through 3 blades, they were still ok, but they cut better new.

I removed all the brakes lines, air lines, and both saddle tanks, then spent all day yesterday grinding, chiseling and punching or 32 rivets. Broke my favorite hammer that I've had for over 20 years. Replace all the rivets with grade 5 flanged 1/2" bolts. I'll be using those bolts and holes to bolt my plates and channel rails to the frame.

But she's in 2 pieces rolled the axle section back 6 ft and I'm ready for my steel parts. I'll post pictures on Monday.

-blizz

[bstark]

blizz, keep it coming, love to see some pic's as you go. Those side frame plates have got my interest piqued!

[J.W. Morgan]

bliz,

looks like tonight you will get to live up to your name! Keep warm! Wish my shop was finished Then I may not be so stir crazy in this weather.

This post has been edited by Pipeline Mechanic: Jan 11 2009, 11:08 PM