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Official TOTM: AdFab Weight Loss Program

Matt S.

NAXJA Forum User
Location
Fresno, CA
That's right folks, with out talking to any of the mods or people who run this place, I have decided to add spice to the AdFab forum with a Topic Of The Month. I will be doing this one time a month with no perfect interval. Just expect one every month!
This months topic is Weight Loss. In this thread, we will discuss the advantages/disadvantages, how to's/how not to's, and anything else that may come up. Hopefully this will be more than a success for you to understand weight loss, but for you to desire it. The only thing I ask is that this TOTM stay on topic and will get you to start other threads to spur more AdFab work.


First things first. A brief explanation of weight and the terms that you may see used.
Weight = The vertical force exerted by a mass as a result of gravity. If you do not know what weight is, please move yourself to a school where you can become educated
:conceited
Unsprung Weight = The weight of all components not supported by the springs of the car. This includes the tires, wheels, axle assemblies, and ONE HALF of the springs, shocks, and control arms (suspension links).

Sprung Weight = The weight of the chassis. This includes the body, frame, engine, transmission, transfer case, all components mounted to these items, and ONE HALF of the springs, shocks, and control arms (suspension links).
Pig = Slang for a car that is very heavy
Balemic = Slang for a car that is very light.



Start with the advantages/disadvantages of weight loss.


Your Jeep slower now than it used to be? Got a winch and the kitchen sink with you? How about huge bumpers that are not only bullet proof but double as armor plating? Maybe you have to many stickers!
Weight is obviously causing your stock motor to work much harder. Now you need a stroker motor or a v-8 just so you can get out of your own way. When you cut weight out of your Jeep, that straight 6 becomes a "v-8". You want speed? Lose weight folks.

So now your Jeep can go at least as fast as it did as stock. You say " I didn't get a Jeep to drive fast!" Well, how about this. You got that Dana 30 still? I do! Can't afford to swap to a Hi9 or 60? I can't! Problem solved! Lose weight! Regardless of what people say about axle strength, its all relative. Weight plays a large role in part failure. With less stress on your axle shafts, drive shafts, tcase, transmission, and motor... you're less apt to break things. Depending on the terrain you wheel and the driving style you develop, you could make weaker parts last just as long as the stronger parts.

Ok, so I have a better chance of not destroying my Dana TURDY, but how does all this help me off road? I thought the heavier you are, the better the traction? True, but think of this. You ever tried to push a person in a wheelchair up a steep hill? Sucks huh? Ever pushed an empty wheelchair up a steep hill? You can find ways to make it fun! Traction will become important by the tire choice, off road ability is largely effected by the ability to overcome an obstacle. The lighter you are, the better your vehicles ability to overcome obstacles.

Wow! So losing weight is just the greatest thing since sliced bread! But wait, what are the really bad sides of it? If you consider choosing to lead a more healthy lifestyle due to the Jeep weight, not taking your mom and your moms moms valuable kitchen, and thinking more liberal when it comes to tools and spares. The largest disadvantage of cutting weight is that levels of comfort are lost most of the time. A small price to pay in my mind.


How to lose weight on a full body rig: Start with carrying only the tools needed to change the spares you must have. Carry only the fluids you need to get you off the trail. Lose those oversize bumpers and winch cables. Switch to lighter and better designed bumpers and go with a synthetic cable for the winch. Ditch all the interior you can handle. Remove carpet, extra seats, panels, power windows, power locks, etc. DO NOT use bed liner as a carpet replacement! That stuff is heavy and black paint works just fine! Removing doors, dash, a/c, heater and hatch is a great way to lose extra weight, but may not be an option for some. Ditch the stock seats and seat mounts. Go with a good quality light weight seat and hard mount your sets safely to the floor or cage.

How to lose weight on a chopped rig: This is harder than it may seem. Get rid of all glass, ditch the dash, a/c, heater, all unnecessary comforts, lose body panels that bolt on and you don't think you need. I recommend keeping the hood:wierd: . Trim all extra brackets and mounts that are no longer used. Strip wiring harness down to the bare minimum. Do not go overkill with the tube. Use only whats needed to serve the purpose. Run air shocks or coil overs to help eliminate the coil and shock weight. Use aluminum rims. Get quality tires and ditch the spare. Switch to a plastic fuel cell and keep it around 10 to 15 gallons. Basically... be creative with it. Just don't sacrifice the safety of you and others.





Care to add anything? What did I miss? Need more details on it? Testimonials? Examples? Lets build this TOTM to a great tech source.
 
Excellent first topic, which I think is often overlooked in buildups. Mine included. :)

So in relation to strength vs. weight - what would you consider the 'minimum' requirements for reinforcing the unibody structure on something that already has heavy axles and tires, to keep it from fatiguing at critical points but not go over the top with plating everything?
 
this is a good topic..
I have a couple questions.. I still have a full body rig, no interior except dash and seats,
what are some good areas to remove weight now.. I would like better seats, but I am boney so I cant see me bouncing on plastic seats..
are there areas I can drill out to remove weight without sacrificing strenghth?
I have seen removing weight from the hood with a hole saw in the structure, where else can I do this? what about building bumpers with said holes, would they still be strong enough?

with relation to the A/C, has anyone removed the evaporator and kept heat? how much of a pain is this?
I hope to be doing alot of this work this winter.. so I will actually wheel it next year...
 
Ludakris said:
this is a good topic..
I have a couple questions.. I still have a full body rig, no interior except dash and seats,
what are some good areas to remove weight now.. I would like better seats, but I am boney so I cant see me bouncing on plastic seats..
are there areas I can drill out to remove weight without sacrificing strenghth?
I have seen removing weight from the hood with a hole saw in the structure, where else can I do this? what about building bumpers with said holes, would they still be strong enough?

with relation to the A/C, has anyone removed the evaporator and kept heat? how much of a pain is this?
I hope to be doing alot of this work this winter.. so I will actually wheel it next year...

I wouldn't go drilling holes in a unibody vehicle, for the limited weight you'll save you'll be weakening the chassis ALOT. Look at replacing the side and rear glass with plastic, glass is HEAVY. Or just back half it and loose the roof all together.
 
Ludakris said:
this is a good topic..
I have a couple questions.. I still have a full body rig, no interior except dash and seats,
what are some good areas to remove weight now.. I would like better seats, but I am boney so I cant see me bouncing on plastic seats..
are there areas I can drill out to remove weight without sacrificing strenghth?
I have seen removing weight from the hood with a hole saw in the structure, where else can I do this? what about building bumpers with said holes, would they still be strong enough?
I have basically the same questions. I think I've taken out everything obvious. I don't have heavy aftermarket bumpers; I have stockers with tow hooks. I don't even have any sort of audio system, unless you count my CB. And mine is a two-door, so it's already lighter than most.

I can only think of two questions right now. I want to ditch most of my A/C to prepare for an eventual OBA system. Do I need to have the refrigerant professionally evacuated before I start removing stuff?

Also, my doors are removeable, and I'd like to replace the big side windows with Lexan or similar before I go wheeling again. But I don't know what to do about the hatch. Has anyone been able to make the hatch easily re-attachable? I haven't looked closely at the hinges/mounting, but how hard is it to put back on once it's been taken off?
 
Thread is useless without pics. :D

I'm on the biggest looser program: :looser:

FileHandler.ashx


I was about 4600 about two months ago. I am hoping to be 3900 or lighter when I am done. Yeah, thie winshield is coming out too ;)
 
cracker said:
Thread is useless without pics. :D

I'm on the biggest looser program: :looser:

FileHandler.ashx


I was about 4600 about two months ago. I am hoping to be 3900 or lighter when I am done. Yeah, thie winshield is coming out too ;)

weld in some tube to keep her from folding and wheel her as she sits :thumbup:
 
cracker said:
Thread is useless without pics. :D

I'm on the biggest looser program: :looser:

FileHandler.ashx


I was about 4600 about two months ago. I am hoping to be 3900 or lighter when I am done. Yeah, thie winshield is coming out too ;)


I don't know man, I think the "Back to the Future" hover board mod is where it's at...

wideshotfront.jpg
 
If you have ever thing torn apart start looking where the factory ribbign anf reinforcemtns go. You should be able to cut the areas that have no ribbing or reinforcements out. Or section I would think atleast. Like the hood, think four holes and leave the bracing.
 
Weasel said:
If you have ever thing torn apart start looking where the factory ribbign anf reinforcemtns go. You should be able to cut the areas that have no ribbing or reinforcements out. Or section I would think atleast. Like the hood, think four holes and leave the bracing.
forget that, the hood isn't structural so cut out the bracing and leave the sheet. just don't stand on it.
 
anyone have some numbers they can post up. doors, windows, carpet, hvac etc...
 
For a full bodied rig fieberglass fenders and hoods are available fairly cheaply, I'm not sure on the exact weight though. Dr. Dyno has numbers on what a few things weigh on his site if I remember right.
 
I am working right now on getting a large amount of wieghts compiled. I wont let these threads die, but I started this one prior to research.:flipoff:

Good link Brett... forgot about that one.
 
Ramsey said:
anyone have some numbers they can post up. doors, windows, carpet, hvac etc...
the rear seat (both pieces) and rear carpit (for the cargo area) is good for 55lbs... in my 92...
 
97+ xj's are the ones cursed with the fat IMO, with the metal hatch and much heavier doors being the main problems. especially power doors, mine have to weigh 70-80 lbs each. usually before wheeling i lose the fronts but i'm heavy on spares (tire, front shafts, one rear, driveshafts, fluids, tools). next summer i'm looking at losing all four doors with tube doors replacing the rears (to keep my junk from falling out :D) as well as a basic rollcage added. She may be fat but that just means i have to go slower ;)

course all this is speculation: i don't know any exact difference in weight between 97+ and 96- but i would be intersted to find out, all the 96-'s i've owned have been faster on their feet than my 98
 
shortxjdoug said:
97+ xj's are the ones cursed with the fat IMO, with the metal hatch
IIRC - the steel hatch is lighter than the fiberglass...
 
XJ_ranger said:
the rear seat (both pieces) and rear carpit (for the cargo area) is good for 55lbs... in my 92...
And if you're pulling the rear bench you might as well pull the seat belts. It may not seem like much, but all the different pieces add up fast.
 
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