Spare tire location - Aerodynamics and centre of gravity

[blistovmhz]

:dunce:

What is the point of this conversation?

Quit hauling around so much chit or deal with it. Should have dropped in a diesel if you were worried so much about economy.

Just because lots of guys can't get their junk tuned properly, doesn't mean no one should. I figure my average fuel economy saves me about 10 or 15% over what most guys spend. That's money for more steel and rubber, and it's greater range on the trail before I have to refuel. Ran into some guys on a longish trail last month who thought I was crazy for only bringing an extra 20L with me and they were sure I'd be walking out for a fuel run. Made it out with 1/3 of a tank remaining plus my 20L can. Everyone I've asked has said to bring a minimum extra 40L if you plan on making it through. Also, I've got roughly double the horsepower of those guys. All the nay sayers can eat a big bag-o-dicks while they putter their way behind me, and then run out of gas.

*edit* They'll need that bag-o-dicks to keep up their energy while they push their heeps home

 

[XJLI]

Is this really an issue? You're getting betting fuel economy with twice the power, an extra half a ton, and tires 8" taller than a stock cherokee. What else more do you want? Like other people said, cut all the extra shit off and lose the weight. Go back to stock, leave the V8.. maybe you'll push 28 MPG if you can keep your foot out of it.

This thread boggles my mind. I'd be stoked if my stock V8 truck got the mileage your modded rig gets.

 

[iluv83vettes]

Is nominating still a thing?

 

[blistovmhz]

Is this really an issue? You're getting betting fuel economy with twice the power, an extra half a ton, and tires 8" taller than a stock cherokee. What else more do you want? Like other people said, cut all the extra shit off and lose the weight. Go back to stock, leave the V8.. maybe you'll push 28 MPG if you can keep your foot out of it.

This thread boggles my mind. I'd be stoked if my stock V8 truck got the mileage your modded rig gets.

Its two issues. Everyone keeps forgetting the cog which IS a big issue. I'm just trying to solve the big issue without raping my fuel economy.
No, my current mileage ain't a problem in the same way that the HP from my 4.0L wasn't a problem. I just dig efficiency and more power. For me, wheeling is as much about the drive as it is about the build. Now that my jeep is at a point where nothing breaks and there's not much for trails in the area that are technically challenging, I'm focused on really fine tuning my rig. The cog IS a problem that needs to be solved, and I will solve it in a way that doesn't come at the cost of efficiency.

Also, what stock v8 truck (beyone 2000) gets less than 18 or so mpg? Even my engine donor (05 Sierra 1500 with an auto) got 18ish mpg, and that's at around 6500lbs.

 

[XJLI]

Fill your unibody rails with lead or cut the roof off.

My truck is a 95.

 

[blistovmhz]

That's the other thing. While I'm still planning a cage, I really have to decrease the COG first as the cage will add another 250 sprung I figure I can lose some of that by truggying the back, which also solves my spare tire issue. Options!

 

[rockclimber]

you could start by getting rid of that parkbench you have for a front bumper.

ditch the roof rack unless you are using it specifically for transporting something.

you're not likely to get a flat in a tire like that daily driving. ditch the tire carrier and throw in a set of plugs for emergency/trail repair. keep your spare in camp on wheeling trips for when you really need it.

and remember, it's an overweight brick. take what you can get.

 

[blistovmhz]

Been thinking about the front bumper for sure. I may very well ditch it when I get around to caging. That'll lose an easy 50lbs or so, while also cleaning up my approach angle (though that said, with my lift, my approach is actually still pretty respectable).
The basket get's used often enough that I haven't removed it, but again, when I cage, the basket will disappear and I'll build a modular basket that I can just drop in place when I need it.
I've never had a flat. I have no idea how. Out of everyone I wheel with, I hit things harder and faster, and I'm 2000lbs heavier. They blow beads or collect bead sand and we constantly have to reset their beads (had to do 3 tires on my roomies truck last trip out), or they blow sidewalls and have to borrow my spare to get home. Realistically, my spare is more for other people than myself. If I didn't have some strange health problem that knocks me out when I over-exert myself, I wouldn't bother with a spare at all, but as it stands, I absolutely can't risk being stranded (long story on that one).
I always carry plugs.

 

[rockclimber]

I still vote ditch the tire carrier.

put the spare inside if you absolutely have to have it.

or do nothing and be happy with what you got.

 

[DJTimyD]

Is this really an issue?... This thread boggles my mind. I'd be stoked if my stock V8 truck got the mileage your modded rig gets.

What boggles my mind is the overwhelming negative attitude some people have towards a fellow wheeler, someone with a ton of on trail and in garage experience. What is wrong with trying to fine tune his right to decrease his COG without sacrificing fuel efficiency, and perhaps improving it as well? I can just see you guys at a local meet-up... Standing in the corner putting down everyone else's rig, while pissing and moaning about your skyjacker lift kit giving you fits.

If you disagree with his goal, move on. If you have something constructive to add to the discussion - great.

And @blistovmhz, I agree about the bag of dicks. Put your money into the steel, not into the tank. I have considered aluminum bumpers because of weight. Everything out there is either Nerf bar or park bench as @rockclimber put it. With the crazy over-engenering on some of these bumpers, the unibody channels will twist way before the bumper does. Sweet bumper dude on your twisted up XJ.

I follow this thread with great interest because your ideas and possible solutions can be applied to a wide range of fab and wheeling skill levels.

Good luck and keep the progress updates coming...

 

[blistovmhz]

The bumper vs the uni is an interesting question. A very solid front bumper, properly tied well into the uni-frame, actually stiffens things up dramatically, but that of course, just forces the twist to occur further down the frame. Ultimately it's an all or nothing proposition. You either plate everything, or you make your bumpers twist easily. I competely raped the rear end of my XJ with my rear bumper before I figured this out. All plated now.

As for weight reduction... It's not as big a deal on fuel economy as you might think. Thermodynamics. An object in motion, stays in motion. Yes you use more fuel to accelerate and to climb, but on a flat road, that mass really doesn't hurt much except a bit of additional load from bearing friction. Around town and while wheeling, the mass is very obviously detrimental to economy, but I'm really mostly concerned about cruising economy first. Trail economy is nice to have, but not at the expense of a rig that flies apart.
I've never liked my front bumper sticking out, but it does make a handy step. I unfortunately can't pull it back very far because my radiator goes all the way to the bottom of the lower support. I can pull the winch back about 2" with some very fancy fabrication, or I can say screw it and just hitch mount my winch, and suck the bumper in flush. The question then is, "do I want to use my winch as a bumper"? I'm undecided on that so far.

 

[themauler]

Thermodynamics. An object in motion, stays in motion.

Thermodynamics :huh:

I hope you meant just physics. Newton would be pissed.

What boggles my mind is the overwhelming negative attitude some people have towards a fellow wheeler, someone with a ton of on trail and in garage experience.

Negative attitude? He asked for all of the ideas. He is hell bent on making a jeep more aerodynamic. Chrysler produce the xj for 20+ years. I think if they would have figured out how to make it more aerodynamic they would have.

I heard pirate4x4 is a good place for nothing but positive attitude and help on aerodynamics.

 

[blistovmhz]

Thermodynamics :huh:

I hope you meant just physics. Newton would be pissed.



Negative attitude? He asked for all of the ideas. He is hell bent on making a jeep more aerodynamic. Chrysler produce the xj for 20+ years. I think if they would have figured out how to make it more aerodynamic they would have.

I heard pirate4x4 is a good place for nothing but positive attitude and help on aerodynamics.

And for roughly the 7000th time, this thread is, as I've stated repeatedly, more about the COG than the fuel economy. Really not sure how I can make that any more clear. Either way, your post contributes precisely nothing to the thread, much like the probably 20 others that haven't actually commented on COG whatsoever, and instead have focused entirely on bashing me for wanting to build a hypermiler (which for the 7001st time, is not what this thread is about).
Once again, I need to lower my COG. Spare tire is in a bad spot for several reasons. Thinking roof may actually be a better spot with regards to COG due to the fact that I'd only be moving the tire up there, instead of the entire carrier. The caveat to that plan is that I don't want to hurt the fuel economy I already have, but for the 7002nd time, that is well beyond a secondary concern.

My god the bullshit that goes on any time anyone mentions fuel economy. Incidentally, I get heaps of guys PM me to discuss mileage issues and I help them increase their economy very often. They just don't bring it up publicly anymore because of idiocy such as that which has gone on in this thread. ****, you can start a thread stating that you're getting 10mpg on a stock XJ, and have 40 guys start chanting "It's a Jeep thing LOL" before hurling insults.

Either way, I've already said I'm going to do some actual testing to see what's what, and I'm probably going to either cut the hatch to lay the tire in the back, or just deal with this problem when I get to the cage as it opens me up to more possible mounting options.

 

[xjintx]

I have since added my Hi Lift mounted to bar too. I can still use back seat if I ever needed it. Mines a 2dr so maybe not as much clearance in a 4dr??? That is not my soare that is actually just a tire I had in shop to test.

 

[rockclimber]

And for roughly the 7000th time, this thread is, as I've stated repeatedly, more about the COG than the fuel economy. Really not sure how I can make that any more clear. Either way, your post contributes precisely nothing to the thread, much like the probably 20 others that haven't actually commented on COG whatsoever, and instead have focused entirely on bashing me for wanting to build a hypermiler (which for the 7001st time, is not what this thread is about).
Once again, I need to lower my COG. Spare tire is in a bad spot for several reasons. Thinking roof may actually be a better spot with regards to COG due to the fact that I'd only be moving the tire up there, instead of the entire carrier. The caveat to that plan is that I don't want to hurt the fuel economy I already have, but for the 7002nd time, that is well beyond a secondary concern.

My god the bullshit that goes on any time anyone mentions fuel economy. Incidentally, I get heaps of guys PM me to discuss mileage issues and I help them increase their economy very often. They just don't bring it up publicly anymore because of idiocy such as that which has gone on in this thread. ****, you can start a thread stating that you're getting 10mpg on a stock XJ, and have 40 guys start chanting "It's a Jeep thing LOL" before hurling insults.

Either way, I've already said I'm going to do some actual testing to see what's what, and I'm probably going to either cut the hatch to lay the tire in the back, or just deal with this problem when I get to the cage as it opens me up to more possible mounting options.

putting the tire on the roof would be worse. I ran my 33" up there for a while, when I moved it to a rear swingout (similar to yours) it did much better.

however, the best option is to leave it off or move it inside.

when I wheel moderate/easy trails the tire stays on. when I go on harder trails the whole carrier comes off and stays in camp.

 

[DJTimyD]

Either way, I've already said I'm going to do some actual testing to see what's what, and I'm probably going to either cut the hatch to lay the tire in the back, or just deal with this problem when I get to the cage as it opens me up to more possible mounting options.

Moving it inside will help both for sure. I keep mine off when daily driving and throw it in when I wheel. I do that because I use the jeep as a "moving Van for my cheap ass friends that pay in beer and Pizza" most of the time and I need all the room I can get. My tire size affords me the ability to lay it flat without cutting. Lucky me.

If you do go the roof rack way, pm me please. You mentioned a modular system... And that's exactly what direction I wanted to go. Plug and play for hunting, camping, fishing, ems, and so on.

 

[831_xj]

If u plan to wheel steeper stuff put it fairly high.. mines even with roof line and angled with the rear window.