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Put your Blazer on a diet

At some point, you have to ask yourself: why start with a K5?
Of course it's easy to say that looking in from the outside, and keep in mind that I've pretty much trashed a really nice K5 in the same process.

With the CG thing, when I messed with finding a vertical CG I had to pick the truck up A LOT to get enough difference in the numbers to make the calculations worth while. Way more than they think you can do in the mag. In theory it doesn't take a big height change, but in the real world, it needed to be up in the air a good bit to make it work. If the numbers don't change much with the front off the ground, you can end up with a lot of variability which means your CG calculations are a waste. Some awareness of the variables involved is a good idea. For instance most scales have some increment they measure in, often your weight will fall in a 20# window which means you don't know if it's at the top or bottom of that window.
One other tip is to block your suspension so it can't extend and compress as you lift it, that can make a big difference. Also keep in mind that you're measuring the height of the total vehicle CG which isn't always relavent for rollover or antisquat calculations. It's interesting and is a big step in the right direction but not THE answer.
 
I guess the only real accurate way to do it would be too lock the suspension and then be able to rotate the whole vehicle like a turkey over a fire to find the true center. But even that is not real world as the suspension still comes into play then.

Maybe the answer would be to find a method that may not be accurate for all situations but just use the method consistalty enough that the numbers generated would be usefull.

I think using a K5 as a start is common just for the simple fact that its a progressive sport and starting with a real vehicle is a great cost effective way to learn what works and what does not.

I keep expecting you to build a tube buggy with Blazer skins any day now. /forums/images/graemlins/thumb.gif
 
Another thing to keep in mind is that for some purposes you want the CoG including unsprung mass, and in some, you want only sprung. These can be substantially different and have a dramatic effect on some things (like suspension behavior) if you don't calculate/use them correctly. And just to make it more interesting, for answering questions like "How far will it go before tipping?", you will need to account for changes in relationships between unsprung and sprung mass.

Ideally, the unsprung CoG is what we want to calculate suspension behavior, and locking the suspension in place is not going to help there…
 
Locking the suspension solid and finding a CG location can lead to a lot of things you need to know when you start applying some math. You can subtract out the weight of the axles and and suspension by finding the weight and CG of each piece. This would leave you with the sprung weight and it's CG for other calculations. It would take me a little while to remember/re-figure how to do this but it's not too hard.

It would also be interesting to raise the front end to the tipping point without the suspension locked down just so you have an actual real world number of when it's going to go over. Of course the fun way to do this is when you're out playing. Keep reverse handy.
 
Well then, perhaps leaving the suspension unlocked would be the better approach as that is normally the case out on the trail.

I might start messing with this one. I would like to try to find the center point of the vehicle and then play around with things like how much weight does make a difference depending on where its placed. Like moving the gas tank forward. We can see the real world results (Dave Cowley (sp?) walking the Rock Pile) but how much forward does it really move the front to back center? 4", A foot?

What is worth it and what isnt?
 
Made some more progress on the truck.

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Made some more progress on the truck

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Hmm seems like both those words are being used VERY loosely! Hehehe /forums/images/graemlins/smile.gif

They say beauty is in the eye of the beholder... this proves it!
/forums/images/graemlins/thumb.gif

Mike
 
ok, this is probably not much, but if you make your skins from cheap aftermarket body panels, they should be a little lighter since the metal is thinner. Probably not much, but along the lines of every little bit /forums/images/graemlins/thinking.gif

Also...If you get the rig quite a bit lighter or are building a full on buggy, couldn't you build a decent dana 44 to handle up to like 40" tires? Wasn't there some little home built rig in Top Truck Challenge a few years ago that was running dana 44's and 44" tires and made it through without breaking them? /forums/images/graemlins/dunno.gif OR if your loaded Mog or Volvo portal axles /forums/images/graemlins/woot.gif
 
Well i finally had a chance to read this topic and have decided to also put my blazer on a diet, nothing serious seeing that i have limited tools/experiance/time and this will be my DD, this is what ive decided on:


Remove hard top and replace with a Specialty Top snap top

Replace tailgate with a PU tailgate (this way i wont have to fix my rear window which i havent been able to get up all the way)

Remove carpet

Reposition battery

AL radiator (needs to be replaced soon anyway)

AL wheels (faaaaaarr future)

Trimming fenders /forums/images/graemlins/hack.gif

Also has anyone mentioned replacing there headers for lighter ones and running a single outlet exhaust system to reduce weight.And replacing the stock hood with maybe an AL one or carbon fiber. Lastly how hard is it to replace the winsheild with lexan and do you get the same visibility as glass? and whats the weight difference for that /forums/images/graemlins/screwy.gif
 
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Also has anyone mentioned replacing there headers for lighter ones and running a single outlet exhaust system to reduce weight.

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removing cast iron manifolds and replacing them with some kind of relatively thin-walled but rust-resistant headers (stainless?) might save some weight... not sure about going from dual to single tho... that weight is pretty low with respect to center of gravity and exhaust tube isn't very heavy to begin with.

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Lastly how hard is it to replace the winsheild with lexan and do you get the same visibility as glass? and whats the weight difference for that /forums/images/graemlins/screwy.gif

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Im not convinced that significant weight reduction can be had here either if the lexan is thick enough that it would be good for a daily driver + offroad machine. If the rig is going to be off-road-only, then it could be pretty thin and there might be some useful weight reduction to be had. Of course, if the rig was going that way, why not ditch the windshield all together? not to many rockcrawling comp rigs have em and if you got rid of it, there is no reason for a windshield frame either (more weight loss!) /forums/images/graemlins/wink.gif

j
 
I plan on trying out the lexan route. It might only be a 35 pound (wild guess) savings but its up high weight so I think it counts more.

I think going to headers amkes a good difference. AL intake also helps. When my water pump goes I plan on replacing that with an AL unit. It might sound like nitpicking but it all adds up.

OK!

I went for an offroad trip that I have not been too since the diet. Huge difference! I was able to power up some sand hills that were hopeless before and take new lines on the rocks with ease. All I have done is reduce the weight.

I did bend in my rear armor. But now it looks used. /forums/images/graemlins/grin.gif
 
I'm not sure what the factory rear window weighs but my lexan one only weighs between 3 and 5 lbs. Finally got it installed and on the truck. I'm happy I went that route. Definitely flimsier than glass but still lightweight.
 
Well I got my fuel cell in. Its a 16 gallon RCI unit with the 90 ohm sender in it. At the very least it will move some weight from behind the rear axle to over it. The whole thing is lighter then the stock skid plate.

tank.jpg
 
Not intending to pee in your Cheereos, but IIRC, those (or some just like them) are the tanks that people have had trouble with out here. The heat apparently causes them to kinda collapse and distort. Apparently people are running plastic tanks inside steel cans to help them hold their shape and protect from the sun. I may be completely wrong, but that looks just like my memory of a tank that a guy showed me last year that looked pretty sad (distorted).

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At the very least it will move some weight from behind the rear axle to over it.

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Hmm, are you tail heavy? Or heavier than you would like? Just curious because I stuck the tank on my truggy as far back as I could to offset the nose weight and move the CoG back as far as possible. Battery and other things were also moved as far back as possible. Still makes for some "interesting" decents, particularly when off-camber. Or is it because the weight changes when fuel level changes? Might make a good argument for putting battery (and tool tray?) behind tank, but still, I would want it as far back as possible with the exception of stabile weight items. That's also where I've got the tank in my new plans, so you have my attention. /forums/images/graemlins/laugh.gif
 
I live in a colder climate. /forums/images/graemlins/thumb.gif

This is the way that I look at it: The gas tank behind the rear axle helps to unload the front axle using the see saw effect (bear with me here). I am basically concentrating on the climbing ability. Moving the tank forward or over the rear axle still has the weight back there but now has a much less effect on unloading the front.

I watched one Dave Cowley (sp?) easily climb the rock pile with no rear bumper, bobbed backend, and the gas tank moved up and forward as far as possible. Hardly any weight at all behind the rear axle. IIRC, he said moving the gas tank was the big thing.

So, I'm going to try it out. I have reduced the weight behind the axle as much as I can without cutting the body off and still running some tube for a bumper. The proof will be in the pudding. /forums/images/graemlins/deal.gif
 
Ahhh, I agree totally. I *LOVE* climbing, and that's what's been killing my truggy a lot lately. /forums/images/graemlins/crazy.gif But my concern, and reason for pushing weight back, is what happens when you need to go down. I've had to drive out of several near front rolls (some that probably felt closer than they were), and frankly the prospect of a forward endo scares the shizzel out-a me! /forums/images/graemlins/eek.gif Especially when there is sometimes quite a ride to the bottom after the first swat. So, it's a compromise thing. Like the hill climber bikes with 7' swing arms and all the weight way out front, they can go up like nobody's business, but that's about it. Just depends on goals... Good luck!

[Edit] I obviously have less weight back there too, with a near 90* departure angle and no body, so that figures in too. Without the tank and battery I would have pretty much nothing back there...
 
I'll also have to watch the endo thing and see how it goes. At least I have that cow catcher on the front. /forums/images/graemlins/grin.gif
 
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