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post #1 of (permalink) Old 11-01-2002, 06:05 AM
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Body and suspention lift

Acording to trail master you shouldn't combine the two. Why? And what are the pros and cons of each? They wouldn't answer this question due to liabilities, that in itself is a good reason to use Super-lift.
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post #2 of (permalink) Old 11-01-2002, 07:27 AM
 
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Re: Body and suspention lift

...and Superlift doesn't recommend tires bigger than 36". It all comes down to liability - you always see guys who go out and buy the biggest suspension and body lift possible, get like 18"+ of total lift, drive like nuts on the street and kill someone. Then they go out and try to sue the manufacturer of the lift to pay for their stupidity.

Both can be used - it all comes down to common sense. A reasonable combination of both is fine - just don't get carried away.

Bottom line is that it all comes down to stupid people ruining things for everyone else - those same people who get ORV closed off. Be sensible, and remember that lifted trucks can't take turns at 100 mph. When you lift a vehicle you increase your center of gravity and can't drive as fast/aggressive as you used to.
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post #3 of (permalink) Old 11-01-2002, 10:13 AM
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Re: Body and suspention lift

The center of mass starts getting too far from the asphalt. As the center of mass gets further and further from the ground the center of gravity gets higher and higher and it becomes more and amore unstable.

6+3 is a common lift. If you're going that high you might as well go with an 8" suspension lift from BDS.
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post #4 of (permalink) Old 11-01-2002, 04:02 PM
 
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Re: Body and suspention lift

<font face="comic Sans MS">Uh... A 6" suspension + 2 or 3" body lift will likely keep the center of mass/gravity considerably lower than an 8" suspension lift... This is because the heaviest components (frame, engine, transmission, fuel tank, etc, all stay at only 6" of relative lift while body is up a bit higher... This still increases COM, however not as much as straight suspension lift does...</font>
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post #5 of (permalink) Old 11-01-2002, 05:50 PM
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Re: Body and suspention lift

With increased body flex and frame flex you don't gain much with a body lift over a full suspension lift.

You might be surprised just how much sheetmetal weighs. I don't think there would be much, if any, gain by going with a 6"+2" over an 8" full spring lift.
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post #6 of (permalink) Old 11-01-2002, 08:15 PM
 
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Re: Body and suspention lift

<font face="Comic Sans MS">I'm sort of curious exactly how you justify saying that... For the sake of argument, we'll use the following numbers... Body: 800#... Engine, tranny, frame, etc, etc, etc: 1500#. Note these #'s are only for the sake of discussion, as I do not feel like going outside in the cold to weigh the body of my vehicle, and then frame, engine, etc just to make my point...

Now I would like you to explain to me how moving the full 2400# of weight upwards 8" keeps the center of mass lower or the same as moving effectively 1500# of the weight only 6" up and the remaining 800# up the other 2-3"... [img]images/graemlins/crazy.gif[/img] According to the physics I've learned the statement you made is impossible...

And if you have any more doubt that it will at least make a little bit of a difference go ahead and draw the situation out... [img]images/graemlins/crazy.gif[/img] Granted it might not be a *ton* of difference depending on a variety of variables, but it is there, can be calculated, and therefore *is* relevant to discuss... </font>
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post #7 of (permalink) Old 11-01-2002, 09:23 PM
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Re: Body and suspention lift

You're dreaming if you think that the body only weighs 800lbs. I can get that with two doors, a box, and a core support. That's forgetting neat things like the tailgate, the front fenders, the hood, the inner wheelwells, and a 500+lb cab. This is skipping piddly-dink stuff like the radiator and all the [bleep] that hangs off the body under the hood (how about a 70lb battery, eh?). Unless you're some kind of goofball you're going to raise the 80+lb bumpers too so you might as well consider that part of the body.

Let's say the motor weighs 700lbs (we're talking a smallblock with all of its [bleep] hanging off it). NP208 and a 700R4 together probably weigh in the 400lb range (250 for the trans and 150 for the case). 500lbs for the raw frame (guessing since I cut up a 77C20 frame this summer), no neat stuff like fuel tanks which weigh ~40 without fuel in them.

If you start doing the math on the unsprung weight you will start to realize that a body lift doesn't benefit you that much as far as COM is concerned. Sure, there's a benefit, but not that much. Add the fact that you now have more frame flex (the twist from corner to opposite corner) the benefit becomes even smaller.

Start talking things like a K5 which has a very large and heavy body and a relatively small frame (shorter I should say) and it becomes even more obvious. You take the newer trucks which have even more bull**** hooked to the body, more weight in the cab, a wider but thinner frame and you really begin to realize how little weight is hooked to the frame.

All in all, a body lift is a cheap lift. It still raises things, well, the distance from the rockers to the asphalt gets larger. The frame and drivetrain is still down there up close and personal. The body mounts see a lot more stress. The frame sees more twisting and flexing. Sure, the difference between having a body lift and suspension lift will be noticeable in the corners, but not by much. The problem with a spring lift is that they can twist (the bigger the arch the more torque applied to the mounts) and you often get a rougher ride.
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post #8 of (permalink) Old 11-01-2002, 09:42 PM
 
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Re: Body and suspention lift

<font face="comic Sans MS">Now how did I know it'd seem like it would turn out once again as a bit of a pi$$ing match?

What part of "for the sake of argument" do you not understand? Was just pulling numbers out of the air to make a point... That any mass you keep lower, keeps the COM lower. Bottom line, end of story... Indisputable fact... [img]images/graemlins/crazy.gif[/img] I mentioned several times that the #'s didn't mean sh**, just there to make a point...

I also mentioned that you may not notice a huge benefit from body lift, but there is a little... Plus a little body lift lets you keep your springs lower...

I am not a big fan of either form of lift, and think it should be used in conjunction with fender modification in order to *really* keep COM as low as possible... [img]images/graemlins/crazy.gif[/img]</font>
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post #9 of (permalink) Old 11-01-2002, 11:03 PM
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Re: Body and suspention lift

It's only a pissing match because you said it was.

You make it sound like there is a big difference between the two lift combinations. Your numbers showed that you believe that there is a big difference between the frame-mounted weight and the body-mounted weight.

Springs don't weigh a whole lot. I looked at a pair of BDS 4" front springs for my truck today. They don't weigh much. And most of the weight will be found near the axle and not at the eyes. Therefore, spring curve has little to do with it. It'd make more of an impact for a person to clean out their glovebox.

In reality, quite a bit more unsprung weight is moved when a body lift is applied than one might think. I imagine the difference between the two lifts is minute. I never said that the center of mass didn't change. I said that the resultant stress caused by a body lift wasn't worth it. If someone is going to go with 4+2 then they might as well go with a plain-jane 6" and not worry about having their box swapping paint with their cab.

I agree with fender trimming after 6" of suspension lift. Chances are that if you're running a lift like that you've got wider tires and wider rims with offsets that stick the tires out well beyond stock. However, I don't like fender trimming on something that's going to be used for street use. Butchered fenders don't look cool. If everyone had the money to spend on a set of cutout fender flares like Jason's (which look pretty good) then life would be grand.
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post #10 of (permalink) Old 11-01-2002, 11:24 PM
 
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Re: Body and suspention lift

<font face="Comic Sans MS">Well if it's not, I'm certainly perceiving it that way... [img]images/graemlins/crazy.gif[/img] Perhaps due to the attempted (or apparently attempted) twisting certain things, and harping on numbers that were made up anyhow, and was stated as such from the beginning... Have had similar experiences in various debates/topics before...

I told everybody straight out that I basically pulled those #'s out of the air for the sole purpose of discussing it... The absolute bottom line is that every component you can keep closer to the ground keeps your center of mass closer to the ground... That was all I was saying...

</font><blockquote><font class="small">In reply to:</font><hr />
Springs don't weigh a whole lot. I looked at a pair of BDS 4" front springs for my truck today. They don't weigh much. And most of the weight will be found near the axle and not at the eyes. Therefore, spring curve has little to do with it. It'd make more of an impact for a person to clean out their glovebox.

[/ QUOTE ]

What the sam hell are you talking about? I'm talking about a little thing called "suspension flex"... The more arched the springs are the worse they will flex (and the rougher the ride will be, with various exceptions of course, and taking into account everything including thickness and number of leafs in the packs, etc)...

</font><blockquote><font class="small">In reply to:</font><hr />
In reality, quite a bit more unsprung weight is moved when a body lift is applied than one might think.

[/ QUOTE ]

Actually 0 unsprung weight is moved with *either* type of lift... The unsprung weight is axles, and tires basically, since they aren't supported by the springs, hence the term "unsprung weight"... [img]images/graemlins/crazy.gif[/img]

</font><blockquote><font class="small">In reply to:</font><hr />
However, I don't like fender trimming on something that's going to be used for street use. Butchered fenders don't look cool.

[/ QUOTE ]

Actually if done right one will be *very* hard pressed to tell they've been cut/trimmed what so ever(even without cutout flares), unless somebody who really knows the vehicle type (i.e. off roader, etc) eyeballs it... Most of the population will have no clue... I have seen a handful that were done *very* nicely, certainly not 'butchered" or a hack job, etc... IMO properly trimmed/radiused fenders look better than stock in many cases, as long as it's tastefully done... [img]images/graemlins/crazy.gif[/img]</font>
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