With a suspension lift, You do not gain any additional clearance under compression unless a bump stop is added/extended. A body lift increases the distance from the body to the bump stop without taking away from the suspension travel.
this is mostly correct....
By adding bump stops, you are eliminating compression regardless how much "DROOP" you allow for.
this is wrong.
For example, I've added bumpstop extensions to my suspension, yet I have more uptravel and downtravel than stock.
Suspension lifts actually use up "DROOP". When you put a 3" lift coil in place of a stock coil, you are 3" closer to reaching your maximum droop at ride height. You could "gain" the full potential of the "DROOP" out of your suspension without a single inch of lift.
huh? this makes no sense.
Whether you're at stock height, 3" of lift or 8" of lift, you have some amount of uptravel and downtravel.
If you extend the bumpstops 3" with a 3" lift, then you gain no travel over stock. However, if you extend the bumpstops 1.5" with a 3" lift, then you gain 1.5" of uptravel over stock.
Let's suppose a stock suspension, utilizing 8" travel shocks. Let's assume a 50/50 travel ratio, which is the most common general trail & road use setup. That means at ride height, the Jeep has 4" uptravel, 4" downtravel. Now, if you lift this Jeep, utilizing a 3" lift with 11" travel shocks, and you determine you need 1.5" bumpstop extensions to prevent the shocks from bottoming out, prevent tire rub, and prevent suspension interferences - then you have 5.5" uptravel, and 5.5" downtravel. That's a 1.5" gain in both directions.
A "proper" suspension will still have atleast 4" - 5" of compression at ride height.
this is a rather ridiculous blanket statement. Stock TJ's (and probably JK's) have about 4" uptravel. Most other vehicles have much less. Some even ride on the jounce bumpers, with little uptravel by Wrangler comparisons.
I'm very aware of other reason for bump stops. I've never denied that. I only stated a Body lift allows for tire clearance without limiting the suspension like a bump stop. And we are only talking about small suspension lifts in the 2"-3" range. Those shocks are not that much longer than stock.
bumpstops don't limit
your suspension's capabilities, they protect
the order of bumpstop necessity is as follows:
1. prevent suspension interferences (such as track bar vs diff or other hard component collisions)
2. prevent shocks from bottoming out.
3. prevent coil bind
4. prevent tire rub
notice tire rub is last. If you can't satisfy the rest, then the tires are the least of your concern.
Clearance for tire size is a matter of the distance from the hub center to the fender/steel at full bump & full flex. You can increase this distance in many ways - bumpstop extensions, remove flares (if you're worried about tires rubbing plastic), cut/modify steel/body panels, and move the body away from the frame (body lift). A body lift MAY allow you to run a slightly larger tire size by providing additional clearance, but it doesn't change the necessities of a properly designed suspension.
You still need to prevent the shocks from bottoming out, avoid coil bind, and prevent major suspension interferences....and if you add much more bumpstop extension than that, you're doing it wrong. You should choose the tire size which fits within those constraints.
Having big tires and crap suspension just proves ignorance, whether you have a BL or not.
If you look at the stock shock lengths and what is typically recomended for a 1"-3" lift, more than a 1" Bump stop is not normally needed for the shock length. A longer bump stop is typically needed because of tire clearance.
why do you want to install a longer bumpstop? what's wrong with the stock jounce bumper? why not use bumpstop extensions instead?
Personally, I do not see the benifit of limiting the suspension more than 1" to allow for longer shocks. Requiring more than that just because of shocks would be counter productive. Esspecially when you consider how little comression they have stock.
What are you considering "little" compression/uptravel?
I'm no JK expert, but stock TJs are about 4" uptravel, and I believe JK's are the same if not more....which is within your previous statement of proper compression/uptravel requirements.
How does extending a bump stop 2" NOT take away from the available suspension travel?
because if you have 4" of lift, that 2" bumpstop extension still allows for 2" more travel than stock. Of course, you'll use a longer shock...which has a compressed length such that it's nearly fully compressed with that 2" extension, resulting in a gain of downtravel as well.
If by using a body lift, you are able to reduce that same bump stop to a 1" extended bump stop (instead of 2"), would you gain travel, lose travel, or would the amount of travel stay the same?
again, a body lift does not remove the necessity to properly setup your suspension to avoid 1) suspension interferences, 2) bottoming out the shocks, 3) coil binding.
Ive given you some links ("sources" that you asked for) to help you understand the relationship between a bodylift, tire size, and Bump stops. In those "sources", it also accounted for flat fenders and the additional clearance they provide and how the flat fenders effect the lenght of the bump stop for a tire size.
well, if you're extending bumpstops a bunch because the tires are limiting factor...then your tires are too big.
whether compensating for something lacking in manhood or trying to "look cool" at the mall, the big tires, that don't fit, will not make up for a lack of driving skill or crappy suspension setup. You're better off with proper suspension, smaller tires and better skills.
For anyone interested in good reading on bumpstops, what they do and how they relate to proper suspension setup, here's some good reading (also see signature):
and when talking about "proper" suspension setup, we can even bring into the discussion anti-squat, roll center, coil unseating and other dynamics which greatly effect performance on-road and off...yet these are most often ignored when installing a "lift kit". those things are well beyond this discussion, but if we want to get detailed about it, we'd have to go there as well.
On a TJ, the benefit of a BL is the ability to suck the belly up tighter...high clearance gas tank skids, tummy tucks, MML's, etc. On a JK, the drivetrain is already fairly tucked at frame level. If you guys have a 1" gas tank lift via an aftermarket skid, like us TJ folks have, then I would see the benefit of a BL. If there aren't any component tuck benefits in the JK world, just add the clearance back into the suspension and forget the BL.