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question about bump stops and there effects on flex...

ericfx1984

NAXJA Forum User
Location
Kansas City Area
I was recently reading a thread, which I can not find ATM, that claimed that having proper length bump stops will actually increase flex...

they went on to explain that while the side of your axle hat is going up contacts the bump stop it will act as a pivot point and force the other side down...

I think this makes sense... anyone want to confirm this?

thank you
 
i dont think that is the case. the bump stops are there to keep you from over stuffing your suspension. in the front end it keep the tire from bottoming out out the fenderwell and the fender. it is very crucial on the rear. the bump stops save your leafsprings. it keeps them from being bent upwards and or warped. imho bump stops are one of the main suspension components. as far as flex goes i dont think so. how can the bump stop act as a fulcrum. maybe im wrong but im pretty sure im not.
 
think of the axle as a see-saw

bam. that. just. happened.

on paper if the suspension binds (any 4 link or radius arm) to the point where the weight of the axle and tire/wheel wont go to the full entent of suspension travel. this lever action will help get that tire closer to the ground.

bumpstops don't hurt flex. you just need to get the rest of the suspension dialed in. the longer bumpstop you run, the longer shocks you can run, and the more suspension flex you can achieve
 
bumpstops don't hurt flex. the longer bumpstop you run, the longer shocks you can run, and the more suspension flex you can achieve


:huh: :confused:

Care to explain!!!!
 
:huh: :confused:

Care to explain!!!!


say you have a 4.5" lift. most 4.5" lifts run 10" shocks.

now you decide to run a larger tire and need to bumpstop to fit them. If you run 2 more inches of bumpstops you can run a 2" longer shock such as a 12" travel shock.

12" is 2" more travel than 10"
 
^^^ THIS


















Is definitely not true
Care to explain your reasoning?

Balance > flex.

Learn it kiddies.

X2. Balanced suspension and traction are better than flex. Just because a tire has left the ground doesn't mean you stop forward progress.
A good quote from Goatman I read a while back.
New guys talk about flex, experienced guys talk about stability. New guys talk about how much lift they can get. Experienced guys talk about how little they can get away with.

Ya, flex is good, you do need to be able to articulate over things. But you do get to a point where flex just becomes too much and doesn't do anything. That is why companies make money on bumpstops and limit straps, for those who realize having a balanced, well designed suspension is better than one tire dropping 20+ inches. Traction is key, and even if a tire is still touching the ground, if that tire has no weight on it, its not doing anything.
 
say you have a 4.5" lift. most 4.5" lifts run 10" shocks.

now you decide to run a larger tire and need to bumpstop to fit them. If you run 2 more inches of bumpstops you can run a 2" longer shock such as a 12" travel shock.

12" is 2" more travel than 10"

that makes since but what about your coil becoming unseated
 
^^^ THIS


















Is definitely not true
YES




















It is.

I have so much flex that my coils will come unseated by almost 4 inches. 4 inches of that flex is useless. When I get the time and money, I plan on buying limit straps and lowering my lower shock mounts in order to limit my droop.
 
Correct me if I am wrong but bump stopping limits up travel but do nothing to increase down travel.
 
Either way, flex is overrated.

Balance > flex. Learn it kiddies.

X2. Balanced suspension and traction are better than flex. Just because a tire has left the ground doesn't mean you stop forward progress.
A good quote from Goatman I read a while back.

I don't know where you guys wheel, but I'm glad I don't go there. Where I come from you definitely need to have some flex. You can have all the balance in the world, but try to crawl over a boulder field and you will struggle for traction as your tires leave the ground. We have have steep hills, tight corners, huge ruts, tight tree squeezes, and large boulders. Flex is very important to keep tires on the ground and maintain traction when going uphill over large boulders, roots, and trees. I have seen well balanced rigs with little flex lift tires and loose traction, or just bounce as they hit a log crawl or boulder field. The trails I wheel have so many big obstacles it is often the guys with tons of flex that do the best. Bottom line is it depends on what you want to do. If you mostly hit mud holes and relatively flat trails with no large obstacles then a balanced rig might be best for you. If all you do is rock and log crawling then you may be better off with more flex. No matter the case I feel that achieving a proper balance between the two always yields the best results.
 
I don't know where you guys wheel, but I'm glad I don't go there. Where I come from you definitely need to have some flex. You can have all the balance in the world, but try to crawl over a boulder field and you will struggle for traction as your tires leave the ground. We have have steep hills, tight corners, huge ruts, tight tree squeezes, and large boulders. Flex is very important to keep tires on the ground and maintain traction when going uphill over large boulders, roots, and trees. I have seen well balanced rigs with little flex lift tires and loose traction, or just bounce as they hit a log crawl or boulder field. The trails I wheel have so many big obstacles it is often the guys with tons of flex that do the best. Bottom line is it depends on what you want to do. If you mostly hit mud holes and relatively flat trails with no large obstacles then a balanced rig might be best for you. If all you do is rock and log crawling then you may be better off with more flex. No matter the case I feel that achieving a proper balance between the two always yields the best results.

i've wheeled all over the country. i was denied on two obstacles in moab bc i didnt have a front locker, never had an issue in penrose, CO either bc i didnt have "enough flex"


these obstacles big enough?

Penrose259.jpg


oh man not enough flex here. needed about 2 more feet of downtravel to keep the rubber on the rocks. kept going though

Penrose256.jpg
 
this thread has soooooo much fail in it.

you guys need to start asking yourself why we want articulation in our suspensions.
here is a hint, its not for one reason or another, its for many reasons.

the most important reasons to have "flex" are to keep the rig stable and level regardless of the terrain and to keep the tires on the ground with weight of the vehicle against them to maintain traction. so you don't want to be dropping springs off the perches, then you are getting almost no ground pressure and you will loose traction, but at the same time you don't want to limit your articulation so much that the suspension cannot contour to the terrain.

there are a lot of factors that play in to how a suspension travels- link geometry, spring rate, shock length, spring height (coil), vehicle weight, spring length (leaf)

when talking about a link suspension:
in an ideal world you would figure out the maximum wheel travel based on your link geometry (which in an ideal world would be perfect geometry) then you would build and mount your shocks, springs, brakelines, driveshafts, vents, etc so that they don't hinder travel anymore

for example lets look at a hypothetical:
if you were to cycle your suspension with no springs or shocks, and you realized that you had say 6" of upward travel before your tire contacted the fender, or the upper arms contacted the frame, etc. you would then bumpstop to that. then you cycled it down and discovered you had say 8" of droop before your control arms were bottomed out against the mounts, or the joints had fully misaligned and your suspension was bound. now you know that you have ~14" of travel available to you, so you need a set of shocks that can travel 14" and a set of springs that can do the same. you would then mount your shock so that full compression of the shock the axle is all the way against the bumpstop and then mount a limit strap so that it is holding the weight of the axle at full droop.

in a leaf spring system you would adjust your shackle angle and length until you got the desired amount of up and down travel without inverting the spring or inverting the shackle, and then limit strap and bumpstop accordingly and mount your shocks the same way in the linked suspension (full bump and full compression at the same point, limited at full travel of the shock)

now, none of us live in an Ideal world with our XJ's. we have to work our suspensions around an existing platform, that means our link geometry will be less than Ideal. also, most of us aren't running coilovers or airshocks that have tune-able spring rates to give us the perfect amount of travel to keep suspension weight on the tires at all times.

since it is really difficult to get any extra uptravel out of our suspensions, due to all the stuff in the way, some people run longer bumpstops so that they can mount the shocks lower and get more droop out of the suspension by sacrificing up-travel.

my .02 is that you bumpstop enough to prevent your tires from contacting your fenders, your shocks from bottoming out, and your upper CA mounts from hitting the oil pan. and then you run a limit strap to prevent the shocks from being torn apart by the weight of the axle.
 
I don't know where you guys wheel, but I'm glad I don't go there. Where I come from you definitely need to have some flex. You can have all the balance in the world, but try to crawl over a boulder field and you will struggle for traction as your tires leave the ground. We have have steep hills, tight corners, huge ruts, tight tree squeezes, and large boulders. Flex is very important to keep tires on the ground and maintain traction when going uphill over large boulders, roots, and trees. I have seen well balanced rigs with little flex lift tires and loose traction, or just bounce as they hit a log crawl or boulder field. The trails I wheel have so many big obstacles it is often the guys with tons of flex that do the best. Bottom line is it depends on what you want to do. If you mostly hit mud holes and relatively flat trails with no large obstacles then a balanced rig might be best for you. If all you do is rock and log crawling then you may be better off with more flex. No matter the case I feel that achieving a proper balance between the two always yields the best results.
So you agree that flex is overrated. Balanced flex is important. A tire with no contact pressure provides the same traction as a tire in the air. If you have monster flex up front and zero in the back, you're still gonna suck. It's important to balance the flex.
 
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