Bump stops, limit straps and all of that such

[Rymadd]

Hey so I'm redoing my rear suspension, and trying to get it all set up really good. First off I do everything high speed dunes, logging roads, mudding rock crawling, snow.

I pulled all my leafs out but the top two so I could flex it easy in my driveway. Sitting flat on the stock bump stops my rear tires are about 3" inches away from getting into my flares. However if I flex the rear axle, one tire compresses the flare and gets deep into the actual quarter panel.

I am measuring for shocks right now and wondering:

Are bump stops only for bottoming out the suspension at high speed (axle relatively flat to the body/frame) or do you guys set them up to stop your tire from flexing up into the body? I'm measuring for my shocks and having the shocks outboard of the bump stops makes it tricky because the shock can have lots of travel left when the axle is flat, yet bottom out when it is at an angle.

Thanks, and I have everything I need to fabricate whatever so I don't need to buy the 3" longer ones some of the vendors sell. I just want to set this up right

 

[bmc69]

You already opened the can of worms in your question. LOL. As a former EB MX racer (sorta like TT except on more traditional motorcycle-type MX tracks) and now just someone who plays on the rocks, I can tell you that the stops and limiting hardware are quite different between the two.

Sounds like you are wanting to focus on the high-speed control aspect, in which case you really need to limit the suspension movement to well within the limits of the shocks and in to a fairly narrow range actually. The travel in my MX truck suspension was probably less than a third of what I have in my flexy ole trail crawler...

 

[welndmn]

So I put a chain around the frame and then hook both ends of the chain to the axle of the floor jack, that lets you compress the spring.
I both both, figure where bump is flat compressed, and when flexed. If your tire is in the body and you still have more up travel, cut the body.

 

[broncnaz]

Yep kind of a can of worms when your driving is across the board. Basically bump stops are there to limit upward travel preventing both shock bottoming and overarching the springs. They can also cushion the springs a little before you totally bottom out.
Limit straps are more basic and just limit down travel which if you get airborne may save the shocks if they are not long enough.
For the most part your going to want the longest shocks you can get and just make sure that your bumpstops are the correct hieght so they dont bottom out.
If your just trying to fab stuff up so you dont have to buy shocks well that can be done as well but your leaving a lot of your suspension on the table considering the wide range of driving you do.

 

[Rymadd]

In response to all you guys, I AM trying to get the longest shock I can, and know the limit straps are pretty simple when keeping the axles horizontal from yanking down on the shocks farther then they will go. Not cutting my body anymore haha and so my question I guess would be are my bump stops already good? just order shocks slightly shorter then when the truck is flat on them? then get limit straps to keep them from over extending?

Or do I get some longer bumps to keep the tires out of the fenders when articulating and then be able to fit a slightly longer shocks and maybe try to tune for some more droop (longer shackle/ bigger spin). What do the prerunner guys do?

I know slamming my rear end up into the truck on a jump is mostly going to happen fairly horizontally, and when flexing over things if the shock stops the up travel it will not have very much force because you are going so slow.

 

[Letsgocrawling]

Hey so I'm redoing my rear suspension, and trying to get it all set up really good. First off I do everything high speed dunes, logging roads, mudding rock crawling, snow.

I pulled all my leafs out but the top two so I could flex it easy in my driveway. Sitting flat on the stock bump stops my rear tires are about 3" inches away from getting into my flares. However if I flex the rear axle, one tire compresses the flare and gets deep into the actual quarter panel.

I am measuring for shocks right now and wondering:

Are bump stops only for bottoming out the suspension at high speed (axle relatively flat to the body/frame) or do you guys set them up to stop your tire from flexing up into the body? I'm measuring for my shocks and having the shocks outboard of the bump stops makes it tricky because the shock can have lots of travel left when the axle is flat, yet bottom out when it is at an angle.

Thanks, and I have everything I need to fabricate whatever so I don't need to buy the 3" longer ones some of the vendors sell. I just want to set this up right

This is my take on this picture, bump stops being physical or hydraulic are secondary absorbtion and bump limiting--up travel, hence bump stops, you have two conditions with that, axle strait up or axle in flex or articulation. There will be a differece between the the two at your wheel to wheel well interference. Flex or articulation will always show less clearance at the wheel well during the movement. So figure that to make the bumpstop calculation. Limit straps are just that, during droop-- down movement of the axle the straps or strap come into play. #1 thought it will keep the drive line from binding stopping the axle from going down into to much droop, #2 is when you have that figured out, next is how all that works with the rest of the suspention. I always go back to the old saying---if it was easy the girls would be doing it!

 

[broncnaz]

Bump stops almost always need to be taller/longer especially with a lift. You really dont want leaf springs to go past flat into a negative arch. Also a lot of shocks for lifts will have more travel and need the uptravel limited so they dont bottom. Some shocks will limit suspension down travel and thats usually why extended shock mounts and longer shocks are used. Otherwise your shocks may be your limiting down travel factor.

On upwards travel you have the springs fighting to pushback against the uptravel. If the springs go into a negative arch then there can be issues with beanding or breaking the spring it will also weaken the springs some when this is done and you can get bad reactions when the spring unloads from its negative condition. its basically like axle wrap and you may get wheel hop.

In any case extened bumpstops are always recommened for lifts. Not real sure why hardly anyone includes them in there kits but maybe they have there shock lenght factored in without extened bump stops.

 

[Rymadd]

Yah I have the limit straps figured out, not sure why I said that in the title. It is the bump stops that I still am fighting with. I don't agree with the people that say if you do a 3" lift you need 3 inch longer bumps. I think bump stops are for keeping your axle from getting into the frame or keeping your shocks from bottoming out or keeping our leafs out of a negative arc? At the stock bumps my leafs are pretty far into a negative arc. Should I move the bump stops down to where the leaf is close to flat? This would also help keep my axle out of the fender when flexing and help save the leafs.

I would then be able to probably fit a 12 or 14" travel shock in my setup (doing custom upper mounts)

 

[broncnaz]

Well Im not sure that lift vs height of the bump stops is always the same. But I believe its pretty close. But bumpstops can serve different purposes it all depends on your setup. In the front the bump stops may either keep the springs from bottoming or the axle from hitting the frame or some people may even use them to keep the axle from hitting the oil pan.
I would set the bumpstop height so the springs are flat when fully into the bumpstop. You can probably do a little negative arch on a rockcrawler with no ill effects. But say your out jumping well that negative arch may show itself quickly in the form of broken or bent springs.