4-link bump stops, opions please!!!

[notaf-ingjeep]

Hey guys, I am finally getting ready to mount my 14" fox coilovers! I've been working on this 4-link for about a year. Getting these coilovers mounted was a little more difficult than I had anticipated. None of this project was easy, but I am a horrible perfectionist. I am a professional machinist building parts with tolerances of .001". So I end up building these brackets to extreme tolerance only to weld them to a 35 year old frame. It's frustrating, everything moves about .040" no matter what as soon as you weld it! On top of that, to a frame that is in no way perfect. Anyway, My 4-link is bad ass, it's just taken a while. I've learned that you can really only build this sort of thing, well, not perfect at least by my standards. Anyway I've got my C.O. mounting figured, I just want some opinions on my bumpstops.

The easiest way for me to mount the bumps would be off of the crossmember that I've built for my coilovers. The crossmember is 1"x 3", 1/4" thick rectangular tubing inset in the frame. The bumps would mount to the crossmember and hit the UPPER LINKS, the bumps would be just like the stock rubber ones. They would contact the upper links about 2/3 up the links, closest to the axle. I've used 3/4"-3/4" heims, I know they are a bit small but they are the same as the cruiser built competition buggy I copied the 4-link from. My links are solid 1.5" steel bar stock, 35" long, and machined to except the heims. The upper links are angled at 18.5 degrees to the center of the axle, from the frame. I know that it would be better for the bumps to contact the axle directly. It's going to be soo much cleaner if I did like this. Some day, I might want to add some air bump stops, in this case I would go to the axle. I want to see how this thing works first, so I'm not planning to add these air bumps any time soon, if at all.

What do you think? Are any of you running bumpstops off of your suspension linkage? My old beast is a crawler and definently not trying to be a trophy truck. I am just not wanting to learn the hard way if at all possible. I want to keep this all as simple and clean as posible. So let me know what you think about my bumps hitting the upper links. I apreciate all your help very much.
thanks
Sterling

 

[John Smith]

All the cool kids seem to run air bumps these days. Poly Performance Inc. :: Bump Stops - JK Synergy Suspension Systems, Fox Racing Shox, Beard, CTM, Johnny Joints®, Currie Enterprises, Edelbrock, Total Chaos, Ramsey Winch, Walker Evans, Wilwood, Mastercraft, CNC Braking, Sway-A-Way (RaceRunner) Shock

 

[mrqtipp]

I am no expert in this matter but I think if you are going to the trouble of linking your rig and using coilovers the point is to have a tunable suspension and you will want a progressive uptravel bump. Air bumps are easily tunable and well worth the effort.

I have seen bump stops on the links but mostly they have been air bumps

I would love to see some detailed pictures of your build.

Please post

Good luck

 

[notaf-ingjeep]

I think your right, it is probably worth the extra $. I looked at some websites, I should be able to get set up for under $500. I would think that a 2.0 fox air bump is enough to do the job. I am only running 5" up travel, so the 2.5" travel bumpstop would be good. It will only cost $40, for each mounting bracket. Using a pair of those brackets I think it will be super easy to mount up. I can try to get some photos up, but I only have a Video camera. So maybe after I get this thing rolling I'll post a video of this thing getting rowdy.

 

[Mace]

FOA OFF-ROAD Shock Absorbers ,FOA Springs, Coil Over, Offroad

 

[BellyDoc]

I'd love to see pictures of what you've built.

Am I reading you correctly that you used 1.5" diameter solid round mild steel alloy for your links?

I've seen solid heat treated aluminum, round and machined I-beam versions. I've seen DOM steel tube, and I've seen hardened chromoly tube. (I went with the latter, 2" 0.250" wall).

I've never seen solid mild steel.

My concern is that the very design concept of a linked suspension is that thanks to the spherical rod ends, the links only transmit push and pull. Once you hit it somewhere in the middle with a bump stop, you're also asking it to resist a bending moment. This is a completely different family of stresses than you'd otherwise get, and not only on the link, but on the rod end and it's mount.

I don't have any desert racing experience, but my understanding is that trophy truck rear links or radius arms that have a shock mount along their length are often made with welded plate sides so that they're trussed against this sort of force.

I'm not saying you're going to go bombing around in your cruiser like a baja racer, but you may hit your bump stops harder, and more often than you think. Every surprise rut in the trail, every rock step you come off of, and every time you back off of an obstacle for a second try, you're going to be hammering your link in the middle of it's shaft.

That doesn't seem like a good idea to me.

 

[notaf-ingjeep]

Yeah I agree, it looked like a simple way to throw some stops in. It would be much better to mount the bumps straight to the axle. I've spent a lot of money allready on this 4-link, so I was thinking quick and cheap. The truth is I just dont know how perfectly it is all going to work, I'm doing the best I can, while making it all fit. I just got my crossmember and upper coilover mount finished and welded in today. My coilovers are going to be a tight fit. I have started to become exhausted trying to think everything through. So I am going to finsh my lower brackets on the axle this weekend...... in theory, and just try it out. I am pretty sure I have covered all of my bases, it should work well, only time and testing will tell for sure. Once I get it put together I plan to cycle the suspension and see where my tires are going to rub. See where I need to limit the travel, and order some straps and probably some 2.0 fox air bumps.

For now I need to figure out how to get these coilovers in there safely. All I have at the house is 2 high lift jacks. I need to jack it up another 10" from where it is on the jackstands and get the bolts to line up to get them in. It sounds pretty scary to me trying to load those things in while it is perched on the high lifts. Then With a floor jack pump up the axle an inch or less untill the bolts line up. This is one of the smaller details I blew off and figured that I'd cross the bridge when I got there. So, I guess I'll try that, if I can't get it to work, I'll have to get the cruiser down to the machine shop and use the fork lift. Moving this old bitch without springs is something I really don't want to do.

Anyway, I'll try to borrow a digi camera and snap some pics. I have a lot on my plate as it is, so documenting it all hasn't been a priority. I apreciate everyones input, it is helpful.
thanks
sterling

 

[brokenparts]

I used a highlift and some good sturdy jack stands to get my coilovers in.

 

[landcruisnman]

Pictures please*******

 

[woody]

engine hoist....grab the rear frame rail and lift

 

[KillerPea]

Considered Timbrens???

 

[notaf-ingjeep]

Considered Timbrens???

I don't know what that is my friend.

 

[mookie]

i saw a thread on pirate the other day about some new edelbrock bump-stops that are around $100 each....

on the links...i have 2" .25 wall dom lowers and they are bent all to hell, next time i hope to use solid aluminum if i can find a good deal on it, or .50 wall dom

x3 on the engine hoist to put your coilovers on with, you can find them pretty cheap on craigslist used sometimes....makes it super easy to adjust them later on too, and works good to check your articulation and clearances with too

 

[notaf-ingjeep]

i saw a thread on pirate the other day about some new edelbrock bump-stops that are around $100 each....

on the links...i have 2" .25 wall dom lowers and they are bent all to hell, next time i hope to use solid aluminum if i can find a good deal on it, or .50 wall dom

x3 on the engine hoist to put your coilovers on with, you can find them pretty cheap on craigslist used sometimes....makes it super easy to adjust them later on too, and works good to check your articulation and clearances with too

Good thinking on craigslist, I bet I could get a used one cheap. I will start looking, I will need it soon though. Since I have pretty much dedicated myself to this kind of build it would be usefull. Its hard to want to drop the cash on something I wont use much. The more I do this kind of serious fab, the more I think that just buying one will be well worth it. I'll probably use it more than I might imagine.

On your links being bent, that is why I went solid. They are solid 1.5" 4130, they were a lot more work and cost, than just welding in some inexpensive bungs though. It was pretty easy to get a good left handed tap, I think it was like $40 or something. The 4130 was cheaper, and WAY stronger than a good aluminum alloy. Aluminum is sick stuff though, light, but brittle. It wont bend without being seriously comprimised and would likely just straightup break. It would be the best thing for a super light weight rig, I know the cruiser built uroc buggy I got my overall 4-link design from, back in 2005 was running them. Other than a full cruiser frame and some tubing there wasn't much there. But regardless of that, I would say it would be something that wouldn't last forever. It would need replacing after they get some hammerin' on. Not a big deal in a competition buggy where the cost is worth the edge you might gain for winning. You just can't trust aluminum after it has suffered trauma, even though it might look perfectly fine. If it were bent for example, It will have cracks, microscopic even no matter what! So given the nature of the alloy I fell it wasn't the best choice for me. My cruiser is complete and just to heavy for me to feel comfortable with the cost of a F-up, even if I were to make a mistake while machining them.

I had an old lathe at my disposal in the shop I work for. I don't remember how long they took to build, a while, you can only cut metal so fast. Steel is real soft compared to most strong materials, stainless, like 316 is hard and slow to machine, tears up your tooling. I think it would be sick to build some links from 17-4, SOOOO mean. No rust and super strong it has a huge tensile strenght, but heavy, oh and expensive! I really don't have much concern for weight though. Foolish? maybe but they don't call it an Iron Pig for nothing. I'm not sure on the weight of my links but I would guess maybe 15-20lbs each with the heims, ballpark.

Like I said before this project is a bit of an experiment for me, I really only did it to prove I could. Leaf springs are great and work wonderful. Very reliable and very simple, definently not much to go wrong. I was happy with my cruiser as it was, good flex, tough, RELIABLE. I only wanted a longer wheel base because I've almost rolled her right over backwards way to many times. I wouldn't advise anyone to build a 4-link just cause they think it is cool or because they think they need it. Most anyone who has actually learned, and built one would agree. Too much work and $, if you really don't know what your in for. If I have gotten eveything right I'll really be able to say if it was worth it. I am pretty sure it was. I'm going to finish the last couple of welds today, give it all a spray bomb attack. Hopefully I will have it all together and moving around on a temporary driveline, very soon.

 

[notaf-ingjeep]

Hey I just wanted to say thanks for the help! I got the cruiser suspended today, finally! It was a great suggestion from you guys to use a shop crane or "engine hoist" to load in my coilovers. I picked one up from harbor freight for $180. Not cheap, but it is a far better unit than I'd expected would come from harbor freight. It is built pretty tough, good thick material, I had complete faith in it. I have to say for loading coilovers this tool is worth it's weight in gold, and the only way to go. It was the safest way by far to do the job, no worries at all. My bolts lined up pretty well at full droop, did not take much convincing to get them in. I will try my driveline and check for binding, I've got a lot of travel. My coilovers are tipped in to the center, and forwar toward the front. It has a little swing and gets a bit more travel because. I realize that you lose efficency in the dampening, but in my case I feel it is worth the travel. It still seems that the driveline will work as far as having enough travel in the spline, I can't say for sure at this time. I will have to pull the springs out and give the suspension a full cycle, to locate any additional problems. If I let her sit a full compression on one corner, I can lift her all the way up with this "crane" on the other. It works nice and slow, so there will be no mistakes or damage to the shocks or other joint-components. Any problems will be super easy to spot. No photos yet, sorry guys...... give me sometime to finalize this thing and I'll put it out there for you all to see. I am completly confident that it is going to work great! I have to say it is a little different than anything I've seen online. I'll keep you updated!
Thanks for the advice!!!!!!!!!!!!

 

[mookie]

what kind of bump stops did you wind up using?

 

[notaf-ingjeep]

what kind of bump stops did you wind up using?

Haven't yet but I am pretty set on the fox 2.0 I haven't decided if I want 2.5" or 3" inch travel. I plan to measure for limit straps today and get it all ordered. So very soon!

 

[Eskimo]

On your links being bent, that is why I went solid. They are solid 1.5" 4130,... The 4130 was cheaper, and WAY stronger than a good aluminum alloy. Aluminum is sick stuff though, light, but brittle. It wont bend without being seriously comprimised and would likely just straightup break.

This is full of misinformation.

Your solid 4130 (I'm going to assume 4130N) links have approx. the same yield point (in PSI) as my solid 7075 links. Alum does bend more easily, however it does not retain its shape until it hits yield.

Unfortunately, because of the diameter, the 4130 link (in a 33" length) has a yield point of ~2500lbs. The 2" 7075 (common size for lowers) has a yield point of ~6900lbs. 4130 is stronger? Nope. Not even if you used 2" solid. Then it would just be comparable.. but a lot heavier.

Brittle? Won't bend without being compromised? (UH-1) Huey landing skids are made from 7075. they bend every time they land, and must return to original without any memory, and they have been doing it for decades.

I think the chances of your links taking a permanent bend (and likely damaging something else in the process) are far more likely than mine are of "straightup breaking", since it would take nearly 3x the force to reach yield on mine. My pile is 4600lbs, it's no lightweight, and I've landed numerous times right on the links. No issues.

Fortunately, the 1.5" solid is slightly stronger than 1.75" .250 DOM, which many have used for years in moderate wheeling with success (IIRC, RE links are this size), so you might be OK...

 

[notaf-ingjeep]

This is full of misinformation.

Your solid 4130 (I'm going to assume 4130N) links have approx. the same yield point (in PSI) as my solid 7075 links. Alum does bend more easily, however it does not retain its shape until it hits yield.

Unfortunately, because of the diameter, the 4130 link (in a 33" length) has a yield point of ~2500lbs. The 2" 7075 (common size for lowers) has a yield point of ~6900lbs. 4130 is stronger? Nope. Not even if you used 2" solid. Then it would just be comparable.. but a lot heavier.

Brittle? Won't bend without being compromised? (UH-1) Huey landing skids are made from 7075. they bend every time they land, and must return to original without any memory, and they have been doing it for decades.

I think the chances of your links taking a permanent bend (and likely damaging something else in the process) are far more likely than mine are of "straightup breaking", since it would take nearly 3x the force to reach yield on mine. My pile is 4600lbs, it's no lightweight, and I've landed numerous times right on the links. No issues.

Fortunately, the 1.5" solid is slightly stronger than 1.75" .250 DOM, which many have used for years in moderate wheeling with success (IIRC, RE links are this size), so you might be OK...

Your right 7075 is bad ass stuff, very costly! I was not saying it was a poor choice, just not my choice. A 7075 t6 aluminum has a ultimate tensile strength of 78 ksi, while the ultimate tensile strength of a 4130 is 97 ksi. Ksi is like saying 97,000 psi. So your right both materials at their best are close, but the steel is stronger. Stronger, heavier and cheaper than your expensive 7075 links. A good choice, but just too much $ for me, especially since my link material was given to me by the boss at the shop. So my words may have been exagerated looking back, sorry. I would'nt call it misinfo though, it is a fact that these aluminum alloys are compremised when bent! You can't tell me otherwise, you may not see the damage but it is there. That s*** will break when bent, try it with a piece of 7075 plate vs a steel plate. The aluminum won't bend to a 90 degree without breaking, steel you can bent to 90 but back and forth before it breaks. It may take more force to bend the aluminum, but if it does you wont bend it back.

Flexing and bending are 2 different things, your aluminum will "flex" to it's yeld then "bend". Once pushed to a "bend" from "flex" passed it yeild, it is at that point which I would refer to "Trauma" having occured. I would be cool with solid aluminum, but I would constantly be inspecting it, and replace it as I saw fit. I personally would never use a 7075 tube for a lower link. Unless I were in competition and wanted to cut as much weight as possibe, without longevity or cost concerns. NOT for me, on this cruiser right now in time. Uppers not such a concern, not really any damage potential. For me personally, that application might be great for some aditional weight cut.

For example, I am a downhill mountain biker, earlier this season I broke a frame made from 7005 aluminum. It was a light, very expensive frame which I replaced with one of the same material. It wasn't a weld, It was the Easton taper wall tube itself that cracked. These frames only last 2 seasons with a mad man like me riding it. Worth the cut in weight since it my ass pedaling the thing around, but I allways inspect it for damage. Even a frame of 6061 t6 is better about it's brittle nature. Less tensile strenth, like 55ksi or something, but keeps it's strength better from dents, gouges and bends where the cracks and breaks happen most! These alloys get stronger but more brittle as you get into these different alloys, in this order, 6061,7005,7075. So a 7075 frame is even more brittle than my 7005 frame. I've broken a lot of bones in my 25 years. I broke my thumb and collar bone in june this summer, 3 times Ive broken a collar bone. Broken bones suck, so good components that I can trust mean alot to me. My experience with aluminum is what I base my choices from. The best at times, but just not worth it in others. A skid plate can take all the damage it wants, wouldn't matter to me. But an unexpected and inconvienient brake of a suspension link could get you and your cruiser killed. I apreciate your response so I could clear up what I was saying. You know, what is opionion and what is fact. Build what you want dont listen to me. Lots of good ways to build a cruiser, and ALOT of potential for stuff hasn't been tried. These things have come a long way in a short amount of time, and have a long way to go.
thank you
sterling

 

[bustanutley]

Introducing a mechanical advantage against a bump stops sounds like a bad idea. I didn't read the whole thread..