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Some Dangers Of Suspension Modification

3.5K views 45 replies 12 participants last post by  **DONOTDELETE**  
#1 ·
THIS IS GOING TO BE UNPOPULAR, BUT IT'S FACT...

When you put over sized tires on a Jeep or any other vehicle, no one considers what happens to the rest of the suspension and drive line...

The first thing that happens is you over stress the lug studs trying to bolt those giant wheels on with 'universal' one size fits nothing lug nuts.
Then you stress the lug stud way past what it was designed to handle, and nearly twist it off trying to keep a wheel that is going to over stress the lug studs way past any acceptable limits time and time again....
---------------------------------

The second thing that happens is the wheel bearings take a beating because no one gets the back spacing on the wheels correct, and the longer leverage line created by the taller tire and wheel combination multiplies the side loading on the wheel bearings, along with the lug studs and every thing else....
It's like pulling sideways on the bearings with a short handle ratchet, which the bearings were designed to hold back,, then putting another 18" longer breaker bar on the ratchet...
Suddenly the wheel bearings are taking up to 15 times the side load that they were ever designed to.
And instead of getting the very best bearings you can afford, you are buying Japanese junk at auto-jerks cause it's $1 less...
---------------------------------

Then you have to consider the steering angles.
In one quick minute you just screwed up years of suspension design and testing...
The spindles, ball joints, steering knuckles, ect, were never designed to have the extra load the leverage the taller wheels and tires are going to produce.
Parts wear faster, parts fail, you get vibrations, the front end 'shimmy', the vehicle wonders all over the road, tires wear on the edges, or cup out, or feather edge, the steering won't center correctly any more, ect, ect,....
Mostly just damned dangerous to operate at highway speeds with all the wondering around...

All symptoms of incorrect front end suspension geometry, usually caused by oversized tires and wheels with incorrect back spacing.
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Now, lets move to the brakes....
With the extra leverage that taller wheel and tire combinations give, the brakes take a beating!
With the increase of the leverage on everything else, you have to consider the increased leverage on the brake friction surfaces.
Longer distance between the centerline of the wheel, and the ground mean that you just gave the wheel a longer ratchet handle to pull on the brakes with.
Considering that the factory, like all factories, use the absolute minimum they can get away with in the first place, then you multiply the load, and it's a recipe for disaster.
---------------------------------

Then add some lift, either body or suspension, to clear all that tire and wheel...
Without any regard for simple physics, you raise the center of gravity, and compound all the above problems, plus create more instability, and throw the suspension and steering geometry even further out of working specifications...
----------------------------------

So, In the end, what I am left with,
(when it comes down to my life over yours, you will hear me say 'I' a lot...)
Is a oversized, overweight, over centered, top heavy, nearly uncontrollable vehicle, that has all suspension parts stressed way past acceptable limits, and can't even stop acceptably if something should occur, hurtling down the highway at me on nearly a head on collision course, at somewhere between 55 and 80 miles per hour, oblivious to the fact that he's endangering every life around him.

Anyone in the vehicle, and anyone on the highway... (namely, ME!!) are in the 'Stupidity Kill Zone'....

And people wonder why I keep my airbags serviced and wear my seat belts...
It's so they can find my body after some rambo wanna-be looses control and slams me head on....

"I Have The Body Of A God... Buddha"
 
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#27 ·
After reading the aforementioned it seems that this paranoid consciousness TR seems to be perpetuating is slowly taking up the strings to weave for us all the perfect protective bubble. AM I THE ONLY ONE LEFT ON THIS PLANET WHO ISN'T SCARED SH%TLESS OF THEIR ENVIRONMENT?

This terrified way of looking at the world will soon propagate so many regulations governing our society.. YOU WILL NOT KNOW IT TILL YOU WAKE UP ONE MORNING AND THERE IS YOUR DOCTOR WIPING YOUR ASS AND FEEDING YOU GERBER BECAUSE you have just regressed back into your happy place.

The survival of off-roading will depend on our ability to fight this exact way of thinking. Our society must start taking responsibility for our own actions. These United States are hardly a war zone. Any human with any common sense and an ability to adapt to his/her surroundings has a great chance of surviving.

In no way am I implying that the above case (doing 70 mph w/40" tires) should resolve any responsibility from the driver. I think it is pretty safe to say his day will come.

I will modify my vehicle past the legal limit if that is what I desire (CT is so tightass, pretty soon you are going to need a permit to step out of your house)

TR, your plea to make the world a safe harbor is in part helping to soak up all of our rights to freedom as citizens of the greatest country there is.

i.e. There is a lake where we all used to go cliff diving and swing out from ropes. A girl fell from the rope swing and broke a couple bones because she ACCEPTED the risk. Now there is no more rope swing, no more reservior for the nearby houses to enjoy, and no more waterfall.

Intelligence, common sense, love, and a third eye to watch out for those who have neither, is all that is necessary to prevail in this world. It is so easy to blame your disposition on your environment. If anything blame it on Charles Darwin.
 
#28 ·
/wwwthreads_images/icons/tongue.gif You have to be a little careful about where you take that line of thinking MGX1.../wwwthreads_images/icons/tongue.gif.... After all, SOME accepted form of regulation is what makes it possible for us to actually meet and pass someone on the hiway since we have AGREED to drive on a certain side of the road./wwwthreads_images/icons/tongue.gif Likewise we have AGREED to stop at a country road intersection where there is an old, rusty stop sign. Personally, I'm not in favor of making restrictions on mods to vehicles; AS LONG AS THEY ARE HALF-WAY ENGINEERED; Otherwise the guy might just as well BE driving on the wrong side of the road./wwwthreads_images/icons/frown.gif I wouldn't put three-ply in as a floor because it could unduly splinter in a severe crash, but in your Jeep I don't worry about it because the splinters would be IN YOU and not in me or in someone else. So you see, there is a difference between a society like the one Algore wants for you and for the hapless citizens of this country; and simply AGREEING to drive on one particular side of the road; or AGREEING that everyone's brakes should actually work./wwwthreads_images/icons/smile.gif As you can see from the results of the wreck that was noted, driving a patently unsafe vehicle IS NOT really a God-given right or a Constitutional right in this country, since it involves the potential destruction of lives and property. Agreeing to rules for survival is a very different thing than living in the pablum-fed, Geo Metro driving, gunless, riskless, GUTLESS, society that Hillary and Al want you to give them permission to foist upon the U.S./wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Tracs modified While-U-Wait by the crack moonguy/wwwthreads_images/icons/wink.gif Quadra-Trac Team./wwwthreads_images/icons/tongue.gif/wwwthreads_images/icons/smile.gif
 
#29 ·
Mizu,
Check out this pic.
Its taken at the top of Cadilac Hill(Rubicon).
It was taken 4th of July weekend, Joe rolled his YJ that weekend, after I had criticized him for spending money on a fancy new paint job, before spending it on a roll cage. He ended up rolling, and was lucky he or his girlfreind didnt get hurt worse, the winshield collapsed on the passenger side , but his girlfreind who wasnt buckled in, was thrown from the rig. scarry
Anyway I/we were able to talk him into installing a roll cage immediately after that.
It is a nice Jeep, Jakes mechanic Brian at Donnys has done most of the work to it, he is also running my old D30 front end with the Warn hub kit, 4.56 gears,and ARB. Those guys are a lot of fun to wheel with.
Anyway here is a pic of all of us.

Jeff
89 Wrangler
I take my Jeep "On the Rocks",usually "With a Splash of Addrenalin"
 
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#31 ·
CJDave,
Hardly was implying a free for all. CJ, the current regulations and restrictions just within the realm of off-road vehicles are blatantly obvious and undoubtedly excessive. We are all being asked to bend down and grab the soap for anything that's sacred!
 
#32 ·
Jeff, I guess I don't understand your point (maybe the picture would help?)

As Magoo said below, the guy made a CHOICE to paint before adding roll bar... Should we make it a law he do the roll bar first, or should we just let him live with the consequences of his CHOICE?

Just trying to clear that up /wwwthreads_images/icons/smile.gif

 
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#33 ·
After reading all 30 or so posts I'm still unsure of the reason for this post. Ever heard the saying,"Preaching to the choir"? I'm sure you have. I feel very bad for the victims of the referenced accident, but it seems to me that ONE of the reasons people use this board is so that they don't make those kind of mistakes. I'm not sure where TR has gotten his holier than thou attitude lately, but it's getting kind of weird. It seems to me there was a certain complaint lately about taking up space with unneeded stuff...

Brad
ORC Land Use Section Editor
http://www.off-road.com/land
Vice-Pres. Rock Garden 4 Wheelers, Farmington, NM
 
#34 ·
I think the point is being missed here. This is a relevant topic as well, and sometimes the choir gets out of tune, so it needs a little refreshing.

Remember the Mike, the guy that was killed from rolling down a hill on his CJ? Well, it brought the dangers of wheeling very close to home, realizing this could happen to any one of us. The same thing has happened, only this time it's on a paved way and not on a trail. All TR is saying is to watch your modifications and don't assume the stock gear is sufficient for what we do, take it into consideration when doing a mod, and do the mod correctly. Your rig can come apart at any time, heck, I would lose a wheel just going home tonight, I don't inspect them every day, but I shouldn't have to.

I'm not advocating a new set of laws on lifted or altered vehicles, there are enough out there, they should just be enforced, kinda like handguns isn't it.

I'm glad he posted this, it's a reminder of what can happen, even when it's least expected, and the resulting consequences. Take nothing for granted.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7" Lift/33" Swampers/REP 8000/RS9000's/Scout II D44's F&R w/4.10's & Lockrights
 
#35 ·
MagooXI,

I really wish you hadn't posted on this subject, especially in such a condescending manner. This thread will now probably turn into a ego-measuring pissing contest (and TeamRush is getting really, really good at these.) If you had been around here long enough you would know a little more about who your dealing with, and more importantly where he is coming from when he writes something like this.

I think its safe to say he was venting when he wrote the original post, and who could blame him? He spends a lot of time helping people do the job right, so that they can drive a reliable, safe vehichle. All anyone has to do is ask for a little help and he gives it without asking for anything in return except that you act responsibly. Time and again all he asks for is responsibility when making changes to your vehichle, so that people wont get hurts, and laws wont be passed that limit everybody's freedoms.

Of course after seeing what he has just seen he would come on here and write a post like that with the clear intention of scaring some sense into people! If I wasn't scared of what would happen I might consider going out and doing everything I could to make my Jeep look big and bad and never consider the safety aspects of what I'm doing. Every once in a while you have to be reminded of what can happen when you screw up. Remaining ignorant of the consequences won't make them any less severe to you and those around you.

Wait until you have children of your own, as many on this board do, and see how willing you are to stick them in your giant Jeep with weak axles and terrible steering geometry, that you could have fixed for fairly little with the information provided on this BBS.

I'll get down off my soap-box now and just hope this doesn't turn into another flaming war, although I'm sure once Aaron reads your post with your un-founded personal attacks, he will retaliate.

Restoring a '74 DJ-5C /wwwthreads_images/icons/cool.gif It was running good, so I messed with the carb to make it run better. Now it wont run at all! /wwwthreads_images/icons/mad.gif
 
#37 ·
/wwwthreads_images/icons/tongue.gif I didn't see TR's post in quite that way....... I saw him warning the less-technical bunch about some of the hidden dangers to just jacking up a Jeep and increasing the tire size. TR; as most of us do; TAKES EXCEPTION to someone rolling down the road in a vehicle which has been modified beyond what common sense and good engineering would allow, and endangering everyone he gets even remotely close to. TR isn't saying "Watch Out" because we ALL have to "watch out" when we do things with Jeeps that the mfg did not intend.......and some things that they DID intend. TR's post just reminded me; for one; about how far-reaching the consequences of a seemingly simple upgrade or mod can really be. I consider TR's post to be an On-Topic, Jeep-Specific post, and I don't see what all the fuss is about?/wwwthreads_images/icons/tongue.gif

CJDave
Quadra-Tracs modified While-U-Wait by the crack moonguy/wwwthreads_images/icons/wink.gif Quadra-Trac Team./wwwthreads_images/icons/tongue.gif/wwwthreads_images/icons/smile.gif
 
#39 ·
there is a valid point here, but the problem lies in the solution..
what are you going to do??
1) pass a law that states lifted vehicles can't go over a certian speed
2) """"lifted vehicles need certian strength axles for certian tires
3) make lifting vehicles illegal(like germany)
the problem with 1 is that if you corner an unsafe vehicle hard at 40 mph, it's more dangerous than a sencible driver doi9ng 65 down the freeway
number 2 is impossible to regulate, and thats the last thing i want anyway.
number 3 is what will happen. it is happening allready all around us and it will not get better.
as far as safety for the individual driving.. i couldn't care less.. it falls into the same ideas of helmet or seat belt laws.. i really dont care if you wear a seatbelt, but i do care if you wheel bearings finally come apart in your dana 30 and your 44" bogger hits me at 70mph.
my brakes will stop my jeep faster than stock(no comment from those who saw me rear end the sniper!). i believe that a dana 44 front axle with all new components should safely handle 35" tires.. especially since i don't drive like an idiot. driving like an idiot and lack of maintenance caused the wreck. the truck being improperly lifted isn't actually a concern since he was an accident waiting to happen anyway. the other people got hurt.. it wasn't their fault, the DRIVER is to blame.. not the truck

~~Elusive~~
tj-7..tellico tested, uwharrie safaried, FOR SALE!/wwwthreads_images/icons/tongue.gif..see it at http://www.jeepgod.net
oh yeah, and a 2000 tj, 4.0, dana 44, nv3550
 
#40 ·
1) pass a law that states lifted vehicles can't go over a certian speed
2) """"lifted vehicles need certian strength axles for certian tires
3) make lifting vehicles illegal(like germany)

Well, 1 wouldn't be so bad, especially if I could modify it more.

2 we already have, and it's based on tire size and GVWR of the axles. It's one of the reasons I went to the 1/2 ton Scout II axles over the jeep ones. I can go up 2 more inches legally due to the larger GVWR.

3 would be terrible, but that's the reason for 1 and 2.

The lift laws are currently left up to individual states. Imagine not having them, it would be more of a disaster than it already is. Sure, some of them are stupid, and as 4 wheelers we want what we think is best for us. But imagine the morons that just want to look cool, if they're putting tires that large on their vehicles now, what would they do without any restrictions?

driving like an idiot and lack of maintenance caused the wreck.

That's what TR has to determine. Would the steering knuckle have given out if new? Maybe a culmination of factors was involved.

the truck being improperly lifted isn't actually a concern since he was an accident waiting to happen anyway. the other people got hurt.. it wasn't their fault, the DRIVER is to blame.. not the truck

Yes, the truck was also to blame. With a properly set up suspension/steering, the knuckle would have had a better chance of surviving the turn, due to it's larger size. I understand the driver set up the truck, but if you or I were driving it, the consequences would probably still be the same (common sense comes into play here, we wouldn't have been drinking or doing 70 mph). If he had been in a Mazda Miata, he probably would have made the corner.

I think we're getting to things confused. There is a fine line between an "accident" and "negligence". An accident happens unexpectedly and unintentionally. Negligence happens through neglect (duh, right?), which means he failed to give proper attention to a particular area of the vehicle, he was reckless and careless.

Mangler:

I saw it as Dave did, a warning to us as jeepers. I guess I didn't read any more into it. Yes, it may have had a negative twist to it, but it's understandable, I knew there was more behind it than he first let on. I guess I saw the "corrections" as understood, there was no need to go into them ad nauseam.

I've been affected by "similarly built vehicles", ones that never should have been on the road, and I thank my lucky stars I still have any family left. Kinda sobering when I think about it for any length of time.

BTW, if this makes little to no sense, please forgive me, my bloodsugar is running low due to working late tonight. Coherent sentences and spelling tend to become a little befuddling, and there isn't a place to get something to eat within 15 miles.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7" Lift/33" Swampers/REP 8000/RS9000's/Scout II D44's F&R w/4.10's & Lockrights
 
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#41 ·
I said my peace on the vehicle safety thing on the other post on this topic, but here's a question. Is there any way that TR could have posted this without having someone criticize him? Can that poor man say a darn thing on this bbs without having someone jump down his throat? Even when he's trying to warn us about potential dangers, dangers that we (especially the more junior amongst us) don't always consider or even see, he gets criticized. Thanks for giving us another perspective TR. When I make mods to my jeep, I'm goin to try to envision all of the possible repurcussions.

Currently looking for corporate sponsors for jeep improvements...will sell advertising space on jeep, will also sell soul/body...make an offer.
 
#42 ·
How about this: can someone on this baord not question TR's posts without people falling all over themselves to defend him or kiss his butt?

TR's a big boy, if he has a problem with the responses I am quite sure he can express that himself.

I could care less who made this post or others, I would question it if you said it, CJDave said it, whoever...

Go back and read the opening line of his first post here - he knew what he was doing. Don't be so surprised when someone tosses out a fireball things catch on fire /wwwthreads_images/icons/wink.gif

 
#45 ·
Right ON.
You should know ... and have the sense to tow it or you should (have had) the sense when it is SAFE to drive it.
I have lived beyond my years (51), so I can tell you that I can not trust anything or any body (though I must)... and I watch myself all the time - trusting few others with my life....
You few idjets can just go do, uncareingly what you want ...
But I have been lucky (so far) ... and have been watching out for you, myself and those other folks ... all the time ...

JAF
http://www.monsterslayer.com/jeep
 
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#46 ·
My take on all this is to upgrade the jeep as a whole. Don't run 40's on a 30... duh.... dont use stock steering junk w/ 40"s (or 33"s for that matter).

That's it, just TR relating a very good point, and then giving the story behind it.

BJ

Hmmmm, someone must have messed with gravity again, everything is falling sideways.
And why is the ground on the side of my Jeep instead of under it?