Does a shock push the axle down?

[sleeoffroad]

OK, I did not want to mess up Bull's thread. Also this is not a John bashing, however he did post something that I wanted to address. I think it is important for people to see this. I know ATS might jump in as well. I would not do it unless I felt people should understand these things.

--- Original Post ------

Originally Posted by ShottsUZJ100
Adding the N74L shocks helps this "problem" as the added rear pressure on the rear wheel when flexed helped to put added pressure on the opposing front. This helped F&R in the articulation dept.

Hijaak, how does the N74L put more pressure on the axle than the N74 when the are valved the same? The only thing that is happening is that the axle droops out more in the rear. It does not push the front down.

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By keeping the rear wheel on and pushed against the ground rather than being in the air.

A regular shock does not 'push' the axle down. Yes there is limited force, but the job of the shocks is to control the axle movement and dampen the springs. OME shocks have a bypass circuit, so if you press down on the shock very slowly you feel little resistance. The reason for this bypass circuit is to allow fluid to go past the valving when you do corrugated roads and not have every small bump transmitted into the truck.

The tire that is drooped out and the spring just about unloaded does not put pressure on the front. The tire that is compressed is that one that pushes the oposite front end down.

Of course if the holes get too deep and there's little to no force on the back wheel then the gain to the front is zero.

The only way that the drooped wheel is going to exert more pressure is if the spring is still compressed. With the L shocks at maximum droop the spring is uncompressed.

The front is so stiff near the bumpstop that it would push the front up and into the air.

What does this mean?

With the longer rear shocks these scenarios have rarely showed. The rear's on the ground so the opposing front is on the ground.

Why would this happen ?

You are confussing the truck teetering on 3 wheels, vs 4 wheels on the ground with stability and forced articulation.

Example pic. Before in this spot my pass front wheel would be off the ground because I didn't have the extension in the rear to swallow the hole.

So previously the truck settled on the rear wheel and lifted the front. Now the axle is drooping a little more and keeping the truck from rocking back, hence your feeling more stable. Kinda like putting your finger out to stabilize you, not pushing with your whole arm.

If the axle was pushing, you would need more force on the spring, which means it should be less extended, which means the L shock is not totally extended. So, you would get the same effect with a shorter shock.

Also, the drivers front would not ba as stuffed. Can't do anything about front extension however adding rear extension has been a big help. It aids in forcing the front down which stuffs the same side front and helps keep the opposite side front on the ground.

How does it do that?

 

[wngrog]

From my experience with the Old Man Emu shocks, the won't even open themselves up when you take the retaining wire off them out of the box.

Actually, that frightens me every time.

My Fox 2" Nitrogen Shocks will push a tire down, because that is all that is on the axle.

On the 80 and 100 series the coilspring pushes the axle down and then gravity takes over if the spring is fully extended and nothing is there to stop it.

Schotts is letting his rear axle droop some more with the longer shock thereby allowing gravity/spring to allow the axle to fall out more than with the shorter shocks.

This mod is good in that it may let the tire reach down and gain a little purchase, but without more pressure than gravity, it won't help a ton.

 

[ShottsUZJ100]

You techy dudes can debate this amongst yourselves. I am not a good writer and don't know all the proper "terms". I'm a salesman.

I decided to try this mod based on comparing my 80 and 100 on the same trails. I also wondered why the L-shock was ever made for the 80-series. Then, I wondered why an L-shock isn't made for the 100-series.

Here's what I found out (true or not?):

The L-shock was made to compensate for taller lifts on the 80 so extension could be regained.

There is no L-shock for the 100 because lifts stop at 2" and the springs would fall out.

So, follow my thought:

L-shocks help an 80 A LOT despite lowering the rear stop by 2". So, with 100 owners running 863 springs now (I run 863 and L in my '93), why not try an L-shock on the 100 also?

I did, and the beneift is the same as the 80.

So here's my question:

If L-shocks are the preferred shock for the back end of an 80, why is everyone disputing they help the rear end of a 100 equipped with a tall-enough spring...like the 863?

A=B
B=C
So, A=C

80: 863 and N74L (everyone loves the setup and it's rear flex)
100: 863 and N74L (everyone slams the setup't merits despite it being the same compeonents offering the same rear flex....why, cause I personally thought of doing it?)

To discredit the improvement the N74L makes to the 100, one must also discredit the improvement to the 80. Everybody running 863 and 863J on their 80's should be told to run non-L's because they don't do anything over the shorter shocks? That's crazy, though that's what people keep telling me about the same setup in my 100.

OK debaters. Enjoy. My truck is more awesome than ever since this swap. I obviously can't explain how or why it's better. And really, I don't care how or why either...just that it is better. I'd never go back to the 100 shocks. And anybody trying the same experiment wouldn't either. I personally don't care if anybody else ever does it though.

 

[sleeoffroad]

You techy dudes can debate this amongst yourselves. I am not a good writer and don't know all the proper "terms". I'm a salesman.

I decided to try this mod based on comparing my 80 and 100 on the same trails. I also wondered why the L-shock was ever made for the 80-series. Then, I wondered why an L-shock isn't made for the 100-series.

Here's what I found out (true or not?):

The L-shock was made to compensate for taller lifts on the 80 so extension could be regained.

There is no L-shock for the 100 because lifts stop at 2" and the springs would fall out.

So, follow my thought:

L-shocks help an 80 A LOT despite lowering the rear stop by 2". So, with 100 owners running 863 springs now (I run 863 and L in my '93), why not try an L-shock on the 100 also?

I did, and the beneift is the same as the 80.

I never questioned why you did it. I just tried to explain that shock (unless it is an air shock like the Fox ones) does not push. They control movement. Springs push. Even salesmen should know this :

So here's my question:

If L-shocks are the preferred shock for the back end of an 80, why is everyone disputing they help the rear end of a 100 equipped with a tall-enough spring...like the 863?

A=B
B=C
So, A=C

No a does not equal c. The L shocks were requested by us to get a longer shock for taller lifts. You can not run a short shock with a tall lift since you will top the shock out and be at max extension on the shock at normal ride height.

80: 863 and N74L (everyone loves the setup and it's rear flex)
100: 863 and N74L (everyone slams the setup't merits despite it being the same compeonents offering the same rear flex....why, cause I personally thought of doing it?)

To discredit the improvement the N74L makes to the 100, one must also discredit the improvement to the 80.

I am not doing that. I am just saying the the shock can not push the axle down. Very simple. As for the other comments, I tried to explain why you are experiencing perceived improvements. I am not saying your truck does not feel better to you on the trail. I am just saying you are not understanding what is happening. Big difference.

Everybody running 863 and 863J on their 80's should be told to run non-L's because they don't do anything over the shorter shocks? That's crazy, though that's what people keep telling me about the same setup in my 100.

OK debaters. Enjoy. My truck is more awesome than ever since this swap. I personally don't care if anybody else ever does it though.

John, you are taking this the wrong way. I just don't like it when someone makes a statement on a modification that is not right.

 

[MoJ]

As I understand it -

A longer shock, all else equal, allows gravity to continue its work and thereby allows the axle to droop further. It also, all else equal, may allow the axle to travel upward further.

If the tire seems (and truely is) more firmly planted it's because the opposite tire is being forced upward by an obstacle and the newly added droop, allowed by the longer shock, is allowing the axle to move more - move more up on one tire and down on the other. Duh right? So while the longer shock doesn't "push" the tire into making contact it does allow more movement so that it can contact places it may not have been able to previously reach.

Of course all that is assuming a solid axle.

If the new longer shock requires you running thicker bump stops to reduce upward movement than the advantage may very well be cancelled out.

A tire touching the ground doesn't mean you'll have traction. You've got to have a force against it (weight) to create friction (traction). Edit: Right or wrong, I'll define traction as the tire having enough friction against it that the vehicle can move forward.

So, like John, I'm just a lowly salesman so this is all "for what it's worth."

In summary, my answer to Mr Slee's rhetorical question is very simply, NO!




EDIT: PS - I too was hoping Bull's nice buildup thread wasn't turning the direction of a pissing match.

 

[sleeoffroad]

As I understand it -

A longer shock, all else equal, allows gravity to continue its work and thereby allows the axle to droop further.

It also, all else equal, may allow the wheel to travel upward further.

All else equal - unless there is enough space between the shock mounts to accomodate a longer shock (which will also be longer shock when compressed) with the axle stuffed, it will not allow more travel, as you mentioned later with the bumpstop.

If the tire seems (and truely is) more firmly planted it's because the opposite tire is being forced upward by an obstacle and the newly added droop, allowed by the longer shock, is allowing the axle to move more - move more up on one tire and down on the other. Duh right?

Right, but again as you pointed out later, the above only works if you have pressure on the tire.

"A tire touching the ground doesn't mean you'll have traction. You've got to have a force against it (weight) to create friction (traction). "

So while the longer shock doesn't "push" the tire into making contact it does allow more movement so that it can contact places it may not have been able to previously reach.

Of course all that is assuming a solid axle.

If the new longer shock requires you running thicker bump stops to reduce upward movement than the advantage may very well be cancelled out.

Yes, that was what ATS was getting at in the other thread. Get more droop, might help some, get more droop and compression. You can a lot.

So, like John, I'm just lowly salesman so this is all "for what it's worth."

In summary, the answer to Mr Slee's rhetorical question is very simply, NO!

 

[MoJ]

So one side of the axle is forced up from an obstacle, the other side gets forced down and that tire makes contact - hopefully enough so that the tire has traction. Pretty basic fact on a solid axle - simple physics.

I'm asking because I don't know-----how does the same scenario play out with IFS?

 

[ShottsUZJ100]

Forget the 100 Slee. I've simply swapped from a shorter shock to a longer shock on the same rig.

So, are you telling me that an L-shock vs a non-L shock on an 80 offers little difference off road too? Had I of been posting this same thing about the change on my 80 from an E to an L would I have been slammed about the merits of the change? (Running 35's and 3" lift)

 

[MoJ]

John - He's just saying that a shock, by its self, doesn't push the tire into the ground with enough force to create traction.

 

[Greg B]

Yes, that was what ATS was getting at in the other thread. Get more droop, might help some, get more droop and compression. You can a lot.

Christo,
Does that mean that if you don't use a bumpstop extension and you're gaining the extra compression, then the N74L's are a pretty good upgrade? Since I am running 295's, I'm not concerned about the tires rubbing the fenderwells. (I noticed in Bull's thread that he said he is running the N74L's without a bumpstop extensions, that's why I'm asking)

Has anyone measured the length of a shock when the suspension is fully compressed and the axle is against the bumpstop? If we have that measurement, we will know if an N74L will work without a bumpstop extension. If no extension is needed or maybe just a 1 inch extension is used, now you've achieved a 2.6" or 1.6" increase in travel respectively. That to me, seems like a nice gain.

 

[ShottsUZJ100]

John - He's just saying that a shock, by its self, doesn't push the tire into the ground with enough force to create traction.

That's fine. He knows better than me.

I don't know or care why the improvement happens. I simply tried the experiment and posted the results which were very positive results. Heck, my wife can tell the difference from the passenger seat.
Then, doubters began tearing apart my results. This brings me to my question which nobody ever answers in any thread (the above post).

Nobody wants to say L-shocks don't help an 80, but many rush to say they don't help a 100.

 

[MoJ]

Nobody wants to say L-shocks don't help an 80, but many rush to say they don't help a 100.

Depending on the circumstance they may help both. But, if you lower bump stops the same distance as you increase upward travel due to the longer shock, they will help neither. It will cancel itself out - 80 or 100 - doesn't matter.

 

[sleeoffroad]

Christo,
Does that mean that if you don't use a bumpstop extension and you're gaining the extra compression, then the N74L's are a pretty good upgrade? Since I am running 295's, I'm not concerned about the tires rubbing the fenderwells. (I noticed in Bull's thread that he said he is running the N74L's without a bumpstop extensions, that's why I'm asking)

If you can run the longer shock without limiting the compression, then yes it is good, provided you can get the spring to be seated. However droop without pressure on the axle does not do much offroad. If anything it makes the truck more unstable. I would run the longer shock, and retain the springs top and bottom. That makes a world of difference.

You know when you go downhill on a steep drop, maybe at a little angle, sometimes it feels like the back of the truck is going to unload and you are going to flip on your roof. Retaining the spring helps the truck not to unload as much and makes it feel much better in those cases.

Has anyone measured the length of a shock when the suspension is fully compressed and the axle is against the bumpstop?

We have done this on a 80 but not a 100. You need to remove the shock then check the spacing.

If we have that measurement, we will know if an N74L will work without a bumpstop extension. If no extension is needed or maybe just a 1 inch extension is used, now you've achieved a 2.6" or 1.6" increase in travel respectively. That to me, seems like a nice gain.

Yes, that is what ATS was getting at in that other long thread.

 

[sleeoffroad]

That's fine. He knows better than me.

I don't know or care why the improvement happens.

Then don't post reasons why it happens that are incorrect.

 

[ShottsUZJ100]

Depending on the circumstance they may help both. But, if you lower bump stops the same distance as you increase upward travel due to the longer shock, they will help neither. It will cancel itself out. That applies to a FJ25,40,45,60,62,70,74,80,100,FJ,Heep,Bronco,Rover,85 Tercel wagon,....

Fine, though specs say to lower bump stops 2" on the 80 and people still boast about their improvement. Why not the 100 then also?

 

[ShottsUZJ100]

Then don't post reasons why it happens that are incorrect.

Look....all I care about is that I did a modification that helped the truck. I don't care if true experts correct my terminology. What I do care about is when true experts discredit the improvement that I've shared with others. That is not fair to the forum members who are looking at how to improve their trucks.

N74L help an 863 80-series
N74L help an 863 100-series

Don't care why. Just happy with the outcome (as others will too).

 

[dclee]

That's fine. He knows better than me.

I don't know or care why the improvement happens. I simply tried the experiment and posted the results which were very positive results. Heck, my wife can tell the difference from the passenger seat.
Then, doubters began tearing apart my results. This brings me to my question which nobody ever answers in any thread (the above post).

Nobody wants to say L-shocks don't help an 80, but many rush to say they don't help a 100.

John, you need to read. Christo is not saying it doesn't help at all, only that it does nothing to push down the wheel.

Talk about not answering threads, go back here and answer my question:

https://forum.ih8mud.com/showpost.php?p=1038612&postcount=218

 

[ShottsUZJ100]

John, you need to read. Christo is not saying it doesn't help at all, only that it does nothing to push down the wheel.

Talk about not answering threads, go back here and answer my question:

https://forum.ih8mud.com/showpost.php?p=1038612&postcount=218

Posts 201 and 202 answered your question. The bars themselves are not progressive. The "system" or "suspension" is however as you overtwist the bar toward compliance after the lift. Had I slapped on the T-bar and not lifted the suspension would cycle better and easier. You know this.

 

[e9999]

didn't read seriously all of the above, too painful, but from skimming through, one thing comes to mind, John, and that is that I don't believe that most/many 80 owners run their 863s with L shocks, as you seem to think. I think most run the 863s with 74Es, not Ls. Now if you have an 863J then you'd want to run it with an L shock, bump stop etc...

 

[Greg B]

Will everybody quit jumping all over each other and consider this for a second. Shotts, Christo, and Darren can all be "right" from their own perspectives.

I think it has been thourougly explained by Christo, Darren, and others how the N74L does not gain hardly any travel if a 2 inch bumpstop extension is used. (.6 inches to be exact)

On the other hand, Shotts has claimed that it has made a world of difference to him since he added the N74L's.

Well guess what, they're all right!

The real difference here is that Christo and Darren are looking at this from a different point of view than John is. They are looking at what it would take to run an N74L. If it takes a 2" bumpstop extension to get the job done, then you're gaining droop but loosing compression. Very little gain to be had.

John is looking at this from a different viewpoint. Long before he added the N74L's, he used a 2" bumpstop extension to keep his 315's from rubbing the wheel wells. When he did this, he lost 2 inches of compression on his orginal N101's. He ran this way for quite a while.

Then a year later, (or however long it was) he added the N74L's to his 100. Voila, he instantly added 2.6 inches of travel to his suspension. Looking at it from his point of view, he just gained some serious travel with a pair of shocks. But that gain is realized because of past changes that John made to his rig instead of doing this all at once.

Now, for the rest of us that aren't currently using bumpstop extensions, adding the N74L's will not give us the same amount of increase as John experienced because we aren't currently loosing that initial 2 inches of compression. Unless we can work out a way to add the N74L's without adding the 2 inch bumpstop extensions.

If someone can pull one of their rear shocks and measure the distance once the axle is compressed to the bumpstop, we can then know how much bumpstop extension is needed, if any at all. Is anyone willing to do this for the group?