Buggy Build/Suspension Experiment

[CSR]

The limit straps are tight at ride height. No down travel. Couple of reasons for this
1. If I allowed down travel at speed through rough terrain, the upper link mounts could drop low enough momentarily to move the upper roll axis down below the center of gravity, suddenly allowing for body roll and it's accompanying axle steer. Could result in a very sudden and extremely squirrelly situation.
2. Up travel is necessary to absorb hits. Down travel is not, unless you hit a magically suspended boulder that is three feet in the air with the top of your tire.

In order to reduce the rebound shock load on the limit straps, I told ADS to do some stiff rebound valving on the shocks. I also told them to valve compression very lightly so that the springs can do their job instead of the shocks sharing the load, leading to heat, blown shocks, etc. You only have to dampen in one direction to control oscillation.

As far as crawling is concerned, lack of down travel may lead to nosing down into some holes, or having my rear end drop here and there. I'm ok with that, given the rig's length and width. No down travel also limits my articulation (which is still pretty good), but my honest opinion is that big articulation is overrated when you are locked front and rear. As long as most of your tires are touching the ground, you are going to move.

The only situation I can think of where it will hurt me is in big breakover situations where my front tires cannot drop and grip to help pull me over. I'm ok with that, too. Stability in all situations is far more important to me than being able to conquer every obstacle.

 

[mbryson]

The limit straps are tight at ride height. No down travel. Couple of reasons for this
1. If I allowed down travel at speed through rough terrain, the upper link mounts could drop low enough momentarily to move the upper roll axis down below the center of gravity, suddenly allowing for body roll and it's accompanying axle steer. Could result in a very sudden and extremely squirrelly situation.
2. Up travel is necessary to absorb hits. Down travel is not, unless you hit a magically suspended boulder that is three feet in the air with the top of your tire.

In order to reduce the rebound shock load on the limit straps, I told ADS to do some stiff rebound valving on the shocks. I also told them to valve compression very lightly so that the springs can do their job instead of the shocks sharing the load, leading to heat, blown shocks, etc. You only have to dampen in one direction to control oscillation.

As far as crawling is concerned, lack of down travel may lead to nosing down into some holes, or having my rear end drop here and there. I'm ok with that, given the rig's length and width. No down travel also limits my articulation (which is still pretty good), but my honest opinion is that big articulation is overrated when you are locked front and rear. As long as most of your tires are touching the ground, you are going to move.

The only situation I can think of where it will hurt me is in big breakover situations where my front tires cannot drop and grip to help pull me over. I'm ok with that, too. Stability in all situations is far more important to me than being able to conquer every obstacle.

Interesting ideas. I'm curious about the lack of down travel but that could be easily adjusted with longer straps if you needed to go there. Intriguing build for sure. Anxious to see it out and on the trails

 

[I Lean]

The limit straps are tight at ride height. No down travel. Couple of reasons for this
1. If I allowed down travel at speed through rough terrain, the upper link mounts could drop low enough momentarily to move the upper roll axis down below the center of gravity, suddenly allowing for body roll and it's accompanying axle steer. Could result in a very sudden and extremely squirrelly situation.
2. Up travel is necessary to absorb hits. Down travel is not, unless you hit a magically suspended boulder that is three feet in the air with the top of your tire.

In order to reduce the rebound shock load on the limit straps, I told ADS to do some stiff rebound valving on the shocks. I also told them to valve compression very lightly so that the springs can do their job instead of the shocks sharing the load, leading to heat, blown shocks, etc. You only have to dampen in one direction to control oscillation.

As far as crawling is concerned, lack of down travel may lead to nosing down into some holes, or having my rear end drop here and there. I'm ok with that, given the rig's length and width. No down travel also limits my articulation (which is still pretty good), but my honest opinion is that big articulation is overrated when you are locked front and rear. As long as most of your tires are touching the ground, you are going to move.

The only situation I can think of where it will hurt me is in big breakover situations where my front tires cannot drop and grip to help pull me over. I'm ok with that, too. Stability in all situations is far more important to me than being able to conquer every obstacle.

I'm still very interested to see how this works out for you, but in my opinion you're pretty far off on most of these things. I foresee changes after you run the thing a few times.

 

[N-Smooth]

Very interesting. Sub'd.

 

[anderson750]

In order to reduce the rebound shock load on the limit straps, I told ADS to do some stiff rebound valving on the shocks. I also told them to valve compression very lightly so that the springs can do their job instead of the shocks sharing the load, leading to heat, blown shocks, etc. You only have to dampen in one direction to control oscillation.

This is all very interesting and I too am interested in the results. ^^^^^This is where I struggle with understanding how this is going to work. This set up where you are limiting the down travel is very much going to behave like what I am used to with setting up our bikes for desert racing. The suspension on a bike is very dependent on the shock being able to return to the ground in a manner that is controlled and be ready for the next impact. The spring rates are very much dependent on the weight of the rider or in this case the rig. However, the ability to resist bottoming is controlled through the compression valving. To little valving will allow it to blow through the stroke and fully compress......too much makes it stiff and you do not get full use of the stroke. On the rebound side, if you do not control that rebound, the spring will then force all that energy back down and cause the suspension to "pogo". If you have to much rebound dapening, the shock will then "pack" and essentially be stuck to deep in the stroke when you make the next impact.

I like it when people think outside the box.

 

[Coco]

Subscribing. Very intrigued on this idea!!

 

[CSR]

I like the input on the shock valving. The shocks may pack some, but I'm thinking that they won't bottom completely because of the large up travel range in which they are working. As the spring compresses farther and farther into this range, it exerts more and more force to counter the shock's resistance to the rebound stroke.

I can see how too light of valving on the compression stroke could result in the spring/shock assembly shooting through its range and bottoming. But I have given it a 13 inch up travel range, which is a long way to go against spring resistance to hit shock bottom. I'm thinking that this large up travel range is the key to this working.

I welcome all input on this as I don't know everything about it.

 

[mesha]

DANG!!
I remember talking to you about this several years ago in your old buggy in Moab. I am glad you are finally going to give it a try!

 

[zukijames]

I always love your builds! I'm sure this one will be just as awesome or better.. Plus no need for a hand crank suck down winch

 

[carsonc1974]

The limit straps are tight at ride height. No down travel. Couple of reasons for this
1. If I allowed down travel at speed through rough terrain, the upper link mounts could drop low enough momentarily to move the upper roll axis down below the center of gravity, suddenly allowing for body roll and it's accompanying axle steer. Could result in a very sudden and extremely squirrelly situation.
2. Up travel is necessary to absorb hits. Down travel is not, unless you hit a magically suspended boulder that is three feet in the air with the top of your tire.

In order to reduce the rebound shock load on the limit straps, I told ADS to do some stiff rebound valving on the shocks. I also told them to valve compression very lightly so that the springs can do their job instead of the shocks sharing the load, leading to heat, blown shocks, etc. You only have to dampen in one direction to control oscillation.

As far as crawling is concerned, lack of down travel may lead to nosing down into some holes, or having my rear end drop here and there. I'm ok with that, given the rig's length and width. No down travel also limits my articulation (which is still pretty good), but my honest opinion is that big articulation is overrated when you are locked front and rear. As long as most of your tires are touching the ground, you are going to move.

The only situation I can think of where it will hurt me is in big breakover situations where my front tires cannot drop and grip to help pull me over. I'm ok with that, too. Stability in all situations is far more important to me than being able to conquer every obstacle.

Very interesting build and Im much enjoying it! But coming from the little desert racing background I have, I think you will find some of this to be incorrect. Couple of things to possibly think about:

-With no Compression valving, and alot of Rebound dampening it will make the Suspension "Pack" and lead to bottoming. Even with 13"s of up travel this will become an issue i think. Luckily it looks like your shocks are approaching 90 degrees at bump with will help with valving.
-With No down travel, there will be no way for your tires to drop into holes. Keep in mind that dips, holes, ruts, ect are all just as knarly as bumps, rocks, berms, etc at speed. Gotta keep those wheels on the ground!
- Also try and reduce unsprung weight where ever possible. That makes a huge HUGE difference at speed!

All that said, I love what your doing, and think it will be one heck of a ride once finished. I really enjoy seeing some out of the box thinking!

EDIT: just finished reading the thread and most of what i said has already been covered

 

[Ashcat]

I like seeing tech and a build like this brought to RME.

 

[CSR]

Her she is skinned out. Still need to install the front ring and pinion, get driveshafts built, pcm programmed, and several other odds and ends.

 

[RockChucker]

Good to see you getting back in it Chris. Let me know when you are ready to get that thing out. I just finished my "jeep" buggy thing (yeah, yeah, I know I said I wouldn't have a buggy). I'd like to see how that thing works.


Sent from my iPhone using Tapatalk

 

[CSR]

Very interesting build and Im much enjoying it! But coming from the little desert racing background I have, I think you will find some of this to be incorrect. Couple of things to possibly think about:

-With no Compression valving, and alot of Rebound dampening it will make the Suspension "Pack" and lead to bottoming. Even with 13"s of up travel this will become an issue i think. Luckily it looks like your shocks are approaching 90 degrees at bump with will help with valving.
-With No down travel, there will be no way for your tires to drop into holes. Keep in mind that dips, holes, ruts, ect are all just as knarly as bumps, rocks, berms, etc at speed. Gotta keep those wheels on the ground!
- Also try and reduce unsprung weight where ever possible. That makes a huge HUGE difference at speed!

All that said, I love what your doing, and think it will be one heck of a ride once finished. I really enjoy seeing some out of the box thinking!

EDIT: just finished reading the thread and most of what i said has already been covered

I may be able to build in some down travel down the line, but I want to try it as is to get a baseline for the experiment. As for unsprung weight, I have a ton of it, almost literally, and that will be a major limitation. I don't expect to be anywhere near the realm of an ifs car, but I do want to see what I can do with poor man's 1 ton axles.

 

[carsonc1974]

I may be able to build in some down travel down the line, but I want to try it as is to get a baseline for the experiment. As for unsprung weight, I have a ton of it, almost literally, and that will be a major limitation. I don't expect to be anywhere near the realm of an ifs car, but I do want to see what I can do with poor man's 1 ton axles.

Awesome! I can't wait to see what you come up with!

Sent from my SM-G900V using Tapatalk

 

[CSR]

Good to see you getting back in it Chris. Let me know when you are ready to get that thing out. I just finished my "jeep" buggy thing (yeah, yeah, I know I said I wouldn't have a buggy). I'd like to see how that thing works.


Sent from my iPhone using Tapatalk

Will do

 

[TJDukit]

Loving this so far. I don't know enough to criticize so I'll just continue to read this as it comes along. It will be great to read the results and lessons learned when it's all said and done. Hopefully your plan works. If not, everyone learned something you've been wanting to teach yourself.

Love the concept and the quality of the build so far.

 

[carsonc1974]

That thing is looking SAWEEET!

 

[Herzog]

I love that you are going into it as an experiment. I'm excited to see the results!

 

[CSR]

Loving this so far. I don't know enough to criticize so I'll just continue to read this as it comes along. It will be great to read the results and lessons learned when it's all said and done. Hopefully your plan works. If not, everyone learned something you've been wanting to teach yourself.

Love the concept and the quality of the build so far.

If the experiment fails, I'll still have a pretty fun crawler. So I don't have much to lose.