a-arms conception

[mxracer]

Hello I am now designing my own long travel a-arms, they will be similar as Houser
I think that my shocks need to be at the same angle as stock it is right?
If my arms are +2 Do i need different ball joint than conventional aftermarket a-arms?( I dont think i will have more travel than standard +2 arms, just longer shocks )
Thank you

[ajr400ex]

There is a little more to it than that...regular (non-long travel) extended a-arms use the same shock mounting location as stock on the a-arms. Basically the same geometry just longer with standard ball joints. Long travel shocks relocate the lower shock mount on the a-arm and use different ball joints to gain additional travel. I am not sure if all the manufacturers use the same mounting location which will effect the shock setup. If you go long travel your best bet would be to copy a set from someone you know and have shocks setup for that brand.

[Jnine]

Hello:

The one thing you will have to know is the amount of side to side movement in whatever ball joint or pivot setup you choose. You will have to either get the specs, or measure the angle accurately. When you have that measurement you can set the angle on the end of your a-arm so it doesn't bind. I'll give you a tip. If you are building for standard length shocks on +2 A-arms, you can leave the shock mount in the same location as the stock a-arm shock mount. Then all you have to determine is the angle at the end as described above. If you are building for a long travel setup, then you'll have to figure it all out, and there are a lot more variables, not the least of which is that most ball joints won't work in that setup.

Take your time, and think everything through. Remember you have to ride it, and you certainly don't want to crash because something was wrong in the design. Before you get everything finish welded, I would simply tack together everything for one side of the quad only, and then install it on the quad, and see how it works both at full extension and at full compression, and turning. If you have any problems you can fix it then. If there is no binding, then finish them up. Good luck!

[mxracer]

Thank you very much Jnine
I began the conception with autoCAD
I chose to make +3 long travel arms
I will buy ball joint or pivot made for long travel arms
Can I purchase that from you Jnine??
Also I have a question; Does the shocks have to be at the same angle than stock position? I think yes but I'm not sure
Also I made the ball joint (or pivot ) at the same angle with the arm than stock. It is correct?
Thank you very much

[Jnine]

Hello again:

Since you have autocad the design part will be MUCH easier. That will be a great thing for you becasue now you can check those angles at full compression and full extension, and see if the ball joint binds. You're one step ahead of most of the other guys already. What you will need to know is the usable range of the ball joint. That is the critcal part of the design. As for buying them from me, we are in the process of changing the ones we use also right now, and we're looking at 3 different options, so I don't really have any to offer you. Now you're on the same hunt as the rest of us! On your question about the angle at the end of the a-arm, that is the mistake quite a few A-arm builders make. You can't just set it at the stock angle, unless you are using a ball joint that is identical to stock. You won't be able to set that angle until you have the ball joint data, and until you have checked your range of motion from full compression to full extension. The full extension and full compression numbers must come from whatever shock you are using, and remember to take into account the sag. (probably between 2 & 4 inches max!) Also, since you are using a 19" shock you can probably maximize wheel travel, but probably not at the stock mount location. Basically you are going to have to do a rough design, and then play around with it in autocad until you can maximize travel (with sag built in) and without any of the deadly ball joint binding.

Start getting the ball joint & shock data!

[mxracer]

My idea is not to have the maximum travel, but a longer shock.
I want +3 arms . If I have the same travel than standard + 3 arms I will be ok with standard aftermarket ball joint.
If I keep the shock at the same angle than stock I will have the same travel than standard +3 arms just a longer shock
The only problem I see is that my shock will be nearest to my wheel. It is realy a problem?
do you understand what i try to do Jnine?

[Jnine]

I understand what you are doing. You can definitely move the shock out towards the wheel a little ways without screwing anything up. You will have to know what the new leverage ratio is however. A lot of the stock locations offer about a 2:1 leverage ratio, and I don't think you want to drop too low. (Can't remember what we determined was a min. ratio!) You will need to know the leverage ratio so the shock guys can valve accordingly. Actually, with the current tie rod ends you probably would not gain much travel anyway, but I like your idea of using the longer shock. It's expensive, and it's not for everyone, but it does allow for a little easier valving. However, a good shock guy with a good setup can get the same ride with a 16" standard length shock. It's just the longer shock gives them a little more margin for error.

[bongwater200]

Just looking at the title of this thread.........

"A-Arm Conception".............. Wow.... that would be painful!

The rubber boots on the ball joints........ would they be considered "A-arm CONTRA-ception?"

Just curious!

[Jnine]

Yes I think they would. And I suppose the threads on the bolt would be considered ribbed for extra pleasure.

[mxracer]

Thank you Jnine
So the best leverage ratio is 2:1?
I don't understand why you said its expensive?
The arms will not cost more to make anf the shocks don't cost a lot more.
Thank you very much

[boogiechile]

"Also I made the ball joint (or pivot ) at the same angle with the arm than stock. It is correct?"


You can not really do this with an extended a arm. The extension itself will add travel unless you move the shock mount out toward the wheel far enough to limit travel to stock. But you want more travel so you need to stay around a 2:1 leverage ratio. Now when you do this you add travel. If you keep the stock ball joint to a arm angle the added travel will be added equally (split between) to the up and down motion off the a arm. All this assuming your joints go there without binding. Now if they are both added to equally then the extra up travel is often wasted because it goes past where the frame bottoms. Your stock travel usually bottoms at about the right place so all the extra travel needs to go to the down motion of the a arm. In order to do this will take a different ball joint angle than stock.

You need to adjust the angle to just use up the motion in the compressed direction (with alittle to spare)when the frame is at the bottoming height you set. Then you will have the max ball joint motion to allow for the a arm to drop. If it will drop to where it needs to be to allow the shock extended length to work, your'e ok. If not you need a ball joint with more range or you will have to move your shock mount out. If you have extra motion available in the joint adjust the angle to have a little extra on the compression to take care of flex and stuff. You need a little extra there anyway.

[mxracer]

Thank you