J Arms Vs. Mid Arms

[CRASH]

It doesn't move through a longer arc. In the rear configuration, it gives a nice anti-squat (near 100% when used with the rest of Curries rear suspension).

In the front, the benefit may be less anti-dive than a regular short arm.

CRASH

 

[XJJPR]

You have to look at mounting locations in relationship to angle of the dangle.

The j arm makes for a flatter angle of attachment between the two points making for a lesser of arch thru it's movement. Thus doing the same thing as a longer arm, be it mid or long arm.

Almost need to look at one to see the angles before it sinks in. Atleast I had to.

mark
orgs mfg

 

[XJJPR]

It doesn't move through a longer arc.

CRASH

yes it does.

mark
orgs mfg

 

[Goatman]

 

[BrettM]

yes it does.

mark
orgs mfg

the end of the arm does, the axle tube does not.

 

[XJJPR]

Where do you think the end of the arm is attached to?

mark

 

[XJJPR]

Here are some photos;

This one is what PaulS did to make a mid arm:
http://www.orgsmfg.com/photos/001.JPG


The next ones are various angles of my stuff.

There is one that I have change recently of the lower font shock mount. I'm not totally happy with it yet, so it will most likely be changed.


http://www.orgsmfg.com/photos/003.JPG
http://www.orgsmfg.com/photos/004.JPG
http://www.orgsmfg.com/photos/005.JPG
http://www.orgsmfg.com/photos/006.JPG
http://www.orgsmfg.com/photos/007.JPG
http://www.orgsmfg.com/photos/008.JPG
http://www.orgsmfg.com/photos/009.JPG


mark

 

[Jes]

I see you fixed that "part" you bent on Rocker Knocker.

Jes

 

[XJJPR]

I see you fixed that "part" you bent on Rocker Knocker.

Jes

I said to myself, Which @sshat is going to see that and give me crap first!

Jes, wins!

hinkley

 

[Goatman]

So, does the axle move through the same arc, or doesn't it? How does the J arm benefit control arm angles?

 

[XJJPR]

So, does the axle move through the same arc, or doesn't it? How does the J arm benefit control arm angles?

As what? With the stock arm at the same lift height? The axle will run a different arch with the j arm than a stock arm, all other things being equal. There is less forward and back movement thru the arch. The same affect you get with a mid arm or a long arm, each has it's degree of change.

Control arm angle has been reduced. You need to put a line from bolt to bolt to see the angle difference, to compare the two.

mark

 

[Jes]

I said to myself, Which @sshat is going to see that and give me crap first!

Jes, wins!

hinkley

Hey, I was nice. I said "part" and didn't say what you bent.

Jes

 

[Safari Ary]

Mark, I totally understand how these work, now my question is, if you built the coil buckets, etc around this idea, do you think it would be feasible to hook the arms over the tubes?? I've got this Tera 50 sitting here with Virgin tubes, so it's a blank canvas. I know you're familiar with Blaine's home-made coil perches for his front axle that I believe he cut from 2x4. Now imagine the height between the tube and the bottom of the perch much taller, as if the perches were cut from 4x6 or something similar. Do you follow? It would be a cheap way to build in an extra two inches of lift since I wouldn't have to change my coils(this is a good thing), and you wouldn't lose any ground clearance either. Thanks.

Ary

 

[Goatman]

As what? With the stock arm at the same lift height? The axle will run a different arch with the j arm than a stock arm, all other things being equal. There is less forward and back movement thru the arch. The same affect you get with a mid arm or a long arm, each has it's degree of change.

Control arm angle has been reduced. You need to put a line from bolt to bolt to see the angle difference, to compare the two.

mark

Just messing, but I caught a few.

What makes it work is the link suspension, since the axle is basically kept level, i.e. little pinion change. At the same amount of droop, with the axle not rotated (like it would with radius arms) the longer J arm mounted in front of the tube has a better angle than a normal arm mounted behind the tube. Since the arm determines the arc of the axle, the axle travels in less of an arc. This would not hold true in a radius arm type design as the axle would rotate, negating the effect of the longer arm.....like on a Land Rover.

I drew it out on the floor in the garage, and with a normal 16" long control arm verses a 21" long J arm, at 8" of axle travel (droop) there is 1" less fore and aft movement of the axle with the J arm.

Now, if it just didn't reduce ground clearance under the axle.

 

[XJJPR]

Just messing, but I caught a few.


Now, if it just didn't reduce ground clearance under the axle.

Ok, I thought some of the Qs from you were sounding weird.


I measured it at around 1/2" max at the first lift I had, now I think it is less.

However, the curve of the arm sure slides over stuff nicely. The arm will also move to the side sometimes and get out of the way.

mark
orgs mfg

 

[Safari Ary]

Now, if it just didn't reduce ground clearance under the axle.

Well, let's see what the man has to say about that....

Edit: so mark, what about over the tube?? Think it's doable? Or do you think the coil bucket would be too tall to the point of :moon: fab??

Ary

 

[XJJPR]

Mark, I totally understand how these work, now my question is, if you built the coil buckets, etc around this idea, do you think it would be feasible to hook the arms over the tubes?? I've got this Tera 50 sitting here with Virgin tubes, so it's a blank canvas. I know you're familiar with Blaine's home-made coil perches for his front axle that I believe he cut from 2x4. Now imagine the height between the tube and the bottom of the perch much taller, as if the perches were cut from 4x6 or something similar. Do you follow? It would be a cheap way to build in an extra two inches of lift since I wouldn't have to change my coils(this is a good thing), and you wouldn't lose any ground clearance either. Thanks.

Ary

I see what you're thinking but the arm does move around a bite and would need alot of room. You would need to do some mock ups to see how everything lines up.

mark
orgs mfg

 

[Safari Ary]

I see what you're thinking but the arm does move around a bite and would need alot of room. You would need to do some mock ups to see how everything lines up.

mark
orgs mfg

Can you give me a guesstimate as to how much the arm moves in relation to the center of the tube from fully compressed to fully drooped?? Do you think we're talkin about an inch? or 3? I'll have to sit down at the drafting table and have a look see. Does Currie's site have dimensions of the arms on it, if not, could you give me some?? Thanks

Ary

 

[Goatman]

Ok, I thought some of the Qs from you were sounding weird.


I measured it at around 1/2" max at the first lift I had, now I think it is less.

However, the curve of the arm sure slides over stuff nicely. The arm will also move to the side sometimes and get out of the way.

mark
orgs mfg

It would be more for me because my arms are even with the axle, but I can see how sometimes they would just move out of the way by rotating sideways. It would be tough to build a set because they need to be so thick, I'd have to buy Currie's and lengthen them.

Hmmm, that would give me about a 26" long arm.

Naw...then I could be accused of having long arms.

 

[XJJPR]

Can you give me a guesstimate as to how much the arm moves in relation to the center of the tube from fully compressed to fully drooped?? Do you think we're talkin about an inch? or 3? I'll have to sit down at the drafting table and have a look see. Does Currie's site have dimensions of the arms on it, if not, could you give me some?? Thanks

Ary

The bottom of the curve of the arm probably moves 2-3" off centerline.

As I got more lift from a new set of coils, now around 6"+ a little eek, I had to cut off most of the stock shock mount to have room at droop. It will be during articulation you'll need to be most concern on clearances.

An example, I had a jam nut come loose and when I tighten it the joints weren't in line. This actually cause enough bind during articulation to limit the amount of droop there was.

So play with it before you commit to it. I'll try and take some measurements at work.

mark
orgs mfg