At any rate ... now that we have the fundamentals down *ahem* .... you folks ARE reading this, right? And not just looking at the pretty pics?


So we start with the crossmember. You already saw (earlier in the thread) the rusted metal mock crossmember. Here is a quick shot showing how it hangs below the rail.






And this is the profile I am looking to attain







While the mock crossmember was in place, I wanted to get a feel for where the UCA mount would sit. I preferred to place it on the driver side because the floorpan afforded more clearance (even though there is a driveshaft & part of an exhaust running in the same area).


The picture below shows just how tight things fit. The short mount to your right would have been the ideal spot (room wise). However, there is not enough vertical separation or distance between the lower mounts and the upper mounts. If you go back to my "techie" post .... you will understand that the lower the vertical separation, the lower your anti dive will be (and your roll axis angle as well). The tall mount on the left obviously has to squeeze between the driveshaft and the transmission.






At any rate ..... new tubing was cut up and shaped to fit.






The pockets were angled and boxed in to fit the Ballistic joints. I tucked the joints as high as I could while keeping the geometry where I wanted. The joint sits roughly 2 inches higher than if I had mounted directly under the frame rail. I also ran the tabs/mounts lower so that even when flexed ... no part of the joint would stick out below the tabs or crossmember.

 

Hey where are my pics?
Looks everything fine to me. Can you add to this little program also the rear geometry data? so that it can mesh it with the front data and plot the real roll axis?
It's definitely not a confort vehicle anymore with 71% of antisquat....

 

Been away for a few days. Funeral .... kind of last minute. I'll try to get them up today.



Both the 3 link & 4 link calculator programs are available around the 'net. Seach on Pirate4x4 --- you shouldn't have much trouble finding it. Use the 3 link for the front and 4 link for the rear. I haven't looked much into calculating the suspension with a leaf spring rear, however most of the same terms apply. They're just applied differently.


71% Anti-Dive isn't very high. Take a closer look at the pictures ... you can see multiple mounting holes. My Anti-Dive is adjustable from 64-91% depending on how the other chassis components react.


Plotting the factory 5 link is a bit of a mess .... if you'd like some help with that --- give me a shout on the side. Probably would be a good idea to get some factory numbers out there for people to see. Maybe I'll make a side project out of this ..... any volunteers that speak English for a first language?



Joe

 

I'm sorry.


I have this: http://performancetrends.com/4link.htm (for free...)


That's because the arms are almost parallel, and the instant center is way out of the chassis.
You? i'll be to old to wheel-build it, at the time you finish it (if you ever will).....
boooo... i spik inglisc weri wel...

 

Are you going to make your cross member center removable?

 

Thanks. Was a cousin through marriage. Was rather sudden.


I have that one stored on the other computer (I'm on the shop laptop right now). Seems good, but haven't used it extensively.


Seriously, look for the pirate one. It's more geared towards wheeling folks. Has pinion angle change options based on droop or compression.


The arm placement has nothing to do with making it difficult to enter in "five link" data. The 4 link calculator has no provision for a track bar, and the 3 link calculator has no provision for a 2nd upper arm. I spoke with Dan about this and will have to explain it to whomever works with me on this little project.



If you really want to do this .... contact me via instant messenger. I need a stock XJ front suspension to start with. In time, I will add other modified suspensions to the list. If you want to do the rear calculations based on the program you just suggested --- I'll try to work with you on it.



Nick .... the center is removable --- I just haven't gotten to that point in this build to show it. If you need to see a picture before everyone else .... give me a shout on the side and sign my release form.




Joe

 

Added you to my Yahoo contact list..

and I might have to take you up on those pics...

 

Well if the arms are perfectly parallel there is no possible instant center point.
The non linear dynamics of the track-bar mess up the calculation of the linear approximation of the CAs. (if it effectively is considered by the 3 link program)
But if it works with the 3 link, it should work with the fourth link too, provided that it is symmetrical to the third. (same angle, length, and dimensions).
I'll have a look at the formulas that are behind the data sheet of the excel page, and play a little with both.

 

Yes and no.


If the 4th link was symetrical to the 3rd line (for the 3 link program) then we would have the effects of triangulation. That would be change of roll axis and roll center height. Of the 2 programs, I would say the 3 link would be more accurate than the 4 link ... because of the major forces the track bar acts upon the suspension.


If you are able to figure it out ... by all means, please do so. I'm curious to how the factory numbers pan out when I'm not trying to "wing it"


In my opinion, if one is going to go thru the bother of "engineering" a suspension from scratch, there should be no reason why anyone would want parallel arms.


I'm on instant messenger if you want to start the preliminary hashing out.




Joe

 

Mmm, there are more things to consider when you talk about a series vehicle.
First of all, it must be cheap. The stock sheet metal boxed arms are very cheap. If it had the "Y" arms like the Nissan Patrol or the Toyota BJ/FJ you would need to build them with some tubing or casting like the FJs, for strength.
Then they are short. Too short for "Y" arms or three link. The axle rotation would be excessive.
Comfort is also important in a series vehicle, the chkee customer target is more families and also women, you can see what is happening to the front susp of the newest GC, independent...

 

As I mentioned before ... it's a tight squeeze between the transmission and the driveshaft.


How does one get around that? By spending money, of course !



Here is a "standard" flex joint (a'la Ballistic, Rubicon Express, Summit Machine, etc).





And here is a Summit Machine "Jimmy Joint" that I decided to use. This picture shows the "normal" width at 2.0 inches wide. I requested Summit Machine make a new, narrower ball for even more room. I did not need the 60 degrees of articulation their joint offered and was willing to give up some flex to gain room. They did a very nice job and worked with me on getting what I needed right away. The bracket has been cut & re-welded narrower. Later in this thread ... I will show you a picture of the new centering ball to give you an idea of how much was trimmed.








Mounted the UCA to the crossmember. If you look closely ... you can see the bracket is leaning forward slightly. Take note of the multiple holes in the bracket. They allow for additional adjustment of my suspension based on how I want everything to react. Basic high school geometry tells us that if we move to the highest or lowest holes, the control arm will need to be lengthed or shortened correspondingly. And THAT is why my bracket sits on an angle. It will allow me to change holes without needing to adjust the joint as much (allowing more fine tuning before running out of thread).

 

MMMM...TIG welds...me likey!!

 

What about threading the arm tubes instead of welding the female bush to the tube?

 

The threaded rods end are made from a stronger steel, and therefore would be the best bet, IMHO!!

 

Either way is equally acceptable.


The threaded bung way was easier for me.


Next time ... I will try 1.75 tubing with 3/8 wall and thread that directly. The loss in strength from the slightly smaller diameter should be offset by the increased wall thickness.



Would also make it a lot easier to mate directly with joints (more room to lay multiple beads down).



Joe