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Free and decent picture tool is irfanview. Just do a search (CNET has it). Re-sizes, ,changes type, can reduce picture content several ways to make is smaller yet readable, shading , color, etc.
There is a windows xp "powertoy" available from microsoft that can resize pictures. It adds "resize" to the options that appear when you right click on an image. It can do individual or bulk. No cropping though.
so i tried for about an hour last night to resize and post but by the time i had them small enough to upload you couldn't read the text in the fields..
i have them in my photobucket acct if anyone feels like messing with it..
Try irfanview. Their is an option to put it into internet 'size' that works very well.
So I measured my ZJ again and here is what I found;
Upper arm, stock length 15 ", long arm cut off frame upper and lower frame brackets and create new bracket so the long are is aproximately parrallel to the ground and arm is 20-21" bolt to bolt.
Lower arm, stock length is 15.5", extend from axle stock mount to 34"-40" and mount to new backet welded to the frame.
The above results with an anti-squat below 40% depending upon actual final lengths and heights.
The only thing left is to decide on lower arm length. Shorter means stronger from a bending perspective. Longer results in a smaller angle but for the dimmensions I have longer does not seem to affect anti-squat much. Any thoughts?
Besides clearance concerns, the angle and the length of your lowers is less significant than the relationship of the length of your lowers to the length of your uppers. The amount of convergence of the uppers and lowers on the frame side is also something to think about... you usually want a little less vertical separation on the frame side than the axle side.
How does adjusting the length of your lowers affect the location of your instant center and your roll axis characteristics?
And what is everybody using for a COG estimate?
I was curious about the other parameters. Any idea what value they should be at or the relationship they establish? For instance roll center, do I care?
My wheel base is 105.9, the spec for a ZJ , the tool had 109 to start. All other I left intact. I will look and see if they change the anti-squat much at for provisional design.
I case anyone is wondering using the factory axle mount approach does not triangulate enough to eliminate the track bar. But since I already have a heavy duty adjustable one it doesn't matter. But my current cost estimate is below $280 DIY.
Last edited by ZJ TINS; 08-12-2010 at 08:52 PM.
You can't eliminate the track bar without going double triangulated and full hydro steering. The steering puts more lateral force on the axle than only triangulation can handle. You'd be popping joints out all the time.
That would only be true if you were running crappy or severely undersized joints and/ or did not have enough triangulation in the suspension.
The main reason to go to full hydraulic steering with a triangualted front suspension is to avoid the bumpsteer that would result from the arc the the drag link follows through its travel and the axle no longer following the same/ similar arc because of the lack of a panhard bar. Full hydraulic steering also simplifies other things that tend to go with a triangulated front suspension like moving the axle forward and potentially gaining more uptravel without extensive chassis modification along with the increased steering force required by larger tires someone with that configuration would likely run.
There are other ways to configure the steering to eliminate bumpsteer with a triangulated front suspension (like a push-pull setup) but none that are really practical unless you built the rig around it or just lived with significant bump steer.
For my lift and reuse of the axle mount approach, i don’t see the parameters change much… maybe 5% for fairly extreme changes in individual parameters, with an exception of the height difference and parallelism of the top and bottom arms themselves drastically affect the anti-squat. A marginal approach seems to have some popularity in the putting the top arm frame end near the bottom arm frame end within a couple inches. This give anti-squat between 96 and 105 %.
My shorter arm and careful place gives me sub 40% range.
Also the long arm close frame end approach changes pinion angle to +5° at 4" up and +7° at -8”. The shorter are approach gives 1.4° at 4" up 3.3° at 8" down.
So the long arm close together puts more stress on the u joints that the shorter arm approaches.
So it looks straight forward, rubber in front johhny joints in the rear. Now just have to decide if it is worth it to get the arms set up to rotate to change lengths (threaded both ends one reverse).
Also with bottom arms in the sub 38" length means no interference with the cross brace I can do anything with that (as in leave it alone, I like Kevins old design).
Still plan on getting some 2" PVC and try some fits and do compression droop tests.
Also I can custom make/fit some frame stiffeners while I am at it.
Found a couple things: roll axis you want as close to 0 as you can. Travel roll axis is the same except when you droop or bump its the current roll axis. That should be kept small also.
Pinion change needs to be near near 0.
You also want to keep the arms parallel to each other first and the and the ground second. At least when i do the numbers for everything come out a lot easier to optimize the multiple parameters.
If the arms are parallel then this 70% arm length ratio does not mean anything. In fact if they are parallel the arm ratio has little meaning. So you have put your arm where you want. Remember i am only looking at +4" bump and 8" droop or so. You guys going much higher would need to mess with the setting and see if it hold true.
Bump.
Hypothetical - if you were building a custom suspension to replace your existing long arm kit, would you do the front first or the rear. (this would be over a extended period of time)
Last edited by rstrucks; 08-27-2010 at 09:42 AM.
I'd start on the rear because there is less to work around. It's usually easier to build without any steering to complicate things...
Some more info on the 4 link calculator:
The roll axis angle defines oversteer(+) or understeer(-). Ideally you want a slight understeer. However multiple articles on different vehicles indicated near zero ( +-3 degrees) is not noticeable is most situations. This is especially true when dealing with a lifted vehicle and offroading. However severe understeer and oversteer could be potentially uncontrollable is certain situations. To me this means keep is near zero and then do not worry about small changes.
I also noticed different ratios (arm lengths, angles of arms etc) can give you almost the same anti-squat and roll axis angle but allow the pinion angle to either change greatly or very little. So is seems prudent to get your design close, then tweak it to get the pinion angle change low for the delta between the maximum bump ciondition and maximum droop conditon.
If the rig was down for the whole time it wouldn't much matter to me. As for "bang for the buck" I think the front would gain the most. Although it also needs to be the most detailed. If it was someones first custom suspension build I would say do the rear first, and use what was learned in that process when you move on to the more complicated front.
I've been looking at taking my claytons, and inboarding the lowers with minimal modification to turn it into a dual triangulated and remove some of the axle steer characteristics I'm getting. I'll be doing a front 3 link before that happens though, simply because if I'm going to build the bracketry for the new axle might as well do it right
Here's a good example of a suspension behaving nicely
Last edited by ATL ZJ; 09-08-2010 at 08:58 AM.
thanks for posting that cam... doesn't even look like my tires spun and its clear I dumped the clutch pretty hard. I really gotta take the time and post my rear link photos and calculator screenshots..
Bringing back up a slightly old thread for some advice.....
Anyone with a 5.9 running triangulated front limiting straps? I wanted to see what your choice for the driver side unibody end mounting was. I only see one motor mount bolt on that side that is in a good position and it's coming through the unibody and the motor mount, but the nut is welded to the motor mount. Is it safe to run a longer bolt and attach it there? Just doesn't seem like a strong setup to me, but I could be wrong.
These are going to be a must with my new setup which is a HP 44, extended radius arms back to a Clayton's crossmember. I'm not running a sway bar currently and it hasn't been a real issue up to this point, but I do feel the front end's tendency to unweight.
I don't run a triangulated strap (yet) but this may apply anyway. I have my front limiting straps attached to the engine mount isolator bolt. It probably isn't the best option but it has worked well for me. For the amount of time the mount has seen extra stress due to the front axle weight hanging off of it, it hasn't been an issue. The rubber isolator looks just like it did before the strap. YMMV.
Last edited by rstrucks; 12-07-2010 at 11:55 PM.
Thanks. That looked like the best place, but I was nervous to run it off of those bolts. I thought the lateral stress from triangulated straps would be an issue.
can you elaborate on this?
this hasnt really been covered at all that i have seen,
what is everyone running for wheelbase?
can you push it forward too much?
same question for rear axle back?
any related info for how far to push your axles?
( i figured this was the best place for this question)
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