Mr. Green's Surgery

[Mike]

Where do you get the calculator? Do they explain how to use it, and what it all means? I'd like to run the numbers on my current set up. Thanks

Sorry to take so long to respond. Thanks Nick for sending the link for the calculator. There is also a three link calculator if you want to use that style.

Let me start by saying that the method of using this calculator has LOTS of controversy surrounding it. Even using a calculator has a LOT of controversy surrounding it, Heck, just bringing the topic up on Pirate can cause a thread with hundreds of opinions and posts.

That said, and since this is a smaller venue, I'll post the guidelines that I have gleaned from many posts and the extensive research that Dirtman13 has done. Keep in mind, there will be many folks willing to argue the guidelines that I have below, so take this as just my opinion:

• Make the control arms as long as you reasonably can
• The length of the upper control arms should be 70% to 75% of the lower control arm length
• A vertical separation of the mounting points of the upper and lower arms at the axle should be at least 6" or more
• The vertical separation at the frame mounting points should be 70% to 75% of the vertical separation distance at the axle
• The lower axle mounting points should be as wide as reasonably possible
• A high roll axis center is good: 25" to 27" if possible
• Shoot for 0% Roll Axis (+/- 2%)
• The Anti-Squat should be between 70% and 80% for rock crawling and road manners.
• The total Anti-Squat (AS) changes from full droop to full bump. The total AS should be between 50% and 120%.

Additionally, all of the measurements are in the plane of the ground or 90 degrees from the ground. True flat and true vertical. The length in the calculator of a control arm is not the actual length of the arm. Instead it is the distance from the centers of the mounting points in a straight line level with the ground. Same principal for the vertical separation measurements.

I hope that this helps.

[Tumbleweed13]

Thanks for the info. :thumbs_up

[Mike]

Well I finally got the rear suspension mounts and truss built and tacked in place. I dummied up some control arms using PVC that Rat gave me:


Only 2 spots that look like they might need modifications. The upper control arm at the frame might hit the tub at full bump:


But I couldn't check the full bump of 5" up-travel due to the cross brace under the tub. I have been planning for this issue though:


In the short term, I plan to hack out a piece of the brace to allow full up-travel. That way, I can see how much the tub will need to be altered.

In the long run, I plan to alter the rear frame like Fred (Flatout) did. I don't need this for the suspension travel. I will need the frame change to support the gas tank that I have in mind.


The control arms slipped a little when I tested the full droop of 9" on the driver's side and the full bump on the passenger, but the results were still good. The driveshaft yokes were still nicely aligned:


At full droop on both sides, the driveshaft angle seems extra steep. I will need to get the specs on this and reach out to Tom Woods or similar to make sure that the driveshaft angle can be made:


Any thoughts from you folks that have done this before?

[aw12345]

As long asa the yoke/ CV doesn't bind you are fine1350 U joint gives more angle then the smaller ones

[Mike]

As long asa the yoke/ CV doesn't bind you are fine1350 U joint gives more angle then the smaller ones

Cool. It looks pretty steep, but there is a fair amount of distance between them. We'll have to wait and see.

As for the Upper Control Arms hitting the tub at full bump, well they do. Not badly, and it would be rare that this would actually happen, but I am going to modify the tub a bit to make sure that it is never a problem:

[dirtman13]

That's what I had to do as well. Looking good.

[aw12345]

Having to clear the tub a bit right under the seats is a given if you want some separation between the links

[Tumbleweed13]

Looks good. I like the way the LCA mounts on the axle are placed. Mine are the same way. It's nice not to get hung up on anything. Coming along great.

[Mike]

Sorry to disappear on everyone, but I have been pulled in multiple directions lately. I've been making progress on Mr. Green, but slowly.

The rear control arms are in place. Fully tested and now welded in and painted. I played around with the idea of using 7075 aluminum arms, but several of you folks helped me to talk myself out of that (even though you may not know it).

I got DOM at a great price from the Patton's dealer in Hesperia. Way better price than the other Patton's in the IE. The finished product seems to have turned out well. Here is a pic at full droop:


Here is a pic at close to full articulation:


I took measurements and planned out the shock mount arrangement and decided to go with a chopped frame in the rear. I think that I may need the frame supports for the new gas tank. If not, it will make a cleaner space in the wheel well. I did the initial chop. Still planning the execution, but Mr. Green looks like this right now:

[flatout]

Looks good Mike. Before you know it you will have it in the dirt. Now that I am done with my swap if you need help let me know.

[Mike]

Looks good Mike. Before you know it you will have it in the dirt. Now that I am done with my swap if you need help let me know.

I would absolutely appreciate any guidance or assistance. You are welcome any time. I may hit you up about the shock set up for coilovers. If you are around this weekend and have some free time, let me know.

[Mike]

I've made some good progress. The rear frame is designed and welded in including new body mounts:


I have mounted the rear shock towers and I have articulated the axle through the various positions and it has good clearance in all positions including with the tires mounted:


So I am stopping on the rear for now and focusing on the front again. I really appreciate Fred (flatout) stopping by today and taking a look at what I am doing. Great input and the help with cutting the front frame off was perfect timing.

One of the things that he suggested that I check first was the tire clearance on the LCA. Good call, because the tire rubs a bit at a full turn to the stops:



Looks like I will need to push the mounts in at the frame a bit. I can't go too far or I stand a chance of interfering with the front drive shaft. I'll tackle this next, then I plan to start building the new front frame. The front articulation looks good with the new shorter radiator that I bought. I'm getting excited about tackling the front suspension!

The machine work and High Steer arms that JP5 Performance did for me turned out well. The clearance seems to be great. The design seems to be strong. Looking forward to seeing how the steering components work with the arms.

[daniel_buck]

Doesn't look like it's gonna rub that much? Would it be bad if it kissed it every now and then? on my TJ the front tire rubs the frame every now and then at full lock when stuffed up, but it doesn't seem to be a problem.

You could take a saw to the corners of the lugs and trim them a bit too.

[aw12345]

Nice progress Mike

[Mike]

Doesn't look like it's gonna rub that much? Would it be bad if it kissed it every now and then? on my TJ the front tire rubs the frame every now and then at full lock when stuffed up, but it doesn't seem to be a problem.

You could take a saw to the corners of the lugs and trim them a bit too.

The worry that I have is that the rub is at ride height. With flex, it will only get worse. It is probably better to try to change it now in my opinion. My options are somewhat limited unless I go to a very radical change.