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Discussion Starter #1
Starting to think about how layout I might endup doing the 4 link design and I am wondering if there is a min length for the control links.

Right now the lowers (red) are ~32" long. Which I can easily adjust by moving the rear crossmember closer to the front of the rig. Will 32" be too short? I should have measured the uppers but i didn't get there far. Plan to do that tonight.

Anyone that wants to bitch about the cinder blocks can do it else where :flipoff2:

 

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If you can go longer defintely do it. I have the same exact setup and mine are 39". Uppers and lowers are the same length. Haven't got to test it yet, though.
 

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Only useful thing I could say is a D90 3 link the upper is 23" if memory serves me. So 32" is considerably longer but I would say try to eek a bit more. And the cinder blocks are ghetto :p
 

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Discussion Starter #5
SuperRanger said:
Did you get a good deal on a bag fly ash or something?:D
I dont follow. I wont have time to look at the setup again untill sat but i am sure I can get some more length. The axle might even end up coming back. I need rims and tires for definate placement.
 

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Since your early in the design phase, the link length issue may need to consider the driveshaft type.

The CV-DC joint shaft will want to point the pinion at the t-case output through the travel range. Pinion angle gain will change with the angle and length of the upper and lower control arms. Make the lengths work for you to help keep the pinion pointed close to the t-case output.

A standard u-joint shaft needs to keep the pinion and t-case parallel. Equal length control arms help keep the pinion angle gain minimal through the travel range.

Short links tend to force wheelbase changes, and steep links, with long travel. Neither is good if you are trying to fit the axles inside fenders, or plan pushing into obsticles while climbing.

The upper arms are usually the space limitation, although length can be added behind the pumpkin (move the axle mount brace back to gain arm length, except remember you have to allow for the pinion brake).

Start designing with the upper arms, with maximizing the length in mind, and then work out the easier positioning of the lower link mounts.

Happy Trails!
 

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Discussion Starter #8
Thanks for all the info. I'll see what i can do this weekend and give and update.
 

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http://www.extremevehicledesign.com/projectelfcruiser/4linkconv.htm

here's my POS, lowers are about 37", uppers are about 39". As someone said above, the lengths aren't too important as long as your angles are good. I would think that 32" would be a minimum though. Because you are doing a double triangulated setup, short lowers will not mean lots of axle-steer. I still need shocks, limit strap, exhaust, etc. before i can wheel mine to let you know how it works. BUT - see how my links are extremely parallel with the ground(the uppers even angle down a couple of degrees), anyways that will keep your AS low, and the roll center closer to the COG for a much more stable rig.

Good Luck!
 

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Discussion Starter #10 (Edited)
Elf_cruiser: Interesting setup. I hadn't considered mounting the lower links on top of the axle for better clearance. I didn't think the angle of the lowers mattered as much as having the uppers parallel to the ground.

Because chunk is at least 8 or 9" tall off the top of housing that should prove to be plenty of seperation between the links.

Is the bracket you have on the top of the chunk machined to fit over the inspection panel? If i remember correctly it isn't flat.

Oh ya. Not exactly what I consider a POS.
 

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The bracket above the center section replaces the inspection cover, and it would be pretty easy to make. Mine is a 3/8" thick spacer ring, then a flat 1/4" plate, both with the hole pattern cut to replace the inspection cover. The ring gear sticks up about 1/4" from the top of the carrier housing. I went with a 3/8" spacer ring just to be sure it would clear.

Actually, the angle of the lowers has more impact on AS than the angle of the uppers. You can change the IC point more drastically by moving the lowers than by moving the uppers. Mounting the lowers above the housing is MAINLY to get a better AS value, but the clearance is a nice added bonus. They are actually up higher than my leafs were, and I never hit those before. And yes, I am not worried about the vert. separation because the carrier is soooo high...
 

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Discussion Starter #12
coil positon

Thanks for the info.


This doesn't concern my links so much but i am gonna try and keep all the tech in this thread. From the below pic you can see there isn't much room to mount the coils. Will i have any problems mounting the coils inbound of the frame rails? Or should i cut a couple angle peices of the same 4x6 material and narrow the front of the frame?

 

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It looks like you have plenty of room to me. Mounting the coils inboard of the frame will make your rig very unstable. I would try to use longer coils that are mounted outboard of the frame. Take a 6"x8" piece of plate and weld it to the top of the frame rail so it sticks out towards the tire(or, where the tire will eventually be...) then, you have a 6"x6" square to mount your coil. Add a few gussets to support it. Then get some coils that are about 20-22" long(my guestimate from the pic...) and fairly stiff, like 200-220 lbs/inch, and you should be good to go.
 

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Discussion Starter #14
Sorry, My bad. I have a set of 16" fox coilovers. Once i get some springs mounted on them i wont have room to even mount them straight up let alone at 10-20deg inward because of the diameter of the springs. The shock itself would rub at this point.

I will probably just have to narrow the front of the frame. I will take some more pics tomorrow and post up my thoughts.

Thanks again
 

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Discussion Starter #15 (Edited)
Update

Well, it was going to be pretty difficult to get the coils to mount on the outside of the frame rails so i decided to narrow the front of the frame. I should have plenty of room know.

I made some upper 4 link brakets that i can bolt to the top of the housing for easy removal. Much thanks to Elf Cruiser, I got the idea from his setup and modified it to work for me.

I was able to move the rear cross member forward and ditch the hoop that I had made because it wont be in the way of the driveshaft now. I think I am going to be able to get away with 40" links for the upper front and rears, plus the RE bushings so 43" total length, bolt center to bolt center. The lowers should be within 2" of that.

What should I am at for link seperation at the frame end? There isn't a hole lot of room. I think i will be luck to get 4-5".

Any suggestions send them my way. Oh and this is prob a stupid question but do i need some misalignment bushings for coilover mounts?

Last question for now. Anyone do anything about the space between the hub and the housing on the rear? You can see in the pic below the red grease. It seems like it will be pretty easy for dirt to get in there. I was thinking of cutting the ring out of the drums and bolting it on for a little added protection but i dont know if it would help.



 

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there's supposed to be a seal there where your red grease is. Link bracket looks good, I guess your links need to be centered over the carrier, and not the pinion?
 

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Discussion Starter #17
There is a seal behind the bearing that is pressed on the spindle of the rear axle but i question how well it is going to work. The grease may just be there because I had a lot of extra. I guess I will just have to run it and see.

I was trying to center the links over the axle. For the rear it ends up being over the carrier. The front is a little different. Without the links centered they would be different lengths, mounting them at the frame rails.
 

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OK, i thought you didn't have a seal. If you overgreased the bearing, then i guess it could spill out like that. I haven't had an issue with mine, and I greased the wheel bearings 2 yrs ago, haven't touched 'em since. They still roll, heh. Anyways, if you notice in my pictures, I have one hub flipped in and one out to center the pinion under the rig. That's why my links converge over the pinion...
 
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