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Originally posted by dirtrod:
<STRONG>It will work fine just use good stuff and make sure you have clearance around the driveshaft when articulating and the tires at full turn</STRONG>
What tubing size are you using? I want to go with 2" .500 wall DOM with 1" or 1.25" heims. I think this will be plenty strong in a straight link configuration (i.e. no bends). I will be running a 1 ton D44 front and a 1.25 ton D60 rear out of a military truck with 39.5" boggers so that is alot of weight to consider. I'd much rather overbuild the hell out of it than have something bend or break on the road or on the trail but I cant really go up too far in tubing size because I have a limited amount of space to work with under there. Oh yeah its for a '95 YJ if that helps at all
 
Great Discussion!!!!

Here are my thoughts for what they are worth.

To set up the rear suspension to drive up hill or to hook up properly when you throttle it you dont want any anti squat. If you have anti squat the rear will try to walk underneath the rig when you hit the gas. Two things give you anti squat. Firstly having the links at too much of an angle going down from the chassis to the diff as what happens when you lift a standard truck up to much. What happens here is when the rear pushes forward it will push up at an angle on the rig and lift it and the rear will start to walk underneath and make the angle worse and so on. Long links fix this and horizontal links also fix it. This is why you should mount all the links on top of the axle to keep the links as horizontal as possible while still giving you the lift you need. Generally the higher you lift the frame off the axle the harder it is to get rid of the anti squat. The second cause is when looking from the side of the frame if the upper and lower links are not parallel and converge to a point (or converge at all). What this does (if they converge to a point) is lift the rear of the rig from the torque reaction of the diff. When you gas it the rear diff trys to rotate backwards and if the links go to a point it will lift the rig at that point and unload the rear and start to walk etc.. If the links are parallel then the rotation of the rear is controlled by the diff pushing and pulling on the frame through the parallel links and does not produce any lift (or anti squat effect)

So I believe the best setup is to have the links parallel and as horizontal as possible (when looking from the side). This means if the rig is lifted they should all go on top of the diff (just like Lances cruiser, from what I here it climbs umbelievable) and be parallel.

These are just my thoughts and I have never built a four link but I am going to real soon!!

<IMG SRC="smilies/biggrin.gif" border="0">

I have got some ideas on the roll centre bit as well but have got to go so if what I have said here is total BS then flame me and Ill shut up other wise Ill post the rest of it soon.
 
Originally posted by BabyWrangle:
<STRONG>What tubing size are you using? I want to go with 2" .500 wall DOM with 1" or 1.25" heims. I think this will be plenty strong in a straight link configuration (i.e. no bends). I will be running a 1 ton D44 front and a 1.25 ton D60 rear out of a military truck with 39.5" boggers so that is alot of weight to consider. I'd much rather overbuild the hell out of it than have something bend or break on the road or on the trail but I cant really go up too far in tubing size because I have a limited amount of space to work with under there. Oh yeah its for a '95 YJ if that helps at all</STRONG>
For the uppers I'm useing 4130 1" x .120
with a 1 3/8 x .095 sleeve over it with rosette welds every 6" oc, the lowers are the same with a piece of 2" sch40 pipe sleeve over that to keep the outer tube from getting kinked on rocks. I'm useing 5/8 x 3/4 40,000lb rod ends and I've beat it harder than I've ever seen anyone beat one of these things, without breakage... so far.

I'm no fuggn engineer, so this is all jmho...
2" x 1/4 or 5/16 would be enough for the lower links, 1 1/2 x 1/4 would be plenty for the uppers. Those 1" rod ends would be nice, but, I bet they cost $60-70 ea. . Make the brackets strong 1/4" or thicker and keep the machine as low and light as possible.
Those 39.5 boggers will eat that D44 every time they get a hold of something, maybe you could try a 8" wheel and 15lbs of air. I was busting a ft44 with 38 x 11.5 boggers on a 7" wheel, on a regular basis, in a 4000 lb cj... 44s are wimpy with big tires.
 
well cody i belive you have got your moneys worth. there is plenty of info to get you started. but i would still wheel it first and see if you have any problems. by the way guys great thread. mike
 
Originally posted by dirtrod:
[QBThose 39.5 boggers will eat that D44 every time they get a hold of something[/QB]
Still not 100% sure about what axle I'm going with. I might just have to pony up the extra bucks for a D60 front so I never have to worry about anything happening to the front. Also, the reason I'm going to go with such a big heim joint is because it will be a helluva lot stronger than what I need, which is good for peace of mind. I'd much rather spend the money up front for something I KNOW will never break because this rig is my daily driver and will be for the next few years until I get out of college(4 and a half more years...damn masters degree). Plus I don't want to have to worry about something coming apart at highway speeds. Better safe than sorry.

On another note, you said you were using tubing that you sleeved with another piece of tubing. What is your reasoning for doing this? Does it make it stronger than a tube of the same size overall? Like if the two sleeved pieces end up being the same I.D. and O.D. as a single piece of tube, which one is stronger?
 
A d60 won't hold up to massive stupid abuse with those 39.5s either, but it will take alot more than a 44.
Like I said I'm not a engineer, but I did the sleeve thing to keep the bar intact if I creased it on a rock. I started with just 1x.120 upper bars with out the sleeve, but I bent one beating the jeep against a rock, so I sleeved the uppers, then I dented one of the sleeved lowers, so I put a big ugly piece of plumbing pipe over the lowers. No problems yet. : )
 
Originally posted by dirtrod:
<STRONG>A d60 won't hold up to massive stupid abuse with those 39.5s either, but it will take alot more than a 44.</STRONG>
Well I'm not one to give my rig massive amounts of stupid abuse but it will see its fair share of use.... It's my daily driver so I can't have huge things breaking on me all the time <IMG SRC="smilies/tongue.gif" border="0">
 
Ok, got it...just remember one thing about a Triangulated 3 or 4 link front (as opposed to a panhard), if a hiem joint or bracket, or a control arm/bar/link/rod or whatever you want to call them lets go, the whole machine is gonna fall off to one side and you won't have any control at all, so if it's a daily driver, be careful and don't skimp on shit.
 
Originally posted by dirtrod:
<STRONG>Ok, got it...just remember one thing about a Triangulated 3 or 4 link front (as opposed to a panhard), if a hiem joint or bracket, or a control arm/bar/link/rod or whatever you want to call them lets go, the whole machine is gonna fall off to one side and you won't have any control at all, so if it's a daily driver, be careful and don't skimp on shit.</STRONG>
One though I had about that was to keep my JKS adjustable trackbar that I'm running now. It's got heims at both ends and is fully adjustable for length. I could just keep that on there with the 4 link and undo it for wheeling. That way I get the best of both worlds...good handling and safety on the street and good flex from the front offroad. The only thing is it might not be long enough with all that lift....guess I will have to see about that when I get everything fabbed up and if its not long enough I can build a bracket to raise it up off the axle. Sound like a good idea?
 
I don't know if you want to follow this Pig Pen guy's advice. He almost rolled his junk on its maiden voyage through campus tonight. I thought I was going to die! <IMG SRC="smilies/eek.gif" border="0">

About link convergence from the side. I see your point about the axle creating a torque around the convergence point. But, that point would need to be so close to the housing to really matter. If you run a regular driveshaft then parrallel links are ok, but for a cv rear shaft they need to converge somewhere so as to keep the pinion pointed at the t-case throughout its range of motion. Besides under acceleration, uphill or otherwise, I would think you would have so much weight transfer that it would easily cancel out any lifting forces. I aggree that longer links are better though.

By the way, my lower links are 1 5/8ths .25 wall dom with 1 1/4 heims at the end. From the info I have that my old roommate left me, at there 40" long length they will hold roughly 7 times the weight of my jeep. Of course its only a cj5 and I am no engineer.

Anyhow see ya,
Kev
 
hahaha.......that was fukin awsome!!! Just hooked up the brakes and took it for a spin (no Shocks yet). Took a corner with a bump on it at abour 25 and just got on it hard. The front drivers side tire pulled 3 feet in the air. I almost pissed my self.
 
Originally posted by Pig Pen:
<STRONG>hahaha.......that was fukin awsome!!! Just hooked up the brakes and took it for a spin (no Shocks yet). Took a corner with a bump on it at abour 25 and just got on it hard. The front drivers side tire pulled 3 feet in the air. I almost pissed my self.</STRONG>
damn, do it again and get pics! <IMG SRC="smilies/eyemouth.gif" border="0">
 
Originally posted by rokcrawla:
<STRONG>damn, do it again and get pics! <IMG SRC="smilies/eyemouth.gif" border="0"></STRONG>
Thats the first thing I thought of after checkin my drawers...After I get use to this and feel the limits i might try and get a pic. However, when the shocks go on I dont think it will be nearly as bad.
 
Originally posted by Ghetto Fab.:
<STRONG>
If you run a regular driveshaft then parrallel links are ok, but for a cv rear shaft they need to converge somewhere so as to keep the pinion pointed at the t-case throughout its range of motion.

Kev</STRONG>
Why wouldn't you want the pinion to be pointed at the x-fer case throughout its range of motion with a normal driveshaft too? So by running parallel links it doesn't keep the same pinion angle but converging links do? So how do you determine the ideal convergence angle of the upper and lower links (when looking at them from the side)
 
Originally posted by Pig Pen:
<STRONG>Not neccessarlily(spell check anyone??) You should keep in mind that driving on the road you suspension doesn't really move that much, so in my opinion that is something to take into consideration. Off road, say your suspension flexs out while you are crawlin, how fast are you driving????? Fast enough to feel a driveline vibe if you pinion angle chages slightly, highly unlikely.</STRONG>

see above
 
Originally posted by BabyWrangle:
<STRONG>One though I had about that was to keep my JKS adjustable trackbar that I'm running now. It's got heims at both ends and is fully adjustable for length. I could just keep that on there with the 4 link and undo it for wheeling. That way I get the best of both worlds...good handling and safety on the street and good flex from the front offroad. The only thing is it might not be long enough with all that lift....guess I will have to see about that when I get everything fabbed up and if its not long enough I can build a bracket to raise it up off the axle. Sound like a good idea?</STRONG>
You really can't run a panhard/trackbar with triangulated links... the links won't let the chassis move from side to side at all, and the panhard won't let the chassis move up and down without going side to side. :0
 
Originally posted by dirtrod:
<STRONG> You really can't run a panhard/trackbar with triangulated links... the links won't let the chassis move from side to side at all, and the panhard won't let the chassis move up and down without going side to side. :0</STRONG>
Yeah I got to thinking about that today during one of my boring classes and I figured that out. Oh well <IMG SRC="smilies/tongue.gif" border="0">
 
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