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post #1 of (permalink) Old 12-18-2002, 06:36 PM Thread Starter
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Rear Cantilever Setup - Problems/Questions

Each day my Jeep gets torn down another piece at a time. I don't really know where I'm going, but know where I want to be. One of my MANY projects I'm working on is redoing the rear shocks. My problem before was they just weren't long enough, so now I'm planning on doing some sort of cantilever setup. I did a few searches but didn't find too much helpful info for me. First off, most the pics I've seen of these types of setups are with the shocks mounted to the frontside of the axle tubes. Is it possible to mount mine to the rear side and tilt them forward? The reason I'm asking is because I believe my traction bar will interfere with my shock. Anyone see any ill consequences of this? I think it'll clear the gas tank ok. The other problem I'm having is how to build the crossmember for the shocks to mount to. I have fuel lines on one side of the frame rail. Will these be hard to replace? Thanks a bunch guys!

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post #2 of (permalink) Old 12-18-2002, 06:44 PM
 
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Re: Rear Cantilever Setup - Problems/Questions

intersteng thread, im watching.

also I really dig those steel toed converse work shoes.

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post #3 of (permalink) Old 12-18-2002, 06:46 PM Thread Starter
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Re: Rear Cantilever Setup - Problems/Questions

LMAO - I just knew someone was going to comment on those. They actually are steel toed. [img]images/graemlins/wink.gif[/img] They are a prototype that Converse let me try out. [img]images/graemlins/grin.gif[/img]
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post #4 of (permalink) Old 12-18-2002, 06:54 PM
 
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Re: Rear Cantilever Setup - Problems/Questions

yeah, the red stripe was a dead giveaway.

im learing here too, ive got some rancho 9012 to go to my rear, and I was theinking the old H8 way of leangin them in, but I fear the anti wrap bar will interfear.

so hopeully we will all benifit fromthis thread!
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post #5 of (permalink) Old 12-18-2002, 10:55 PM
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Re: Rear Cantilever Setup - Problems/Questions

The farther away you get from parallel with the motion
of the axle (not necessarily straight up and down) the less
effective the shock is.

For instance, at a 45 degree angle the shock only moves 50%
of what it would if parallel. So, the more the angle, the
stiffer the shock needed for the same effect.

And something to think about - shocks compress easier than
stretching - mainly they control rebound.
Notice most leaf spring rear ends have one in front of the
axle, the other behind.
That's not accidental - it's done that way to help control
axle wrap - both on acceleration and braking.
The one in back of the axle resists most on acceleleration
(it's stretching then), the rear on braking.



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post #6 of (permalink) Old 12-18-2002, 11:36 PM
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Re: Rear Cantilever Setup - Problems/Questions

Here is how I did mine, but my fuel lines were already on the top of the frame rails and my traction bar is more to the center. If you mount the shocks on the back of the housing, can you do the upper mounts behind the axle also? or do you have to tilt them forwards for space requirements?
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post #7 of (permalink) Old 12-19-2002, 02:21 AM Thread Starter
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Re: Rear Cantilever Setup - Problems/Questions

That's something I may of forgetton to mention. I'm probably going to have to tilt them forward some for clearance issues. Think this will be a problem? What do you think I could about my fuel lines? Does anyone sell fuel line like they sell brake lines?

RRich - Thanks for the input. I wasn't sure on the numbers, but knew they don't work as affectively. Do you think if I put in some stiffer shocks, and have my traction bar setup, that I'll be alright? What are your thoughts on me mounting them behind the axle on the tube and have them point slightly forward?
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post #8 of (permalink) Old 12-19-2002, 08:32 AM
 
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Re: Rear Cantilever Setup - Problems/Questions

Jammie-
H8 and many others have mounted thier shocks angled toward the center on top like you have them propped up with yer feet.
Square tubing across the top of the frame rails are a popular mounting structure.
Search H8Monday's posts from last spring for a pic of how he set his up.
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post #9 of (permalink) Old 12-19-2002, 09:23 AM
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Re: Rear Cantilever Setup - Problems/Questions

Most anything will work, but to what degree?

Consider this - take it to the extreme - what if one end of
the shock was on the axle, and the other end was attached
to the frame but at the same height? Like the pic is
canted in but way more, really flat.
The shock would do absolutely nothing.

Remember the axle rotates with spring wrap - on braking or
acceleration - symptom is wheel hop, breakage etc.

Say on braking hard - the axle nose tries to tilt downward.
The shock attached to the axle behind the axle goes into
collapse mode, hardly resisting the torque.
The shock attached in front of the axle goes into stretch
mode, resisting much better - it's doing most of the
controlling.

That doesn't mean the axle doesn't rotate, it just slows it
down to a more tolarable level.
If it rotates too fast it can break things, cause wheel hop,
even cause a loss of driver's control.

And a little trick - you can multiply the effectiveness for
the wrap control by the lower axle shock mount itself.
Measure the distance from the center of the shock's lower
mount (pivot) to the center of the axle tube. That's the
moment arm.
Double that distance you double the wrap control without
affecting the "up/down" body control or stiffness.

But too long that long moment arm will work against you too.
As the body bumps up and down, the shock tends to try to
rotate the axle, so keep it reasonable.

Sometimes subtle changes in the geometry can be used to make
up for location and clearance problems.

The use of the radius arms completely eliminates the axle
wrap tendancies, so the shocks can now be placed wherever it's
most convenient.
Those are great pictures by the way, thanks.


"IF" there was a PERFECT way to do it -- everybody would do it
the same way.
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post #10 of (permalink) Old 12-19-2002, 03:50 PM Thread Starter
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Re: Rear Cantilever Setup - Problems/Questions

Jaffer - I've seen the pics of H8's and other's rigs with similar setups. But all of their setups have the shocks mounted to the front of the axle tubes. I'm asking about mounting the shocks to the rear of the axle tubes. Make sense? I'm thinking I'll mount them on the rear side of the axle, then tilt them somewhat forward to clear the gas tank. Any problems seen with doing it like this?

RRich - I hate to say this, but your post confused me very much. I get the basic gist of what you're saying, but not quite sure what you are getting at. I understand the shocks in this type of setup don't do as good of job as if mounted the other way, but they will not need to control axlewrap(as that's what the wrap bar is for), and if I put in stiff enough shocks, they should work out pretty good, right? Slap me around if I'm wrong Thanks for you help BTW!!
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