Thanks for the pic Brandon. That coilover will affect ride height but it does it indirectly by preloading the spring. Just for everyone's reference, I've attached a picture of a coilover that adjusts ride height and pre-load separately.



[IMG]local://upfiles/81674/4055186A95424C4B9D636E1F78E0560A.jpg[/IMG]

You can see that the shock body gets screwed up or down inside the lower mount to adjust ride height. Then the lower spring perch will screw up or down the shock body to adjust spring pre-load.

 

I disagree with it preloading the springs 100%

This might be the case if the part of the coilover that extends was BELOW the adjustment but it is not. Maybe I am not seeing it right but by threading that adjuster you are simply lifting the vehicle, maybe slightly decreasing the amount of uptravel but I don't think the coilover is the limiting factor in our IFS trucks.


I don't really see what your pic does, unless the part that moves is below the adjuster, that way then yea, you are preloading the spring with the upper adjuster.

 

There is someone selling some in the parts section, I've spoken with him in PM's a bit but I don't have the money to go forward with it right now so I didn't ask him to take measurements, he seemed willing to though. If you have measurements for ours you should get in contact with him, long as the measurements match up they should fit.

Here's a link to his thread: https://dodgeforum.com/m_1146103/tm.htm

 

With the coilover in your picture, it appears that the only adjustment is the lower spring perch. Assuming there is some compression on the spring with the truck at rest, adjusting the perch upward will increase the preload on the spring and thereby extend the shock and raise the truck. You can keep doing this until the shock is fully extended but there is a penalty; At this point the ride will be very stiff, with no down travel available.

With the coilover in my picture, the lower spring perch can also be adjusted for pre-load. Generally the best ride setting is just tight enough to take the slack out of the spring when you assemble the coilover. Of course, when you install it onto the truck it'll sag some (just like the stock suspension does) which is a good thing (it gives you both up and down dampening when riding down the road).

Now, to adjust ride height, the body of the shock can be adjusted up or down inside the lower mounting piece. Once the ride height is adjusted, it'ssecured by tightening the locking ring to the mount, just like you lock the perch in position.

I don't know what is the limiting factor on the front suspension. When I changed shocks, I removed the coilovers from the truck without using spring compressors but I disconnected the sway bar and stillhad to stick a long pipe in the hub and stand on it to get the coilovers off the truck. I bet it would really be apain if I had some of those 2-1/2" leveling spacers in there!

 

I still don't get how you are saying it is preloading it. Preloading would be having load without weight on the truck. The spring rate determines how far that spring will compress with a load on it. The amount the spring is compressed at rest is the same no matter what the adjustment of the coilover, therefore the ride is the same. Only difference is the total distance between the mounting points is changing IMHO. Not that it matters, the ride on our hoopty's is a way to soft so we could use it stiffer anyway - I bottom out on my commute on the highway!

 

Brandon I think you'll find the TM kit will help with that some (just make sure you install it according to the new instructions on thier site), I noticed it made a difference for me. I actually want to take mine off and put the lowering shackles on but I refuse to even think about it till I can get better struts.

 

yea, I can't wait to put it on. I just need an excuse to get my wife out of the house for like an hour. I figure jack up one side and throw on spring compressers, lower and remove coilover, install spacer and reinstall then do other side. Guess I need to go read the directions though. Murphy says take how long you think it will take and multiply by 10.

 

OK, let's try this another way I'm just using general numbers for this example.

Let's say thecoilover has 6" of travel and when you set the truck on the groundit compresses 3". That gives you 3" of compression and 3" of extension of the shock itself. The Dak has a motion ratio of about .6, so that would give you about 10" total wheel travel, with 5" up and 5" down to deal with bumps and dips in the road. Now, if you jack the truck up and adjust the lower spring perch so that it compresses the spring 1" something has to change. When you set the truck down the coilover will only compress 2" this time and the truck will set about 1.7" higher because you've pre-loaded the spring. Now the truck will have 6.7" of compressionand 3.3"of extensionat the wheel and will have a stiffer ride. Whether that's good or bad depends on whether the ride was already too soft, too stiff, too low or too high.

Now, let's talk about 3 points on the coilover; #1 is the top mount, #2 is the lower spring perch and #3 is the bottom mount. If you adjust the distance between #1 and #2, you will affect ride height and ride stiffness by pre-loading (pre-compressing) the spring and that's what happenswhen you adjust the lower spring perch. Now, if you can adjust the distance between #2 and #3 you can raise or lower the ride height of the truck without affecting the ride stiffness and that's what happens in my picture when you screw the shock body into or out of the lower mounting piece. Now, let's take the same example above but instead of adjusting the spring perch, let's screw the shock body out of the lower mount by 1". That makes the distance from #2 to #3 and the total length of the coilover 1" longer but doesn'taffect the spring. Now, when we set the truck down, thecoilover will still compress 3", it'll ride about 1.7" taller, ride stiffness will be un-changed and it'll still have 5" up and 5" down wheel travel to deal with bumps and dips in the road.

Now, if desired, you can adjust both the lower perch and the coilover length in combination to tune ride height and ride stiffness independantly. Just remember that when you adjust the spring preload it reduces the effective rebound dampening of the shock by increasing the force the spring exerts on the shock in extension. FYI, even on desert racing trucks with up to 30" of wheel travel, they typically set them up for about 1/2 compression and 1/2 extension.

 

how do you figure it will have a stiffer ride, you haven't change the spring rate? It still sits with the same amount of spring compression at rest but it is now taller.

By moving the bottom mounts you shock still has the same amount of up and down travel but once again that isn't the limiting factor, your IFS is.

I agree your changing the travel but I don't think the shock is the limiting factor. If we had a solid axle rig them things might be different. I see what your saying, ok it is preloaded but once you drop the weight of the truck back down on it then the spring rate is the same and you will never fully unload the thing because it is limited by the suspension (I am guessing). I guess what I am saying is that I seriously doubt it is going to matter on an IFS truck and if it it somehow does stiffen the ride all the better.

 

[sm=bustedsign.gif]I stand corrected on using the term "stiffer ride" If it's a linear spring and you haven't preloaded it so much that the truck won't compress it, it still takes the same amount of force to compress 1" anywhere along it's range. What does change is the spring's affect on the rebound action of the shock. If you have a spring that's say, 600 lb/in, it takes 2400 lbs to compress it 4". So then the force of the spring trying to extend the shock goes from 2400lbs to 0 lbs as the shock rebounds (if there's no preload) If thespring has 1" of preload then it takes 600lbs to start it moving and3000lbs to compress it 4" and the force of the spring trying to extend the shock as it rebounds goes from 3000lbs to 600lbs at full extension (never drops to zero) This will have the effect of reducing the rebound dampening of the shock and tend to give a "bouncier" ride. Our OEM shocks are way short on dampening as it is. That's what gives it the Love Boat ride

With the double A-arm IFS on the Dak the extension travel is probably limited by the bushings. They're designed to twist rather than rotate and as a result work harder against the spring the farther they get from resting position. Otherwise they may be limited by the articulation of the ball joints. Compression travel is limited by the bump stops on the shocks but are also affected by the bushing twist. The only way to tell would be to jack the truck up, remove the wheel, remove the sway bar connection, remove the strut and loosen all the a-arm bolts so that the arms rotate freely and take measurements. Then put the strut back on without the spring and measure again. Let us know how it turns out It's all good! [sm=deal.gif]