It will still take 650 pounds for each additional 1", no matter how much the spring is already compressed.


jruz, Actually there is a formula that you use for determining this:
C=WR/(MR)(ACF)

ANGLE CORRECTION FACTOR (ACF) and The MOTION RATIO(MR) Where C= spring rate WR=wheel rate there's a lot more to it, but all in all it doesn't make a dramatic change. Robinhood150 is try to keep his explanation as simple as possible for the average DIY.........

 

well thats poopy cuase Ill bet my truck didnt sag more than about an inch and a half when I let the truck off the jack stands. hmm This is why ive always been confused.

 

No, there is no difference between using a spacer outside the spring/shock assembly or within it as far as preload or lift amount goes. As I see it, there are 2 reasons "outside the assembly spacers" might be needed. 1) to move the shock assembly to clear joints/control arms 2) to add lift without extending the shock absorber like a "inside the assembly" spacer will do. There might be other reasons, but that's all I could think of right now.

Spacers will have the same effect on progressive springs as they do on linear springs, that is, nothing. Remember the coils, whether linear or progressive, are not compressed any more at ride height when a spacer is used. There is still a fixed amount of weight on the springs.

 

Are you asking whether the change in angle of the control arms adds preload? If so, then congratulations, you get a box of donuts, Bob will send them to you shortly . However, the preload should actually decrease slightly because the lever arm is shorter (see figure 2 in the writeup). I haven't run the numbers for this because nobody is paying me to, so I don't know how much it decreases. But one of my technical advisors assures me it is negligable. That's why I didn't include it in the writeup and it gets way beyond the scope of the writeup.

 

It would also decrease slightly with the reduced gravity of the truck at it's new altitude too...right? I dunno, we could split hairs all day.

Anywho, kudos on the write-up...I don't think I ever put all that together to see that the spacer lift doesn't really compress the springs more...

Jim

 

When I put a spacer in the coilover that has a progressive rate spring, it preloads it. The spring is acting in a shorter distance than before and the rate is effectively changed since it is acting during a different part of the rate.

What I meant on the other spacers is the nominal impacts. All gain ride height, some gain extension.

 

After re-reading my box of donuts comment I realize that could have sounded like sarcasm, but really, I am impressed that anybody thought that the control arm angles could change the preload. I hope you didn't take offense at that.

 

Nope, unless your suspension is completely extended at ride height the spacer does not compress the spring any more than normal. See figure 1 in the writeup.

The shock extends to compensate for the space that the spacer takes up.

 

Nice article!

I've always wondered why Toyota went from front coil springs to torsen bars and then back to front coil springs on the Tacos.

My '88 2wd PU rides a lot like my uncle's old '69 Plymouth Roadrunner which also had a front T-bar/rear leaf suspension setup. Very stiff and unforgiving over potholes and ruts/crevices on the road. Take a ride in a new 2wd Taco or similar truck like an S10 with a factory front coil spring suspension setup and you'd think your riding in a luxury car compared to my truck.LOL!

I would think that using coil springs in the front susp. would generally improve the overall ride than an archiac T-bar setup. Do you think maybe the difference in ride quality between the two designs is due to the fact that T-bars typically have more "preload" built into their design than a typical coil spring?

I remember looking at a mid '70s 2wd Toyota PU once and to my surprise it also had coils in the front like the new Tacos. I didn't know those old early PU's had coil springs in the front. I thought they came with the T-bars setup like mine. I wonder if Toyota will go back to using T-bars on their small PU's once again. I guess with them, you never know.LOL!

 

Nah, don't sweat the sarcasm...that's me in a nutshell.

Another factor is the binding in the joints (of the A-arm & CV). If you've ever had the coilover out of there, it is increasingly harder to push that thing down...makes it interesting to get them back on.

Jim