Help Please! Suspension Reassembly Questions
 

I'm beginning to reassemble my front suspension and I have some questions about the proper sequence, and about indexing the torsion bars. Yes, I've done extensive searches on Pelican and really can't find what I need to know - bits and pieces here and there but I can't get the big picture. The repair manuals only address changing the torsion bars with the rest of the suspension still assembled.

The suspension was completely disassembled from the car so I no longer have any reference points for reassembly. The only thing I noted was how many tiurns the T-bar adjusters had when I removed them. I just want to assemble everything so that when I drop the car off the jacks, I'm at least within the range of adjustability on the ride height. Trying to avoid shooting in the dark and multiple reassemblies.

The car has Elephant Polybronze bushings and rear mounts installed. The control arms are installed to the car and adjusted, and they swing free through their entire range. The struts are rebuilt with Bilstein Heavy Duty inserts, not installed yet. I have new 21mm torsion bars, not installed yet. I went ahead and reinstalled the stock front sway bar, thinking it would be easiest to install with the control arms free to rotate.

I'm shooting for about 24.25 to 24.50 at the front wheel opening. I realize that the stiffer bars are going to allow me to run a little lower ride height, and that the new Bilsteins are going to want to jack the car up a bit.

HERE'S MY FIRST QUESTION: I'm ready to install the torsion bars. At what angle do I position the control arms before I slide the bars in and install the adjusters?

I'm completely in the dark here. Do I position them horizontally, or above or below horizontal (if so how many degrees?), straight down pointing toward the ground???

HERE'S MY SECOND QUESTION: Am I even doing this in the right sequence? Should I go ahead and install the struts BEFORE the T-bars so I have a point of reference for the control arm angle? Should I have not installed the sway bar yet?

I'd really appreciate it if someone could walk me through this or point me to a source.

Thanks!

Since the splined torsion bar end cap is removable, there is no need to index the bar as you would the rears. The cap might need to be indexed, but if it comes out too low or high, just jack the car back up, remove the adjustment screw, index the cap, and then drop the car back down again.

Definitely attach the struts onto the control arms before you do this. There's no point in setting the ride height without them on the car anyway. The front adjuster screw allows for a lot of adjustment thereafter, but considering the simplicity of the design, don't worry about installing the cap at too severe an angle. Your first try might be off, but the second try will likely be good enough, and it's not difficult to remove the cap repeatedly either.

I will answer # 2 first. Put the struts in. Once they are in and sitting at full droop, lift up on the a-arm with your floor jack so that you lift the arm up about 3-4 inches from full droop. Slide on the adjuster. If you lower the car and you are off, you can very quickly re-index the adjuster. It will take just a couple of minutes.

Jeff

set the adjustment screw in the middle position when reassembling. that way you can go either way for fine tuning.

Well there you go! I thought it was more complicated than that, but this should get me in the ball park. Can't wait to get to the rears and give the Ferch Method a try!

Thanks guys, I really appreciate it.

I know it's dangerous, but I've been thinking. There has to be a way to get the static ride height close the first time. This relates to Jeff's "3-4 inches" advice above - why not set it where you really want it? .Does this make sense?









http://forums.pelicanparts.com/uploa...1127164058.jpg

And here's with the car on stands:

http://forums.pelicanparts.com/uploa...1127223022.jpg

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Initial Ride Height......
 

Wavey,

Install the strut, TB, the indexing cap (parallel to the ground) and thread in the adjusting screw until it touches the aluminum cross member (no load). Perform this for both sides and lower the car. This will be your starting (reference) point.

Allow the car to settle its weight and measure the ride height. Adjust the final ride height accordingly. CW turn increases the height and CCW reduces the height. You should be able to get the 25" ride height at this initial setting.

Re-index cap (up or down) as needed.

Tony

OK, here's where I am on this. I'm not trying to second-guess any advice given so far, just trying to understand the dynamics of the entire assembly.

Eugene doesn't mention any preloading during assembly. Jeff says to preload the strut 3"-4" before attaching the torsion bar cap. Tony doesn't mention any preloading. On another thread, Wil Ferch hasn't commented yet, and Zeke says that my proposal (2nd diagram) won't work (and I now understand why). I came up with the diagrams trying to understand how everything works. I'm a visual learner so bear with me.

My goal is to find an assembly method that will allow the front ride height to be predicted fairly accurately, in order to avoid multiple trips on the jack, and multiple reassemblies. Will did this on his rear torsion bar indexing calculator, and I'm trying to do the same thing for the front.

One of the problems is that with the tub up on 4 jack stands, the rest of the suspension can not exert it's effect on the corner you're working on. There are a lot of other variables that effect ride height, including car weight, % on the front, torsion bar diameter, location of the lip on your particular fender, and tire OD.

The tire OD and position of the fender lip are measurable. By using the jack, the car weight and distribution, and the strength of the torsion bar, are automatically considered when you take measurements of the assembly.

So it seems to me that if you have everything setup as in the diagram, you should be able to:

Assemble the strut and torsion bar without the adjuster installed.
Jack it up to some predetermined point (maybe the the suggested 3"-4"?)
Installed the adjuster.
Jack it up more until the car just starts to lift off the jack stand.
Calculate what the ride ride height would be as assembled, using the diagram above.
Do the match to figure out how much you need to adjust the preload (up or down) to get the ride height where you want it.
Drop the jack, remove the adjuster, alter the preload as determined in the last step, reassemble, jack up and measure again.

Seems like it should be fairly easy to figure out. Wouldn't it be nice to have a method like this, so that along with Wil's rear calculator you could drop the car and be close enough to fine tune it with the adjusters?

Comments welcome, including "you're a fool" or whatever. I'm not proud. Chuck M? Bill V? Wil? Zeke? Souk?

Dave,

I made some notes during the last suspension rebuild I performed, and I'd be happy to help you along. I'm just a little swamped at the office right now. You are welcome to call me tonight (I should be available after 8PM CST), and I'll walk you through it. Setting up a calculator shouldn't be too difficult for the front. The amount of adjustment available for the front with the adjustment screw allows for a considerable margin of error, so we need not be too scientific....or precise.

I think your proposed method sounds like it could work, except I am a bit wary of repeatedly using a floor jack on a sprung member supporting half a ton of weight. Still, your "trial and measure" method might still require at least two iterations of the process, while the regular trial and error method uses about the same. This is due to the large amount of adjustment that the preload screw can provide. Also, considering how the front assembly only requires the removal of a screw and cap to reindex the bar, "multiple trips on the jack" shouldn't really be abhored. Besides, using the jack as a "virtual floor" may still require multiple trips. That being said, if you could refine the process to consistently minimize the number of iterations, then I applaud all efforts. Best of luck!

Methinks you're overthinking this. Put it together, put the cap on, screw in the center of the range or so, and settle the car, measure, reset, resettle if lifted. I think 101 projects has a formula for rough # of screw turns = how much change at the lip.

Its really a simple process. The rear is another story entirely due to the limited amount of adjustibility and the pain of reindexing. In front, even if you need to reindex (rare) its a couple minute process.

Thanks Souk and Eugene. I'm at this point right now, so I'll test the idea on my own car and report back. I took some measurements last night and here's what I've figured out so far:

A = 24.25" - Ride height (at fender lip) I'm shooting for.
B = 12.05" - Installed radius of tire from Yokohama's chart.
X= 12.20" - Desitred dimension, spindle center to fender lip

23.25" - Extended strut length, top of mount to bottom at ball joint.
4.25" - Bottom of strut to spindle center.
1.125" - Stut mount (in body) to fender lip, using a level to measure.

Therefore, with strut assembled on car and NO preloading, spindle center to fender lip should be 17.875". I'm shooting for 12.20" (using the first diagram).

I think that gives me enough to give it a try.

Thanks, Souk - I may do that if I don't get back too late, or maybe Saturday some time.

HEY - did you ever get the package I sent you???