generic question about sectioning struts

[BTF/PTM]

Not sure if this counts as belonging in our suspension forum, mods please move if you deem it so. I've been reading up on sectioning struts, and just want to know if I understand specifically why it's a good idea to section struts when prepping a z car for a lowered and/or adjustable suspension.

As I understand it, struts are sectioned to match the shorter length of performance strut inserts with a correspondingly shorter strut tube. This allows the strut insert to retain full travel when the car is lowered (or raised, I suppose).

Also, as I understand it, the reason sectioning the struts is not necessary is because a spacer placed inside the factory strut tube can be used to take up the empty space that the shorter performance strut insert left. This is convenient, but sacrifices strut travel.

Am I understanding the functionality of this process correctly? Please correct me if this is incorrect or incomplete!

[John Coffey]

Strut is the steel tube that is part of the suspension. Shock is the suspension damping unit installed inside the strut.

Its all about bump travel. If you lower the car you reduce bump travel by close to the amount you lower the car. The S30 starts with about 3" of bump travel before you're on the bump stops. Lower the car 2", and now you have 1" of bump travel, which is inadequate for a street driven car. You can get about 1.5" of that bump travel back by shortening the struts and installing shocks with a shorter shock body. ALL shocks installed in struts must be positioned at the top of the strut tube. This may require a spacer under the shock in the strut.

[BTF/PTM]

Hi again,

I've a new question to add to this topic. Let's propose that a set of struts must be shortened (sectioned) by 1.5 inches to fit new performance strut inserts. Most websites indicate that a pipe cutter is effective for doing the job oneself. My question is in relation to this process as, although simple and effective, probably isn't the best for a precise length measurement. How much slop is there inside the strut tube, either factory length with a factory insert, or an accordingly sectioned tube with its accordingly shorter insert? Does the factory threaded cap have a retaining spring that pushes against the insert to take this up?

[jmortensen]

There isn't a whole lot of room for error and there is no spring inside to take up the slack. If you cut the strut tubes long, you can use thick washers under the strut inserts to shim them up. When you have the height right, the gland nut will get tight with a couple of threads showing. What you don't want is the gland nut to tighten down on the strut housing before the strut insert is contacted. You should be able to get the struts roughly the right length with a pretty bad saw. I now have a band saw for metal, but when I sectioned my struts I used a $50 Harbor Freight chop saw, and it worked fine. I purposely made the strut tubes 1/8" long and shimmed to get the right height.

Once you have the tubes cut and beveled for welding you can use a piece of angle iron and some hose clamps to get everything aligned. Do some tacks around the edge and then stitch it shut from there. I like cutting the tubes about 2" from the top because if you were to overpenetrate with your welds you can grind it out easily.

[BTF/PTM]

So taking up a SMALL amount of slop inside the strut tube is acceptible using a washer or other equivalent spacer provided only a thread or two is visible with the cap nut tightened in place. Thanks!! This is mostly for my own curiosity, but I'm scheming on various methods of rebuilding the ol' girl's suspension so coil-overs and sectioned struts may end up being a part of that project.

p.s. - I've got zero experience as a welder, so although I'm sure I could handle disassembly, cutting and prepping of the parts, I'd be handing them over to a competent person for that part of it.

[5thhorsemann]

Although I never sectioned a strut tube, I have seamed pipe and tubing many times in the past. Therefore, I would recommend the following bit of advice for your undertaking.

Remove and disassemble your suspension, clean and inspect all the parts thoroughly, gather all the parts that need to be replaced, as well as the new struts and springs. Mark all the parts in box’s as to the corner of the car they came from.

Do not cut the struts if you are not going to do the welding. I say this because if you bring me a screwed up cut and expect me to fix your mess and give you an excellent finished product, it will cost you a lot more. Just hand the unmolested struts, along with the new inserts over to the pro and let him do what you are paying him to do.

I would recommend the tubing or pipe cutter to make the cuts for the following reasons. First, if properly done, the pipe cutter will make the “squarest” cut, giving you you’re best mating surfaces and most accurate tube length when the job is done. Second, the pipe cutter will leave a slight bevel cut, so there is less grinding required to get you’re root welds rite and get full penetration with less heat. And finally, the math is easier with the pipe cutter, people forget that abrasive blades remove a thickness of metal that is equal to the thickness of the blade. If you are using a 1/8 inch thick blade and make your cuts in the wrong location, your tube will be ¼ inch short when you are done.

Just my 2 cents.

[Philliousfog]

Hi, I have successfully sectioned some series one struts using a $20 pipe cutter between the spring mount and the brake hose bracket, I removed 1.5" from the fronts and 1.75" from the rears, the earlier front struts had lower spring mounts by 1" compared to my series two car so I ended up with a 2.5" drop on the front and 1.75" rear with standard springs.

[Philliousfog]

I'll correct that, the spring mounts were 3/4" ish lower making it 2.25" lower on the front and 1.75" rear.