Strut Sectioning - parts and procedure?

[Guest Anonymous]

Consultation with the best suspension experts I could gather (that's YOU people) has led to the conclusion that my understeer problem is caused by suspension bottoming. I have GC coilovers on all 4 corners, with standard length Tokico 5-way struts.

 

Q1 - AIR, there is a VW strut insert that is the preferred choice when shortening struts. What year/model VW? Tokico part #? Any other choices? Is that car similar in front-end weight to a 280Z? Any caveats with this strut?

 

Q2 - The rears can be shortened by removing the extension tube at the bottom - how much travel gain?

 

Q3 - How much will this strut shorten the tube/increase compression travel?

 

Q4 - Best to cut section near top, in middle, where? Also, is a butt weld sufficient? What about putting a slightly larger tube over the strut and welding it on as a splice?

 

Any other advice, experiences, "gotchas", etc. greatly appreciated.

 

[ May 07, 2001: Message edited by: jpd280z ]

 

[ May 07, 2001: Message edited by: jpd280z ]

[Guest Anonymous]

I was surfing through a bunch of Z sites this weekend and saw the following:

http://240z.jeromio.com/frontsusp2.html

 

This guy did a good write up of sectioning front struts. I can't speak for the process though as I haven't done it myself, yet...

[TimZ]

quote:

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Originally posted by jpd280z:

Q1 - AIR, there is a VW strut insert that is the preferred choice when shortening struts. What year/model VW? Tokico part #? Any other choices? Is that car similar in front-end weight to a 280Z? Any caveats with this strut?

---

 

We had a pretty good discussion on this a while back: http://www.hybridz.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=000319

 

 

quote

Q2 - The rears can be shortened by removing the extension tube at the bottom - how much travel gain?

 

Extension tube? Not sure what this is. On a 280Z, you can lower the car by an inch, while keeping the same travel, just by using the rubber isolator assembly from the front - they are about an inch shorter. If you are using camber plates, you might also be able to get away without sectioning - depending on the plate, this can lower the car by 1.5" or more, as I recall.

 

quote

Q3 - How much will this strut shorten the tube/increase compression travel??

 

Compression travel will be increased by the amount the strut is shortened, all else equal. You also need to look at the difference in mounting height between the stock isolators and the camber plate, if you are using one.

 

quote

Q4 - Best to cut section near top, in middle, where? Also, is a butt weld sufficient? What about putting a slightly larger tube over the strut and welding it on as a splice?

 

A butt weld should work fine, as long as the joint is prepared well, and the weld has good penetration.

 

I sectioned mine in the middle - it seemed easier to put braces on them to keep them straight while welding this way. In retrospect, it probably would have been just as easy if I'd made my cuts near the top. This would minimize problems that would occur if sections weren't welded back together perfectly straight. Just make sure that you leave the threaded part, so you can attach the gland nut.

 

I clamped the tube sections together between two long pieces of angle iron to keep them straight. Also, I'd recommend buying or renting a tubing cutter that's large enough to fit on the strut tube (~2-1/16"). It might not be able to cut all of the way through, but it will get most of the way, and leave a nice straight cut for you to work with.

 

I would think that for a piece of tubing to be strong enough to act as a splice, it would end up being thick enough that it would interfere with the spring. It would definitely interfere with the spring collar - you need to slide it over the strut to install it.

 

Hope this helps - good luck.

[jeromio]

I'm the guy with the 240z.jeromio.com website.

 

I tried using a large tubing cutter for the fronts, but bagged it and just used my cutoff saw. The tubing cutter was just too much work - that's some thick tubing. Squareness isn't much of an issue if you score a line verically (orthagonal to the cut) and use that as a guide when cutting out the section and when welding the 2 pieces back together - any deviation from square will not matter, just as long as the 2 cuts are consistent.

 

For a good butt-weld, you just need to bevel both edges. This also helps to counter any "unsquareness" since you can hammer the 2 pieces together a bit. The sharp beveled edges will mash together. This is possible when you stick a piece of exhaust tubing inside the tube. For the fronts I used pipe, but it didn't fit inside perfectly - I found some tubing at a muffler shop that fit inside very snugly. Mine are 240z strut tubes though, which are slightly narrower. The tubing was actually kinda hard to remove. But it made the strut tube perfectly straight. This worked much better than the angle iron clamping technique which I used for the fronts.

 

As to your specific questions:

 

Q1 - I used front 85 rabbit GTI cartridges - the Tokico non-adjustables. I like them, but there was a great deal of discussion here, after I bought these in which it was decided that the rear MR2 struts should be used. But I'm not sure if the year was mentioned.

 

Q2 - I have a 240. No idea what this extension tube is...

 

Q3 - The amount of susp. travel (re)gained when sectioning the struts is directly related to how low you want the car. Clearly you can't gain back factory travel with this mod, even if you only lower the car by the amount of sectioning (unless you also modify the isolators). But you will gain at least the amount you section. If you use the GTI cart, you can section up to 1 7/8 on the front. I know that 280 rear tubes are longer than 240 tubes, so, you may be able to section more than the 1.5 inches that I did and use 240 front carts.

 

Q4 - section the middle. Don't use a splice.

 

As Pete mentioned in another one of these threads (this comes up alot), make sure there aren't any pinholes in the finished weld since you'll lose the heat transfer oil.

 

Can't think of any other tips....

[Guest Anonymous]

Great info - thanks guys! Now, which Tokico Illumina MR2 strut DOES fit the 280Z tube? Part number please?

 

As far as the heretofore unheard of "extension tube", the Tokico Illumina rear strut inserts for the 280Z are the same as the fronts, but with a short section of pipe fitted on to the bottom end to make it long enough for the tube. Pull the extension off and VOILA! you have the same strut as what you just took off the front.

 

I've already used the front spacers on the rear, so sectioning the rear struts will ensure that I don't trade front bottoming for rear bottoming.

[blueovalz]

IMHO I would think that structurally, a weld (splice) at the top, anywhere above the spring support would make the most sense. this way the weight of the car is still on the undisturbed portion of the tube, and the weld need only support the tension/compression loading associated with the resistance of the cartridge.

I used an "exhaust pipe" pipe cutter to section the strut. I looks like a tubing cutter on steroids with 4 large diameter cutting wheels that can make a 360 degree cut with only about 90 degrees of back and forth movement.

 

Terry