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Thread: coilovers / shortening housings / the usual ...

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    another classic car guy EricB's Avatar
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    Default coilovers / shortening housings / the usual ...

    Hi guys,

    i've been reading a variety of old posts here and on hybridz and feel pretty confident about what I am about to start on...

    however i do want to think out loud to everyone here (John C, JMortensen, 2ManyZs, etc) to make sure that i've dotted my i's and crossed my t's

    i am using advanced design struts with 280 housings.
    for now, i am going to use the 1.5~2" piece of pipe GC supplied to space out the front struts inside the stock housing. I may turn something nicer on the lather somewhere down the line.

    for the rear, we're looking at about a 4-5" difference between the AD strut and the stock strut - so there's some sectioning needed.
    Instead of having the rear inserts sit all the way down in the housing (I do need some kind of spacer, or they will bottom out on the valve), I was thinking of using the same 1.5~2" piece of pipe on the rears as well.

    I figure this will give me some flexibility down the line if I need it...
    I think it's better to have not sectioned them enough, than sectioned them too much, right?


    As far as locating exactly where the weld-on threaded coilover sleeve perch goes, I was thinking of positioning it such that the top of the coilover sleeve is flush with the underside of the gland nut. Does this sound good to everyone?


    -e

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    You want the front struts to be about 3" shorter than the rears for the 280 struts. When you buy Tokicos, for example, you get the same basic struts front and rear but the rears have a 3" tube pressed onto the end of the strut to make it longer. 240Z's are the same way, but the rear struts are only 2" longer than the front on the 240.

    I'm not sure how long the AD strut is, but whatever you do to the front will determine how long the rears should be. The fronts need to be sectioned due to running out of travel more often than the rears do as a general rule because most people lower the front end more than the rear and end up with a little rake.

    I set up my sleeves so that the spring fits with no slop against the strut top and the spring perch at the same time. Wherever that locates the sleeve, that's where I put them on my car. That does not allow you to preload the spring, but I knew I was going to run the car low enough that preload wasn't an option anyway so I figured that didn't matter. I think this is the case for 99% of the people running coilovers on a Z.
    Jon

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    Jon

    the AD struts are also same length front and rear.
    they sent along two small pieces of pipe (about 1.5~2" long) to act as spacers.
    They did not send 4. Perhaps that was a mistake?

    The valves at the bottom of the ADs extend beyond the bottom most part of the strut - so a spare is required otherwise they get mashed.

    I found an old thread where someone drilled the bottom of the strut housing with a 1/2" hole to allow for the valve to sit in there...

    if I put the spacers in front 280 housings, and then the AD struts, and then the gland nut, everything seems to fit perfect.


    but you're saying I should still section the fronts (no spacers then?) and have the rears always be longer than the fronts? am I reading you right?

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    Quote Originally Posted by EricB View Post
    the AD struts are also same length front and rear.
    they sent along two small pieces of pipe (about 1.5~2" long) to act as spacers.
    They did not send 4. Perhaps that was a mistake?
    I'm guessing the spacers are probably for the rear. Front to be used with no spacers, and a hole drilled in the bottom of the strut housing. Really on a 280 the rears should be 3" longer than the fronts. Most people race 240s though, and then the rears should be 2" longer, so that would be an understandable error.

    Quote Originally Posted by EricB View Post
    The valves at the bottom of the ADs extend beyond the bottom most part of the strut - so a spare is required otherwise they get mashed.

    I found an old thread where someone drilled the bottom of the strut housing with a 1/2" hole to allow for the valve to sit in there...
    I assume the first sentence was supposed to say that a "spacer is required". I think the hole in the front struts makes perfect sense. You'd still have to disconnect the steer knuckle to adjust the struts, but you don't have to adjust your struts every day...

    Quote Originally Posted by EricB View Post
    if I put the spacers in front 280 housings, and then the AD struts, and then the gland nut, everything seems to fit perfect.
    This tells me that the AD struts are 2" shorter than stock. That's about right, and so you should section the front struts to fit the housing without the spacers. Ask GC for a 3" spacer or make your own and assemble. So basically yes, you were reading me right.
    Jon

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    Ok thanks for clearing things up Jon.

    I appreciate it.

    -e

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    Happy to help. Good luck.
    Jon

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    Instead of having the rear inserts sit all the way down in the housing (I do need some kind of spacer, or they will bottom out on the valve), I was thinking of using the same 1.5~2" piece of pipe on the rears as well.
    The shocks in both the front and rear struts need to positioned at the top of the strut housing. You do this with spacers underneath the shock.

    As far as locating exactly where the weld-on threaded coilover sleeve perch goes, I was thinking of positioning it such that the top of the coilover sleeve is flush with the underside of the gland nut. Does this sound good to everyone?
    Where the threaded collar is positioned on the strut tube depends on the length of the threaded collar (typiccally 5"), shock travel, length of the strut tubes, spring length, spring rate, car corner weight, tire OD, and your intended static ride height. A 5" threaded collar positioned at the top of the strut is absolutely too high for 12" tall springs, probably too high for 10" tall springs and maybe OK with 8" tall springs.

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    john - thanks for the reply. I guess I'm looking for a ballpark location as to where to weld. I can always & probably will get different springs while I am fine tuning the rates.

    You posted a pic of your coilovers with EMI camber plates & I thought I recognized the same AD struts as what I have. In that pic it seemed like yr threaded coilover sleeve was flush with the underside of the gland nut.

    If they are in fact AD struts then you would have used the same 280z housings & would probably have sectioned them the same amount, no?

    Did I not see things right?
    Last edited by EricB; 03-19-2008 at 07:33 AM. Reason: Extra detail

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    jon - I measured the spacers GC included and they are definitely 1.5". Not 3" like you were saying. The dimension you gave is an approximate one (depending on rates/spring length/etc) or should it be exactly 3"?

    Thanks guys

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    You posted a pic of your coilovers with EMI camber plates & I thought I recognized the same AD struts as what I have. In that pic it seemed like yr threaded coilover sleeve was flush with the underside of the gland nut.

    If they are in fact AD struts then you would have used the same 280z housings & would probably have sectioned them the same amount, no?
    I haven't installed a set of AD struts on a 240Z. Mostly Koni 8610s and 8611s and Tokico HPs, Illuminas, and HTSs. Sometimes I install the threaded sleeve up close to the gland nut and other times its as much as 2" below it. It all depends on the specific application.

    Right now I'm building a suspension for a street 240Z running a LT1 and big wheels/tires. I'm using the stock upper spring isolators, coil overs, and 8" tall springs. In this particular case the 5" threaded collars are 1/2" below the gland nut. If the customer had provided 10" tall springs the threaded collar would be 1 to 1 1/4" below the gland nut.

    There's no one set rule regarding where all this stuff get's positioned for a S30 car. I adjust things based on the customer, the intended use, budgets, and what will work given the above constraints.

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    Quote Originally Posted by EricB View Post
    jon - I measured the spacers GC included and they are definitely 1.5". Not 3" like you were saying. The dimension you gave is an approximate one (depending on rates/spring length/etc) or should it be exactly 3"?
    99.9% sure it should be 3" for a 280Z. Stick a tape measure into the strut tubes and measure the lengths. Subtract the difference, there is your answer. When you section you'll want to have at least the same difference in length, if not have the fronts even shorter in relation to the rears, again because of the tendency for most people to run the front end lower than the rear. The idea is that when you're done you want the front and rear struts running in the middle part of the travel.

    Maybe this will clear things up a bit. Sectioning the struts lowers the car. You might say it lowers the maximum ride height. So you can still extend the strut all the way, but it is now shorter, so to put the body on the strut the body comes down. Make sense?

    So if you sectioned the rear to fit the housing as you had originally stated you would lower the back end 4.5" (3" to match the front, then the 1.5" spacer) and the front not at all. The ass end would drag on the ground and the front would be close to stock.
    Last edited by jmortensen; 03-19-2008 at 08:26 AM.
    Jon

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    John & Jon

    Thanks again for the extra details.
    This stuff along with the strut sectioning FAQ on HybridZ is perfect.

    Random question: while I am pretty sure that the front hub will be unaffected by changing from 240 to 280 housings (bearing part numbers don't change), it looks like there is a different rear stub axle for 280, so I can't re-use my 240 one right?

    -e

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    Oh man, there's a can of worms...

    The 280 stub axles are 27 spline, the 240s are 25 spline. This means that the 240 stub is theoretically weaker. Either stub fits in either housing, and the bearings are the same. You MUST use the correct spacer between the bearings, that part is critical. Every single strut I've had apart has had a "B" spacer, but supposedly there is an "A" and a "C" as well. The 240 and 280 rear brakes are slightly different, I don't think this will be much of a problem for you, except when ordering replacement parts.

    If you're swapping in the front struts from a 240 the hubs are different than your 280. The bearings are the same, but the 280 hub has a different offset, so 240 and 280 rotors are different, and I think the calipers are different as well. What's more, the size of the strut tubes themselves is different, so the coilover parts need to be ordered for a 240 or a 280. If you aren't going to camber plates, then the top hats on the struts are also different (the 280 has an inch taller rear top hat).

    Can you give us a list of what exactly you are changing? If you're going to camber plates for instance, you'll lose those rear strut tops, and then you would probably want to section the rears less than the fronts. If you're going to an aftermarket front brake kit, a lot of them require 280 front hubs and won't work with 240 hubs because they need the extra offset.
    Jon

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    Jon

    1973 240z

    280z housings front & rear (I did get the rear stub axles + spacers with them)
    AD struts & GC camber plates

    I still for the time being have stock 240z brakes & hubs on the car
    I will swap to rear disk at some point, maybe not right now unless the rear 280 housing mandates the use of the matching rear stub axle which it itself requires something else than rear 240z brakes

    Need anything else?
    thanks

    -e

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    Camber plates or stock rubber isolators?
    Jon

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    No info on the possibility of camber plates yet, but you should section the struts just like you would 240 struts, because they're going in a 240. The reason the 280 struts are different is because the rear strut towers are higher inside the car, and so the top hat and the strut have to be taller to get all the way up there. DO NOT use the 280 isolators in the rear. Use 240 parts, because the 280 stuff is an inch taller. The fronts are the same as I recall, so no problems there.

    You can check on the hubs and brakes in the front, but I think you may need to use the 280 hubs, discs, and calipers, even though they're heavier. I don't have too much experience here, so double check that.

    I believe the rear hub offset is the same, so you can use the 280 brake parts with 240 stub axles, but the 280 stub axles are again theoretically stronger so you might want to go that way.
    Jon

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    Hi Jon

    Yes I do plan to use camber plates...
    Have the strut tower already marked up for cutting but haven't gone through with it yet

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