Sunday, April 24, 2011

How To: 240z Ground Control Coilovers w/ Sectioned Struts

This weekend I was finally able to finish my suspension build.

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A few weeks ago my buddy Bruce came over and we measured everything and read all of the instructions for the build.

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We used a combination of the instructions that shipped with the Ground Control kit and the write up by John Coffey from Beta Motorsports available HERE. Read the whole article, but the last part is what was most helpful since it is specific to the Tokico Ilumina BZ3099 and BZ3015 Inserts.

Everything I read gave different measurements, but the basic information was the same. Cut the strut tubes in half and remove a section from the top equal to the difference in length between the stock struts and the struts you are installing.

This is easy enough but I had to find my own measurements and cut and section the tubes strategically so everything fits and works. The most important measurement of this whole thing, is the overall height of the tube as measured from the inside (Internal Height).

Here are the measurements for sectioning 1973 Datsun 240z strut tubes to work with BZ3099 (AW11 MR2 Rear), and BZ3015 (240z Front) strut cartridges. But please remember, before cutting or welding anything, measure everything like nine times.

Front:
First, remove the stock spring perch with an angle grinder.

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You will have to grind off the welded perch ring so that the strut tube is smooth.

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The first cut you make is to cut the strut tube in half 6.5" up from the top of the spindle casting.

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Cutting at 6.5" gives you enough room to install the new spring perch later whithout interfering with the stock brake line bracket.

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Now the overall internal height of this tube needs to be 13.5". My stock internal height was 15" so in order to achieve this measurement I had to cut 1.5" from the bottom of the top strut tube section, making the top piece 7" long when all is said and done.

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When you are using a big baller pipe cutter like mine it creates a lip on the inside of the tube where it cuts. This lip needs to be ground out or you will not be able to slide your strut cartridges in.

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Once you get them cleaned up it's time to weld them back on.

Luckily my stock strut cartridges were blown so I didn't have to worry about heating them up too much. I was able to use them as guides for welding the tubes perfectly straight.

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Then weld them up!

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Once Bruce was done working his metal magic, I had to grind down the weld a bit so I could slide the new perches over them.

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This is the sectioned and welded strut tube with the new perch location measured and marked with the perch around it ready to weld in. I welded the new perch so that the bottom of it was 5.5" from the top of the spindle casting. Also, make sure that the flat side of the new perch is facing the spindle side.

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Tack it up and weld it in.

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Once it's welded all the way around you're done!

Test fit.

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Since the first one went pretty much perfectly (except for the whole stuck cartridge housing fiasco), we just repeated these steps for the other front strut tube.


Rear:

The rear strut tubes were a little easier to do because if you cut it right, you can cut the original perch weld right out of the tube without grinding it all the way down.

You do however have to cut it off.

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Once the stock perch is gone, you need to cut the strut tube in half at 8.5", as measured upward from the top of the hub casting.

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Grind out the lip.

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The stock rear strut tubes measure 16.75" tall as measured from the inside. Since I am running front struts in the rear I need to cut them so that when welded up, they will measure 15" from the inside. This meant I had to cut 1.75" from the bottom of the top section of the strut tube.

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Once cut, I test fitted the new strut and it fits perfect. Just enough room for the threaded cap.

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Again I used the blown rear strut to help align the strut tube for welding. Never do this with a strut tube that is not blown.

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Grind down the weld so the perch can slide over it.

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Then have your buddy weld up the perch. The rear perch should be welded so that the bottom of the perch is 7" from the top of the hub casting. This places the previous weld under the threaded tube and out of sight.

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Once that perch is welded all the way around you're done!

Test fit.

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Just do the same thing with the second rear strut tube and you're dancing.

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Please take this as a reference on how it worked for me. If you are going to be installing these parts, make sure you take all of your own measurements and confirm whether or not these will work for you.

The worst thing you can do is cut these strut tubes too short. The overall internal height needs to be very precise and cutting them too short is not easily fixable.

Hope this helps some of you guys that are thinking about building this setup.

If anyone notices any technical errors or if something is unclear, please post up so I can fix it.

Thanks to Beta Motorsports for the writeup! That proved to be very helpful and special thanks to my buddy Bruce who is the mack daddy boss man welder master of the universe.

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Peace.

20 comments:

  1. Nice project. It's going to be great when you finish.

    I just found your site a few days ago and had to start from the beginning to make sure I didn't miss anything. Your post about removing the diff was especially helpful since I am at that point on my fairlady. Me and a buddy had the entire rear suspension and diff out in just over an hour thanks to your post.

    I love that you are posting each step with pics and a lot of details.

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  2. Wow, glad you like it man!
    I'm super stoked that it helped out.

    Thanks for the comment!

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  3. Dude awesome write up! Totally needed this in order to tackle the next project for my girls 280 L28 S30. Just needed to see it done to make sure I was on the same page. So you took the measurments directly from what Ground Control said to do specific to the car type i.e. 240/260/280. With that being said what kind of drop did that give the car front/rear? She only needs maybe 2" (even though she wants 3) to be practical for daily use and still handle well. Also what shocks did you end up using for front and rear.

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  4. This comment has been removed by the author.

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  5. Werd I am actually going to grab a set of stock struts from a local salvage yard off of another 280 to cut up just so I have a back up incase something goes horribly wrong with my measurements. So you used tokico MR2 struts and 240z struts. Correct me if I'm wrong but you use the 240's for the front and the MR2's for the rear right? And yes the measurements for the a 240 to a 280 are considerably different. I think by 2 inches if memory serves. The write up on beta is pretty good however haing the pics makes it way mo easy.

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  6. Nope, I used the MR2 struts in the front and the 240z front struts in the rear. That way both are shorter by approx 1.75".

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  7. Ahhhh that makes sense. Thanks for the help.

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  8. I'm curious as to why the tube would need to be cut down so far when a section of the removed piece just gets welded back on to add length. Why not just cut that much higher up the tube in the first place? Your write-up is fantastic.. much appreciated!

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  9. Hi BPMcCarthy, it is because the top of the tube is threaded to receive the strut tube cap.

    The cuts are relatively strategic based on not wanting to remove the brake line mounts and minimizing grinding off sections of the stock spring perch.

    You also just need to make sure to weld the top back on extremely straight. Perfectly straight.

    Good luck!

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  10. They are 87-89 REAR struts, not front. Bought the wrong ones, please change it if you get this message

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  11. I already did the sectioning of my fronts and rears (I used 280z rear assemblies for the bigger tubing and the bigger hub/spindles) the backs worked perfect but the fronts worked after welding but wouldn't recieve the cartridges after they cooled...Is there a way to fix them? I thought I would buy some 1.5" cartridges...But that would be more money...see below: (copied front a section of:

    http://datsun1200.com/modules/mediawiki/index.php?title=Strut_Insert_Part_Numbers )

    VW Golf/Rabbit

    318 body length / 511 Extended / 352 Collapsed

    324 / 511 / 359'

    • Stroke: 158mm (6.25 in)

    • Bilstein part number W0133-1604944

    • Get Bilstein (1.507 in) or KYB brand at about 1.5 inch outside diameter. Tokico and KONI are too big around to fit 45mm strut housings.

    • Golf Mk I insert is nearly 4 inches shorter than stock and will need a simple spacer made to make up the difference in length in the bottom of the tube.

    PS these are comments from a 510 write up!!!

    PSS is there anything else that I can do with the botched fronts?

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  12. Hey there,

    If the shaft distorts when cooled it is most likely to be hanging up at the welded joint (as mine were). I would use a long die grinder to shave away any contracted steel from the inside of the tube at the weld.

    I'm not sure if this will reach in your case but I would go grab one of these with a nice wide bit to see if you can clean it up a little in there.

    http://www.harborfreight.com/electric-die-grinder-with-long-shaft-44141.html

    It's not going to shrink too much during the cooling process to be completely irreparable.

    Let me know if that works.

    - Alex

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  13. I just noticed a typo thanks to "Anonymous" for pointing that out on 9-28.

    What I should have written was:

    "Hi Phil,

    Copied from above I used: "BZ3099 (AW11 MR2 REAR), and BZ3015 (240z Front) strut cartridges" for my 73 240z.

    I did not use all of Ground Control's measurements but most of them were ok. I read John Coffey's write up on Betamotorsports.com, and the GC instructions to come up with my own measurements.

    Don't use my measurements above on your 280z though because I think the strut tube lengths are a little different. But I posted those too so you can check for yourself.

    Let me know how it goes!"

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  14. They are from the rear of the MR2 but go on the front of the Z.

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  15. Alex, GR8 write-up!! I had been planning on just installing Illuminas w/ GC coilovers on my '72Z, but after researching the benefits, your article convinced me that I could do this. THANX FOR THAT!! One measurement that I just can't seem to get my brain around is in the paragraph after the 7th photo (Long Hammer bottle photo) which states ".....making the top piece 6" long when all said and done." 15" overall strut length - 6.5" cut (lower piece) = 8.5" upper piece - 1.5" cut off bottom of upper piece = 7" resultant upper piece length. What am I missing here??
    THANX again for posting this information for all of us Zeophyites.
    KAMIKAZI'72

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  16. Good catch! I fixed the obviously sloppy math fail.

    The important part is that you remove the correct amount to make the overall height (measured from the inside) to 13.5" which is correct for that particular strut tube.

    Sorry if my error caused any issues and thanks for catching it!

    -A

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  17. That's wonderful I had no clue about all this until the moment I discovered this entry of yours over here. Also I would like to know one thing. Do you own any useful data about how to protect your thoughts from being stolen without notifying you about it?

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  18. Alex, we should talk. I live in Fitchburg, MA and have parts and expertise in Zs. I'm running http://www.cardomain.com/ride/704271/1972-datsun-240z/ in the New England SCCA events.

    Also, nice writeup on the GC setup!

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  19. Would probably help if I gave you contact info... drivefast@d3vc0n.com

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  20. so, 87-89 mr2 rear strut inserts for the front correct?

    - Richard

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