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240z SCCA vintage race car, restoration


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Posted (edited)
1 hour ago, JMortensen said:

Was thinking my first set from GC in '95 or so had 5" adjusters. Just to clarify. Looks to me like you might run the spring to the bottom of the adjuster without getting the ride height you want. You could grind the perch off of the strut tube, but that's a hassle. The other solution is to run a shorter spring. Shortest spring that doesn't coil bind is always the best choice because it's lighter and it will resist bending sideways when it compresses. I started off with 10's, worked down to 8's and now run 7's, but I also have super stiff springs and run very low, so don't need 6" of travel.

 

Just checked, and they are 8" springs. Rear's are 300lb, fronts are 350. The strut is sitting pretty high at the moment (control arms nearly level), so I will put some wheels on just to check ride height. If I understand correctly, the overall height of the assembled strut is ultimately set by the height of the shock? I am using 8310-1437's all around. The spring is snug in top spring perch, so lowering the adjuster anymore will just unseat the spring under no load. A little irritated at the moment since I provided GC all my specs so not sure what went wrong. I am a total suspension newbie, so il chalk this up to experience. 

 

Fingers crossed my only problem is the 1.5" of collar rising above the gland nut, since that is pretty easy to solve. Otherwise, I'm more worries about the combination of the shock length with an 8" spring. As you said, if it sits too high now I need to go with a shorter spring (damn).

 

Diff is in, so il add some weight to the trunk to simulate fuel and axles. Still, brakes, steering is all apart so not sure how to release the pre-load pressure (in the direction of camber) on the tires so she will sit higher when I lower her in the garage then she will after a drive. 

 

thanks again for all your help!

 

EDIT: threw a wheel on and snapped a pic before I put on the ground. 

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Edited by AydinZ71
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Posted (edited)

I think I found the bust. The GC instructions seem to be for a 10” free-length spring (see attached) Mine are 8”. The adjustable sleeve is 6” long. With that in mind, I’m leaning on the side of not needing to get shorter springs. 
 

 

image.jpg

Edited by AydinZ71
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Posted (edited)

Gosh this is strange... 

 

So I called Ground Control and sent them pictures. They said the 7" dimension I am showing is from the bottom of the strut tube to the spring perch is correct. They are telling me the shock is too short... However, the 8310-1437's seem to be used by a lot of folks, so I am still lost what I did wrong. Was I supposed to drop a spacer in the bottom of the stock tube to prop up the shock by a few inches? 

 

I threw a wheel on there, and it sits pretty high up even with the shock extended fully. Im thinking about propping up the shock by 1.5", and adding 1.5" of strut tube back.  

3E6B8C8D-533D-4558-84F6-644176637A6E.jpeg

Edited by AydinZ71
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Posted (edited)
3 hours ago, AydinZ71 said:

Gosh this is strange... 

 

So I called Ground Control and sent them pictures. They said the 7" dimension I am showing is from the bottom of the strut tube to the spring perch is correct. They are telling me the shock is too short... However, the 8310-1437's seem to be used by a lot of folks, so I am still lost what I did wrong. Was I supposed to drop a spacer in the bottom of the stock tube to prop up the shock by a few inches? 

 

I threw a wheel on there, and it sits pretty high up even with the shock extended fully. I'm thinking about propping up the shock by 1.5", and adding 1.5" of strut tube back.  

3E6B8C8D-533D-4558-84F6-644176637A6E.jpeg

 

Out of curiosity, how much did you initially section out of your struts when you shortened them? The full extension of the strut shaft dictates max droop travel, so depends on the length of the strut body and how far the shaft will travel in it. I followed the guide here, cut 1.5" from the fronts and 1.75" from the rears. Used 240z front struts in the rear and Toyota Ae86 rears in the front (IIRC anyway, I can dig up specifics on my build thread over at Ratsun if desired).

 

http://dirtys30.blogspot.com/2011/04/how-to-240z-ground-control-coilovers-w.html

 

This plus getting rid of the stock giant rubber isolator in favor of weld-in T3 camber plates resulted in about a 3" drop vs stock, my rear wheel sits here at full droop (225/50/15's - 23.9" diameter) for reference:

 

SV84PFe.jpg

 

Approx location of my coilover perch seat (can measure if desired):

 

ibi2dL7.jpg

 

 

Given how high yours is sitting, did you cut more out of your strut bodies? Would explain the difference.
 

 

 

Edited by Noll
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I am not sure I am following all your issues, but yes it is common to add a spacer under the strut cartridge to get the proper fit at the gland nut. I usually cut down some 3/4 pipe.   And the tubes should be longer in the rear, hince a longer spacer used there. I thought the GC stuff was set up for 10" springs, but I have not used their coil over kit in awhile. Either way, the ultimate goal is to have the strut rod sitting at mid distance when static loaded. So if the Koni's have 5.5" travel, the rod is compressed 2.75" with static loading and you have max travel available in both directions.  The GC directions are an approximation to get you close (hopefully enough). There are some good write ups in this forum from John C.

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The rear strut tube should be 2" longer than the front, and yes, you need a spacer under the strut if you are running the same insert front and rear.

Because you lose an inch more in the rear on a 280 by removing the taller isolators, and the front is the end that runs out of travel, you really don't need to section 280 struts in the rear at all. 

If you dig enough you might come across some posts from me from about 10 years ago when a guy had sectioned his rear struts and was trying to run it anyway. He had preloaded the crap out of the springs trying to get the ride height higher and that just meant that the suspension kept topping out. He spun A LOT that day. A LOT. LOL

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@Noll @clarkspeed

 

My issue was I used intuition instead of the write-ups. I followed the instructions from GC correctly (which they confirmed), but I neglected to realize the Koni insert is much shorter than OEM. So when I sectioned the struts, I just slid the insert in just cut the strut tube to the right length. I figured as long as the gland nut ended up with 50-90% thread engagement, the precise length of the tube was irrelevant. This approach would have worked just fine, had I put in the 2" spacer in the bottom of the tube. (DOH!) 

 

I read the posts that were available but obviously missed the 2" spacer in the bottom of the tube. I think it was one of those "I don't understand, so I'l gloss past it" moments. This was my first experience with any suspension adjustment at all, so even the terms were new to me. At lease I know its fixable!

 

Going to add 2" of strut tube back, just below the gland nut threads. 

 

 

1 minute ago, JMortensen said:

The rear strut tube should be 2" longer than the front, and yes, you need a spacer under the strut if you are running the same insert front and rear.

Because you lose an inch more in the rear on a 280 by removing the taller isolators, and the front is the end that runs out of travel, you really don't need to section 280 struts in the rear at all. 

If you dig enough you might come across some posts from me from about 10 years ago when a guy had sectioned his rear struts and was trying to run it anyway. He had preloaded the crap out of the springs trying to get the ride height higher and that just meant that the suspension kept topping out. He spun A LOT that day. A LOT. LOL

 

YEP! I just found that post a few hours ago. I didn't have the balls to drive the car with it clearly not having enough droop. At least I caught my mistake :) Still its going to be a pain in the ass to add material to the strut tube. It looks like I do have 2" of material from what I cut to add-back. 

 

 

THANKS AGAIN FOR ALL YOUR HELP GUYS! the community is great. 

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Posted (edited)

@AydinZ71 Aha, that makes sense. Easy enough mistake to make, good thing the culprit was found. We've all been there with one thing or another I'm sure.

 

It shouldn't be TOO much of a pain to fix as long as you have the old cutoff sections still; if you have an old stock strut insert lying around, it can be handy to put it in the housing as a guide as you weld to make sure it all gets welded in straight (just make sure to drill a hole or something to make sure there's no pressure in the old strut first; compressed gas and heat isn't good for obvious reasons).

Edited by Noll
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42 minutes ago, Noll said:

@AydinZ71 Aha, that makes sense. Easy enough mistake to make, good thing the culprit was found. We've all been there with one thing or another I'm sure.

 

It shouldn't be TOO much of a pain to fix as long as you have the old cutoff sections still; if you have an old stock strut insert lying around, it can be handy to put it in the housing as a guide as you weld to make sure it all gets welded in straight (just make sure to drill a hole or something to make sure there's no pressure in the old strut first; compressed gas and heat isn't good for obvious reasons).

 

Yep! I am super glad I kept the old lower perches with about 3" of tube each. I'll lop 1/2" off each side to get them square and to an even 2" a piece. 

My technique (worked the first time) was to wrap the koni in tin foil and gently shove it into the tube. The foil does 2 things...

 

1) acts like a "bushing", centering the strut in the tube and providing resistance to the "loose" tube section from pivoting off-axis (falling out of concentricity).

2) acts as a heat shield while I tack four equidistant spots onto the seam, leaving a 1/32" gap. The tacks hold it concentric. 

 

Then I pull out the shock and finish the weld. voila! Trick is not to penetrate too deep with the weld or you will get interference when you drop the strut back in. 

 

@calZ Thank you! I already had these guys sand blaster, painted, and the lower perch welded so I will give this a shot. I may reach out to you if I screw this up, and you still have them available? 

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Better method than tin foil: use a couple pieces of 1" angle iron on opposite sides of the strut tubes. Hold everything with hose clamps. The angle iron will center the tubes and you can tack them together, then pull the angle iron off and weld it up. 

 

Won't be exposing your strut to any heat and really holds the tubes firmly. 

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19 minutes ago, JMortensen said:

Was thinking that might be hard to understand, so made a shitty drawing.

strutalign.png

Thanks a bunch!! I will 100% do it this way :).  Il snap some pics for the community. I got the assemblies off the car yesterday but naturally I forgot to pick up a pipe wrench for the darn gland nut. Borrowing tools never works when you think it’s “one and done” haha. 
 

good call on the hose clamps. Without that tip I would have probably tacked them on. 

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Update. Everything disassembled again, and bought some angle stock per Jmortensen. For the spacer, I went with 1-5/8, 0.14 wall 6061 AL. Fits pretty well (see pic). I didn’t want to go solid stock since I don’t want to flatten the natural curvature of the strut inserts bottom. Hollow also helps with concentricity. 
 

figure this is dead weight and only in compression, so why not AL. Stuff is practically free in my metal supplies discount bin. Let me know if you guys see an issue there.

 

 

82A81BD2-BE3F-4FCF-8D17-7395354BEC82.jpeg

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While I scavenge the time to re-section my rear struts, I thought I would look forward a bit to the flywheel/clutch scope. I’m pulling the short block and 4-Spd soon so I can check what flywheel/clutch the previous owner had on there before I rush into buying new parts. I already hear from you all that I should go with the lightest flywheel I can. I’m looking at the 10-lbs steel unit sold by a handful of sources.

 

How about the clutch? Given the modest torque of even a race-prepped L24 on SU’s, are there any reasons to run a A/M clutch for a racing application? I chatted a bit with Greg Ira on this topic, and he thinks the exedy OEM unit should be just fine since you are t really slipping the clutch that often during a race, and should be rev-matching on downshifts anyways. 
 

naturally, he runs a lightweight high performance clutch but he also has sponsors.

 

what are your thoughts? OEM clutch OK? 

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Exedy OEM on a lightweight flywheel is a great choice, Exedy makes good stuff. ClutchMasters makes a good flywheel for our cars, I'd recommend that as well. You don't need extra clamping force with stock + power levels, so no need to go full stage 6 unsprung whatevers. 

 

A Tilton 5.5" would be the next best thing, just because it will reduce rotational mass enormously, but it's at the expense of everything else. 

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Posted (edited)

7243D5F8-DA6A-41F6-AF8B-DA695D0360C6.jpeg.6bc5cb22afcd1c20fbf57736441a62e5.jpegThanks as always Ben! Then I’m going for the Exedy and the 10-lb forged steel flywheel. Zcargarage has one listed for $350. Anyone have any experience with them? 

Back to the rear suspension. Got one completely welded. Wow this was a lot of work, but @JMortensen’s technique for keeping the tube concentric worked like a charm. Strut slid in and out. The weld is messier than I wanted, but I had to be sure I did not penetrate the tube. I did get some 1/16” bead penetration in some spots, but I was lucky it was on the short side. I was able to use a die grinder to clean it up. I also welded a bunch of pitting that had accumulated at the base of the bottom OEM perch. 
 

Soon onto the fronts. The GC directions call for a 5” gap between the bottom of the strut tube and the bottom of the coilover perch. Do I need a spacer for my Koni’s in the front? 

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Edited by AydinZ71
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