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280zx struts/ 510 conversion- Am I missing something?


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So I finally put my 280zx struts on my '71 510.  I did not cut my housings... I used Suspension Techniques sport springs, tokico 3038 inserts(280zx), I used the 510 spring perches, cut down 280zx top hats, 1" LCA spacers,  I put the perches on so there was about 1 inch of preload on the springs, just enough to keep the perches tight against the slip collars.....

 

The fender still sits about 2.75" above the tire.

 

Am I doing something wrong?

 

I suppose I could lower the spring perch, but when I do that, and I raise up the car, taking the load off the suspension, the spring flops around.

 

I tired to imagine what would happen if I put coilovers on without cutting the housing, but I can't see how that spring wouldn't just flop around the same.

 

I want the fender lip to sit about 3/4" above the tire.....

 

The car rides great, but I was expecting more drop.  Any advice?

 

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Post some pics of how you have the struts setup...

 

.... It appears I forgot to take some pics before I put them on the car.....  I have a bad habbit of working, and not taking pictures for you picture whores....

 

What are you looking for?  Would a pic of them installed do it for you?

 

I put the slip collars over the housing, 510 spring perch on next, strut insert down the hole, with the nut on, poly bump stop next, spring on next, 510 top spring perch next, bearing, then top hats.  Strut nut torqued to spec.  Then I compressed the springs, and mounted the lower perches so there was one inch of spring compression once I released the spring.... Just enough so it wouldn't flop around when the suspension load was off the wheels. 

 

I did mark my housings so I would get the exact positioning from one side to the other:

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I haven't had a problem yet. Of course preload is the proper way to do things. Maybe undo the preload till the spring just stars to seperate from the hat. Then try it out and see how you like it

 

I can try that. 

 

I used the slip collars everyone seems to love.  Everyone also says you can tighten them down and forget about them.... Well I tried that, and they didn't hold up.  So first I had to re-do my work, then I ended up putting some tack welds on them to help hold them in place. So I will have to do some grinding first....

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If you have the stock springs they are around 90 pounds/inch. Work out how many coils to cut to get your 200 lb/in and see how low those are. If too low you can add spacers to lift it (plus the preload)
 
The formula is 11,250,000 X wire thickness (in inches) 4
___________________________________________
8 X number of active coils X coil diameter (center to center) 3

 

 

 

 


I can try that.
 
I used the slip collars everyone seems to love.  Everyone also says you can tighten them down and forget about them.... Well I tried that, and they didn't hold up.  So first I had to re-do my work, then I ended up putting some tack welds on them to help hold them in place. So I will have to do some grinding first....

 

 

Yes I did the tack welds also.

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Yes I did TenafterFive. But I'm running the stock 280zx hubs.  I like the offset of them for now.

 

I thought about that, but I think it's dependent upon the strut inserts I'm running.  The springs are preloaded to the top hats which are held on by the nut at the end of the strut insert.  If I'm not mistaken, the only thing to do would be either shorten the housing and run the MR2 insert. Or, find an insert with the same body length, but a shorter extended length....

 

A taller spring would only change the location of the bottom spring perch, right?

 

Maybe a softer spring like the stock spring would allow the weight of the car to "sag" more?

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So the springs are about 10" tall if I remember right. 

 

5 full coils

 

5" on center

 

.5" thick coil

 

I found this:  auto calculating

http://www.pontiacracing.net/js_coil_spring_rate.htm

 

So it looks like 192 lb/in springs, so probably advertised at 200 lb/in.

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I was just thinking you could go lower with preload with a longer spring. And I wouldn't go to low without cutting the tubes or you will bottom out or bounce of the rubber bumper on the strut.

 

Maybe I'm not envisioning what your thinking, but I don't see that working....  I don't think... the length of the spring has anything to do with it.....  Can you paint me a picture?

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So by using this chart;  http://www.pontiacracing.net/js_coil_spring_rate.htm

 

My stock 510 springs come to 91.18 lbs/in

 

15/32" / .4687 wire diameter

5" spring diameter

8 active coils

 

So yeah, Mike is right on the money.

But, I'd have to cut it down to 4 coils to get 182.35 lb/in....

 

Just for reference:

7 coils = 104.2

6         = 121.57

5         = 145.88   Again the springs I have now are 5 coils, .5" wire diameter, and 192 lb/in

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That's why I posted the formula. You would have to plug in some numbers and see what you get. 4 coils is no good. On my 710 1 1/4 coils increased it 50% from 100 to 150 lb/in.

 

 

Note in my formula the diameter of the coil is center to center not across the full width. On line calculators may take this into account.

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If my memory serves me right, I recall that people used to wire the spring down to the spring perch so it would stay in place when no load was on it. I think there is an article about it in a old issue of the dime quarterly or maybe it was FTA or was it UFO? 

 

 

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Unless its a rally car that will get some air time I don't see any problem with the spring being loose at full droop. It won't ever get to that point driving it on the road anyway

 

I used to think the same thing until I decided to add a little bit of preload to the front springs on my 510.  It made a big difference in ride quality... your mileage may vary.

 

FWIW, I called Eibach and the representative on the phone said springs should have at least 0 preload.

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