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Yet another post about wheels, tires and suspension.


OmahaJames

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How would you ever get zero pre load? The suspension would bottom out on the stops.

 

What you are describing you have installed is a zero preload situation. Preload would be the amount of load against the damper (strut in this case) when it is at full extension. You have MUCH more droop travel than the car requires.

Here's what I have. With everything installed and strut fully extended and spring loosely between top hat and lower perch, the car weight would crush down and compress the spring and bottom out the suspension.

 

So if you were to run this particular set up, I would suggest using a longer main spring and a tender spring, you would then be simply changing the position of the spring in the car to get ride height, yet still keep tension on the spring stack. Typical EIBACH tender spring would be roughly 70mm long open, and 25 @ block. Which gives you a little wiggle room with spring length and position on the threaded collar.

A stock strut would have pre load built in because it was designed for an end result ride height.

 

Yes, it would, that's because the engineers chose a spring rate and in order to fit the package, and hold the car up the spring would need to be fairly long. That is spring preload.

The replacement struts were slightly shorter than the stock and the spring rate increased by 50% to 150 lb/in. Car was lowered a couple of inches.

 

How much shorter? As much as you lowered the ride height?

The stock oil bath dampers work just fine and will shed more heat than a strut insert. I don't know the stock viscosity but seems watery like hydraulic jack oil. I have replaced it with 20W Bel Ray motorcycle fork oil because of it's anti foam/rust properties.

 

This is a very subjective area, but without verifying damper forces on a dyno....you are shooting in the dark.
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i do recall seeing a 280zx, did you need complete set up? top hat down to the spindle?

 

 

Honestly I am not entirely sure what I need, but I currently just have the stock B210 suspension, so I probably need the complete setup.

 

 

For the cheapest shipping, you would just need the strut tube/spindle, the hub, and any/all hardware. You can buy new rotors and rebuilt calipers cheap on RockAuto (and these are the heaviest items), as well as new shock inserts. Then all of the upper bits (spring, top hat, etc) will come from your B210 struts. 

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What you are describing you have installed is a zero preload situation. Preload would be the amount of load against the damper (strut in this case) when it is at full extension. You have MUCH more droop travel than the car requires.

What I have is identical to a coil over but the looks. Strut, spring and a means of adjusting the ride height. If my strut were removed as a unit you would find the spring is compressed between the top hat and the bottom perch. If that isn't 'pre load' then what is?

 

 

 

So if you were to run this particular set up, I would suggest using a longer main spring and a tender spring, you would then be simply changing the position of the spring in the car to get ride height, yet still keep tension on the spring stack. Typical EIBACH tender spring would be roughly 70mm long open, and 25 @ block. Which gives you a little wiggle room with spring length and position on the threaded collar.

A longer spring would be softer. To keep the 150 lb/in it would need to be thicker, fewer coils or smaller diameter. Only advantage to a longer spring is more travel before binding. Binding is not a problem.

 

70mm is 2 3/4" ???

 

 

Yes, it would, that's because the engineers chose a spring rate and in order to fit the package, and hold the car up the spring would need to be fairly long. That is spring preload.

 

I guess so... A stock passenger car needs a longer spring because the suspension must travel farther to absorb bumps and be 'comfortable'. A lowered car does not expect to have the same suspension travel (else the risk of bottoming isn't addressed) and comfort is traded for a firmer ride. The spring constant or 'stiffness' holds the car up. The stiffer the spring the less it sags under weight. Length of spring (assuming the spring constant remains the same) only determines how far the suspension can compress before bottoming. A two foot long 150 lb/in spring and a one foot long 150 lb/in spring will compress the same amount under the same load. The shorter spring will bottom out sooner is all.

 

 

How much shorter? As much as you lowered the ride height?

Strut might be 1 1/2" shorter. Car dropped maybe 2 1/2". Spring 50% stiffer to reduce suspension travel.

 

This is a very subjective area, but without verifying damper forces on a dyno....you are shooting in the dark.

 

This isn't a race car. Even a race car can experiment with what works and what doesn't regardless of what a dyno might indicate. If it feels right... it is right. These are Nissan dampers with a built in compression and rebound proportional to the car it was from and not generic inserts that fit a variety of vehicles and the spring rate. I kept the spring rate identical but my 710 will be lighter. I expect some stiffness. 

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For the cheapest shipping, you would just need the strut tube/spindle, the hub, and any/all hardware. You can buy new rotors and rebuilt calipers cheap on RockAuto (and these are the heaviest items), as well as new shock inserts. Then all of the upper bits (spring, top hat, etc) will come from your B210 struts. 

 

Thanks for the tip, really any information helps I am just learning as I go.

 

 

Does anyone know if I run 15x7 wheels with a 0 offset and P195/50R15 tires will that fit without rubbing once I swap to the 280ZX front struts?

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What I have is identical to a coil over but the looks. Strut, spring and a means of adjusting the ride height. If my strut were removed as a unit you would find the spring is compressed between the top hat and the bottom perch. If that isn't 'pre load' then what is?

 

 

 

A longer spring would be softer. To keep the 150 lb/in it would need to be thicker, fewer coils or smaller diameter. Only advantage to a longer spring is more travel before binding. Binding is not a problem.

 

70mm is 2 3/4" ???

 

 

 

I guess so... A stock passenger car needs a longer spring because the suspension must travel farther to absorb bumps and be 'comfortable'. A lowered car does not expect to have the same suspension travel (else the risk of bottoming isn't addressed) and comfort is traded for a firmer ride. The spring constant or 'stiffness' holds the car up. The stiffer the spring the less it sags under weight. Length of spring (assuming the spring constant remains the same) only determines how far the suspension can compress before bottoming. A two foot long 150 lb/in spring and a one foot long 150 lb/in spring will compress the same amount under the same load. The shorter spring will bottom out sooner is all.

 

 

Strut might be 1 1/2" shorter. Car dropped maybe 2 1/2". Spring 50% stiffer to reduce suspension travel.

 

 

This isn't a race car. Even a race car can experiment with what works and what doesn't regardless of what a dyno might indicate. If it feels right... it is right. These are Nissan dampers with a built in compression and rebound proportional to the car it was from and not generic inserts that fit a variety of vehicles and the spring rate. I kept the spring rate identical but my 710 will be lighter. I expect some stiffness. 

I must have misunderstood, my comments were directed at what I was looking at shown in the OP's photos.  Based on what you mentioned about your set up, I assumed it was pretty much identical to the OP's set up sans threaded collar and 2.5" coil-over spring.  So yes, if you do not have a gap between the spring and upper hat and the spring is under tension, then yes, this is certainly what I call preload.  It is also possible to have a couple of mm's of preload, it doesn't have to be inches, but again, this is totally dictated by spring rate and or position on the strut.

 

A longer spring would be softer?  You can purchase the same rate in multiple lengths.....ie. Eibach has 6" and 18" 150 lb springs....so im not sure where you are going with that one.  What you said about spring design doesn't really make sense.  Spring rate is determined soley on the wire diameter, number of active coils, mean diameter and the modulus of steel you are working with.  Chrome silicon spring wire designs can use a much smaller wire diameter and gain more travel, fewer active coils (more deflection) vs. chrome vanadium material with all aspects of the spring design being the same (similar spring rate and length and ID).  High Tensile strength spring steel designs can reduce wire size even further gaining more deflection and still remaining block resistance (the spring will return to its designed fre length after traveling to coil bind.  Depending on the package, a longer spring could allow one to wind preload into the spring (position on the strut).  yes, a 12" 150lb spring would have more travel and could support a higher load that say a 8" 150lb spring.  At Eibach all of the pro-kit (application specific) springs are designed around a load point, this is why most of their parts are progressive, the progressive or lighter rate is designed to keep preload at full droop whilst allowing lowering.

 

I'm not sure that i follow the last comment about race cars. It is way more difficult to tune a street suspension to really work.  I am not arguing at all re: real world testing, however, a dyno is a reference tool.  I would be surprised if your struts had matching forces left to right.  Are those 'NISSAN' wet bath pistons banded?  OE wet bath dampers are NOT performance parts. As I mentioned above that little piston is not gonna generate much force.  The koni insert would be a much better route if one was ok with spending a little $$, not to mention the KOni is externally adjustable....albeit LSR only, but that is your biggest tool in gaining platform in a vehicle. That's cool if you have something that you feel works and i'm sure you saved some $$.  But to knock a suggestion about a known tried and tested product that is offered by a company that is legit seems kinda balls.  But hey to each his own.

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Okay, I finally got my hands on some 280ZX struts and I am trying to figure out what I need to do from here. I know that the spring on the 280ZX struts wont fit on my B210 and I've read that I can move the spring seat from the B210 struts to the ZX struts, but that is where I get kind confused, how do I remove the spring seats, do I just cut into the strut tube below the seat?

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https://technotoytuning.com/nissan/s130/front-weld-coilover-kit-datsun-280zx

 

Buy this and take your 280 struts to a shop that can weld. Pull the inserts in the housings, buy new ones, weld TTT kit to 280 strut housings install 'race' springs, install new strut inserts and mount with new top hats or camber plates. Done.

 

Okay, I work at a community college so I have access to facilities to do that. When you say install 'race' springs are you saying install the springs that come with this kit? I assume since these are smaller in diameter they will fit onto my B210. Since this is my first time modifying the suspension of a car do you know if I will need the camber plates, what is the risk without them, uneven tire wear and handling?

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Yes, install the springs that will come with the kit. Race springs are liniar rate springs made for racing. You will probably want an 8in free length and a 200-250lb spring. Camber plates are not needed but are nice for adjusting camber during alignment. It really depends on how much you lower the car if they will be needed and if camber is out of spec on the alignment the tires will wear funny. The kit comes with everything required for fitment to the 280z strut housings.

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