OEM Internals on ZX Struts?

[ByStickel]

I just picked up a set of really nice ZX struts at the yard; no rust, great calipers, like-new pads, and unworn (but rusty) rotors. Cheap, too! When I went to remove the insert, I found that they still have the OEM open-bath internals. I drained the oil, which still had color to it, and had the following questions:

 

1. With the ZX being a bit heavier, why does nobody mention using ZX internals, either OE or aftermarket, on their 510? Too stiff, too soft?

 

2. If the answer to the above it that the ZX damping is great for 510s, then is there a reason to avoid the OE open-bath internals, provided it's all in good shape? I like the idea that I can alter oil weight, and possible alter the ratio of compression-to-rebound.

 

3. How do you remove those OE internals. A moderate pull didn't do it. Is there a trick?

 

Thanks!

[thisismatt]

You have to pick out the o-ring that was at the bottom of the gland nut

[datzenmike]

 

I use a dental pick.

 

 

 

 

I'm running the stock internal oil bath dampers (shocks) and highly recommend it to anyone who will listen. To increase the damping to make firmer I do what motorcycle owners have been doing forever. Simply replace the thin watery hydraulic  oil with a thicker weight of oil. Thicker viscosity oil resists being pushed through the compression and rebound valves. For my Maxima struts I used RellRay 20W motorcycle fork oil.

 

It's a shame more owners don't do the same and simply spend money on a generic damper that usually is not even made for the application. Keeping the old oil bath dampers retains the stock compression and rebound valving. A liter bottle is enough for 3 struts and is under $15 US.

 

For my wife's 710, now gone, I used ATF (automatic transmission fluid) which has a viscosity of around 8W. I didn't think she would appreciate a firmer ride. I would guess any hydraulic oil would do.

[ByStickel]

Came here for amazing Datzenmike knowledge. Leaving satisfied!

 

I'm going to keep those stock internals. Thanks guys.

[datzenmike]

While the struts are off you can make the height adjustable for under $25 just like $1,100 coil overs!

 

The zx spring is too large a diameter for the 510 so using a hacksaw or angle grinder lightly trim around the lower spring perch above the weld and remove it. In it's place you can do the same to the stock 510 lower perch and put it and the stock 510 spring on the zx strut by grinding the old weld smooth.

 

 

 

 

 

Now you can assemble the zx strut using the 510 top hat, spring and lower perch. To support the spring perch in place on the strut, and allow you to slide it up or down to adjust the height I used a pair of 2" split collars. About $25.

 

 

They don't look like much but each are rated to hold 5,000 pounds or 2 1/2 510s each. Install everything and compress the spring upwards using a jack and a block of wood and tighten the split collars.

 

 

 

 

This procedure is a bit tedious and time consuming but once you get the ride height where you want it you are probably never going to change it again anyway. I mean what's the sense of spending hundreds of dollars on coil overs that you set and then never adjust again???? All that money just along for the ride.

 

Spring

 

The 510 spring rate is just under 100 pounds per inch. lb./in. Fine for a stock 510 but soft if a serious driver. If lowering, you risk bottoming out the under side of the car so along with the lowering a stiffer spring rate that limits body travel is probably a good idea too. A physical property of a coil spring is that if you shorten it, it becomes stiffer. Course you can't just lop off spring and hope to get what you want and if you go too far you can't put it back. With a few accurate measurements of the stock coil spring and some multiplication and dividing you can work out the spring rate you would like. You need to measure the thickness of the coil wire, the diameter of the coil center line to center line and the exact number of coils that are active and not touching each other. The formula is 11,250,000 X wire thickness ⁴  / 8 X number of coils X coil diameter ³. Everyone is different and what ever I set mine at is unlikely to be what you want but if you have driven someone else's 510 and liked their body firmness you could start with what they used. Be advised that the rears also play a part in this and should be stiffened to roughly match. On my 710 the stock spring rate was just over 100 lb/in so I increased 50% to 150 and never felt the need to go higher. (but I'm old) most 510 owners run in the 175-225 lb/in range. Alternatively if you know the rate you want you can just buy springs in that rate, but what's the fun in that?

 

I cut the end of the spring that fits and locks into the spring perch. Looks like 1 1/4 coils removed was the trick. Do the math.

 

 

Angle grinder is all that's needed for this.    

[Stoffregen Motorsports]

Ground Control has been selling 510 coilover conversions for decades and the cost is much less than what you say.

 

https://groundcontrolstore.com/collections/510

https://groundcontrolstore.com/collections/510/products/coilover-kit-datsun-510-610-710-etc-front-only-pair

https://groundcontrolstore.com/collections/510/products/camber-caster-plate-68-73-datsun-510-pair

 

You need the coilover kit, but camber plates are a good idea too. Both are less than $600 combined.