Adjusting/setting rear coilover

[plasmid]

Hello,

I've done a bit of searching but can't really find anything decent.

I'm looking for a 'how to' for adjusting/ setting rear coilovers that are a seperate spring and shock/divorced setup. Which most are for the S550.

In particular pre-load, adjusting height and matching that by adjusting the shock.

I hope that makes sense.

Cheers on advance.

Sponsored

 

[BmacIL]

There's a perch that has a preload collar that the spring sits on. You adjust the collar just like a conventional coilover.

 

[plasmid]

I've used coilovers on my other cars in the past but not this sort of set up.

As I understand it, once the rear end is completely assembled, I was going to adjust ride height to the desired level using the coil over spring adjuster. Leaving the shocks off for the moment.

Then use a jack under the lower control arm to lift or put on 5-10mm of preload on the spring and tighten the collars.


Then install the shock, adjust the shock length so it lines up with the upper and lower mounting points.

?

 

[BmacIL]

I've used coilovers on my other cars in the past but not this sort of set up.

As I understand it, once the rear end is completely assembled, I was going to adjust ride height to the desired level using the coil over spring adjuster. Leaving the shocks off for the moment.

Then use a jack under the lower control arm to lift or put on 5-10mm of preload on the spring and tighten the collars.


Then install the shock, adjust the shock length so it lines up with the upper and lower mounting points.

?

The shock length is fixed, so there's no reason to not install it at the same time. The shock adjuster is damping.

 

[plasmid]

The shock length is fixed, so there's no reason to not install it at the same time. The shock adjuster is damping.

Hey BmacIL.

Thanks for your response.

I'm looking at purchasing a set of XYZ Coilovers. Hence the research. I'm pretty sure the the rear shocks are adjustable for length. They have a locking collar on them. You can shorten and lengthen depending on the height you set with the spring. This allows for the correct shock travel.

I think....

 

[DivineStrike]

Hey BmacIL.

Thanks for your response.

I'm looking at purchasing a set of XYZ Coilovers. Hence the research. I'm pretty sure the the rear shocks are adjustable for length. They have a locking collar on them. You can shorten and lengthen depending on the height you set with the spring. This allows for the correct shock travel.

I think....

if you have an adjustable rear shock body then yes you are correct. Essentially the shock body is what determines the preload on a divorced setup. The ohlins have this adjustment in the rear.

 

[BmacIL]

if you have an adjustable rear shock body then yes you are correct. Essentially the shock body is what determines the preload on a divorced setup. The ohlins have this adjustment in the rear.

If the shock and spring are divorced, changing the shock has zero change to preload at all. That is at the spring perch.

 

[DivineStrike]

If the shock and spring are divorced, changing the shock has zero change to preload at all. That is at the spring perch.

you are right in many cases, however not 100% accurate in this one. when the shock has an adjustable shock body length, it is how you apply preload to the spring. Of course it also depends on the length of your spring, now obviously if you set your shock length to a position that gives preload and you try “raising” the spring perch, then yes you are adding additional spring load.

 

[BmacIL]

you are right in many cases, however not 100% accurate in this one. when the shock has an adjustable shock body length, it is how you apply preload to the spring. Of course it also depends on the length of your spring, now obviously if you set your shock length to a position that gives preload and you try “raising” the spring perch, then yes you are adding additional spring load.

Only if it's a rear coilover. If you're creating positive preload from a divorced shock, your shock is bottomed out. Changing the shock body length does not add preload, it changes the position of the piston relative to the shock topped/bottomed positions. I don't want to start posting memes for how that's not how this works... But it isn't.

 

[DivineStrike]

Only if it's a rear coilover. If you're creating positive preload from a divorced shock, your shock is bottomed out. Changing the shock body length does not add preload, it changes the position of the piston relative to the shock topped/bottomed positions. I don't want to start posting memes for how that's not how this works... But it isn't.

memes won’t change that you’re wrong in this, sorry. I have a divorced setup with an adjustable shock body length and it’s exactly how it works. Your shock is bottomed out (perhaps this is the wrong use of words, fully extended would be more appropriate or maybe “topped out” ‍) when its completely unloaded, I had to adjust the length of my shock to apply preload to my spring, otherwise My spring with the spring perch maxed out (which would have a ride height higher than stock) would still have no preload on it and would become “loose” if completely unloaded in a sharp corner. On a true coilover if you adjust the strut body length then you are not effecting preload, only the spring perch collars control that

 

[BmacIL]

memes won’t change that you’re wrong in this, sorry. I have a divorced setup with an adjustable shock body length and it’s exactly how it works. Your shock is bottomed out (perhaps this is the wrong use of words, fully extended would be more appropriate or maybe “topped out” ‍) when its completely unloaded, I had to adjust the length of my shock to apply preload to my spring, otherwise My spring with the spring perch maxed out (which would have a ride height higher than stock) would still have no preload on it and would become loose if completely unloaded in a sharp corner. On a true coilover if you adjust the strut body length then you are not effecting preload, only the spring perch collars control that

OK now I see what you're saying. The shock itself is not providing preload but it is topped out, therefore you cannot add any preload with the spring perch. You should have a minimum of 2" of wheel droop from ride height if you have enough travel. If you have less, you risk damaging the shock.

 

[DivineStrike]

OK now I see what you're saying. The shock itself is not providing preload but it is topped out, therefore you cannot add any preload with the spring perch. You should have a minimum of 2" of wheel droop from ride height if you have enough travel. If you have less, you risk damaging the shock.

yes lol, glad we’re on the same page now, and thanks for the wheel droop info. I’ll have to go back and check it, I only applied a little preload when lining up the strut so it should have as much droop as my setup allows

 

[shogun32]

My spring with the spring perch maxed out (which would have a ride height higher than stock) would still have no preload on it and would become “loose” if completely unloaded in a sharp corner.

Isn't there a mechanical limit to wheel droop? Your spring at full extension (and preload ramps fully collapsed) should still result in say 5mm of preload on the spring. In other words, you should be forced to unbolt the subframe bolts to get enough extra droop to install the spring+ramp assembly just like people do with "normal" springs. Otherwise your spring is WAY too short. Or there is a setting on the preload ramp device that you must NOT exceed lest there be zero preload on the spring at the limits.

Can you elaborate whose shock and spring length?

Furthermore the shock should NOT be the device limiting droop of the wheel unless it has an internal bump stop. On compression, the mechanical limiter is typically an external bump stop sitting on the exposed shaft.

@BmacIL have you had a chance to measure the motion ratio of the shock? We know for example the spring is at 0.5.

 

[BmacIL]

Isn't there a mechanical limit to wheel droop? Your spring at full extension (and preload ramps fully collapsed) should still result in say 5mm of preload on the spring. In other words, you should be forced to unbolt the subframe bolts to get enough extra droop to install the spring+ramp assembly just like people do with "normal" springs. Otherwise your spring is WAY too short. Or there is a setting on the preload ramp device that you must NOT exceed lest there be zero preload on the spring at the limits.

Can you elaborate whose shock and spring length?

Furthermore the shock should NOT be the device limiting droop of the wheel unless it has an internal bump stop. On compression, the mechanical limiter is typically an external bump stop sitting on the exposed shaft.

@BmacIL have you had a chance to measure the motion ratio of the shock? We know for example the spring is at 0.5.

0.72
Stock spring is 0.49

 

[DivineStrike]

Isn't there a mechanical limit to wheel droop? Your spring at full extension (and preload ramps fully collapsed) should still result in say 5mm of preload on the spring. In other words, you should be forced to unbolt the subframe bolts to get enough extra droop to install the spring+ramp assembly just like people do with "normal" springs. Otherwise your spring is WAY too short. Or there is a setting on the preload ramp device that you must NOT exceed lest there be zero preload on the spring at the limits.

Can you elaborate whose shock and spring length?

Furthermore the shock should NOT be the device limiting droop of the wheel unless it has an internal bump stop. On compression, the mechanical limiter is typically an external bump stop sitting on the exposed shaft

for oem length springs that is true but using a 6in spring in the back (a 7 inch spring would be perfect... maybe an 8 inch would work but it would be difficult to install without removing the subframe or spring compressors I think) with adjustable perch it can become loose enough to become dislodged, it won’t fall out but just get loose. And yea I was forced to unbolt the subframe to remove and install the new springs. The spring perch seats of the ohlins insert into the rear control arms hole but without a certain amount of preload part of the “circle” sits above the hole. Car is currently 700 miles away so I can’t really demonstrate it. That said I believe the height is low enough now that I may not need to disconnect the subframe to adjust the rear ride height lower. (Rear is at 14.5 inches from fender to wheel center while the front is at max height and at about 14 inches from fender to wheel center. The range in the rear would allow me to have greater than 15 inches from fender to wheel center)

I imagine the rear sway bar helps limit droop if I’m remembering correctly.

Sponsored