Do you have any suspension droop ?, is my understanding of it correct

It's the amount of travel you have between the static ride height, and full extension. Bump travel being the travel between static and fully compressed (bump stop).

You want as much as you can get, without enough the car won't be able to ride bumps properly and will lift wheels all the time.

For the most part though, running 0 preload will give you the best compromise. Adding preload will increase droop travel (given enough damper stroke length) but lose bump travel and vice versa. Spring free length and rate will have to match the damper stroke available to get the optimal travel.
Droop is always compromised when using high spring rates, simply because the spring doesn't compress as much under the cars weight.

 

My understanding of droop & preload on coilovers is simply the amount the spring is under tension when there is no weight on it.

Put your car on axle stands and see how much the spring physically is able to move up & down between the top & bottom perch's.

Zero preload means that the spring does not move up & down freely, but you should be able to spin it fairly easily by hand, so its not under much tension.

Adding droop means the spring is physically flopping about, and has X-mm of play between top & bottom spring perch.

Adding preload means the spring is already under compression, which is bad.

I have CS2 coilovers which come with helper springs, meaning I'm running droop by default. The helper spring is there to ensure the spring is not physically loose, but its not required, its just a bit of safety.

10mm droop rear, 5mm droop front is good starting point. It easy enough to try out & test, see what you think. Also bear in mind adding droop reduces ride height, by a certain extent.

 

out of interest what would people recommend for a non drift car on coilovers for comfort

i.e i need to stick some coilovers on my gs300 but dont want to kill the comfortable ride on it

 

From my experience, lots of droop. Also being a GS300, that's a heavy car, try a lot of droop and see how you get on.

 

No worries. By no means am I an expert on the subject, but I too was confused about it and I've done a ton of reading about it. The thing that I think most people get confused with is people explain it differently/wrong with incorrect terms.

I've played around with preload/droop myself though - I can confirm, in general, running a bit of droop is good!

Means the spring is actually doing more work, as its not under tension by the bottom spring perch as static. I spoke with Billy (SR32) about this a while ago, and he got more technical with it, regarding the weight of the car, and the height of the spring/coilover, etc.

 

"Droop: Vertical movement of wheel down from chassis. aka rebound. In racing, the terms 'bump and droop" are used together to define suspension travel; in industry, "jounce and rebound". [bump, jounce]"

As previously said droop is the amount of downward travel that you coilover can do before bottoming out.

Imagine your car lifts up after hitting a bump, the wheel to stay in contact with the ground will need to drop / droop downwards from the car body to stay in contact with the road surface. Rally cars on forest stages and 4x4's for off road will require a lot more droop than a car competing on nice flat tarmac. So as a drifter you'll understand that you need more droop at Pod than at Teeside to keep all 4 contact patches on the track surface haha.

The amount of droop you can have is limited by your coilover design. My advice is to set your preload to zero and crack on, unless your regually having problems with 3 \ 2 wheeling over bumps then its not effecting you dude

 

Having the spring loose is not droop and will not increase droop. The shock will only rebound as far as the spring can push it. All you are doing really is reducing the available bump travel of the shock. There is no merit in doing this on a dual perch type coilover.

I mentioned increasing preload will reduce bump travel also, this is because you are effectively reducing the available 'travel' of the spring, and it will become coil bound more easily, probably a negligible effect though.

 

Thank fuck for that means I don't have to sit in the cold with you later adjusting coilovers. Oh shit yeah I do, need to do mine

 

No.

1) Moving the spring position will effect rebound/bump travel. The shock will also rebound as far as it physically can given the correct circumstances (the arb is normally the limiting factor), the spring doesn't have to "push" it.

2) Increasing preload will not effect linear spring rate spring travel (unless you compress the spring more than the cars weight would, which is unlikely). For example, with the weight of the car on it a linear spring's compression is the same at 0 preload or 50mm preload.

 

sorta on the right track Daze,

superclarkey is the best person for this.

basically if you run zero droop your coilover is trying to top out all the time. so theoretically if all weight is removed from the car suddenly the coilovers will top out hard (in a similar way to the coilovers bottoming out the other way)

you run droop so that your coilover runs in the middle of its range.

on HSD mono pro's this is about 20mm droop all round. on CS2's this is about 25mm (the top stop is smaller on CS2's inside the shock)

the reason some coilovers come with helper springs is to essentially run droop but not have a loose spring (a loose spring is an MOT failure) Superclarkey has said he actually removes these and runs the droop instead as the compressed helper spring uses up travel (the overall length of the compressed spring)

a loose spring isn't a bad thing. i run 20mm droop on my HSD's and ran 25mm droop for two years on my CS2's and i've never once felt them twang as they re seat.

basically think of the coilover as having a top point just like it has a bottom. and that the shock works at its optimum in its mid range. which is about 20mm droop on HSD and 25 on CS2's.

EDIT: actually yes Daze thats right after re reading.

its worth mentioning as you've said that adding droop over zero pre load will lower the car almost directly as much as you droop the shock. well, on a single wishbone setup like the front of an S body this is directly proportional.

 

Struggle does the best job of explaining this. I'm no expert on what the best ratio of bump to droop is, so I'll just stick with the manufacturer recommendation though. Droop is to do with wheel travel though, and I would argue has no real relationship with slack in the spring and is the wrong term to use to describe that.

 

I'd keep the helper if you have them, it's rare that you'll use full travel in either direction really so you're not missing out on anything.

It's not actually all that important on a properly specified suspension system like HSD/CS2 - we recommend 0 preload as a retailer to keep the car MOT legal and a really simple clear reference for set up.

 

setting droop dictates the angles of suspension are travel the spring operates over. Running Pre load can reduce maximum travel of the wheel up into the arch, running lots of droop stops the spring beeing effective when the suspension arms are at their lowest angles.

Pre load/droop will effect stiffness at different suspension arm angles but if you run loads of droop for example your suspension arm angles are likely to start out lower (lower car) which means you might be limited by the bump stops over the springs. Theres nothing rong with running droop if you're not expecting to use the lower suspension arm angles as you'll effectively never see the drop when driving. Unless you're doing big jumps

 

For reference, I removed the helpers (fr) and set it back to 0 preload because of tyre clearance issues. It never lifts a wheel no matter what.

 

Yeah, terms are getting mixed up

Droop (rebound) travel is the wheel moving downwards from it's position at a static ride height.
Spring droop is the distance between the spring and spring seats at full suspension droop/rebound.

Droop (rebound) and bump travel will be effected by spring position/slack - but doesn't directly correlate with the above "droop travel" due to a number of other factors.

*You know when you've typed a word that many times it doesn't even look like it's spelt right anymore

 

So for those reading that. DW recommend zero droop purely for mot and road compliance. Superclarkey recommends 20mm all round on hsd and 25mm all round on cs2 WITHOUT the helper spring. So with the helper I'd suggest zero pre load.

clark3y just raise the bottom cup for tyre clearance. Pre load and ride height are seperately adjustable on a fully threaded coilover.

edit: for those reading what ive said. By droop I mean how slack the spring is. So 20mm droop in my language is 20mm between spring and purchase.

 

Would have meant shit loads of preload (fully compressing the helper and then some) to get he spring cup above the tyre that way though, removing the helper removed the problem and never had any downside that I notice or care about. Bigger spacer would be the real solution but I couldn't be arsed borrowing another car and going to buy them at the time.