Suspension Brakes 1st Gen Remove Preload from Coilover?

Discussion in 'Tuning and Performance' started by M^Cubed, Oct 27, 2009.

  1. M^Cubed

    M^Cubed Member

    May 24, 2009
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    What would be some of the downfalls of relieving my coilover of any preload besides loss of stroke?

    Would there be any chance of reaching enough droop on the street to unseat the spring from the top hat?

    Basically I have a cross setup that I would like to lower ride height beyond static sag. Preload is currently one turn past the point when the spring doesn't have any play at full extension.

    P.S. the coilovers are cross, and currently the body is fully recessed into the bottom housing so the only way to go any lower is by removing preload. The front sits rather high in my opinion. There is 1.625 inches from the top of the tire to the lowest external point on the arch. The rear sits right about flush with the same point on the arch and I would like to get that same "stance" on the front.
     
  2. Dr Obnxs

    Dr Obnxs New Member

    Jun 11, 2009
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    The problem here

    is when the suspension extends all the way the spring comes loose and can come of the seats. Then as you're driving, besides having a shift in ride height, you'll get massive thunks when they shift back, if they do at all.

    When I have the stiff springs on my Ledas, I have to use some helper springs. They are very soft and keep the springs under compression at maximum extension.

    Matt
     
  3. M^Cubed

    M^Cubed Member

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    Best bet would be to pick up some helper springs just to fill in that gap?
     
  4. Dr Obnxs

    Dr Obnxs New Member

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    Yep

    Here's a photo of a Hypercoil helper spring....

    [​IMG]

    these are shaped to keep the spring centered as well, but depending on the details you may need spring stackers that keep the two ends alligned. I've got Hypercoils so these work great for me. I may have two more around somewhere, I'll do some digging...

    Matt
     
  5. Steve

    Steve Administrator
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    Apr 23, 2009
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    A 1.65" difference in gap front to back? That seems rather extreme, as in poor design level extreme. Are you using the original springs or are they custom?
     
  6. M^Cubed

    M^Cubed Member

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    I am using different springs. The front spring is longer than the rear spring. For some reason I can't remember if the stock ones were the same way or not.
     
  7. M^Cubed

    M^Cubed Member

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    OK, the front springs are longer with the cross setup too. The were 7kg before and they are now Swift 10kg. The sag with the 7kg setup sat a little high to begin with, not too bad, but noticeable.

    I'm thinking RMW uses a different setup than what Cross sells as the MINI kit. The kit listed on Cross uses a 8/7 spring combo and my setup from RMW used a 7/6 spring. Not sure if the actual absorber body is longer than normal too. I remember one company sold a setup with a longer rear for more travel and it also meant that the car couldn't go as low.
     
  8. Dr Obnxs

    Dr Obnxs New Member

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    If you start swapping springs...

    Get intimately aquainted with the specs of your struts and springs. There's a lot going on here, like bind length, corner weight, geometric factor, free length, strut travel and on and on. It's easy to mess up.

    Matt
     
  9. Steve

    Steve Administrator
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    #9 Steve, Oct 28, 2009
    Last edited: Oct 28, 2009
    Wait a minute, I guess I wasn't paying attention before...I just re-read your first post and now I'm confused.

    The gap in the front is greater than the gap in the rear so you want to lower the front, but if you decrease/remove the front preload, aren't you decompressing the front springs by extending the length of the assemblies, thereby raising the front (i.e., increasing the front gap)? Aargh, my brain must have gone to mush sometime after midnight...gonna have to ponder this again tomorrow. :skep:
     
  10. Rally

    Rally New Member
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    May 5, 2009
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    1.65 is a big difference, but I don't think the design of the coilovers is 100% to blame. Our rear arch openings are vastly smaller than our front arches. To get the wheel gaps even, one has to REALLY rake the car forward and drop the front much more than the rear. If you lower the car evenly front to back, you will have more gap up front. (example below).

    I'm not sure the RMW's are any different in terms of getting the front "slammed". I know a few friends with the RMW Cross's that can't get their fronts "low enough". The cross's really weren't designed with stance in mind as they're really aimed at being performance coilovers.

    Another thing you're going to have to be careful of is travel. With this design of coilovers where the ride height is independent of preload (threaded body design), they often sacrifice a little travel. If you start lowering it with the preload perch, you start cutting into your travel. MINI's already have very little travel up front to begin with.

    Here's an extreme example, but a good illustration of the uneven arch diameters. You can see by the sideskirts that the car is raked forward a good deal. I've dropped the front more than the rear, but you can see that rear still tucks more. This is very common among newer hatchback designs and among BMW's (think about the rear tuck on an e36).

    IMG_4850goodsm.jpg
     
  11. Rally

    Rally New Member
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    The springs are a determined length. He already has them set with little to no preload so they are at their max length. His plan is to remove the preload fully by spinning the perch down. Spinning the perch down removes the preload, but it also moves the mounting point of the spring downwards, thus lowering the car. This is the method that most coilovers use for height adjustment.
     
  12. M^Cubed

    M^Cubed Member

    May 24, 2009
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    Thanks Rally - you hit the nail on the head. If I want to lower the front any more I will probably have to pick up helper springs to be on the safe side.

    The helpers from swift come with the spring stack adapter.
     
  13. Steve

    Steve Administrator
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    I've never noticed that big difference between front and rear arches before looking at this pic -- very helpful.

    For some reason last night I was fixating on the type of coilover without a perch for spring length/preload independent of height adjustment. Odd, esp. since the C/Os I'm most familiar with are the ones on my own car and they DO have an independent spring perch. Amazing how much difference a fresh brain can make. :yesnod:
     
  14. Dr Obnxs

    Dr Obnxs New Member

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    You decrease pre-load

    by lowering the lower spring perch. That lowers the car and results in a larger space for the spring when the strut is at full extension. If the spring is too short, you end up with a gap that can cause problems.

    Matt
     
  15. M^Cubed

    M^Cubed Member

    May 24, 2009
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    exactly Matt... Since there isn't much travel to begin with - normal everyday driving could possibly cause it to unseat itself. That is the concern here.
     
  16. Dinan604

    Dinan604 New Member

    Oct 29, 2009
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    Do you have a picture of how the springs currently sit? I take it you've replaced them with Swift springs correct? I have the Cross suspension also but the regular kit (8k/7k) F/R spring combo. I'll see if I can get a picture of mine on the weekend and compare.

    Cheers,
    Steve
     
  17. M^Cubed

    M^Cubed Member

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    [​IMG]

    The body is all the way turned down. It stops at the same spot on both left and right sides.
     
  18. ninjlao

    ninjlao New Member

    Nov 2, 2009
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    I'm not sure if I fully understand what's being said here, but if you're looking to lower your ride height then you should be using the bottom bracket to adjust ride height. Loosening the collar just to achieve a desired ride height can have an adverse effect on your coilovers. Coilovers that do not have independent ride height adjustment ADD pre-load to the spring, not loosen it, so that the vehicle will sit lower.
     
  19. M^Cubed

    M^Cubed Member

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    Yes, I have lowered the bottom as far as it goes - thus the only way to go lower would be to lower the top adjusters. Adding pre-load could lower the car, but it would reduce the spring stroke and ride quality would be un-desirable.
     
  20. Lil Blue Coop

    Lil Blue Coop New Member

    Jul 4, 2009
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    Looking at your photo it looks like you have the strut at its max height. On my setup I only have about an inch between the upper and lower locking rings.
     

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