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Old 12-17-2004, 05:42 PM   #1
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Short Spring Height and Unload: Truth or BS?

Hey all. Wondering if you can tell me if this guy is ahead of the curve so to speak on setup? Or he is smoking something we all should avoid?

These two conversations are In reference to the Xray M18. A aftermarket company finally released some springs that are low enough that the sedan can at neutral load lay in the middle of suspension travel versus being always with too much preload at full travel in a neutral setting. You can use spring spacers to adjust how it rides in its travel with these new springs.

For those not familiar with the car, it would ride at full height with the only option to use droop screws to adjust ride height. But again, on rebound it would have no neutral area and ride at full height.

I think this person is misunderstanding tthinking that the lowered springs are too short is the closest I can come to fantoming what he is saying. (Which they aren't) Given that. He really didn't answer my question about 1/10th shocks. Since they rely on the same principle.

1st Conversation (friend):

3:57 pm [Guru?]: with m18 the only
safe way to lower you car is to adjust your droop without haveing your
springs unload on you" im not exactly sure what you mean by adjust
w/o having my springs unloa?
4:15 pm [Guru?]: lol
4:16 pm [Guru?]: your ride hieght can only be adjusted with your
droop screws
4:16 pm [Guru?]: with the lowering springs you have slop on
rebound cause of the length of the springs
4:16 pm [Guru?]: do you understand?
4:16 pm [Newb]: not really

2nd Conversation (me):

4:35 pm [oXYnary]: so you order those lowering spring yet?
4:36 pm [Guru?]: ewwwwwwwwwwwwww
4:37 pm [Guru?]: you will have slop on unload
4:37 pm [oXYnary]: you will normally with most 1/10th schocls
4:37 pm [oXYnary]: whats your point?
4:38 pm [oXYnary]: its better than having it at the full load all the time
4:39 pm [Guru?]: hard cornering will be affected with the slop that will be present when the springs are at there max depression
4:42 pm [oXYnary]: ok what is your description of slop?
4:43 pm [Guru?]: if the spring is fully extended in hard cornering the inner wheel wont have anything forcing the wheel down cause of the lenght of the springs
4:45 pm [oXYnary]: ok so whats separates a 1/10th shock? Since their springs are also shorter?
4:45 pm [Guru?]: if and when in a corner the inner wheel lifts the spring wont have any effect at that moment due to the length of the spring
4:46 pm [Guru?]: we use spacers and o-rings to compensate for that
4:46 pm [Guru?]: and for some droop screws
4:46 pm [oXYnary]: the inner wheel will be more compressed, Im not sure what the length of the spring has to do with it
4:46 pm [oXYnary]: right
4:46 pm [Guru?]: no
4:46 pm [oXYnary]: you realize the springs come with spacers
4:46 pm [Guru?]: the inner wheel is the one that has the less stress in a turn
4:47 pm [Guru?]: but spacers??? your just compensating for the space the shorter spring doesnt cover
4:47 pm [Guru?]: thus you car isnt getting lower
4:47 pm [Guru?]: you just have shorter springs
4:47 pm [oXYnary]: again, what separates us from 1/10th
4:47 pm [Guru?]: nothing
4:48 pm [Guru?]: we dont call them lowering springs...
4:48 pm [oXYnary]: so are you saying that 1/10th need springs that require no spacers and rely on droop screws to set ride height?
4:48 pm [Guru?]: the way we lower our cars is to put o-ring in the inside on the shock shaft
4:48 pm [Guru?]: no!!!!
4:48 pm [oXYnary]: or use droop screws
4:49 pm [oXYnary]: and dont tell me no they are a few 1/10th that use these
4:49 pm [Guru?]: 1/10 we use droop screws to set the travel of the shock
4:49 pm [Guru?]: .....
4:49 pm [oXYnary]: which is the same thing as puttin o rings inside the shock


If he's right, hes right. Though I hope someone can better explain. I really thought think hes missing something. His little speal to both of us about being Sponsored for 6 years (IE he knows more than us) pissed me off.
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Old 12-17-2004, 06:59 PM   #2
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It's pretty complicated to try to explain but I will give it a shot.

A properly designed will "sit" into the springs at ride height. I dont believe 1/18th scale cars are designed properly in this aspect for whatever reason the designer may have chosen. Compressing the spring when you lower the ride height does a few things too the car:

1) Most obviously it lowers the CG of the car.

2) Increases the wheel rate by compressing the spring (basically makes it stiffer).

The problem with this method is that when the car is travelling over road irregularities, there is no room in the down travel in the suspension so instead the tire must come off the ground. Not a good thing.

By using shorter spring too lower the car. You have the following problems:

1) Unless the spring must be made stiffer to account for the compression at ride height that the original spring is under.

2) When travelling over road irregularities you have the same problem, the wheel might stay on the ground, but without the spring to push it into the track surface, it might as well be off the ground.

I would stick with the factory suspension as this is how the designers intended the car to be run, whether I agree with it or not. To try to change thier design might introduce other unforseen handeling characteristics into the chassis.

And based on the conversation you had with the guy, he seems to have no clue as to what he is talking about.
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Old 12-17-2004, 07:12 PM   #3
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easy answer : in TC you NEVER EVER use the droop screws to set the ride height. it doesn't matter if there is slop or not.
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Old 12-17-2004, 08:20 PM   #4
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So with the stock springs the shocks were adjusted all the way and still wasnt low enough. So you were using the droop screws to lower it is that right?

He is right about not having any slop in the springs tho. A guy around here once told me he set his droop by the slop in the spring he would just adjust it up or down until the spring was fully extended. But that didnt change ride height. And it did actually work. I set mine like that for a while but I would use a droop gague afterwards and set it to the least droop of the two so they were even. Now I just set it as downtravel.
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Old 12-18-2004, 07:39 AM   #5
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Thanks all for the responses.

Jack: The M18 shocks are pretty much the same as a 1/10th TC. Except having no dampening (which xray has been promising oils for a year now!).

The lowered springs are alot stiffer than the standard. And xray has yet to offer any stiffness than the standards if offers. At least for me running these new springs on carpet works great, and the car feels less "mushy" now with a more equal turning radius.

I understand what you are saying about "pushing" the tire down. But there is no slop or "freeplay" in these springs though. When I lift the nose up, the springs dont suddenly come "loose" on the body-even without spring spacers (Which they come with). Thats what confusing me with how he goes on about it.

TRF415boy: The problem with the stock m18. Thats the only way one could adjust ride height! Thats what makes these lowered springs a godsend.
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Old 12-18-2004, 09:13 AM   #6
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"I understand what you are saying about "pushing" the tire down. But there is no slop or "freeplay" in these springs though. When I lift the nose up, the springs dont suddenly come "loose" on the body-even without spring spacers (Which they come with). Thats what confusing me with how he goes on about it."

If what you say is true, then you should have no issues. Maybe you have the droop adjusted so that they never leave the travel of the springs. If that's the case, your car should be fine.

You have just discovered most people on the internet have no clue what they are talking about, including me.
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Old 12-18-2004, 11:40 AM   #7
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look you guys the darn 1/18 xray isnt anything near the 10 scale cars in the shock dept.

second the car was designed that way!
the forces acting on a 10 scale are far greater then the micro.

third when you compress a spring it DOES NOT MAKE IT STIFFER!!!! all it does is make the spring react qicker.

On real cars they make lowering springs the correctly designed ones will be almost as high as the standerd ones but when installed the few coils that are wound at the top are designed to take up slack. thus there is some preload for purpose of the spring not moving out of the perch.
on our cars because the deficulty (10 scale) this is controlled via droop. if you take the droop screw out of sedan the suspension will drop and the spring will bounce around.

on the micro being that the car is so small its verually impossible to make the suspension work like its bigger cousin because of space limitations of the scale body. install associated 12scale shocks and youll get what you want but then the hieght will make the body look funny

Ride hight should be set with adjustment collars suspension down travel restricted by droop screw and weight transfer via spring rates, dampening via oil. Sometimes we use combinations to control these functions.
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