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Location:
NSW.south coast.Drifting
Registered:
February 2004
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 AE86 front suspension
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Sun, 06 June 2004 06:06
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hello i am in the process of doing my suspension in the AE86, which im using for drift, but driving it daily.
i am looking at getting a ground control/paradise racing coil over sleve kit. i have a few questions about these sleve kits.
1)there are 2 ways to install them 1)just slide them down so they rest where the spring did or 2)cut off the spring support and weld it there. AM I RIGHT?
now what i need to know are short stroke shocks a good investment? if i decide to go this route, what other modifications will be needed to be done to the strut/coil over kit?
i am thinking about this bcause i would like the car low and the normal coilover kit only allows 2" of adjustment.
i was thinking about using 400 and 300 lb/in rates (works out to be about 7.1kg/mm front and 5.35kg/mm rear. is this a good setup (simon?)? what shocks would be adequate for these rates? would like them to be adjustable? prices and places to call?
any other suggestions?
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: AE86 front suspension
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Sun, 06 June 2004 06:34
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| 45aken wrote on Sun, 06 June 2004 16:06 |
i am looking at getting a ground control/paradise racing coil over sleve kit. i have a few questions about these sleve kits.
1)there are 2 ways to install them 1)just slide them down so they rest where the spring did or 2)cut off the spring support and weld it there. AM I RIGHT?
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yes you can do it either way, paradise says to slide it on a normal strut it will work but if your going to run a coilover setup id be welding it on
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now what i need to know are short stroke shocks a good investment? if i decide to go this route, what other modifications will be needed to be done to the strut/coil over kit?
i am thinking about this bcause i would like the car low and the normal coilover kit only allows 2" of adjustment.
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you will need to shorted the strur casting about 40mm for short stroke setup, not hard, use spacers if you need. rememebr if you cut them real short (ie 40mm) you cant go up in height, only down. this is because the spring seat will be at the top of the windage
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i was thinking about using 400 and 300 lb/in rates (works out to be about 7.1kg/mm front and 5.35kg/mm rear. is this a good setup (simon?)? what shocks would be adequate for these rates? would like them to be adjustable? prices and places to call?
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that setup would be a good mix of streetable rate with enough firmness to slide or grip depending on driving style/ability
as for short stroke shocks, tokico HTS are the best bet in my opinion, that or TRD (which are rebadged tokicos anyway) or even you koni's if your that way inclined
as for places to call. try ben or brian @ bel garage, tell them garth sent you (www.belgarage.com.au for contact details) they can order you anything from japan including kg/mm brand springs or tokico HTS'
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Location:
NSW.south coast.Drifting
Registered:
February 2004
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Re: AE86 front suspension
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Sun, 06 June 2004 06:50
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do i HAVE to cut the strut 40mm? what length would be suitable to cut it at so i can raise and lower, without the setup bottoming out?
how much would a workshop charge to remove the perch, shorten the strut, then weld the sleve on? as i am not quite confident in doing suspension mods (to that level anywyays) myself.
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Location:
Adelaide
Registered:
August 2003
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Location:
Terrigal
Registered:
May 2002
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Re: AE86 front suspension
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Sun, 06 June 2004 09:02
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There is heaps of shocks that are shorter and will fit the AE86 housing.
AE92 shocks for example are somewhere around 60mm shorter? You can cut out say 40mm and add a 20mm spacer.
GT4 shocks are 70mm or so shorter.
Camry and Holden Camira shocks are also shorter.
All of the above you should be able to get in most brands (Koni, KYB, Monroe - dunno why you would though!).
It's just a matter of working out the length required and then finding a suitable shock. You don't need to stay with ones designed for the AE86.
I'm trying to find out how to match shocks to the spring rates but still not sure. I talked to KYB's technical department and even they couldn't help me with it.
I figure if you have a look at what the donner cars spring rates are that will give you a good idea what you can run.
The GT4 is a very nose heavy car so the shocks out of that should support a heavy spring, whereas the AE92 is a lot lighter so I imagine the shocks would be matched for a softer spring.
Hope this helps a bit
Cheers,
Joel
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Location:
NSW.south coast.Drifting
Registered:
February 2004
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Re: AE86 front suspension
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Sun, 06 June 2004 09:18
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thats why i want to have some adjustable ones  hard at the track, softer on the street.
i saw in some car mag fully adjustable sports shocks for under $1000. i think they were KYB or AGX or something? red im pretty sure.
from what that artices i've looked at, the only advantage i can see with having coilovers is the height adjustment-am i right?
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Location:
GoldCoast/Brisbane
Registered:
May 2002
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Re: AE86 front suspension
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Mon, 07 June 2004 00:29
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I need more info on the actual Tokicos to use please... thanks.
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Location:
NSW.south coast.Drifting
Registered:
February 2004
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Re: AE86 front suspension
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Mon, 07 June 2004 01:24
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just called up KYB and there AGX shocks (8 way adjustable) are $650 for the front pair. they only make shocks for the ST204 GT4 celica. will these fit the front struts of my AE86? what has to be done to modify the strut to run these?
any info on the tokico illumnia's? cuz i can get those cheaper aswell?
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: AE86 front suspension
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Mon, 07 June 2004 04:17
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speedy - Tokico HTS 102 Short-Stroke Shock Absorber
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Location:
Adelaide
Registered:
May 2003
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Re: AE86 front suspension
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Mon, 07 June 2004 08:02
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Illuminas are crappy versions of HTS102s.
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Location:
Adelaide
Registered:
May 2003
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Location:
Adelaide
Registered:
May 2003
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Location:
Melbourne
Registered:
January 2003
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Re: AE86 front suspension
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Mon, 07 June 2004 08:13
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| takai wrote on Mon, 07 June 2004 18:04 |
Die Post Die.
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Didn't you start all this suspension talk ? 
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Location:
NSW.south coast.Drifting
Registered:
February 2004
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Re: AE86 front suspension
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Mon, 07 June 2004 08:18
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how crappy are the illumina's compared to say, KYB's or koni's? the adjustable ones. there not short strokes right?
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Location:
Madrid - Spain
Registered:
August 2002
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Re: AE86 front suspension
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Tue, 08 June 2004 00:33
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| TurboRA28 wrote on Sun, 06 June 2004 19:02 |
I'm trying to find out how to match shocks to the spring rates but still not sure. I talked to KYB's technical department and even they couldn't help me with it.
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Damn, you got me thinking now.....curse you I hate thinking....it has been a long time since I studies this sort of thing at uni, but if my memory serves me correctly (it rarely does), spring stiffness is a direct result of displacement, whereas theoretical damping only affects velocity, A bit like putting friction into the suspension, slowing it down.
Car suspension is supposed to be critically damped, that is it should return to the nominal (static ride height) position as quickly as possible. If it is under-damped, it will porpoise and if it is over damped it will be too slow to return to the nominal position.
Looking at the standard equations for damped simple harmonic motion, it is clear that the magnitude of the damping (damping constants are negative) needs to be increased (more negative) for an increase in the spring stiffness.
acceleration + (velocity x damping) + (displacement x natural frequency^2) = 0 ------------For all thoes who care to look.
where the natural frequency is the square root of K/M and K is the spring constant.
Now being that the damper and spring are coaxial, it may be that we can come up with a way of comparing the spring and damper, ie if the spring goes up by 20% then the damping should go up by 20%. But I will need to read up a bit more before I could recommend that approach.
Oh and Joel, if you talk to the sales department, you will only get what the catalogue tells you. You need to get in touch with their engineering department for answers to any difficult questions.
I will do some reading over the next couple of days and see what I come up with.
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Location:
Terrigal
Registered:
May 2002
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Re: AE86 front suspension
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Tue, 08 June 2004 01:22
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Hey mate, after reading that post a couple of times i'm still scratching my head
I'd be very interested to hear what you come up with though.
For instance in my case I have Pedders replacement RA28 dampers, but then have put 5kg springs in which are much stiffer than factory. So would be good to know what damper can support this spring rate.
Cheers
Joel
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Location:
Madrid - Spain
Registered:
August 2002
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Re: AE86 front suspension
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Tue, 08 June 2004 03:08
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Yeah it's got me scratching my head a little, It's been 6 or 7 years since I thought about this kind of stuff. I know the spring rate will change the natural frequency of the suspension which obviously changes the speed of oscillation, but being critically damped and a forced oscillation, I don't know if it is a linear relationship or not. Simple if it is and complicated if it isn't.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: AE86 front suspension
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Wed, 09 June 2004 05:19
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Well on some preliminary reading of some old uni texts, I found that the equation for critical damping is
Ccr = 2(k.m)^0.5.... ie 2 x square root of (spring stiffness x mass)
This looks promising because it means that to maintain critical damping, if you change the spring stiffness from k1 to k2 then critical damping will change as follows
Ccr2 = Ccr1(k2/k1)^0.5..... ie multiplied by the square root of the stiffness ratio.
Thats assuming that you have a known combination of stiffness and damping that gives critically damped motion to compare with.
I might look a bit further into it and let you know what I come up with.
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Location:
Melbourne
Registered:
November 2003
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Re: AE86 front suspension
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Wed, 09 June 2004 05:52
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Is the stiffness ratio dependant upon the distance of the deflection? If you replace a set of linear springs with a progressive rate of same 'rating' then I would assume the stiffness ratio to change over the length of the deflection. Does this mean, from the equations you posted, that you'd have to average the stiffness of the progressive spring over the deflection distance in order to be able to plug it into the equation to find out the extra damping requirement?
...and also, if you have a set of springs that were installed prior to you owning the car (like mine were), how do you measure the rating of the spring? Is something that you have to take to a suspension shop to get done or is there a simple home recipe?
Cheers,
Dan
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Location:
Adelaide
Registered:
August 2003
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Re: AE86 front suspension
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Wed, 09 June 2004 06:16
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when you guys have finished calculating..can u guys just tell us the conclusion? i don't know what language you guys are talking about....i'm still not sure if 1+1=11??
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Location:
Terrigal
Registered:
May 2002
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Re: AE86 front suspension
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Wed, 09 June 2004 06:19
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Dan, places like Noltec and Whiteline will tell you the rate of your springs. You have to take them off the car.
Cheers
Joel
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Location:
Melbourne
Registered:
November 2003
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Re: AE86 front suspension
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Wed, 09 June 2004 06:32
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places like Noltec and Whiteline will tell you the rate of your springs. You have to take them off the car.
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Cool, thanks for that. I haven't gotten around to it yet but the TA22 needs new shockers so I was interested in this thread because I thought it might give me some clues as to what to put back into the car. The springs I've got are shorter progressive springs than normal and so I wasn't sure if the original spec shockers would be up to the task (I have been told they will be incidently). Seeing as the struts are out of the car already as a part of the brake upgrade it won't be too hard to take the springs off and down to a place like the aforementioned shops to get them measured.
Cheers,
Dan
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Location:
Madrid - Spain
Registered:
August 2002
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Re: AE86 front suspension
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Wed, 09 June 2004 06:34
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Progressive rate springs are different because the spring stiffness is dependent on the amplitude of oscillation. You could put together a simple program to integrate the equations of motion and simulate it but I don't think it will have much of an influence. My reasoning is as follows;
the dampers have the biggest influence on the system as the motion approaches the nominal position (ride height) this is because this is when the undamped system's maximum velocity is reached.
Progressive rate springs only start to increase in stiffness as the coils begin to bind. that is at large deflections. At this point of the travel the velocity is low and the dampers will have little influence on the movement.
This is a fairly loose assumption and I am sure if you were keen enough you could show some kind of influence on large displacements due to the progressive rate, but for most driving conditions displacements are small and the assumption holds true.
Spring rates are easy to measure accuratly with the right equipment. If you don't you could always measure the guard height and then get someone to sit on it and then remeasure it. Knowing their weight and the ammount of movement, you can measure the spring rate. ie kg/mm. This is very rough and will under estimate the rate due to the strut angle, but it will bet you in the ball park.
Well I'm going home now.....
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: AE86 front suspension
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Wed, 09 June 2004 09:18
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that reminds me, one of the zillion things i am going to do after my last exam is measure the spring rates of my stock sprinter springs.
someone remind me on the 20th of this month 
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Location:
Adelaide
Registered:
August 2003
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Re: AE86 front suspension
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Wed, 09 June 2004 14:31
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yes..hmm..talk about semester break..i cant wait!
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