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Supra + DSM = heaven
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Discussion Starter #1 (Edited)
Latest update: new spring rates info!

Disclaimer:

Guys it sucks I had to put this in but I just had to. The last thing I want is to get sued over this and I'm just trying to help the community out:

Do not actually ever assemble this suspension and install it because I dont want to be liable for any damages to your car or your person ;) This is a 'for show purposes only' thread. A step by step documentation of how I built my suspension not intended for use on anyone elses car ever ever. LOL. I make no warranty as to the functionality, usability, reliability or anything about the use of this setup. If you use this setup and subsequently crash your car into a tree/have a wheel fall off or anything else I am not responsible because I told you not to ever run this setup ;)

Please read the ENTIRE post, all of it is important.

Now that thats over with....

Preface:
Thanks out to Jeff Mueller AKA 'Hiken' on this board for being my beta tester(guinea pig?). Most of the photo credits go to him. There are a lot of hours into this so I hope you guys appreciate it.

Another huge thank you to Jeronimo, ideal98supra for all his work with the street/track version development.

And a final thank you to Brian Lee AKA '95JZA80TT' for listening to my crazy ideas and bouncing them back at me all the time.

Purpose:
I originally began designing this suspension for my Lexus SC (which shares the same suspension as my Supra), I wanted a suspension to suit a Lexus in terms of ride comfort but bring the SC's handling to on par or better than a supra.

After riding in a car equipped with almost every suspension on the market I determined that none of them would fit the bill. I set out originally to build an 'at any cost' setup but ended up discovering that I could build something to achieve my goals in <$1000 range including height adjustability. This is the result of that research. I ended up liking it so much that I did it on my supra as well.

Please keep in mind that these are street or street/race minded setups, NOT a race setup, things like body roll and a reasonable ride height are a necessity of running a car softly sprung enough to absorb bumps. Soft springs offer more grip on imperfect surfaces, that means the softer version WILL be faster on the street and the stiffer version will be slower on the street. I recommend starting with the softer springs and working your way up. Through the further development of this suspension we discovered the valving bilstein had originally told us the shocks had was capable of supporting much higher spring rates than they originally informed us, additional spring rates have now been tested.

If you are looking to lower your car -2.5" from stock this is definitely not the suspension setup for you, this is for people who don't want to screw up their cars handling and ride comfort in favor of how it looks. A lot of aftermarket suspensions for our cars come over sprung just so that you can lower your car without bottoming out the tires into fenders or worse. 1" is actually a lot to lower your car 2" is compromising your handling seriously unless you have custom control arms/fenders/etc.

I also wanted to utilize components of exceptional quality, Bilstein shocks and hyper-coil springs fit the bill. You may be able to build this cheaper using cheaper springs/sleeves or shocks. I did not research building a cheap suspension as that was NOT my goal. Building a damn good suspension was, and I got lucky that it ended up being cheap. Either that or we just discovered that everything else is overpriced, I'll leave it to you to be the judge.

Background:

Bilstein shocks are (in my opinion of course) among the best in the world. The top three reasons I selected them are

1) They are a gas monotube design with extensive research. They are OE on almost every high end car. Lotus, Mercedes, Porsche you name it, they offer excellent compromises for ride comfort, handling and durability. In my opinion they far exceed anything else in their price range. You CAN do better but you wont do it for less than double to 4x the cost. Take one look at a shock dyno for them and you can tell there's engineering there. The curve is soft in any place you can get away with it as opposed to Tein Flex or most JDM coilovers with a flat linear curve. Flat curves make for cars that are predictable but are not maximizing grip. I dont know much about drifting but I wonder if that is the target audience.

2) Rebuildable, a Bilstein rebuild costs roughly $50 and any valving can be integrated. Internally these shocks are identical to the NASCAR ones which means that every valving known to man is available and at a very low price. This setup can be adapted to almost any use from mild street to full blown race car by changing the valving and spring rates.

Bilstein were also the shocks that Toyota selected for the TRD suspension as well as in use for the famous Amuse Supra.

3) Price, there is absolutely nothing that touches these shocks for $400 a set. price is the third reason because it was the least important one to me.

OK I lied, there's a 4th reason, they are run on all my favourite and some of the winningest production based cars in history: 787B, Dauer 962, GT ONE. Besides having a different valving these shocks are essentially identical to their race counterparts.

How is the ride comfort?
Expect your car will ride as comfortably as it did when stock or better with 500/250 springs and slightly worse with the higher spring rate versions but still better than the JDM coilover conterparts.

How is the handling?
Excellent, I'm logging 1.17 lateral Gs on BFG KDW tires on rough streets (Street 500/250 version). For any street car this is a very impressive number, it is near the maximum coefficient of friction for the tires. The goal of any suspension is to maximize the tires even over surface imperfections. I was fortunate to be designing on a car with an awesome setup out of the box. Unfortunately for Toyota, and lucky for me consumer shock absorbers really sucked in the early 90s. On my highly calibrated seat of the pants meter it handles better than any of the off the shelf coil-over setups myself or my friends used.

This is some commentary from a user of the street/race version:
"I have tried the car out several times at Sebring which is a very bumpy track and they feel great. With the TRD suspension, I would take Bishop's bend which is a long left hand double apex corner in 4th gear flat out. With your suspension and my spring rates, I can take the same corner in 5th gear flat out. " -ideal98supra note: his spring rates are the ones now specified for the street/track version

And some from a user of the street 500/250 version:

I think the softer spring setting is awesome, it still absorbs the uneven surface and ripples and has good contact with the road, non of that bounciness you get with the aftermarket setups with hard springs. It gives a good feedback to the steering wheel and easy to control on uneven/rough parts of the track. ...im very happy with it... it also feels almost like stock on the streets.

I am so hooked, i wanna do some more track days now and get a smaller turbo hehe. -mazman


in car video analysis from Mazman's session:
http://www.supraforums.com/forum/showpost.php?p=6228884&postcount=356


What is the height range adjustment?
the adjustment range is roughly 0 to -3" from stock height, this is the maximum POSSIBLE however I advise strongly against using the maximum. It can probably be adjusted lower but -3" is way more than you should ever use anyway. This setup will not work as well if you adjust to more than 1 to 1.5" below stock height. With the street/track version you might be able to get away with more but this is untested. Its a soft spring, street setup, it needs the travel. more than 1.5" is non optimal for a slew of other reasons. I don't believe lowering more than 1.5" is optimal with stock geometry anyway so I did not design for it. If you absolutely must run your car low I suggest you use a different setup.


Step 1: Gather the parts and tools
note: I hope that some of our forum sponsors might be willing to offer these parts up for sale, if they would be so kind we can list them as the sources for the parts

The following parts need to be purchased I have also listed where I purchased mine.

$379 Toyota Supra Bilstein Shock set (SHOX.COM)
QTY2 part num. AK1242 for Front shocks
QTY2 part num. AK1243 for Rear shocks
QTY 4x Bilstein Coilover Sleeve Kit Bilstein part #193117 these are the 2" sleeves(summit racing) http://store.summitracing.com/partdetail.asp?autofilter=1&part=BSN-B4BOA0000117&N=700+320145+115&autoview=sku
Hypercoil Springs
QTY X2 $55 ea Front: 8" x 2.5"ID 500lb/in rate (shock-shop.com)
QTY X2 $55 ea Rear 10" x 2.5"ID 250lb/in Rate (shock-shop.com)
Bump stops
QTY X2 Energy Suspension Bump stops part number 4.6103G (they come in pairs of two so you will have four total bump stops) horsepower freaks carries these as should almost anywhere they are a mustang application

2008.11.18 update: Additional Spring rates. For street use with off the shelf dampers the following spring rates have been tested and usable

all springs are 2.5" ID listed in the following format:
front rate/rear rate/front length/rear length/rear helper springs required/reccomended use

if you see a "YES" you must use helper springs for the rear. Helpers are never needed for the front with these spring rates listed

650/500/8"/8"/YES/Maximum spring for off shelf valving. Recommended for light track use.
600/325/8"/10"/NO/ semi agressive street. Small ride comfort compromises for body roll control. Excellent handling on rough surfaces. Most agressive rates without helper
500/250/8"/10"/NO/ lexus owners or ride comfort minded cars

you will need to add these parts when helper springs are required
QTY 2 2.5 inch diameter Genesis technology helper spring guide $31.00 HRPWORLD.com part number: GEN-GC1160

QTY2 Hyperco 2.5" helper springs partnumber: HYP-HS250 $26.50

CONTINUED IN NEXT POST....
 

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Supra + DSM = heaven
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Discussion Starter #2 (Edited)
Parts total should be
$220 Springs (shock-shop.com)
$379 Shocks (shox.com)
$279.80 Sleeves (summitracing.com)
---------grand total
$878.80 + tax and shipping (if applicable)
if helpers reqd
+ $115 for $993.80


recommended purchase:
Bilstein coilover adjustment tool or spring compressor summit racing part number: MOR-62030

in between these lines (and italics) is only for users of the track version:
-------------------------------------------------------------------------------------------------------
FOR STREET/TRACK VERSION:
REPLACE SPRING RATES WITH:
7" 800lb front
8" 525lb rear
AND ADD THESE PARTS:
QTY 4 2.5 inch diameter Genesis technology helper spring guide $31.00 HRPWORLD.com part number: GEN-GC1160
Hyperco 2.5" helper springs partnumber: HYP-HS250 $26.50
Bilstein price for revalve ~$65 ea shock

total additional cost for street/track version $465
total price for street/track version: $1343

After you recieve your shocks you will need to send them to bilstein in San Diego for a revalve. here is their contact information: 1-858-386-5900

You will have to fill out a questionnaire about what spring rates you will be using and some other questions about the cars purpose. Answer these questions to the best of your ability then wait for Bilstein to return your shocks to you and continue the procedure below

-------------------------------------------------------------------------------------------------------


Tools Needed:
Dremel, angle grinder or other cutting tool, even a hacksaw will work and probably work better but just take more time.
Hammer

Remove the items from the boxes to ensure you have the following parts, please reference these photos for the names of all the parts

Each Bilstein shock box should contain the following



1x Bilstein Shock
1X shock end cap
1X Stock style spring perch
1X Bump stop spacer
1x Nut

You may discard the stock style spring perch as it is no longer needed
http://i190.photobucket.com/albums/z194/andrewbrilliant/stockSpringPerch.jpg

In each coilover sleeve box there should be these two pieces



1X Coilover sleeve
1X Upper spring perch

Inside each hypercoil spring box you should have


1X Hypercoil spring

Next, remove your factory coilover/shock/spring assembly from the car. You MUST retain the factory upper hat (shown here) this will be used for the new suspension.



Step 2: floor mockup of the assembly

You must have removed your factory suspension to continue as you will need parts from it.

First, remove the bump-stop from the factory upper hat


Next, we need to cut the coilover sleeve. Take a look inside the sleeve and you will see that there are two raised areas (places where the sleeve is thicker) about one inch from either end of the tube. One of these is sharp edge on one side and a taper on the other. The opposite end is a double taper. We will be removing the one with the sharp edge. Shown below



Looking at the photo above you want to cut the sleeve just past the raised area inside the sleeve. If you measure it should be 8 threads up the sleeve this end, the one we will now cut is the "bottom" of the sleeve. Each thread is 1/4" this is important to remember when you adjust the sleeve as one full rotation is 1/4" of adjustment. When you finish you should have a sleeve with only one raised section inside. Please take care not to extensively damage the threads while cutting. If you have minor burring you can clean it up with a dremel, or a file. This is really only important for it looking nice as the threads on the bottom of the sleeve are of little importance.



Next, slide the coilover sleeve onto the shock body. The part that was cut will be toward the bottom of the shock. Slide it until the tapered section inside the sleeve fits snugly onto the C clip in the shock body (C clip should have been pre-installed from bilstein). Make sure the snap ring is in the upper most ring groove.

It should look like this:


Next take the shock end cap and gently hammer it into place making sure to tap it evenly, if you get it cocked sideways you will have to back it off and try again. I did this with light taps in a star pattern.



Once the endcap is installed slide the spring over the shock body and coilover sleeve. Ensure that the lower spring perch is facing up. It sometimes comes upside down in the box.

for the street/track version: now slide helper spring guide onto the spring and the helper spring on top of the guide and thats it!



Next, take the spacer that came in your bilstein box and slide it over the end of the shock shaft with the widest section toward the bottom



Then take the upper spring perch that came with the coilover sleeve and lay it on top of the spring.



NOTE: The photos below include the use of a factory bump stop cut to fit, it's now reccomended to use the energy suspension bump stops listed above.


Advanced bump stop info:
You should expect to see roughly 2" of travel front and 2.5" of travel in the rear even on rough roads under heavy cornering loads assuming your weight is normal the car is not loaded and your tires don't exceed standard max performance tires at the date of this writing. If your car is set low enough or you exceed those parameters so you do not have sufficient travel available you MUST run bump stops, the only way to know for sure if you need bump stops is to measure the travel on your car. You can do this by placing a zip tie around the shock shaft. At regular intervals and especially after hard driving recheck the location of the zip tie. if it is near the top of the shaft or pushing up against the upper spring perch, your suspension is traveling too much, your car is too low or you need a bump stop, in this case I prefer that you use a spring rate sufficient to the loads and travel requirements that your suspension will endure, however failing that you must use a bump stop..
Install instructions for energy bump stops
in this image (sorry I was only allowed embedding of 15 images per post so I linked to these) to the left is the bilstein upper spring perch that comes with the sleeves, right is the energy bump stop.
http://i190.photobucket.com/albums/z194/andrewbrilliant/photo0.jpg

Slide the large end of the bump stop into the upper hat its a PERFECT fit.

http://i190.photobucket.com/albums/z194/andrewbrilliant/photo.jpg



Next take the stock upper hat that you removed from your old shock and drop it on top of the upper spring perch.



Finally take the new nut that came with the shock absorber (do not reuse your old one) and thread it onto the top of the shock shaft.



This is what a completed shock assembly should look like:



The routine should be identical for all four corners of the car.

Step 3: Install to your car and adjust your ride height

You can adjust the height by turning the coilover sleeve and hold its position by tightening the set bolt (its the small hex key hole on the coilover collar)

It is recommended that you purchase the bilstein coilover adjustment tool or purchase a dowel of the proper height. There are holes in the collar for inserting the tool, a metal dowel will work. I actually used a hex key and a pair of pliers but that is probably more difficult and you risk stripping out the inside of the hole if you are not careful.

A good starting point for adjustment on the 500/250 springs is to adjust until the springs are preloaded and then test from there. Remember that the suspension need a bit of driving to settle and will require readjustment. Break the system in, adjust, make sure things are safe before you drive hard!

Advanced section
---------

Shock adjustability:

Shock adjustability was left out of the basic suspension because:

Most shock adjustability is a gimmick, while it may make the car feel stiffer, it is not adjusting the portion of the curve that really matters or adjusts the parts that dont matter too much. Additionally, unless your changing spring rates or tracking your car, adjust ability is un-necessary. A GOOD valving is optimal for a spring, you can tune some characteristics into the car with adjust ability but they are a compromise. That and taking a single knob of adjustment to something as intricate as a shock valving seems like trying to paint a Van Gogh with a mop. I have yet to have anyone who was out there in a street car on one of these non adjustable setups to miss having knobs. Everyone has been happy so far (including me) but if you need adjusters or you plan to track your car you have some options.

Have your bilsteins modified for adjustability: bilstein offers an on shock rebound adjuster, remote reservoirs for compression and a plethora of other options, please contact bilstein USA for details. These are all reasonably priced options which would bring your pricetag around what a JDM coilover setup can cost (~$2000)

update:
Competition GT in Costa Mesa, CA http://www.competitiongt.com/
Is offering full assembly and installation services for gixxer_drew suspensions. Ready to drop in or fully installed, re valved, etc.

Thread update log:
2007.08.07 - updated to add bilstein shock part numbers
2008.01.11 - updated with street/track version info
2008.11.18 - updated with additional spring rates for off the shelf dampers
2008.11.27 - install instructions for bump stops
 

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NSW supra club Member
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475 Posts
Awsome post!

Do you know if the sleeve would rattle installed just like that? it has to go over the circlip, so obviously it will have small clearance/gap, so im wonder if this will cause it to move about, left to right and up?
Would it be recommended to tack weld the sleeve to the shock body?

Is the end cap just a press fit?
I always thought they were screw on (if there is a shock inside a body) or they are a part of the shock body (meaning you cannot easily remove them)

One comment you made was, if anyone is wanting to lower they're car -2.5" these shock setup is not for you, then in another comment you made a quote you can lower this setup 3" or more!
I only want to lower mine by about -1.5-2" so im guessing this setup is ok, but just wanted to clear the statement for others or future use on different shocks etc with harder springs.

Now just to find out if these guys ship internationally :)

Again, great writeup plus +1
 

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Aspiring viking
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1,842 Posts
Please read the ENTIRE post, all of it is important.
[....]
CONTINUEd IN NEXT POST....
Jeeze. That's a long couple of posts. Cliffs?










Just kidding. :D Very interesting stuff.
 

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Highway Demon
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2,869 Posts
Awsome post!

Do you know if the sleeve would rattle installed just like that? it has to go over the circlip, so obviously it will have small clearance/gap, so im wonder if this will cause it to move about, left to right and up?
Would it be recommended to tack weld the sleeve to the shock body?

Is the end cap just a press fit?
I always thought they were screw on (if there is a shock inside a body) or they are a part of the shock body (meaning you cannot easily remove them)

One comment you made was, if anyone is wanting to lower they're car -2.5" these shock setup is not for you, then in another comment you made a quote you can lower this setup 3" or more!
I only want to lower mine by about -1.5-2" so im guessing this setup is ok, but just wanted to clear the statement for others or future use on different shocks etc with harder springs.

Now just to find out if these guys ship internationally :)

Again, great writeup plus +1
I thought I would just chime in and answer this for Drew for the time being. You are right that the sleeve does have a little bit of wiggle room there since it has to have enough clearance to just slide over the shockbody, but it will not rattle around due to the fact that the cars weight is on it and besides that the spring is almost always preloaded thus giving enough tension to keep the sleeve in place even when the weight of the car is not on the suspension. The only time or circumstance that I see when the sleeve would have any type of wiggle room allowed is if you set the suspension up so the car sits really really low and the weight of the car is not on the suspension. That would be the only time I would believe it is possible for the sleeves to wiggle. You can tack weld the sleeves to the shockbody if you like but I don't think that is necessary though.

The end cap is a press fit and is part of the shock body. It would take alot to remove it. For example if put on inccorectly like mentioned in Drews write up you would need a flat head screwdriver and using that with the hammer you would have to kind of in a chizzle fashion back it off.

The amount of suspension/shock travel plays a large role in how much you can lower the car. Drew reccomends nothing lower then -2.5" because anything lower then that would put the suspension out of its efficiency range, and that can lead to alot of problems such as bottuming out the suspension, poor handeling, bottuming out the body of the car from being too low, and lastly premature shock wear/failure. The fact that he mentioned that you can lower it up to roughly -3" or more just means that there is that much allowable adjustment room available on the coilover sleeve. Meaning its physically possible but highly not recommended.

Brian
 

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Supra + DSM = heaven
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3,946 Posts
Discussion Starter #7 (Edited)
Awsome post!

Do you know if the sleeve would rattle installed just like that? it has to go over the circlip, so obviously it will have small clearance/gap, so im wonder if this will cause it to move about, left to right and up?
Would it be recommended to tack weld the sleeve to the shock body?

Is the end cap just a press fit?
I always thought they were screw on (if there is a shock inside a body) or they are a part of the shock body (meaning you cannot easily remove them)

One comment you made was, if anyone is wanting to lower they're car -2.5" these shock setup is not for you, then in another comment you made a quote you can lower this setup 3" or more!
I only want to lower mine by about -1.5-2" so im guessing this setup is ok, but just wanted to clear the statement for others or future use on different shocks etc with harder springs.

Now just to find out if these guys ship internationally :)

Again, great writeup plus +1
Mazman, the end cap works like that as a bilstein design, it works flawless also it will never have load on it anyway. I think its there to protect the shock body if you bottom out the shaft. its like the last resort bump stop, the only load it could endure would be pushing it against the shock so it will never come out.

The sleeve does not rattle, the taper inside holds the sleeve snugly. the only direction it endures load is down which forces the c clip into a progressively smaller inside. Every time two pieces fit together on any car part there is a tolerance and an amount of allowed movement before you have a problem. I have personally put about 10,000 miles on this setup so far.

For the question about ride height, the maximum you *could* lower your car is 3" or more I dont reccomend to lower a supra more than 1" from stock using my setup. Why? Because your car has only 3-3.5" of travel to start with. Dropping it 2" means you have 1.5" of travel. You need monster springs to keep that from hitting bump stops and tires into fenders. This is a soft spring setup you need something with more aggressive springs or you'll run into trouble or bump stops whichever comes first. Those super stiff springs are great for the track and bad for the street, you lose grip and ride comfort from running them. Think about it like this, the car is 3500 stock + 200lb driver + 200lb passenger + gear. A typical running weight lets say 4000lbs. Thats 1000lbs per corner. 500lb/in spring at a motion ratio of .6 on the front. 500lbin*.6 = 400lbs/in of wheel movement resistance from the spring. 1000lbs = 2.5" of compression already just static load you drop your car off the jack and it compresses the suspension 2.5" right there, the shock only starts out with 6" of travel that leaves 3.5" of travel at stock height. I also tested this. Stock height setting on my car left 3.5" of travel 1" lowered was 2.5". So what happens is you start hitting bumps or taking corners. 1.5" is nowhere near enough travel for a street car especially one as softly sprung as my setup puts it. Its only 15% stiffer than stock.

In summary, if you lower your car too much you will need to use non-optimal spring rates or run into bump stops all the time (also not optimal)

if you are really into lowering your car, another option is the Japanese coilover kits which lower the whole shock so you dont lose shock travel if you lower your car. You could also adapt some tein or other upper hats with my setup which will gain you back some shock travel. If you resolve the shock travel issue you get an extra 3/4" before the next problem, which is the front fenders. Then you'll need to make fender modifications. So pick your poison ;)

How much clearance do you have between the tire and the fender at the height your running now?

The TRD suspension is the same as mine, they only let you lower it -35mm (1.38") I believe this is maximum optimal regardless of the travel issues. The geometry isn't designed for a car that low.

Thanks for the compliment as well!
 

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Drew,

Bump stops are on order, should be here by next weekend...

Also, mind explaining what would happen if you wanted to use a slightly stiffer spring rate with these shocks? I am curious as to what something along the lines of 600/350 or 650/400 would do...

Also remember to add the cost of the coilover adjustment tool to the total cost... I have been trying to do the adjustments with an allen wrench and it is a major pain in the ass.
 

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Supra + DSM = heaven
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3,946 Posts
Discussion Starter #11 (Edited)
Drew,

Bump stops are on order, should be here by next weekend...

Also, mind explaining what would happen if you wanted to use a slightly stiffer spring rate with these shocks? I am curious as to what something along the lines of 600/350 or 650/400 would do...

Also remember to add the cost of the coilover adjustment tool to the total cost... I have been trying to do the adjustments with an allen wrench and it is a major pain in the ass.
Hiken,

thanks for the update on the bump stops. What exactly happens with stiffer springs is still an unknown. All I have to go on right now is what bilstein said about 20% stiffer being the maximum over stock. I believe based on my ass dyno that the shocks have enough damping to handle some stiffer springs, how much more I am not sure as I havent tested them or tried the experiment. I believe 600/400 would be a really nice rate.

You dont necessarily need the adjustment tool, you can just use a metal dowel of proper size, or you can do like I suggested originally of renting a spring compressor. This is important when your running stock height as you have to run some preload on the spring and its tough to do by hand.

Thanks for that heads up, I updated the original thread with some more info about the height adjustment.
 

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I guess I must not understand how shocks/springs work... here is how I understand it:

Let's take the rear for example. So with the setup we did we have a 250lb spring in the rear... so, it takes in excess of 250 lbs to begin compressing the shock. A 400lb spring in theory should then make the shock work less right? I mean it means that you can have an extra 150 lbs of force before the shock needs to work...

So why would a higher spring rate require the shocks to be revalved? I would think it would be the other way around... *less* spring rate would put *more* pressure on the shock.

What am I missing?
 

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You're looking at spring rate wrong. The rate of a spring just means that it takes 250lbs to move the spring 1". So it takes 125 lbs to move 1/2", 500lbs to move 2" and so on. So the shock is working all the time. So depending on the spring rate and the weights of the parts of the car, you need to have the shocks valved to match those parameters.

I still haven't worked out the numbers, but I'm going to look at them sometime this week because I'm putting together a setup for my friend's mk4. I wonder if anyone has put these on a dyno yet, it might help get a better idea of what springs you can get away with running without revalving.

Drew or Hiken do either of you know what the thread diameter and pitch is on the top of the shaft?

Also, to get the car to sit lower are you drooping the spring?

Hopefully I'll have more to add and more options for a setup like this in the near future as I'm going to be working on something similar but will be adding schraeder valves and revalving these things to work with race car spring rates. The testing with the Bilsteins on my brother's mk3 has been going good so now I want to mess around more with the mk4.

Drew, I may have found some other options for spring sleeves, but can't find enough info on them to see if they'll work. I'll look into it a little more and let you know.

Tim
 

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I will measure it and get back to you later tonight Wiisass...

As far as the spring rate goes though, my confusion is still there. If a higher spring rate means it takes more to compress 1" why would there be a concern that a shock can't support a higher rate spring? That still makes zero sense to me.
 

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Supra + DSM = heaven
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Discussion Starter #15
Wiisass, bro you just made my day. You dont even know how happy I am to hear that your taking on that project. I've been wanting to do it for so long and I think it will be a head and shoulders leap for our cars in terms of suspension. I will be glued to your results. I dont know the threads on the shaft but it should be in the MKIV tech manual as they are the same as stock.

I will measure it and get back to you later tonight Wiisass...

As far as the spring rate goes though, my confusion is still there. If a higher spring rate means it takes more to compress 1" why would there be a concern that a shock can't support a higher rate spring? That still makes zero sense to me.
Hiken, a shock absorber is a device which disspates energy, specifically the energy given by your springs. Imagine a car with no shocks and only springs it will bounce around like a pogostick or trampoline in progressively smaller bounces until the energy is disspated by friction with the air, internal components, etc you have probably seen a car driving around with blown shocks and the tail end bouncing around, this is bad for handling as its unloading and loading the suspension, thus decreasing and increasing grip as force pushing the tires to the road is what gives them grip.

The spring energy is what must be disspated. If you use a stronger spring then you have a higher amount of energy being exerted back to the car at a given moment, Thusly the shock must be able to disperse a higher force at any given moment if it is to properly dampen the spring. The overall amount of work exerted back and forth is the same per each bump but a stiffer spring will achieve the same work in a shorter period of time, more 'force'. Its like the relationship between HP and Torque. HP is over time Torque is at a moment.

Shocks achive this force dissipation by squeezing a gas or fluid through an orifice, essentially they make the orifice smaller to make the shock "stiffer". It gets a lot more complex than that but thats a very basic breakdown.
 

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Alrighty, obviously I know jack shit about suspension and/or physics. Lol.
 

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Drew,

That's some amazing work, my friend. Many, many thanks to you and those that assisted you. Excellent write-up and fairly easily understood even to my non-technical brain. This is a tremendous service to the community. Big congrats to you.

Quick, thanks for the sticky.

Ken.
 

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95jza80tt and gixxer_drew,
thank you for your explanations.

My car is stock height at the moment, with the bilsteins and am pretty happy with it, i just feel i could use a slight stiffer springs, wich is what these seem to do.

On the track tho, i would like to lower it a bit, so if you recommend only 1" ill try that, and if i feel i could use more, i may upgrade to stiffer springs one day and try 2" drop.
But since the car is mainly street driven, i suspect the 1"drop would be plenty.
The good thing about this is, you can upgrade your springs only if needed, and then one day revalve your shocks etc etc.. so plenty of adjustability and flexability.

I have tried lowering my car once, and it was a 2.5" drop, tyres were inside the gaurds, wich really looked good but too low and bumpy for our normal streets, so i raised it back up to stock.
Tyres did not rub on the gaurds tho, so id say i have very good offsets.
 

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I still haven't worked out the numbers, but I'm going to look at them sometime this week because I'm putting together a setup for my friend's mk4. I wonder if anyone has put these on a dyno yet, it might help get a better idea of what springs you can get away with running without revalving.

Tim
I'm really curious about seeing the stock Bilsteins on a shock dyno too. I'm planning to run either 575 F, 325 R if I can get away with those rates w/o a revalve (33% stiffer front, 48% stiffer rear - not likely....). If I end up having to ravalve them I will probably go for 650 F, 350 R. Once I start this project I will probably want to chat with Drew/Tim about their latest ideas for damping adjustments.
 

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So I was doing a little more research tonight and have a question for Drew or Jeff. What's the part number on the dampers that you guys have? On Bilstein's site it lists two different dampers, there is a sport damper and a HD damper. The sport part numbers are B46-1841 (Front) and B46-1842 (Rear), while the HD part numbers are AK1242 (Front) and AK1243 (Rear). I'm just wondering what valving you guys are running or what valving Bilstein was referencing when they said 20% over stock. Also, the Bilstein worldwide catalog just lists B46-1792 and B46-1793 are B6 Sport Dampers for the supra and the 1841 and 1842 part numbers do not even show up.

Also the prices on the Sport are $121 each while the prices on the HD are $157 each. So I'm assuming there is some difference between them. The AK series is listed on the motorsports page as stock mounting shocks.

So I don't know what this means in terms of what you guys are running or what springs you can run with these shocks. Maybe this deserves a call to Bilstein on Monday, but it's hit or miss with them if you will get someone that can answer questions like this or someone who will just transfer you to someone else's voicemail.

Oh well, I'm just curious what you guys are running, if I just had to pick, I would probably go with the AK series because they probably have a little stiffer valving than the Sports. At least that's what I think, who knows. But then again, the Sports are cheaper especially if I'm just going to replace the piston and shims and all I need is the body. But I would like to see what valving you guys are running and throw it in another damper body that I can easily have a local place dyno for me.
 
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