chrisnick

:flamesuiton:

I'll try to make this one quick as there's a TON of information in the Miata community about doing this. Notably these threads The Better Bilstein Ebay Coilover Thread - Miata Turbo Forum - Turbo Kitten is watching you test compression. and The Quintessential Ebay Coilover Thread - MX-5 Miata Forum. Going onto my '97 Accord coupe that I DD, autocross, and drag race occasionally. See link to build thread below and in signature.

The biggest downfall of the eBay coilover conversion is that people put them on shocks that can't handle the increased spring rate and decreased ride height. The Bilstein HD's are a VERY strong shock and I could tell that they were very over-valved with the Skunk2 springs that were on them. My main goal with this was to get the benefits of a true coilover system, without the huge cost, and maintain ride height. No, I don't want to go stupid low, no I'm not going to lower it more. 13" from hub center to hub center is all that I want. I am not a greedy man, I drive my car daily, and roads here SUCK. At 13", I have PLENTY of stroke/travel in the suspension(especially in the rear, holy **** did Honda design a lot of travel back there), I'm not constantly smacking the front UCA into the inner fender(in fact, it's never touched it), I can fit a taller tire if necessary(great for winter)(and I've fit up to a 25" tall tire on it previously), the LCA's stay at a nice angle to the ground, and it rides nice over the nasty bumps and holes that seem to populate the roads of BorHio.


$118 total investment(not including the Bilstein HD shocks I previously had on the car). 550lb spring rates.


The parts:


New rear upper shock bushings from Honda($26):


$50 generic Civic/Integra/Hondawhatever eBay coilover sleeves(measured and calculated to be around 550lb spring rates for front and rear):


Energy Suspension front Shock bushing kit #16.8016G($22 from autozone):


Energy Suspension 2.5" ID spring isolators($20):


Fronts assembled:




51mm for the ID of the sleeve, Bilsteins measure 50mm OD shock body. A couple quick wraps with some electrical tape around the shock near the top of the body and just above the perch keep the sleeve tight against the shock body. The spring perches could be removed, but there's some horror stories of snapping/losing the rings out of the grooves on the shock body with just the coilover sleeves riding on them(see above linked threads). They'll stay as it gives a nice solid place for the sleeve to sit on and I don't feel like bashing on the perch all day just to get it off.

Adjusted back to my 13" hub center to fender measurement of the previously installed Skunk2 Sport springs, and under full droop, we have some room between the tophat and the springs, oh well.

Yes, I believe the front's need longer springs. As it sits, they're about 7.25" long, and at full droop, are about an inch or two too short and have no preload. A tender or helper spring could work well here, but I'm aiming to keep a linear spring rate under compression.

Yes, the rears DEFINITELY need longer springs. Also at 7.25" long, there's a good 2-3" gap between the top of the spring and the tophat. A tender or helper spring could work well here, but I'm aiming to keep a linear spring rate under compression.

Both of the above mentioned problems will be resolved eventually as I play with spring lengths and rates.

Post the taken off Skunk2 Sport springs for $100. $18 investment once those sell, so far.

Ride height pictures? You'll get none. Why? Because ride height hasn't changed, silly.

Performance: Definitely stiffer, not bouncy or harsh. I'd dare say it's a bit more comfortable now with these rates than previously with the progressive rates of the Skunk2's. WAY, WAY, WAY, WAY, less initial roll on turn in. Extremely responsive. Love it. The rear of the car is much stiffer than previously. Potholes and such still suck, but the car doesn't bounce as much and settles much quicker. Larger dips and bumps are much more quickly absorbed as well. Still crazy smooth on the highway. Gotta love the Bilstein's low speed damping. With the HIGH amount of high speed damping Bilstein's naturally have, the stiffer springs feel much better at controlling the faster movements that come with potholes and small, quick hits from road imperfections. Haven't driven it hard enough to really feel how it rotates, but that's because I don't drive that hard on the road and save it for autocross.

I'll post more updates in my build thread, http://www.hondasociety.com/board/showthread.php?t=153841

Questions, comments, feedback all welcome.

B serious

iTrader: (1)

Why do you want preload at full droop?

If you use a 50lb helper spring, it will compress fully...and you'll have a linear rate....once the car is on the ground.

Have you clocked your suspension bushings for your new height? That helps with not having spring looseness at full droop because the bushings are preventing excess suspension extension. This is assuming you have rubber bushings.

kristo

Yòu measured these, all four, how?

Where did you use these?

chrisnick

Not saying that I WANT preload, but I don't want it completely unloaded and just bouncing around. I'm sure it probably won't happen while driving, but it is a little nerve racking knowing that it could happen. Trying to be prepared for the worst, I guess. I've been looking around for some tenders/perches for a while now, haven't come up with something super budget friendly, yet. For what I've found, it's nearly as easy on the wallet to get a proper length spring in any rate I want for the same cost as the tender and perch.

All points where bushings are were tightened with the vehicle on the ground, vehicle weight loaded on tires after ride height set. No binding. I've tried to keep as many rubber bushings on the car as possible, almost everything on the front end is new, or newer.

Spring rates were measured by measuring overall length, individual coil diameter, and number of active coils; came out to 533lbs. I'll have to find it again, but I used a calculator that's linked in one of the threads linked above; there is a screen capture that is also in my build thread. Also tested with some gym weights in my basement, 1" of compression was about 550lbs. Not super scientific that way, but close enough.

EDIT: found it


The 2.5" coil spring isolators were used on the top of the coil spring between the spring and top hat.

Reyes

iTrader: (1)

Rate calculators are good at getting an idea of the spring rates but cannot be 100%. The quality of the material and production methods will have an impact on the final product and how long that rate maintains.

Helper springs are specifically designed for keeping tension in the system while the spring is "unloaded" and have a minimal effect on ride height. A longer spring will reduce the chance of the spring coming loose, but in many cases can limit your ride height options.
Helper springs can be a bit expensive. This is mostly because they are made from a flat spring wire which is more expensive and requires different tooling to produce.
For example: all Eibach Helper springs are made at our factory in Germany, then shipped to the US. further increasing the cost.

chrisnick

This was mainly a test to see how things would work out. So far, it's great. I honestly can't believe how well it rides, firmer than with the Skunk2 springs, which have the same spring rate and design as the H&R Race and Neuspeed Race springs, and leads me to believe they're the same with different paint. They're definitely firmer, but the valving on the Bilstein's seem to keep the springs from going crazy on compression and rebound. So far, impressed. If I have to, I'll either replace the springs with Hyperco's and tenders if I come into a pile of money, or just try a slightly taller spring in the rear from Summit/QA1.

Reyes

iTrader: (1)

Check out the for sale sticky in the road race section. people are always posting coilover springs for sale in there.

I know that neither Skunk2 or Neuspeed produce their own springs, so it is possible they came out of the same factory.

chrisnick

Will do! If I'm understanding this right, a taller spring with the same spring rate will compress the same amount, so I'd have to lower the perches on the springs the same amount as the taller spring? Would QA1's high travel or Swift's springs compress more considering less and thinner coils with the same spring rate? Removing the complete unloading while extended is my primary concern at this point.

B serious

iTrader: (1)

A linear spring will compress (X) inches per (Y) load. If the rates are the same, it won't matter what type of construction or the thickness of the coils.

To figure out how much it compresses per corner, you will need wheel rate data. You'll then need to translate spring compression to desired wheel position via motion ratio.

If you want to calculate it.

Spring rate.
Spring length.
Corner weight.
Wheel rate.
Motion ratio.

Translates into:
-Spring compressed length.
-Desired wheel position (2" drop, for example).

IIRC, an accord's rear motion ratio is like....1.5:1? ish?

Meaning for every 1.5" of vertical wheel travel, there is 1" of shock/spring compression.

Based on that, you'll need to find the spring length and rate to use and make sure that your threaded sleeve can go low enough to compensate.

B serious

iTrader: (1)

Although, I can't figure out how you'd get a linear spring to gain preload at droop, but still keep the same drop and spring rate in a fixed shock length scenario.

Using a soft helper spring is 100X easier and more viable. All you need is a motion ratio and helper spring dead length. Fill the gap with the helper spring. Lower the threaded collar by the helper spring's dead length (with motion ratio factored in).

chrisnick

I think it's closer to 1:1 than 1.5:1. There's a TON of travel back there. I'll have to look through the technical docs posted on cb7tuner to get it figured out. Thanks for the info though, I thought about it after I posted that and realized what I was thinking was wrong. Probably just 50x easier to get a taller softer spring than mess around with the tender/helper. The front "feels" a lot better in terms ofspring rate vs damping compared to the rear, which "feels" a bit over sprung with 550lb springs back there.

B serious

iTrader: (1)

The accord motion ratio isn't 1:1. The shock attaches inboard of the hub quite a bit. 1.5:1 or even 1.6:1 wouldn't surprise me.

550lb springs are very heavy for the back. You'd do better with a long 250lb spring. Unless you're planning on tracking this?

Reyes

iTrader: (1)

[QUOTE=chrisnick;50506990]Would QA1's high travel or Swift's springs compress more considering less and thinner coils with the same spring rate? QUOTE]

Yes,
A spring with either smaller wire diameter or fewer coils will result in more compression travel. The question to ask is, do you need more travel than what you are currently using? If you aren't going to use the travel. The only useable benefit is less weight of each spring.

Before you buy a high travel spring, I would look into how much travel they actually offer. I did a quick search and QA1 does not publish specs of the springs.
Swift's high travel springs are only available in 10" lengths or longer.

Eibach offers a barrel spring for the 2.5 ID springs which offers more travel/fewer coils over the standard coilover springs. but again, if you aren't going to take advantage of the travel. it wont have much benefit.

B serious

iTrader: (1)

[QUOTE=Reyes;50511065]Was OP's question on this regarding the spring's minimum length at full compression like you're explaining? Or amount of compression per amount of load?

I would assume the latter. On this application, the shock will almost surely bottom out before you see coil bind on a "standard" wire type spring.

Reyes

iTrader: (1)

Agreed,
I was just trying to point out that a "long travel" spring might provide any benefit in this application.

The easiest solution is a helper spring.

B serious

iTrader: (1)

100%

chrisnick

Agreed on that point, as well, if I were to keep the current spring rate. From a cost perspective(which was the original reason I attempted this), it's not very friendly. I certainly don't mind spending the money to get the correct results, I'm just experimenting a bit here to see what can be done on the cheap for a future build I'm planning to do for a GRM $201* challenge.


Since this is more or less focused on the rear, we'll talk about that. The front is pretty darn close, maybe a 1" gap between the top of the spring and underside of the tophat completely unloaded. Pretty close up there, and I like the spring/damping feel.

I'd guess it'd almost be a bit of a waste to have all that travel available and not try to take advantage of it somehow. On my daily commute, I haven't been able to get the rear spring completely unloaded yet. That being said, I'm more worried about when I autocross it. I don't run a front bar, but I do run a large Progress rear bar, and will have my 225/45/16 Toyo R1R's mounted on it by the next event at the end of the month. I never had an issue unloading the rear springs before(well, duh, I wouldn't be able to considering the old design), and I'd hate to get enough suspension extension out back now that the spring comes unloaded, gets that sudden force back on it, and rebounds like crazy, lands on the spring wrong and causes a massive bind, or beats the shock up since it probably can't take that type of force on it. I could be wrong, but I'd be much more warm and happy inside if the spring was taller and left as little of room as possibly at full droop, just incase I lift an inside rear tire. Like I said, I don't mind stepping down on rear spring rate if I can take advantage of a taller spring.

I was more or less asking this:

- 7" standard spring with 550lb rate compresses 1" when 550lbs is placed on it.
- 9" "high travel" spring with 550lb rate still compresses 1" when 550lbs placed on it, or would it compress more? I'm thinking since it's rated the same spring rate it would compress the same amount?

Maybe I'm not understanding the high-travel style springs correctly. Free length is free length, but if both are the same rate and compress the same amount, what's so different about them other than weight from their construction? Or would the "high travel" springs compress MORE with the same spring rate? Sounds like Reyes already answered "Yes" to the both, if I'm understanding correctly.

I guess what I'm looking for is a taller spring by about 2-3" when not compressed, but compresses down to roughly the same height, while attempting to find out what spring rate "feels" and "works" best. I'll try to take some pictures and measurements when I get some time. I know the shock has about 3-4" of compression at a static ride height of 13" from hub center to fender. There's easily about another 5-6" of shock travel/body left.

Just a little unnerving to know that the springs come fully unseated at full droop.


I really appreciate all the help and discussion, you're not only helping me understand things better, but also helping a whole community figure out what length/rate works well.





QA1 high travel springs:
2.5" I.D. High Travel Springs | High Travel Coil Springs | QA1 Suspension

CB7 Accord chassis dynamic data:
Accord Dynamic Data - CB7Tuner Forums

Reyes

iTrader: (1)

You are on the right path here.

1. A spring rate of 550lbs will compress the same, regardless of the spring length. A longer spring will have more compression travel simply because the spring is longer.

2. A high travel spring will have more compression travel than a standard spring of the same length. Fewer coils = more space between each coil and therefore more compression travel. The free length or rebound travel will not change because the spring will not go beyond it's free length.

3. Provided there is room to lower the spring perch, you can use a longer spring without affecting the ride height.

What B serious and I were saying about the Helper springs is.
They are designed specifically for this situation. While they aren't cheap, they really aren't much more than buying longer springs.

chrisnick

Cool. On another thread on another forum, someone posted that they've received a 9.25" spring with 280lb rate for the rear. 380lb front with an 8.25" length.

At the price Summit is selling the long-travel springs($38), I may jump on a pair of 10" 450lb springs for the rear. I have about 1.5" of adjustment before the collar bottoms out on the sleeve. 9" may be a better option and are $47 a pop.

cruizinmax

iTrader: (2)

Getting a longer spring is not going to help whether it is a long travel spring or not. Unless you are raising the car up higher than the threaded sleeve will allow a longer spring is not going to keep the spring seated. Long travel Springs just allow the spring to be compressed more before the coils bind. Getting rid of the extra droop travel to keep the spring seated could be accomplished by shortening the shocks, tender springs, limiting straps to prevent the suspension from dropping so much. A softer spring would also be a solution.