Megan Racing Coilovers keep changing height as I drive.

[GTO Assassin]

You will have to forgive Scotty. He's just in a bad mood cus skippy is ignoring him today

You know the worlds against you when even the fucking Aussies are using roo jokes. lol

Scotty

[DG]

The proper solution is to remove the junk shocks and replace them with a real shock, like a Bilstein.

Honestly guys, there is an off the shelf Bilstien application for this car; if you didn't want to keep the OEM active suspension (which works surprisingly well on a street car) that's the way to go.

The temporary fix is to pick up a set of 2.5" Torrington bearings and install them between the spring seat and the spring. Not only does this sharply reduce the amount of stiction in the spring (almost as good as a Hypercoil hydraulic perch for a fraction of the cost) but it eliminates the rotary jacking force that is unscrewing your spring seat collars.

More details can be found on Autocross to Win.

DG

[3000GTPro]

I just did a quick google, and I'm not sure how you can put any other shocks in Megan coilovers. I actually don't know how you take these things apart beyond loosening the rings and unscrewing the threaded lower half completely, but I have wondered if that's just a sleeve, or if it's part of the oil filled shock itself. I have an exploded view that gives me the impression that the shock is threaded for the coilover.

The bearing idea however sounds great. I'll check that out.

[DG]

Yes, the spring perches screw directly onto the shock body, so the entire shock must be replaced to get rid of it.

This is a good thing. Those shocks are utter garbage. They are, at best, ballast.

All decent shock companies make threaded sleeves that slide over their shock bodies and rest against a snap ring. These things have a bad reputation amongst the riceboi set because somehow they aren't "real" enough. Quite the contrary, these threaded sleeves work quite well and have the added benefit that damage to the threads on the collar doesn't ruin your shocks.

Very high end racing shocks (like Penske) use threaded bodies, but the shocks are serviced after each race and the bodies are replaceable (they're a sleeve that the top and bottom end caps thread into) There's no good reason to use a threaded body shock on a street car; it really doesn't buy you anything at all - except, typically, more weight (yes, steel threaded body shocks are heavier than smooth body shocks with a slide-on sleeve)

The only issue with the slide-on sleeve is that the OEM fitment shocks typically place the spring seat snap ring groove in a location compatible with the OEM spring seat height. This may or may not be a reasonable place for the groove to go to mount the threaded sleeve. To fix, you either cut a new snap ring groove into the shock body, or you use a threaded sleeve where the internal "shoulder" is located to place it in the right place relative to the OEM spring perch groove height. Ground Control is pretty good at this.

Oh, and don't be hornswaggled by the secondary height adjuster on the foot of the Megan (and other crappy shocks) that supposedly allows the setting of ride height without changing spring preload. Bogus! It does too change spring preload - extra complexity, weight, and points of failure for NOTHING.

Seriously, the best thing you can do is pull those Megans off and throw them away. Then get Bilsteins, Ground Control threaded sleeves, and a set of Hypercoil springs. You will have a far, FAR better handling car, the setup will be lighter, more reliable, and ultimately cheaper.

Friends don't let friends buy Japanese or Chinese shocks. JIC, Tein, Megan - these are all GARBAGE.

DG

[stealthee]

I would NEVER put Ground Controls on after having Megans. Megans ride well. Ground Controls do not even compare.

[J. Fast]

I've gotta side with DG on this one. I would pick a Bilstein w/ground control over a Megan all day long. It's definitely not my ideal setup but for the sake of comparison if they were both corner balanced my decision would be quite simple, Bilstein. Why are you opposed to them Stealthee?

[IPD]

i'm not one to bash, but i'm thinking DG works for bilstein.

most of the people who put coilovers on their cars are NOT using them for racing; and that is precisely why a $500 set of ebay nex coilovers is perfectly suited to the task.

imho, megans are a great choice for our platform, but so are D2's and ksports (the "budget" level). if i was demanding of my suspension system, i'd upgrade beyond those three; but i wouldn't stop till i hit KW--or at least a set with external reserviors.

been 2 months that i rode on my d2's and i have ZERO complaints about them--other than perhaps that they are a very slight bit firmer than stock (on the softest setting). and honestly, that's what i'd expect from any coilover.

[jba3]

Ground controls/bilsteins don't provide adjustable damping, do they?

[DG]

I'm in the Army, but a few years ago I owned my own race team. That team did so well that I was hired on as the race engineer for a Corvette team, and as a side business, we built/rebuilt and sold shocks.

I had my own personal shock dyno, and I dynoed hundreds of different shocks. Almost every single manufacturer (less, oddly, JRZ) crossed my dyno, and I got to see how they did.

I also rebuilt Penske and Bilstein, and specified Koni. Koni wouldn't let me rebuild shocks; they have been bit by too many fly-by-night "shock tuners" and are very picky about who they allow to service their shocks. (A decision I understood, although it was annoying, because I had plenty of potential customers who were tired of the people who were allowed to service Koni and who wanted be to do their rebuilds. It sucked having to turn business away.

So I didn't work for any shock company, and I was free to build and sell whatever worked best. I also made a point of including a dyno plot for each and every shock I sold (even off the shelf, un-revalved stuff) so that you knew EXACTLY how THAT SPECIFIC SHOCK performed. Not "representational" plots, not "ideal" plots, but YOUR shock got dynoed and you got the plots for YOUR shock.

If I revalved your shock, you got the shimstack list too. It's YOUR shock - why should I try and hide the valving from you? All the secret squirrel bullshit some "shock tuners" do is just horseshit and usually an attempt to cover up their ignorance.

Anyway, the huge surprise I got when I got into that business was just how shitty most aftermarket shocks were. And I don't mean "valving didn't match the springs" (although there was a lot of that too) but stuff like:

- Adjusters that didn't work;

- Adjusters, that as you went from hard to soft, went from soft to hard to soft;

- Four shocks, same part number, no force overlap anywhere in the adjustment range;

- Two shocks, same part number, valvings mirror images (meaning a shimstack was installed upside down);

- Shocks with "rebound adjusters" that crosstalked so hard to compression that they were actually compression adjusters with a little bit of rebound crosstalk;

- "16 way" adjusters that only had two settings;

and the list goes on and on. It was an utter parade of horror.

By far the worst culprits were Japanese and Chinese tuner shocks. Customer after customer would show up with pretty green, purple, or orange shocks, and they'd go on the dyno, and the dyno would show the truth - garbage.

The first time it happened, I thought the dyno was fucked up. I couldn't believe a brand new shock was that bad. I must have ran that shock a dozen times, and finally checked my reference shock (a box stock C5 Z06 shock that I kept around as a sanity check) and it dynoed out exactly the same as the last time I ran it. I finally had to admit the dyno was working, I was making no procedural mistake, and the shock really WAS that bad.

The only shocks worth anything are Penske, Bilstein, Koni, Ohlins, Dynamic Suspension, and Sachs. Everything else was garbage. And not "DG is a super picky uber racer elitist asshole" but "that shock does not pass basic quality control" - and we haven't even gotten to discussing valving yet, which is a whole 'nother can of worms.

Penske, Ohlins, Dynamic Suspension, and Sachs are all Real Race Car stuff that is really overkill for a street car. No street car needs Penskes, because Penske's biggest advantage is that their adjusters work nearly flawlessly (and they are completely modular so they are easy to rebuild and most can be rebuilt and repaired after the car hits the wall) Street cars don't have the instrumentation on them to really make use of that - how many of you have suspension position sensors logged at 500 Hz on your street cars? So unless your goal in life is to just spend ridiculous coin on shiny bits so you can be more extreeeeme than the other guy, these shocks are overkill.

That leaves Koni and Bilstein.

Bilsteins are awesome. Bilstein uses the exact same internal parts on every single one of their shocks. All the pistons are interchangeable (for a given tube diameter, they have two) all the shim stacks are the same materials, all the bits are made to the same standard. The parts in a $100 Bilstein HD are the EXACT SAME used in their high-end NASCAR and road race shocks. Any two Bilsteins with the same part number will dyno within 1% of each other, and when they make a fitment for a street car, it FITS. They strong, reasonably light (although not weight weenie light) and they can go for nearly forever without service. And when you do service them, parts are CHEAP because they make them by the millions.

The only downsides to Bilsteins is they take a little bit of work to make rebuildable, and (up until very recently) you got no knobs. Yes, they made the PSS9 with a knob, but the adjuster was junk and the knob detent was worse. They only started making real adjustables this past November.

An off-the-shelf Bilstein is probably going to work with a car that is close to OEM in weight (within a couple of hundred pounds) and using spring rates close to OEM or a little stiffer. Put a coilover sleeve on it (use Bilstein's or Ground Control's; both work well) use a spring that is about 10% stiffer than stock, drop it an inch, and you are good to go.

If you start using really stiff springs, they'll need to be revalved, which means welding on a bung and installing a Schraeder valve in the nitrogen chamber. That costs a little bit of money, but with that done, revalving the shock from that point on is stupid easy. Then you can easily (if somewhat messily) tweak the shocks to match your springs. And then fuhgetabboutit; it's done forever.

If you really really really have to have a knob - and you probably don't, but some people Just Gotta Have 'Em - the decent choice is Koni. They're not perfect; forces for a given part number can vary a bit, so it's better to group-buy and dyno the lot and make matched sets from there. And the knob is REALLY nonlinear, so the adjustment range is about half what you think it is. They are also twin-tubes instead of monotubes like a Bilstein, which is mostly neither here nor there but might maybe give up a little sensitivity to a Bilstein. Maybe. Bilsteins do tend to have less hysteresis, but not enough to get wrapped around the axle about.

What people don't realize is that once the damping is properly set, it's set. Forever. It makes no difference if the road is smooth or bumpy or whatever - the shock is designed to produce different forces at different shaft speeds and when the curve is right, it's right. The knobs on adjustables are primarily there to let you match shocks on the dyno, not to tune for different conditions. F1 cars use non-adjustable shocks on race day (all the tuning work was done on the 7 point shaker rig back at the shop anyway)

The only real exception is for cases when you are running soft springs (for ride comfort) and occasionally swap on sticky tires for track use. In that case, if you aren't swapping on stiffer springs to go with the tires, cranking up the rebound can act like "fake springs" (at least during transitions) and can act as a crude band-aid.

But far cooler is if the shocks could self-adjust in response to what the car is doing, staying properly matched during normal driving, and only getting stiffer when the car needs it. Guess what? That's EXACTLY what the OEM ECS does. The OEM shocks have 3 different rebound positions, and when the car detects certain maneuvers, automatically cranks up the rebound in proportion to the type of maneuver going on. It's a little crude, but it is also brilliant and works very well. I am an ex pro shock engineer, and I use the OEM shocks because you'll never find anything like it in the aftermarket.

So then, summing up:

1. Street car? Keep the ECS. It works.

2. Street car with no ECS? Off the shelf Bilstein with a coilover sleeve and Hypercoils slightly stiffer than stock.

3. Street car with no ECS and Gotta Have A Knob? Koni Yellow with a coilover sleeve and Hypercoils.

4. Going racing and have a budget? Convert Bilsteins to take-aparts, use a coilover sleeve and Hypercoils. Investigate the new Bilstein adjustable shaft if you gotta have a knob.

5. Going racing and price is no object? Ohlins (Penske doesn't make McStruts)

DG

[GTOX]

Interesting post.

Have you tested or do you have an opinion on KW Variant 3 coilovers?

I've been using them for a few months now on my GTO which is daily driven. The ride comfort is quite good IMO.