Fuster_Cluck

I am getting ready to order suspension for my 95 Hatch - Ground Control coilovers w/ custom rates (most likely 400f/450r) with Koni yellows.

I have been researching top hats and trying to figure out the purpose of extended top hats such as the ones made by Ground Control.

It seems that the shock will be compressed (closer to bottoming out) even further with a 2-3" top hat.

Can someone please explain extension top hats and how would I know if I would benefit from them or not?

Thanks!

Understeer

Increased shock travel without going into too much details.

Tyson

when working properly with compatible shocks, they give back shock travel that was lost due to lowering with adjustable spring kits.

when the shock body diameter is bigger than the inner diameter of the hat, then its not compatible and does nothing but limit full droop.

suspendedHatch

Extending the top hat 2-3 inches doesn't move the strut housing up 2-3 inches or at all. The strut housing is mounted to your LCA.

When you lower the car X inches, the strut piston gets pushed down X inches. If you modify the upper strut mount by raising it X inches, you correct for the amount of lowering and the strut can perform as designed.

Some problems caused by the strut piston being pushed down instead of centered when you're at rest are 1) on all struts except Konis, there is different resistance in each direction on the strut piston than if it were centered 2) you have more piston in the upward direction than in the downward direction. These problems cause a loss in performance in the strut. The job of a strut is to keep the tire planted on the ground. A loss in performance in the strut means that the strut is not doing the best it can to keep your tires planted.

The biggest problem as already mentioned is the loss of strut travel caused by the strut housing being closer to the body of the car since the car is lowered. If the upper strut perch allows the strut housing more upward clearance, you regain you suspension travel. If it doesn't, then you still gain the benefits of having the strut piston centered.

If you modify the upper spring perch without lowering the car, or if the new strut mounting point is higher than the amount of drop, you get the same loss in performance in the strut except that you don't lose suspension travel.

Fuster_Cluck

Thanks for all the info so far

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by suspendedHatch &raquo;</TD></TR><TR><TD CLASS="quote">Some problems caused by the strut piston being pushed down instead of centered when you're at rest are 1) on all struts except Konis, there is different resistance in each direction on the strut piston than if it were centered</TD></TR></TABLE>

Will the Koni (yellow) benefit from the GC extended top hats? I plan to drop the car approximately 2 1/4" (0-1 finger gap all around) Not really understanding "there is different resistance in each direction on the strut piston than if it were centered". Is there a thread or link I can read up about that if it's to complicated to write out?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">If you modify the upper spring perch without lowering the car, or if the new strut mounting point is higher than the amount of drop, you get the same loss in performance in the strut except that you don't lose suspension travel.</TD></TR></TABLE>

If the extended top hat gives an additional 3 inches and the drop is 2 inches then the shock is extended more than than OEM specs? IF this is correct is this bad? Not sure what you mean with the bold above; so you would lose performance with a 3" extended top hat / 2" drop?

Sorry for all the q's. Thanks for any help! Much appreciated

AutoXer

When you lower your car, you loose shock travel. By using an extended top hat, you will get some of that back. That's pretty much all there is to it:

Removed image to prevent confusion...




Modified by AutoXer at 2:01 PM 8/7/2006

94eg!

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hybrid93Hatch &raquo;</TD></TR><TR><TD CLASS="quote">Will the Koni (yellow) benefit from the GC extended top hats? I plan to drop the car approximately 2 1/4" (0-1 finger gap all around) Not really understanding "there is different resistance in each direction on the strut piston than if it were centered". Is there a thread or link I can read up about that if it's to complicated to write out?</TD></TR></TABLE>

Koni's work great the GC top hats. You must have GC coil-overs to make the system work though. The upper mounts require a spring with an inner diameter of 2.5" and Ground-Controls are the only coil-over spring (2.5" inner diameter) system that are compatible with Koni shocks...

My 94 Civic CX is lowered 2.5" with top hats only on the front, and the combo works great. They are not as helpful in the rears because there is already quite a bit of travel back there. Plus you cannot fit your plastic interior covers back on with them in place.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hybrid93Hatch &raquo;</TD></TR><TR><TD CLASS="quote">If the extended top hat gives an additional 3 inches and the drop is 2 inches then the shock is extended more than than OEM specs? IF this is correct is this bad? Not sure what you mean with the bold above; so you would lose performance with a 3" extended top hat / 2" drop?</TD></TR></TABLE>

Your are correct in thinking that, but the GC upper mounts only give back about an inch of travel. I know that doesn't sound like much, but that equates to about 1.5" of wheel movement. That means you can hit bumps that are 1.5" taller than before & the impact will still feel the same. That is quite a huge difference when your actually driving the car...

Tyson

heres some pictures that illustrate the issue with incompatible (oversized) shocks.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lam.N &raquo;</TD></TR><TR><TD CLASS="quote">


</TD></TR></TABLE>

Modified by Tyson at 10:32 AM 8/7/2006


Modified by Tyson at 11:00 AM 8/7/2006

suspendedHatch

There's more to it than just travel. With Konis the only benefit is travel. But with Illuminas, the difference is so big that you will have to change your stiffness settings. I did. I would compare the difference in performance to that of going from some nasty 17 inch chrome wheels and heavy tires (that were on the car when I bought it) to replacing them with 15 inch Rotas with decent street summer tires. The drop in weight at the wheels helps keep them planted over rough surfaces, which happens to coincide with what a good set of struts will do for you.

With a 2 inch drop and 3 inch extensions, you are actually negating the purpose of the extended top hats by 1 inch. Not only that, but you wont have clearance under the hood for 3 inch extensions, and it's not going to give you more travel since the upper control arm is going to hit the strut tower anyway. Ideally the extensions are the exact same length as the amount of drop, but any amount of correction will give you a noticeable improvement.

Here's mine. 1.5 inch extensions in the front (barely fit beneath the hood with some triming to the skeleton), 1.75 inch extensions in the back. Car is lowered approx 1.75 inches.



They fit beneath the plastic covers just fine . Hole saw please.

Go ahead and talk **** about my strut brace. It's going to get welded at the pivot points soon enough.

Inside the strut housing is some fluid that is forced through chambers that offer up variable amounts of resistance to the piston. If the piston is not at center where it is intended to be when your ride height is stable, then you're not going to get the initial amount of resistance that was intended by the designer of the strut.

Tyson

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by suspendedHatch &raquo;</TD></TR><TR><TD CLASS="quote">Inside the strut housing is some fluid that is forced through chambers that offer up variable amounts of resistance to the piston. If the piston is not at center, where it is intended to be when your ride height is stable, then you're not going to get the initial amount of resistance that was intended by the designer of the strut.</TD></TR></TABLE>

thats simply not true.

it doesnt matter where the piston is in the shock. fluid passing through the orifices of the piston doesnt matter if its at the top or the bottom of the shock.

you say you had to change your adjustment settings on your illuminas when you put on top hats. im really not sure why you would have that experience.



Modified by Tyson at 11:00 AM 8/7/2006

suspendedHatch

Are you talking about Koni's or Illuminas? It's not true of Koni's.

You would know how I had that experience if you had my coilovers and you tuned the settings to your satisfaction, later installed extended top hats and found you were no longer satisfied with how the struts were performing, then re-tuned them and were relieved to find that they now performed even better than they did originally.

Tyson

ive used them on my illuminas. ive not had the same experience as you. i just had to find my ride height again. i only used them in the rear. i had already lowered my front illuminas in the shock fork for extra shock travel so it was unecessary in the front.


your custom top hats look pretty high actually. what is the length and spring rate of your springs? were you overly preloading them??

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by suspendedHatch &raquo;</TD></TR><TR><TD CLASS="quote">With a 2 inch drop and 3 inch extensions, you are actually negating the purpose of the extended top hats by 1 inch. Not only that, but you wont have clearance under the hood for 3 inch extensions, and it's not going to give you more travel since the upper control arm is going to hit the strut tower anyway. Ideally the extensions are the exact same length as the amount of drop, but any amount of correction will give you a noticeable improvement.</TD></TR></TABLE>
You don't know what you're talking about. The motion ratio of stock suspension is not 1:1. Wheel travel (the "drop") is not equivalent to shock travel.

chrisw85

From what i understand, the GC tophats were originally designed to eliminate excess droop. I have full length GC sleeves on standard length koni spss3 valved shocks, and i have top hats; so it won't fit inside b/c of the full length sleeves, but i did eliminate quite a bit of droop.

Tyson

they were designed by gc to fit and work with koni yellows specifically. they recommend putting the sleeves on the lowest perch to prevent interference.

if you shocks were shortened, well thats another issue. you dont want them bottoming out on the sleeve.

chrisw85

i have spss3 valved regular length konis and the full length GC sleeves--they cover the entire length of the shock body. They don't make them anymore. I suppose I could chop off some of the top of the sleeves to make it able to go into the top hat.

In anycase, hitting the bumpstops is not good either way. And you wouldn't want to run top hats with shortened shocks, you'd be limiting your droop by a lot.

Tyson

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chrisw85 &raquo;</TD></TR><TR><TD CLASS="quote">
In anycase, hitting the bumpstops is not good either way. And you wouldn't want to run top hats with shortened shocks, you'd be limiting your droop by a lot.</TD></TR></TABLE>

exactly. it would be redundant.

better to hit bumpstops than metal-metal. thats what theyre there for.

94eg!

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chrisw85 &raquo;</TD></TR><TR><TD CLASS="quote">i have spss3 valved regular length konis and the full length GC sleeves--they cover the entire length of the shock body.</TD></TR></TABLE>

I do believe that the full-length sleeves were designed long before the extended upper mounts. Their interference is probably part of the reason they were discontinued. That and their unnecessary expense with no added function...

Voodoo_s2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">
Koni's work great the GC top hats. You must have GC coil-overs to make the system work though. The upper mounts require a spring with an inner diameter of 2.5" and Ground-Controls are the only coil-over spring (2.5" inner diameter) system that are compatible with Koni shocks...
</TD></TR></TABLE>

Ground Controls are not the only springs that will work with the Koni's. Swift springs for example will work just fine.

Tyson

he said "system". meaning the sleeves. as we all know, GC doesnt make the springs. they use eibach race springs. GC is the only one that makes suitable sleeves that fit koni shocks.

theres also hypercoil springs.



Modified by Tyson at 11:54 AM 8/8/2006

94eg!

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">he said "system". meaning the sleeves. as we all know, GC doesnt make the springs. they use eibach race springs. GC is the only one that makes suitable sleeves that fit koni shocks.</TD></TR></TABLE>

Exactly... Also Koni makes a coil-over sleeve kit to fit their "sport" shocks, but I've never looked into them so I cannot comment on price/springs/etc...

Fuster_Cluck

So does anyone run GC top hat extenders on the rear?

Tyson

i did. i was using a 6" spring tho.

Fuster_Cluck

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">i did. i was using a 6" spring tho.</TD></TR></TABLE>

How will they work with the standard GC spring?

Tyson

fine.