Pillowball Upper mounts and coaxial Spring hats needed for 1 inch drop?

[hsk8te2006]

I'm planning to dro pmy car by 1 inch. Opinions... is a pillowball upper mount and coaxial spring hat needed for a 1 inch drop set-up for a 2g FWD?

Also.... different answers front and rear or same?

 

[hsk8te2006]

Anyone?

 

[asian312]

I'm going to say no based on what I've gathered.

 

[gixxerdrew]

"needed", no. OEM cars dont come with pillow ball mounts you don't "need" them but I'm not sure thats what your after. Although it would seem to me that if your just going for 1" drop springs of unknown quality your probably not going for broke on handling in which case I would save the pennies for something else.

Also if your spyder is like my spyder doing much to the suspension is not going to help until you stiffen the chassis a good bit. As I worked on the suspension I got way too much movement from chassis flex.

 

[hsk8te2006]

I'm currently considering Ground Control Coilovers... probably 450/350 or so, with koni Sports (yellows). (Any recommendations for spring rate a street car that I would like to improve the handling of but not become too harsh?)

What did you do to stiffen the chassis on your spyder?

 

[gixxerdrew]

I'm currently considering Ground Control Coilovers... probably 450/350 or so, with koni Sports (yellows). (Any recommendations for spring rate a street car that I would like to improve the handling of but not become too harsh?)

What did you do to stiffen the chassis on your spyder?

The GC spring rates are fine, I am running a much stiffer rear trying to balance the car out but its really a work in progress I will not end up with thats spring rate. I'll probably end up with staggered tires to get the balance right 245f 225r or something like that. The GC spring rates are a good starting point. I have done quite a few things to stiffen up the car where the front bumper was is a hard curved bar 1.5square tube to tie the front spars together RRE braces under and upper, full 10pt cage welded to A and B pillars, some mild through the floor reinforcements. My chassis and suspension is undergoing a major rework actually so this stuff will be all different soon. I was extremely excited to discover that KW offers an off the shelf variant 3 coilover for our cars now, thats a huge huge step forward.

Remote reservoir triple adjustable PROPERLY DAMPED setup, good things. The KW spring rates look to be set for proper natural frequencies, and thats why i am thinking towards tires and sway bar to balance out the car. The tough thing on FWD is getting the car balanced without upsetting all those other things from what is optimal for grip.

 

[ACM]

Are they needed ? No. Are they advisable ? Yes.

The front shock absorbers are at an angle, the upper mounts are angled to match. When you lower the car you change the angle of the shock assembly, but the upper mount does not change. This puts a bending moment on the damper shaft, which in turn causes considerable stiction, and shortens the damper seal life dramatically (hence lowered cars' front dampers blowing regularly). The more the car is lowered the more extreme the problem becomes. The spring is sitting on one 'corner'.

From the factory, the angles all match under normal loads, and the spring rates are soft enough not to introduce significant side loads under normal conditions - plus there is a soft rubber spring seat to absorb some of the variations. Shift to a 'sporting' suspension setup and the soft thick spring isolator vanishes, the spring rates double, and the angles are mismatched _all_ the time

This translates into harsh suspension that does not respond well to changing surfaces. This in term gives the tyres a hard life, and stops them from delivering as much grip p(or comfort) as they were designed for. This can (and is) taken further, substituting spherical bearings for rubber damper bushings, changing the upper spring seat to a damper-centric design, and even using flat roller bearings under the spring to allow the sprnig to float.

The rear of a 2g is nowhere near as bad, as the shock assemblies are near vertical - however these steps still help as the rear is fairly light and optimum springs rates tend to be fairly high.

Charles

 

[gixxerdrew]

IMHO, I disagree.

As long as you have proper bushings in place a shock designed for DSM should have accounted for the side loading expected to be seen under all normal travel for a DSM shock. Which is not much because we have such limited travel in the first place stock suspension is frequently finding the bump stops I'm sure. The real advantage for the coaxial upper hats is spring deflection effect on rate.. and that a certain amount of your movement isnt being damped by the spring but by the bushing... just another thought on the subject anyway.

 

[ACM]

IMHO, I disagree.

As long as you have proper bushings in place a shock designed for DSM should have accounted for the side loading expected to be seen under all normal travel for a DSM shock. Which is not much because we have such limited travel in the first place stock suspension is frequently finding the bump stops I'm sure. The real advantage for the coaxial upper hats is spring deflection effect on rate.. and that a certain amount of your movement isnt being damped by the spring but by the bushing... just another thought on the subject anyway.

Once the car's lowered the shock upper bushings would need to be an asymmetric design to remove the bending load - I've never seen any designed that way. Also aftermarket bushings are much stiffer than stock, in turn increasing the bending loads on the shock.

2G front shock assemblies experience significant movement in every plane; the virtual pivot creates significant fore-aft travel and the lateral angular change increases as the car's ride height is lowered. All of these conspire to give the damper a pretty hard time.

Even Ground Control top mounts are not effective in this situation - the bushings are very stiff. 2 ways to reduce the problem with GC mounts is to leave the damper shaft nut finger (with a locking nut added of course) so that the bushings are not compressed. A second (and I think preferable) approach is to buy the aftermarket anti-roll bar bushings for domestic vehicles - one end is domed, if that end is in contact with the GC plate it will reduce the bending loads over a wider range of movement. They have to be shortened to work effectively though.

Charles

 

[ACM]

I'm currently considering Ground Control Coilovers... probably 450/350 or so, with koni Sports (yellows). (Any recommendations for spring rate a street car that I would like to improve the handling of but not become too harsh?)

What did you do to stiffen the chassis on your spyder?

Ride quality is dependent on the damper performance much more than the spring rate (assuming you're not bottoming out).

I have three 2G suspension setups :
1) Koni/Ground Control, GC upper mounts, 500 fr/350 rr
2) ShockTek Bilsteins, ShockTek pillowball upper mounts, coax spring hats; 700fr.550rr
3) Ankeny Penske triples, RRE pillowball upper mounts, coax hats; 800fr/650rr

Guess which setup has the harshest ride ? Number One.

It's the dampers and their fittings that control ride comfort more than anythng else.

I have never run pillowball mounts without a coaxial spring hat, so I don't know which of the two makes the biggest improvement. I would suggest the same Koni/GC setup I use above, but add RRE upper mounts with coax hats, that's probably about as cheap a combination. A sunroofed car or Spyder will ride a lot better, as chassis flex will absorb some of the harshness. I was most surprised at the difference in ride stiffness when I move my Koni/GC setup from my 98 with sunroof to my 95.5 which has no sunroof. Very surprised indeed. Very uncomfortable.

Charles

 

[hsk8te2006]

The RRE plates... are they pillowballs?

Any recommendations on where to buy coax hats?

Also... to make sure I get the right coax hat, do they need to be matched to:

1) The shock
2) The pillowball mount
3) The fact it's going on a dsm
4) The spring ID (diameter)?

 

[ACM]

The RRE plates... are they pillowballs?

Any recommendations on where to buy coax hats?

Also... to make sure I get the right coax hat, do they need to be matched to:

1) The shock
2) The pillowball mount
3) The fact it's going on a dsm
4) The spring ID (diameter)?

I believe you can get everything from RRE, and their plates are pillowballs. The hats have to match both the damper shaft diameter and the spring ID, the plates have to accomodate the damper shafts, which is done using top-hat spacers. Spring hats are also often sized using spacers/inserts.

If you plan on really wide wheels and tyres, I suggest 2.25" ID to gain a little extra room, otherwise 2.5" ID springs are the easiest/cheapest to acquire. There are also 2" ID springs, but they are correspondingly more difficult to obtain, and more expensive again. 2.5" springs have the widest range of lengths and rates.

You will need spacers to go between the hats and the pillowball plates, otherwise the fronts seats will hit the plates, with very ugly results. Again, I believe RRE can supply all of this. Don't forget to request the spacers in Stainless Steel, and you want Stainless Teflon-lined bearings in the top hats, since these are for a street car - they'll all rust quickly otherwise.

If the RRE plates are still the same design, I suggest you epoxy the studs in place, there are only a few threads in the Aluminium plate (they're countersunk bolts), and they can strip - not a big deal, but then you have to fish around in the wheel arch with an Allen wrench to stop the stud from spinning when you try and bolt it down.

Charles

 

[gixxerdrew]

Once the car's lowered the shock upper bushings would need to be an asymmetric design to remove the bending load - I've never seen any designed that way. Also aftermarket bushings are much stiffer than stock, in turn increasing the bending loads on the shock.

2G front shock assemblies experience significant movement in every plane; the virtual pivot creates significant fore-aft travel and the lateral angular change increases as the car's ride height is lowered. All of these conspire to give the damper a pretty hard time.

Even Ground Control top mounts are not effective in this situation - the bushings are very stiff. 2 ways to reduce the problem with GC mounts is to leave the damper shaft nut finger (with a locking nut added of course) so that the bushings are not compressed. A second (and I think preferable) approach is to buy the aftermarket anti-roll bar bushings for domestic vehicles - one end is domed, if that end is in contact with the GC plate it will reduce the bending loads over a wider range of movement. They have to be shortened to work effectively though.

Charles

Charles, I agree 100% with everything you've posted here and I also have a set of those shocktek's (although now converted to bilstein take aparts) and also a Koni/GC combo. It's just this one thing about the upper hats and the sideloads on the shock that I disagree on but I'll explain.

You are right in the general sense, suspensions always do as you describe but the DSM suspension in particular wont have an issue with this because of a problem specific to our application that I am guessing you might not have been aware of and what I am speaking to here.

In stock trim the 2g suspension uses near 100% of available travel. The travel is very little even in stock trim, almost all of it is used up the bump stop goes super stiff just before the control arm bottoms out to the fender, this is with stock height stock springs. Lowering the car won't use any more travel because there wasn't any more available. There is no new and extreme positioning happening when you lower the car because you were already within a very short distance of bottoming out the control arm into the fender. So you end up going very little outside stock parameters for suspension position in terms of compression.

Under all normal circumstances the conditions you describe would be precisely true but in the particular case of 2g DSM suspension you cant get to the point where you have that problem because our design sucks and that travel isn't even available to get us into trouble with the bushing. There are other collatoral issues at work as to why the coax hats are superior just as you described above. I 100% agree on this too but just in terms of side loading you wont see much past stock due to lowering.

for the record, I do run coaxial hats 8)

Hopefully you can take this as my feeling on the subject I dont want to get caught up in a horn butting thing on here so I'll step aside if theres further disagreement. Thats what I know from what I have seen.

edit: Also regarding the spring diameter, are you talking about 1g or 2g? because on a 2g the tire runs into the upright before it gets near the spring/shock?

 

[hsk8te2006]

2g - my '96 spyder

 

[ACM]

We're not arguing, we just don't agree Arguments are two doors down the hall, this is the disagreement room...

On my car as the lateral Gs increased, I started to have to run wheel spacers - first on the rear and later on the front as well. My rear tyres were rubbing on the spring - it was another .2G before the caught the upright as well... The fronts contacted the uprights only (I think). This may be as much to do with production tolerances as anything, as Fedja's car rubbed on the front first (I think). We're pushing things so far now that a 1mm difference is enough to cause a problem, and in an area like the upright/damper mount, those are not at all critical dimensions to the original engineers, as nothing was even vaguely close. Another example of tolerances, my racecar doesn't run out of travel until my tyre hits the upper/inner fender, and that's with the outer lip of the outer fender cut back (the outer fender would the limiting factor otherwise on 285/30/18s)

As far as travel goes, I don't agree that we're using 100% all the time or even much more than occasionally. 90% of the time we're using virtually none at all - poncing down the (relatively flat) highway, we're rarely using any travel at all, and when the car's parked its using zero travel. If the dampers are at the angle the engineer intended there's zero side load for that 90% of the time - that other 10% of the time is accommodated by the very soft upper shock bushings - the ones we all throw away and replace with Energy Suspension or whatever. If you lower the car, the damper environment is reversed, it's now almost always under some degree of side load, and that side load will be increased for any given angle due to the increased stiffness of the bushing material we all use.

BTW, I completely disagree with the notion that 2G suspension sucks or is a bad design - I think it's an extremely good design, let down only by the extra compliance of the lower front bushings, required to accommodate the extra 2D movement generated from the virtual pivot design. If Mitsu had used ball joints on the inner pickups and then isolated the NVH in the subframe, 2G suspension would be better than pretty much anything for under $100k. Those lower bushings kill the geometry control, but it's a lovely design if that could have been avoided. The camber curves we get from the front and rear are something Evo, STi, M3 racers would kill for - ours are easily adjusted if you run in any non-stock class. Weight distribution on the other hand...

We don't agree, but each to his own - I'll buy the next round

Charles

 

[hsk8te2006]

When you suggest that I need to get spacers for between the hats and pillowbwll plates, what exactly do you mean?

 

[hsk8te2006]

ACM... you mentioned a harsh ride with your Koni/GC/GC mount set. Are you referring to the hard black plastic upper mount pictured here: Ground Control Suspension Systems

or the mount they sell pictured here: Ground Control Suspension Systems

Also... when you suggested tightening the damper nut only finger tight so the bushing isn't compressed, is that bushing the black rubber thing in the picture in teh 2nd link?

Thanks again guys... this infornmation is really helping me make sure I get this right the first time.

 

[ACM]

No, those are spring isolators. The bushings to be concerned about go onto the damper shaft, one each side of the GC mount. They're about an inch diameter, half inch thick.

ACM... you mentioned a harsh ride with your Koni/GC/GC mount set. Are you referring to the hard black plastic upper mount pictured here: Ground Control Suspension Systems

or the mount they sell pictured here: Ground Control Suspension Systems

Also... when you suggested tightening the damper nut only finger tight so the bushing isn't compressed, is that bushing the black rubber thing in the picture in teh 2nd link?

Thanks again guys... this infornmation is really helping me make sure I get this right the first time.