SHO Sway Bars / Suspension

Alex Winbow


    In theory, the SHO has a much better handling suspension than the SLO, derived from the Police version and with its own springs, struts, and sway bars. In practice, Ford stayed true to the original idea only up through GenI, and by the end of the GenII handling had become a complete crapshoot. In any case, Ford's best work was only a start; simple suspension modifications can drastically affect how the car drives.

    The following information was derived from a long thread on TechSHO May 22-25 2002 originally titled "more sway bar debate", and also from a few postings on the SHOForum. I have attempted to distill it here for clarity, but since I understand the subject only poorly, questions should be to the lists. However, please send any corrections. Where I have explicitly quoted someone else, or nearly verbatim-copied their words, {credit is given like this}.

Updated 4 Jun 02: testimonials, cleanups.
Updated 19 June 02: sway bar deflection rates, endlink bushings
Updated 20 June 02: spring rates
Updated 21 June 02: Cargo coil details.
Updated 30 April 04: trivial changes.

Glossary and Quick Suspension Overview

Springs
Support the car and provide travel between the wheels and body. Determine ride height. May be linear (constant spring constant) or progressive.
Shock absorbers
Dampen out the movement of the springs. Without shocks, the car would "pogo" endlessly on the springs.
Struts
Modern form of shocks that combine structural support.
Swar bars
Metal bars with peculiar curvy shapes that connect the left and right sides of the car's suspension. They act as incredibly  stiff springs that tend to counteract the rolling of the car when cornering. Available in many diameters and associated stiffness. Sometimes called anti-sway bars or ASB. Specific to front and rear, sometimes called FSB/RSB. They connect to the car in two places each side: along the bar to the frame ("sway bar bushings"),  and at the ends to the strut towers ("sway bar endlinks").
Subframe bushings
Look under your engine. Find a long, low, broad, strong, traverse piece of metal that looks like an good jacking point (though it may not be ideal.) Where it connects to the rest of the car are circular pads.
Strut tower braces
The strut towers (big round objects in engine compartment) can be connected together with a solid bar under the hood, locking them together and reducing lean when cornering. Also for the rear
NVH
Noise, Vibration, and Harshness.





Sway Bars

Sources of sway bars for the Taurus body:

Vehicle
Front
Rear
SLO
?
?
SHO
20.6, 24
19, 21, 23, 26
Police (93-95?)
?
25
Wagon
22
inapplicable

    Some of these sway bars can be bought directly from Ford. For example, {John Holowczak} writes "They are still avilable new from Ford for around $105 list, MUCH cheaper than a new 26 mm bar.  Uses the same bar to frame bracket bushings, if memory serves." (Confirmed.)
There is also a semi-mythical 28mm sway bar, "No known Ford PN as far as I know but Nook has found them in junk yards." {Don McKinnon} It's also available from http://www.iptech.tv

    This table was derived from the well-known SHOTimes version, with minor additions from the thread. Clearly, Ford went all over the place with supposedly "stock" SHOs, producing everything from some kind of neutral handling to horrid understeer.

Common Stock Stabilizer Bar Diameters

Model

Front

Rear

'89, '90, '91

24mm

26mm

'92, '93 5-speed

24mm

23mm

'93 auto

23mm

23mm

At least one '93 ATX
20.6mm
19mm

Most '94-'95 5-speed

??

23mm

At least one early '94 auto

23mm

19mm

Most '94-'95 SHO auto, some '94-'95 SHO 5-speeds

20.6mm

21mm

At least two 1995 MTX
20.6mm
19mm

Towards the end of production, Ford was using whatever was in the [SLO] parts bin. The sway bars combos are aggravated by SLO springs, especially in the rear, and maybe even SLO struts.

To determine what size sway bars you actually have, use a caliper, or (purportedly) set of metric open wrenches. However, I have found that the
wrenches don't always seem right, eg my 19mm wrench does not fit my (caliper-measured) 19mm bar.

Sway Bar Deflection Rates

(derived from the information at http://www.v8sho.com/SHO/rearswaybar.htm)
Sway bar spring constant (deflection force) goes as the fourth power of the diameter, so we obtain the following:
Front Bar (Relative) Strength
100%
130%
184%



Front Bar Diameter
20.6
22
24










Rear Bar (Relative) Strength
100%
149%
215%
300%
351%
472%
Rear Bar Diameter
19
21
23
25
26
28




What Size of Sway Bar Should I Have?

John Hrinsin's Table

    "Okay, I did a little more digging on the subject and according to what I found to get the "best balance" in the SHO you want to have the K factor of the FSB to be about half that of the RSB (at least for the ridge unit Gen III or a Gen II with SFC's and STB's).  So using the graph and equation off the V8SHO site, thanks to Sheriff Buford T. Justice, and some quick measurements of my FSB while still on my car (not 100% sure they are absolutely accurate), here's what I came up with."   (I've made two additions to the table by interpolation.)

Front Size/ Rear Size
Ratio
Comments
20.6mm/19mm
1.55
(author's  95 MTX as OEM)
24mm/23mm
1.34
you have got to be kidding
19mm/19mm
1.13

20.6mm/21mm
1.04

22mm/23mm
0.94

26mm/28mm
0.84
safe predictable understeer
24mm/26mm
0.82

19mm/21mm 
0.75

20.6mm/23mm 
0.72 (author's present pairing)
24mm/28mm
0.61
good overall balance
22mm/26mm
0.58

19mm/23mm
0.52
Gen III optimal
20.6mm/25mm
0.52
 
20.6mm/26mm 
0.44
on the tail happy side
22mm/28mm 
0.42

20.6mm/28mm
0.33
sick oversteer
19mm/26mm
0.32

19mm/28mm 
0.24
yeah, right


    "Sway bar bushings material, sring rates, strut type, settings and mounts, degree of unibody stiffing, sub frame bushing material and differential type all have an effect on the above.  I think it's time for Dexter to get out of the laboratory and get on with some field and/or track testing. Deedee, don't touch my sway bar bushings!" {John Hrinsin}

    "The 20.6mm/26mm combo with the full TPR or poly bushing treatment on a open diff MTX, even with SFC and STB's, tends to be on the oversteer side of things, fun for autocross, maybe a handful on a road course.  Several people have reported that the 22mm FSB (from a SLO wagon) with the 26mm RSB combo is very neutral setup.  The same maybe said for the 24mm/28mm combo, but that just seems way too stiff IMHO." {John Hrinsin}

Differential Considerations

   "A SHO with 24/26 bars and either stock or Eibach springs is going to be a devoted, confirmed understeerer and, in open-diff form, will have trouble getting power to the ground in any corner more than medium-tight. ... Stiff front anti-roll bars and open-diff FWD do not mix.  The bar tends to lift the inside wheel, reducing grip and producing one-wheel peel." {John Miller}
    "Without a Quaife the 22/26 combo gets power down much better and is more neutral.  With a Quaife the 24/26 combination works okay, it's still got plenty of reassuring understeer but one-wheel peel won't kill all your speed any more.  The 20mm front bar ends up too tail-happy for anything but autocross, especially with a Quaife - a big dose of lift-throttle oversteer in Turn 9 at Laguna can make life interesting in a hurry." {John Miller}

    "Now, pesky inside wheel spin on corner exit . . . is why I think a  non-Quaiffe MTX car should use the 20.6/26 combo.  Tighten up on the front bar and you get load transfer to the outside wheel, letting the inside spin . . and spin, and spin." {John Holowczak}
    Also, "The nose heavy ATX's need a heavier FSB." {John Hrinsin}


Bushings Materials

{Nearly all Ian Fischer}
Rubber (OEM)
Compress easily, wear out, crumble. Lead to a very soft feel when cornering.
Delrin
Early aftermarket upgrade. Very hard material, but wears quickly. No longer available..
Aluminum
Solid bushing material
Polyurethene
Harder than rubber, less so than Delrin. However, they bind, wear out, and squeek/squeal horribly unless frequently lubricated.
Thermoplastic Rubber (TPR)
Harder than polyurethene, but aren't supposed to wear, bind, or need grease.
SHONut supplies RSB bushings & endlinks, and front strut rod bushings  http://www.shonutperformance.com/tpr.htm
Polygraphite
Harder than TPR, embdded with graphite to supposedly self-lubricate.
Generic FSB bushings available from http://www.p-s-t.com

If you're looking for rear sway bar end links and bushings, see my big writeup here. Includes what, where, and how much.





Types of Bushings (Many!)

Subframe Bushings

    "As far as Aluminum goes, Aluminum subframe bushings are available to replace the factory rubber ones that wear out and cause the subframe to shift while turning the steering wheel. With the Al bushings, the turn in is much more precise." {Ian Fisher}
There seems to be a wide variety of opinion about whether these solid bushings increase NVH. Generally, the people who want them most don't care about such things.
    {David ?} on corrosion: "The aluminum will not rust. It will corrode slightly in salty areas, but this should not pose a problem for these thick bushings. On some cars, there will be rust where the lower bushing half pushes through and seats against the subframe. A little bit of rubbing with some sand paper, steel wool, or a dremel pass will clean it right up and the bushing will slip right in."

Sway Bar Bushings (Front/Rear)

    "Sway bar bushings" are the bushings that connect along the bar (each side) to the frame. They determine part of the effect of the sway bar, but can also increase NVH. "Hard bushings will not make a thin swaybar harsh, and rubber bushings will not considerably soften a thick swaybar. The bar makes 90% or more of the difference, the bushing, 10% or less." {David ?}

Sway Bar Endlinks (Front/Rear)

    "In 94, Ford updated their front sway bar endlinks with composite/plastic ones (the white ones). These are preferable over the older style metal ones that broke due to lack of flex (more specifically, I believe that the bushings and ball socket joints wore out quickly)." "If you have a 94-95, you should already have the newer FSB endlinks. If you don't have the original FSB endlinks, you could have anything on any year SHO. The newer ones are white and feel like a hard plastic. The older style are made of metal."{Ian Fisher}

    Rear sway bar endlinks have four bushings: an upper/lower pair at the top of the endlink to the strut tower, and an upper/lower pair at the bottom of the endlink to the sway bar.  "Rear endlinks on the Taurus/Sable are very puny and tend to flex and sometimes break. Some of us have upgraded using NAPA Mastercraft endlinks or the Addco (p/n#007). These are basically hardened bolts with a metal sleeve around the bolt and polyurethane bushings..." {Ian Fisher}

See my big writeup on Rear Sway Bar End Links. Includes what, where, and how much.

Strut Rod Bushings 

Front at Subframe

Front at Lower Control Arm

Rear Strut Rod to Body

Rear Strut Rod to Spindle



Springs and Struts

    Springs are the main determiner of ride height, so a common handling modification is lowering springs. Because the lowered car has much less travel between the top of the tire and the bottom of the wheel, the springs must be much stiffer to avoid "bottoming-out". Stiffer springs call for stiffer struts to avoid "pogoing". To make matters worse, after seveal years the stock springs sag badly, resulting in a half-lowered car with poorer handling.
    Figures derived from Helms manual (SLO), SHOTimes (SHO), or manufacturer (Moog, Eibach, Tokiko, Koni).

Springs Type
Stiffness lbs./in
Front/Rear
Comments
SLO
155/100
Was used on some later GenII SHOs (author's 1995)
SLO HD
200/130
SLO Heavy Duty. May have been SHO springs?
SHO
200/160
SHOTimes figures.
Wagon

SLO fronts but different rear suspension (uses shocks), progressive 270-481 or 330-564
SHOShop Linears
210/170
Special SHOShop linears, no longer sold. Lowering?
Intrax
Progressive. "20-25% stiffer than stock". Lower 1.5"/1", or 1"/0.75", depending who you ask.
Eibach
150-260/
150-194
Most common lowering spring; progressive. Lower 1"/0.75", or 0.75"/0.25", depending who you ask.
Moog Cargo-Coil
159-??/
145-??
Very stiff nonlinear rear spring; first bit of travel is soft, then quickly becomes very stiff. Designed to maintain original ride height even when car is heavily loaded down.
Made by Federal-Mogul, sold by NAPA (but not on their website), not certified for SHO.
Spring rates given for first inch only, progessive maximum unknown but probably large.
Front (CC858): Free height: 17.56; Install height: 13.00; 128 lbs/in.; 561 lbs.
Rear (CC859): Free height: 14.63; Install height: 12; 137 lbs/in.; 374 lbs.



Strut Type
Stiffness
Comments
SLO
?
weak
KYB GR2
?
replacement for SLO
SHO
100%
stiffer than SLO, now discontinued.
Sachs
100%?
Reportedly OEM SHO struts, available at http://www.shox.com
Tokiko
115-125%
(different figures!)
Very stiff, performance strut.  Very commonly used with Eibachs. Expensive. Supposedly not suitable for stock springs, although reportedly some have found it handled fine.
Koni
115-155%
Strictly speaking, an insert for the OEM strut, though sometimes sold as a single unit. Knob-adjustable. Also commonly used with Eibachs. Expensive. No longer available?



Further Suggestions of Items to Replace

    You may care to grease any fittings that are greasable, (but it is unclear which stock parts are greasable) {Jeremy Thomas on SHOForum}
    "Make sure your ball joints are in good shape. If not, replace them with the Moog greasable units (I just did mine today).When you replace the springs make sure to get new insulators for the front struts....this is often overlooked. Replace all the pinch bolts and make sure you have washers on hand for the strut assembly....I took mine off the old ones but it would be a cake walk if I didn't have to compress the old struts and take the hardware off them to transfer. ... FWIW, my car was way out of alingement after I did my full suspension. I had to drill out the 8 (four on each side) spot welds to get it back into spec. You might want to do the same."  {MeShoHorney on SHOForum}



What is "Good" Handling?

    "Someone on the MR2 list once pointed out that people's perception of a well balanced, decent handling car may vary. There are usually two types of people.
1. People who think that a car that corners flat and grips well in a curve is a car that handles well.
2. People who think that a car that does the above yet handles sudden transitions (usually side to side) without loss of control (ie evasive maneuvers or slaloming without having the car break loose)is a car that handles well.
I am not asking a question here, but thinking out loud..I think that what works well on an auto-x course may not work best on an open road course. Auto-x is normally filled with sudden transitions that allow for the back to get a little happy, but not too happy. Open track at higher speeds (from what I have seen) does not really allow for the back to break out much if at all. I would thinking that street driving is somewhere in between." {Ian Fisher}

    "Some people associate turn in crispness with "better handling", e.g. put a 24 mm sway bar on the front of their car and they will naturally say it handles better, even though its lost ultimate traction on say a 200 foot skidpad. Tranistional handling is certanly important, but that is much more the job of the shocks, and sometimes chassis stiffness.
    Going up from 155 to 200 lb/inch front springs, however, just took alot of lean out of the car, such that to me the car "handles better" even though max. grip on those 40 foot radius runway turbarounds is about the  same.  Slalomming just feels more contollable at the limt, probably through better road feel as well as less rapid body lean." {John Holowczak, in reply}



Sway Bar Testimonials

Name
Front
Rear
Trans
Springs/Struts
Bushings/
Endlinks
Not-Exactly Quoted Comments  (freely edited for brevity)
Ian Fisher
24mm
26mm
MTX

Poly rear
Rubber front
As it is now, my car plows hard when I go into a turn (understeers). Once it gets on track, the back snaps out hard. So, I really don't feel confident with  this setup.
Ian Fisher
20.6
26
ATX


a lot more predictable/tossable
R McCoy
24
26
ATX


prefer
R McCoy
22
26
MTX



Dave P
24
28
MTX

Poly rear
Rubber front
HD rear
The bigger rear bar really helped tighten up that dragging ass my car had through long turns, and I can really say that I probably picked up a good 10mph thru some long sweeping highway onramps here at school.
Joseph van Oss
24
26
MTX


definitely plows  (Gen1)
Joseph van Oss
20.6
26
MTX


very neutral and predictable  (Gen1)
Steve VanderSloot
24
19
ATX


[24] made a world of difference in cornering   [over 20.6]
John Holowczak
20.6
26
MTX?
GSR 200/130

prefer ... for the NESHOC high speed autocrosses (25 mph runway turnarounds through 70 mph sweepers/high speed slaloms)
[Am] using the deeper front spring perches of the 90 to 93 SHO.
John Holowczak
22
26
MTX?
linear
155/100

[22] sharpened turn in, at the expense of ride quality. My car
would 4 wheel drift at around 60 mph, but would still understeer at
lower speeds.
John Vitamvas
20.6
26
MTX

TPR rear,
rubber front
pretty benign with the SO-3 tires at 35psi all the way around.  It doesn't even feel loose anymore.
Don McKinnon
20.6
26
MTX
SS Linears
205/155
Rubber front
poly rear
Handling is very neutral and predictable with even air pressures front & rear. Quaife.
James F. Ryan
24
26
MTX
SS Linear,
Konis
poly all
I agree with Joe - my stock setup is good but not great, it definitely pushes at the limit.  (Gen1)  f&r strut tower braces
Alan Fanning
22
26
MTX
OEM, Tokicos
Rubber front
poly or TPR rear
very happy with it's handling on twisty back roads
ES bushings on custom stainless rear endlinks, rear ES strut rod bushings,  Moog strut rod control arm bushings and OEM red strut rod bushings in the front
Robert Bade
24
26
MTX
Eibach, Koni
poly front
TPR all rear
personally like this set-up. naturally, have much less push then the OEM 24/24 setup. rides like a brick over choppy surfaces, NVH increased dramatically with the rear work, pretty much as expected.
the rear is about as tight as I can get it
FPS rear c-arms, H-brace rear torque box, full length SFC's, [30psi fr/36psi rear].