I want to upgrade the suspension on my 968 Cab this winter. The primary goal is to get all the performance possible while staying the P9 class for PCA and B Stock for SCCA.

I believe the class rules rule out coilovers.

Currently I am debating between Koni adjustables and Bilsteins that would not be adjustable. I also plan to change every bushing possible to new or where possible better materials.

I would really like to hear your suggestions on what components I should use.

Thanks in advance.

 

I don't know anything about 968 setup, but I wanted to point out that a) "coilovers" is a very imprecise term, but threaded shock bodies are legal in SCCA Stock as long as the stock dimensions and springs are retained, and b) upgrading bushings is illegal in SCCA Stock with the exception of sway bar bushings.

Steve

 

Steve, I guess we should start out by declaring that I do not know what a "coilover" is. I believe it to be a shock with an adjustable mount for a spring that fits over it and that adjusting that spring will change the ride height.

Currenly for PCA I am using the 5 points allowed for P9 with factory Torsen LSD and Victoracers. So I cannot afford any handicapped changes. These are the relevant PCA rules

A-2.4.5. Free Suspension Modifications. The following modifications are allowed without effect on classification provided any limitations defined are not exceeded:

(a) Adjustments - Any adjustment of the standard suspension components is permitted, provided no machining is required for the adjustment.

(b) Removal of Hydropneumatic Suspension - This modification is not only allowed but suggested.

(c) Springs and Torsion bars Any coil spring may be replaced by any other coil spring. Any torsion bar may be replaced by any other torsion bar.

(d) Shocks - Any shock absorber may be used.

(e) Sway Bars - Any anti-sway bar may be installed.

(f) Camber Compensation - Any rear camber compensating device may be used.

(g) Bushings - Non-standard (non-elastic) suspension bushings may be used, including shock tower mono-*****.

(h) Spring plates - Adjustable spring plates are permitted.


A-2.4.6. Handicapped Suspension Modifications. The following modifications are permitted within any defined limitations; however, class-progression points are assigned to these changes:

(a) Machined Suspension - Any adjustment may be made and machining is allowed (such as machining to attain negative front camber on 356-series automobiles.)

(b) Front Shock Tower Brace - A shock tower brace may be used in any automobile provided that (1) it can be quickly and easily removed, such as bolted in rather than welded in; any number of attachment points may be used; (2) all attachment points are within three inches of a vertical plane passing through the top center of the shock absorber.

These are the relevant SCCA rules for B Stock

13.5 SHOCK ABSORBERS

A. The make of shock absorbers may be substituted providing that the number, type (e.g., tube, lever, etc.), system of attachment and attachment points are not altered, except as noted below. The interchange of gas and hydraulic shocks absorbers is permitted. The following restrictions apply: 1. No more than two separate external shock damping adjustment controls. Gas pressure adjustment is not considered a damping adjustment. 2. Suspension geometry and alignment capability, not including ride height, may not be altered by the substitution of alternate shock absorbers. 3. Adjustable spring perches are allowed, but the spring loadbearing surface must be in the same location relative to the shock mounting points as on the standard part. Shims may be used to achieve compliance. 4. The fully extended length must be within plus or minus one inch of the dimension of the standard part. 5. Electronically controlled shocks may not be used on vehicles not originally equipped with such units. Vehicles originally equipped with electronically controlled shocks may use the standard parts or non-electronically controlled alternative shocks subject to all the requirements of 13.5. Non-standard electronically controlled shocks are not allowed.

B. The mounting hardware shall be of the original type. The use of any shock absorber bushing material, including metal, is permitted. This does not permit the use of an offset shock bushing. A shock absorber bushing may be imlemented as a spherical bearing. The bushing attaching the end of a strut to the body or frame on a strut type suspension is a suspension bushing, not a shock bushing.

C. To facilitate the installation of commonly available aftermarket shock absorbers, struts, or strut inserts whose shaft size is larger than the center hole of an upper shock mount assembly, that hole may be enlarged by the minimum necessary to accommodate the shock shaft size, provided the following restrictions are met: (1) the enlarged hole must remain concentric with the original configuration; (2) the enlargement of the hole does not require modification of a bearing (as opposed to a washer, sleeve, or plate); (3) neither the hole enlargement not the location of the shock shaft changes any alignment parameter.

D. A suspension bump stop is considered to be performing the function of a spring. Therefore, the compressed length of the shock at the initial point of contact with the bump stop may not be increased from the standard part, although the bump stop may be shortened for the purpose of installing non-standard shocks. Bump stops installed externally and concentric with the shaft of a shock may be drilled out to fit a larger diameter shock shaft. Bump stops may be substituted for the purposes of installing non-standard shocks.

E. A hole may be added through the bodywork to route the line from the reservoir to the shock absorber body. Such holes may serve no other purpose.

F. A hole my be added to an interior body panel to provide access to the adjustment mechanism on an allowed adjustable shock absorber. The hole may serve no other purpose. Interior panels are defined to be those pieces which cover the interior of the vehicle and are accesible from inside the vehicle. They do not include structural panels, such as wheel wells or inner fenders, which may also be accessible from inside the car but which actually form part of the body of the vehicle.


13.8 SUSPENSION

Standard, as defined herein, suspension springs must be used. They may not be cut, shortened or collapsed. Cars with swing axle suspension may be lowered sufficiently to achieve no more than two degrees of negative camber at rest, and may use a camber compensator.

Both the front and rear suspension may be adjusted through their designed range of adjustment by use of factory adjustment arrangements or by taking advantage of inherent manufacturing tolerances. This encompasses both alignment and ride height parameters, if such adjustments are provided by the stock components and specified by the factory as normal methods of adjustment. However, no suspension part may be modified for the purpose of adjustment unless such modification is specifically authorized by the factory shop manual for non-competition purposes.

Suspension bushings, including but not limited to those which carry the weight of the vehicle and determine ride height, may not be replaced with bushings of a different material or dimension.

Replacement control arms for vehicles having integral bushing/arm assemblies must be standard factory parts as per Sections 12.4 and 13.0. 90

If authorized by the manufacturer, the use of shims, special bolts, removal of material to enlarge mounting holes, and similar methods are allowed and the resulting alignment settings are permitted even if outside the normal specification or range of specifications recommended by the manufacturer. If enlarging mounting holes is specifically authorized but no material removal limits are specified, material removal is restricted to the amount necessary to achieve the maximum factory alignment specification.


I would really apreciate your thoughts on what I can do within these rules and where you would invest.

You rated the 968 with a "mid" competitive level in BS in another thread, a Cab which is 300 pounds heavier must be atleast a "mid-". I love the car and want to get all I can out of it.

 

I should repeat my disclaimer -- I know nothing about 968 setup. I'd suggest searching the web for "944 autocross setup" and variations thereof (my reasoning being that 968s are fairly rare, but most 944 advice should still be relevant).

Wow -- the P9 rules are very liberal, much more so than the SCCA Stock rules. That will present a bit of a dilemma for you: a maxxed-out P9 car will be illegal in SCCA Stock (it might be legal in Street Prepared; I'm not familiar with the SP rules), whereas a maxxed-out Stock car will be woefully underprepared for P9. Which class you prep your car for depends on where your priorities lie.

Personally, I'd go the SCCA Stock route and prep in the following order:

• Alignment. Usually costs under $100 and can make a big difference in the way your car handles. Generic advice is to dial in a lot of negative camber front and rear, a touch of toe out in front to aid turn-in, and rear toe to taste. You'll have to search the web for 944/968-specific alignment advice. Note: going crazy with the alignment will really help on the autocross course, but can also significantly increase tire wear on the street.
  

• Replace worn-out shocks or bushings. If you bounce on the front or rear end of the car and the car keeps on bouncing after you stop, you could probably stand to have some new shocks. I don't really know how you'd diagnose worn-out bushings. Just replacing tired shocks and/or bushings with new ones should make a noticeable difference.
  

• Front sway bar. SCCA Stock rules only allow substitution of the front bar, but pretty much every RWD sports car out there benefits from a bigger front bar for autocross anyway -- it will reduce body movement in transitions, which will make the car easier to drive in slaloms. I'd surmise that reducing body roll would be especially important for the 968 since it has struts.
  

• Upgrade shocks. Both Koni and Bilstein make good shocks; I'd go with the Konis since they're adjustable, and thus offer a way to tune the car's behavior.

I should repeat one more time -- I have no 968-specific knowledge, so maybe someone on this board who does can step in to help.

Steve

 

Bruce, I know nothing of SCCA auto-x rules, but since rear coilovers were a factory option (via the M030 package) on the 968, I'm confused as to why you couldn't install them on your car. Surely those cars equiped with factory coilovers are legal in their class. Perhaps Steve can comment on this point.

 

Does your car have the M030 option? If not, upgrade to those specs, and you can run stock P9 as well as SCCA BS. While PCA will allow for some more goodies that would be benefiical (ex: 8-inch wide wheels in the front and a thicker rear sway bar), SCCA won't let you do much more.

-Z.

 

Zman - don't you think he wants some advice from someone who actually runs a modified suspension!

The M030 is going to be a minor increase in stiffness at best (normally the M030 is 25% stiffer than stock). I would say forget about autox classes and get the suspension you want...real men drive at the track anyway!

 

I really appreciate the advice from all sources. At this point I want to figure out what I can do within the rules then decide what to do.

M030 is something I have considered. It was not a factory option for a Cab but it could be dealer fitted. Koni adjustables cost less and may be better than the M030 shocks / struts. I would like to upgrade to M030 sways.

I have been reconsidering staying in BS. The SCCA BSP rules are more similar to PCA P9 rules. What do you guys think about a suspension setup for P9 / BSP ?

For P9 / BSP I am thinking of stiffer (perhaps progressive) springs, adjustable shocks / struts, the best bushings I can get in the best materials and M030 sways front and rear. And both P9 and BSP allow chipping the car.

Thanks again for all of your advice.

These are the relevant SCCA rules for Street Prepared.

15.5 SHOCK ABSORBERS

Vehicles may only exceed the allowances of 13.5 as specified herein.

A. Shock absorber bump stops may be altered or removed.

B. On cars with lever-type shock absorbers, a tube-type shock absorber may be added. If the lever-type shock serves no other purpose, it must be removed. If the lever-type shock serves any other purpose, it must be retained.

C. Any shock absorbers may be used. Shock absorber mounting brackets which serve no other purpose may be altered, added or replaced, provided that the attachment points on the body/frame/ subframe/chassis/suspension member are not altered. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed. The number of shock absorbers shall be the same as Stock. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment. MacPherson strut equipped cars may substitute struts, and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel. This allowance differs from Improved Touring Allowance 17.1.4.D.5.d.1.


15.7 ANTI-ROLL (SWAY) BARS

Vehicles may only exceed the allowances of 13.7 as specified herein. Substitution, addition, or removal of any anti-roll bar(s) is permitted. Bushing material, method of attachment, and locating points are unrestricted. This does not authorize removal of a welded-on part of a subframe to accommodate the installation, or the cutting of holes to route the bar or links. Non-standard lateral members which connect between the brackets for the bar are not permitted. The bar may serve no other purpose which is not explicitly permitted elsewhere herein. Components such as anti-roll bars and strut housings which serve dual purposes by also functioning as suspension locators may not be modified or substitued in ways which change the suspension geometry or steering geometry, and may not be installed in positions (e.g. upside down) other than that of the original configuration.

15.8 SUSPENSION

Vehicles may only exceed the allowances of 13.8 as specified herein.

A. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers which alter suspension geometry, such as those between the hub carrier and lower suspension arm. Springs must be of the same type as the original (coil, leaf, torsion bar, etc.) and except as noted herein, must use the original spring attachment points. This permits multiple springs, as long as they use the original mount locations. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered, and their position may be adjustable. Spacers are allowed above or below the spring.

B. Suspension bump stops may be altered or removed.

C. Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location. Offset 114 bushings may be used. In a replacement bushing the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (for example ball and socket replacing a cylindrical bushing), or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the Stock bushing accommodated multiaxis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings, but may serve no other purpose than that of retaining the bushing in the desired position. Differential mount bushings are not considered to be suspension bushings and are not covered by this allowance.

D. The following allowances apply to strut-type suspensions: Adjustable camber plates may be installed at the top of the strut, and the original upper mounting holes may be slotted. The drilling of holes in order to perform the installation is permitted, but the center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.

E. Camber bolts may be installed, providing these parts use the original, unmodified mounting points. Caster changes resulting from the use of camber bolts are permitted.

F. Live axle suspension allowances:

1. Addition or replacement of suspension stabilizers (linkage connecting the axle housing or De Dion to the chassis, which controls lateral suspension location) is permitted.

2. Traction bars or torque arms may be added or replaced on live axle suspensions.

3. A panhard rod may be added or replaced.

4. The upper arm(s) may be removed, replaced, or modified, and the upper pickup points on the rear axle housing may be relocated.

5. The lower arms may not be altered, except as permitted under 14.8.C, or relocated. Methods of attachment and attachment points are unrestricted, but may serve no other purpose (e.g. chassis stiffening). This does not authorize removal of a welded-on part of a subframe to accommodate the installation.

G. Changes in alignment parameters which result directly from the use of allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing which meets the restrictions of 15.8.C are allowed, including those resulting from a change in the pivoting action to (a) about the mounting bolt, or (b) about the bushing itself. Eccentric bolts are permitted for suspension adjustment only if they are as specified by the factory, per the last paragraph of 13.8.

 

Hello all,

I'm aiming to do pretty close to what Bruce is doing. I have a '92 968 Coupe I've been Autocrossing with both the PCA and SCCA, and I'd like to remain in Stock classes for both clubs. I'm willing to be less competitive in the PCA in order to max out the SCCA class. I also don't have the M030 option. At the same time I'm doing this as maintenance, I'd like to replace anything and everything that's worn with new. Also, I'd like to get it all done once and then have the car aligned, rather than going back and forth.

I spoke to one of the SCCA tech inspectors who had been a 968 owner, and he made it quite clear that while the M030 package is stock, installing part of the package would bump you to prepared. (With the exception of the front sway bar, which is allowed anyway.)

If you had the M030 option, I believe you could substitute rear coil-over shocks like these : http://www.paragon-products.com/prod...rearcupkit.htm
Or these : http://www.klaindustries.net/rearcoil/rearcoil.htm Without issue.
You would have to include the entire M030 package : http://www.weissach.net/968_M030-Option.html

So here's what I'm going with :
2 Strut - Koni Sport, front, KONI-8641-1414S
2 Shock - Koni Sport, rear, KONI-8040-1035S
1 Koni Adjusting ****, KONI-****
2 Bump Rubber - Koni, competition, KONI-70.34.95
2 Strut Dust Cover, PP171.412.135
2 Strut Mount, PP951.343.018.04
1 Sway Bar - front, 30mm, 968M030FRONTSWAY
1 Sway Bar Bushing - Front Complete Set, Delrin, RE_MC-4100SET
1 Sway Bar Bushing - Rear Center, Delrin, RE_MC-4000

Price for all this over at Paragon Products is $2092 delivered, with them doing the strut insert conversion and including the core charge for the old struts.

I would prefer to use these strut mounts : http://www.klaindustries.net/strtmnt/strtmnt.htm
Which are $114 for the pair instead of $352 each, but they appear to violate the B-Stock suspension rules by eliminating the rubber portion of the OEM part. The prospect of paying more for less handling is frustrating. Am I reading that rule wrong?

My question to the board is, am I missing any bushings, bearings, worn out rubber bits that will affect my alignment?