Suspension Upgrades


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Upgrades & Enhancements

Suspension Upgrades

Replacement Shocks
Replacement Springs
Strut Braces
Sway Bars


So, your car has a little too much body roll? This has been a problem with these cars since they were new, probably because they are heavy. To alleviate this problem, you might consider upgrading the shocks and springs instead of simply replacing the OEM shocks. 

The stock 90Q20V has a slightly different setup than the CoupeQ. They are a little higher and softer. The 90Q20V Sport has upgraded suspension, which might just be the same as the CoupeQ's. 

Replacement Shocks
Boge are OEM on these cars, but the ProGas or TurboGas are probably stiffer than stock and are reasonably priced. Bilstein are very good, but you may have problems finding them for the rear. Bilstein America doesn't officially support quattro models, but Bilstein Germany does, and several vendors in the U.S. will supply the right shocks. I've heard good things about Koni Sport which are adjustable, but I've also heard of a few reliability problems.

Here is a list of P/Ns for several of the high quality brands:

Front Rear
Boge TurboGas 32-846F 32-301F
Bilstein Sprint (use w/lowered springs) P30-3006 P36-3058
Bilstein Sport (aka Heavy Duty) P30-3005 P36-3017
Koni Red (Special) 86-2066 80-2403
Koni Yellow (Sport)
    86=gas, 8610=hydraulic & ext. adj.
    ?maybe? (check with Koni)
86-2066 SP
8610-1262 SP (ext. adj.)
86-2066 SPD7 (50mm drop)
8610-1262 SP (50mm drop, ext. adj.)
80-2403 SP
80-2403 SP20 (25mm drop)
86-2433 SP

Make sure you replace the upper strut bearings in the front during installation. Use OEM bearings only! Aftermarket ones won't last. Some people have gone to the blue ur-quattro upper bearings for a bit of added stiffness, and some report that their CQ came with them from the factory. These supposedly lower the car a fraction. They are P/N 857 412 323 B and can be had from The Parts Connection.

Replacement Springs
It seems that all aftermarket springs will lower the car. If you like the stock ride height and your springs aren't damaged, don't change them. Personally, I think the car will be fine a little closer to the ground, and I haven't heard of any problems from those who have done it. Stiffer springs will really help tame that body roll and brake dive.
Coupe 90Q 90Q Sport
H&R Progressive Rate Springs* 50311 -- 40mm lower 50311-- 45mm lower 50311 -- 25mm lower?
Eibach ProKit** 1510.140 -- 25.4mm lower 1510.140? -- ? lower
Koni Suspension Kit
    Includes ext. adj. shocks
1110-2010 -- 30mm lower 1110-2010 -- ? lower

* Some people have reported a strange squeaking sound after installing the H&R springs. It is thought that this might be caused by the first few coils touching each other. The solution is a Honda part. (gasp!) It is called a spring isolator, and is a circular molded urethane tube with the approximate radius of a spring coil, slit along the inside. It has drain holes and a contact adhesive on the inside. The Honda P/N is either 3077864 or 52442-SH3-000 depending on what numbering scheme the particular Honda dealer uses. They should be less than $10 a piece (try for good deals). Put one on the bottom coil, and a second on the third coil, where the spring slope changes. Even if the squeak is only on one side, you may want to install them on both sides to prevent any lean from different ride heights. (Rick Zehr)

** Beware that the Eibach springs are linear in the front and progressive in the rear. This is opposite from what you might expect, so be sure your installer knows which ones go one which end.

Several companies have begun offering coil-over kits for our cars. Basically, the strut tube and spring mount are modified allow the spring perch to be adjusted up or down. This gives you the ability to vary the ride height quickly and easily. You also have the flexibilty to choose your own spring rates.

2Bennett Audimotive has a coil-over kit that was once sourced from Ground Control, but now Ground Control carries nothng for the 90. The components are pictured at right, and include special linear Eibach springs in your choice of spring rates. Now 2Bennett uses their own bits plus a Koni shock to produce the Coilovers. They can be reached at (530) 758-7325.

Vortrag motorsports produces a custom coil-over kit as well. Their kit is reported to be of very good quality.

*As always, double check my P/Ns with the distributor and/or manufacturer before ordering.

Check out The Suspension Bible page for a great explanation of the details of suspension systems. For great prices on virtually all of the better brand shocks and springs, check out RD Enterprises, Autobahn International, MacNeil Automotive, Vortrag Motorsports, and Imparts.

Strut Braces
These cars have quite a bit of body flex. When the top of the strut towers flex, it translates into a bit of slop in the suspension. Luckily, this can be cured with the addition of a strut brace. Basically, it's just a bar that has each end mounted to the top of the two strut towers. This prevents the struts from flexing in relation to each other.

Several vendors offer a bar for the front, but most of them just resell the same bar made by Jamex but sold (what is left) by ForceFedRacing. This particular bar mounts by either welding or bolting an included bracket to the top of the strut tower in the engine bay. For some mounting tips check out Huw Powell's page. The bar itself is actually two pieces that bolt to the brackets, with a turnbuckle between them to adjust the fit. The bar is shaped to avoid interference with the battery, but you may have to relocate some pieces of the cruise control. Jamex no longer sells direct, so you'll have to find a vendor that carries their stuff. Check around, because prices vary greatly. For reference, the direct price from Jamex used to be just under $100. The P/N is 310000.

The Coupe probably benefits from a rear strut bar more than the sedan, because the 90Q has the gas tank mounted between the towers, and the rear seats don't fold down. There used to be a specific rear bar available, but it has been discontinued. Some people have been able to mount a generic bar in there, though. If you get one, make sure it is easily removable, because otherwise it will limit your cargo carrying capacity (Coupe especially). The Jamex part pictured below is P/N 311001.

Sway Bars
The early '90 cars came with just a front sway bar. Later '90 and all '91 came with a bigger front bar and a rear bar, too. Several of the normal performance vendors will add/upgrade both the front and rear bars. The following basic details are for adding a rear bar to the early cars, or beefing up the bar on the later cars. Be aware that adding/changing the rear bar without modifying the front one will change the car's handling characteristics--specifically, it will have more tendency to oversteer.

Adding a 4000 Quattro front sway bar to the rear of a 20V (Ray Tomlinson, Rick Houck)
The rear control arms on the 20v are identical to the front control arms on the 4KQ. Here are the parts required:

You will need to fabricate two brackets to support the bar against the subframe. One option is to find a generic swaybar mounting kit and bolt the swaybar mounts to the bracket that holds the inner portion of the rear tie rods. You also may need to find some subframe mount bushings other than those listed that will fit into your custom bracket.

See also: Bushings, Suspension Problems

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