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European Car Magazine - GTV6 Project

 

 

Part 2 - Suspension Upgrade

European Car Magazine - March 1995

Author - Paul Mitchell
Photos by Brendan Lopez and Paul Mitchell
 

   

You're approaching the left-hand, off camber sweeper quickly; almost too quickly, in fourth gear.  While trying not to lift off the throttle abruptly and yet brake, you double-clutch down to third.  As you turn in, aiming for a late apex, you feel the car begin to shift its weight to the right, and the tires reach their maximum slip-angles and take a set, right at their limit of adhesion.  

What happens next?  Either a difficult corner is successfully negotiated or it is significantly and, probably painfully, not.  It is this one point in time that a lot of us look so forward to, and work so hard for.  It's also why many of us own Alfa Romeos They are known as one of the most consistently neutral handling cars.  Their suspensions are engineered for this one purpose.  Not for comfort, nor economy, just cornering.  

Returning for this article is our Alfa Romeo project car-a 1983 GTV-6. You'll remember in our last article (ec,1-95) we undertook engine  reliability and performance upgrades.  These have resulted in a 25-30 bhp increase (pending dyno results) and vastly improved reliability with lower maintenance.  

But let me first begin by making a correction to our first article: We listed the wrong phone number for Sperry Valve Works.  Mike's fax machine will never be the same again.  The correct phone number is (310) 988-5960.  His outstanding porting and polishing of the heads of our GTV-6 were featured in the 1-95 issue. 

Due to its similarity, I've also decided to include a 1989 Milano 3.0 in this discussion.  Except for a very few design details, the Milano can essentially be looked at as four-door GTV-6.  Especially in chassis and suspension design, they are virtually identical.  It only makes sense to include the Milano here for the benefit of our readers who may wish to enjoy the benefits of improved handling.  

While many manufacturers every few years tout their newly redesigned multilink suspensions, Alfa has without fanfare or criticism used essentially the same basic suspension layouts since the '50s.  It's not because Alfa's engineers are lazy, but when they proved that something worked through competition they stayed with it, choosing instead to refine a design rather than re-invent it.  For example, this constant refinement is evident in that one can trace the De Dion rear suspension used in conjunction with a rear-mounted transaxle in these cars back to the 159 Alfetta Grand Prix cars, and the 2000 Sportiva.  You may also note that many Ferraris and a hodgepodge of other classic sports cars used this layout.  

In staying with established designs, Alfa has left itself open to the facile ridicule of those who are more concerned with following trends than coming to grips with technology proven and well established.  This is evident by the fact that the Milano 3.0 develops a .83 lateral g on the factory supplied 195-55-15 tires.  This is a figure comparable to its direct competitors using "new" suspension designs and much larger tires.  And the Alfa provides handling as tossable and as neutral as most mid-engine coupes due to its 50/50 weight distribution.  

When starting with such a good platform, it's difficult to improve upon it without messing it up.  Many well intentioned but poorly informed owners have slapped on stiffer springs, lowered their cars, installed different shocks, and ended up with a car that handled far worse.  In fact, some changes result in vices it never had originally, such as bump-steer.  

Putting together and testing a suspension package of your own design is an expensive and time-consuming process.  It truly doesn’t make much sense when there are complete packages available.  Your main concern should then be choosing a set-up that has been thoroughly tested (preferably through competition) for reliability and increased performance.  

That is the purpose of this article, to present the reader with our choice of a suspension package that provides the maximum amount of cornering ability while still maintaining a decent ride.  

For the selection of the equipment, our job was- made somewhat more simple by the fact that there are only a few reputable suspension packages available for the GTV-6 and Milano.  I have relied on my own experience with these two cars and on the vast technical knowledge and experience of Rex Chalmers of Omega Motorsports of  Culver City, California. 

Not only has he provided many of  his customers with improved handling over a number of years, he has both a GTV-6 and a Milano 3.0, both of which enjoy the improvements which we'll set into soon.

But let's take a look at the stock suspension on both models.  These unique cars are rear-wheel drive with an all-aluminium engine placed in the front.  At the rear, an all-aluminum five-speed transaxle and clutch assembly (dual-plate on the GTV-6) provide helps provide the ideal weight distribution.  To take advantage of this, in the front there are un-equal length A-arms sprung with longitudinal torsion bars and a swaybar.  Uniquely, the rear is equipped with a DeDion tube laterally located with a Watts linkage.  This provides the low unsprung weight advantage of a fully independent suspension, with none of the disadvantages, such as unwanted camber changes when braking or cornering.  To further the unsprung weight advantage, the rear brakes are mounted inboard at the transaxle.  Additionally, the front shock absorbers are mounted in an inverted position to further decrease unsprung weight. 

This photo of the left front suspension also shows the sway bar, castor rod and stout Brembo brake calipers

This is the right front sway-bar mount with the Shankle re-inforcement plate beneath it. Once in place, it is MIG welded to the body. To the right is the finned aluminium oil sump.

The rear suspension is sprung with variable-rate coil springs and is also provided with a swaybar.

The stock suspension has no real handling or reliability problems.  Turn-in is precise and ample road feel is transmitted through the rack and pinion steering ( ZF speed-sensitive power-assist on the Milano).  The stock dampening is more than sufficient, and enough attention was paid to the placement of the roll center so that the car has that glued-to-the-road, cornering-on-rails feel but is still exceedingly tossable.  The term agile constantly comes to mind. 

With very little understeer, corners may be entered very quickly.  In fact, to induce oversteer, one must enter the corner quite quickly, turn in a little early, and as the chassis begins to set, step on the throttle.  This results in wonderfully controlled four-wheel drifts. 

And when the apex is reached too quickly, lifting off the throttle completely disastrous in some cars-simply causes the GTV-6 to tighten its line through the corner with no sign of oversteer.  A wholly desirable and unique characteristic usually only found in mid-engine cars, it's a direct function of the Alfa's 50 / 50 weight distribution. 

This technique allows the GTV-6 driver to plunge into corners and then bleed off speed by lifting off the throttle just before the apex, when drivers of cars with trailing throttle oversteer are having a hard time staying out of the weeds.  Many are left wide-eyed by this technique, and their estimation of your driving skills will jump off the scale. 

The suspensions of these cars are very reliable with little maintenance and are relatively easy to service with few special tools required.  To perform the operations we'll be covering, I recommend having the Ball Joint Tool #ST60, available through Alfa Ricambi for $37.90. and the Torsion Bar Removal Tool, Alfa part #A.3.0374, available through your Alfa dealer for approximately $85. 

These procedures are not terribly difficult but do require some mechanical aptitude and knowledge of basic hand tools and safety procedures.  If at all uncertain about any of these operations,  you'll find the factory service manual a great asset, and I recommend always having it on hand.  You can find it also through Alfa Ricambi and your dealer for approximately $75. 

The bushings are well designed and manufactured, many by Pirelli.  The bushings which usually require the most attention are the upper castor rod bushings in the front suspension.  They are available through Alfa Ricambi or your dealer for about $4.00 each.  

If you have a Milano with a leaking power steering pump, the driver's side castor rod bushing will have deteriorated and needs to be replaced due to being saturated with power steering fluid from your P/S pump above it.  

The only other items which may require attention are the lower ball joints.  They are usually trouble free, but it is likely that they will go away before any others.  They are also available through Alfa Ricambi or your Alfa dealer for about $25 each.  To install these properly you will need the previously mentioned ball joint tool.  Having used it to free the lower ball joint from the steering knuckle, remove the nut securing the ball joint to the lower A-arm.  Use a cold chisel or air chisel if  necessary to separate the ball joint from the A-arm, taking care not to damage the A-arm.  This ball joint tool is also required to adjust the  torsion bars for ride height, which we will  get into later. 

Service of the ZF power steering pump and rack of the Milano, which tend to leak if neglected, will be the subject of a subsequent article. 

As a matter of course, though, should the boots of your steering rack be damaged in any way, they should be replaced immediately.  Boots are available through the sources mentioned above and are cheap insurance for rack longevity. 

The rear suspension is as close to being trouble-free as any you'll find.  Bushings within the Watts linkage seldom require attention, and the DeDion tube bushing tends to be fairly long lived.  Its passing into the afterlife, where all bushings must inevitably go, will be marked by a clunking sound upon acceleration or deceleration.  Keep in mind that this could also indicate that a passenger side transaxle mount has joined our De Dion bushing in the afterlife, so be sure to check both.

The castor rod bushing, visible in the centre of this photo is probably the weakest of all bushings. Luckily, they only cost a couple of dollars and require little time to replace.

Looking at the left front suspension, we see the lower ball joint as described in the article. Also visible is the inverted front shock, sway bar link and torsion bar.

Modifications

The purpose of these modifications is to improve the handling through decreased body roll, provide a slightly lower center of gravity while maintaining proper roll center geometry, and increased dampening-all while still maintaining a reasonable level of ride comfort and clearance. 

After inspecting and the subjective  testing of several available suspension systems, Chalmers and I decided that the Shankle Super Sport provided the best combination of handling and ride. Consisting of front torsion bars, rear coil springs and front and rear sway bars, it has been thoroughly tested in competition and street use by many enthusiasts.  Shankle has spent considerable time developing suspensions for Alfa Romeos and will usually have several choices available for your car, beginning with the 750 Guiliettas of  the 1950s.  Shankle also produces a full line of Alfa Romeo performance products and tools.  Alfa Ricambi is the  exclusive distributor of Shankle. 

The Shankle Super Sport components will lower the GTV-6 approximately 1.5 to 2.0 in. and stiffen the ride by 39 percent for the GTV-6 and 57 percent for the Milano.  We elected not to go with the torsion bars but to stay with the stock bars, as we felt that good balance was reached when combined with the Shankle rear springs, L0470.  We then would adjust the front ride height to match that of the new rear springs.  The rear springs are manufactured of 9254 steel and have a rate of 143 lb/in. 

The front sway bar, AL4705, is manufactured of 1018/1024 steel and has a diameter of 27 mm.  The rear bar is constructed of the same material and its diameter is 25.4 mm.  When installing the front bar, it's recommended you also install the Shankle way bar reinforcement plates, AL5775 and AL5776.  These will protect against a tendency of the front swaybar  mounts to crack due to the additional stress caused by a bigger bar.  

For improved dampening we chose Koni high-pressure gas shocks for the GTV-6 and Koni special D shocks for the Milano.  Keep in mind that since the suspensions are virtually identical, shocks could be interchanged, and this invites experimentation.  We felt that our choices made here were the best, considering the cars and their respective drivers. 

You may personally feel that you may want more or less dampening.  Koni also produces an excellent low-pressure gas shock for these cars, so you may want to try that also.  Alfa Ricambi and many quality aftermarket distributors carry Koni products, so you shouldn't have any trouble finding them. 

When properly installed, these components will significantly improve the handling and maintain proper suspension geometry.  I have had this very combination installed three years on my Milano 3.0 and have had no problems while delivering absolutely outstanding performance.  

 

Here we see the rear suspension, Including the
deDion tube and Watts linkage, which provides
lateral location of the deDion tube. Also in the shot,
the rear mounted five-speed gearbox and the
in-board rear brakes.

Procedures

Most of the procedures involved in installing these components are very straightforward, and here we will only concern ourselves with those specific to these models.  To go forward, you should have available the previously mentioned Ball joint Tool and the Torsion Bar Removal Tool.  You may substitute the Torsion Bar Tool by using a socket with a larger inside diameter than the rear end of the torsion bar.  Bv placing this over the rear of the torsion bar mount, then placing a large washer over the back of the socket and inserting through it a bolt which will thread into the threaded hole in the torsion bar, you may extract the bar, thus alleviating the need for the tool. just buy the tool.  

While you're there, buy the factory manual, too.  It will get you out of more situations than I'll get you into.

Ride Height Adjustment
Ride height adjustment is carried out by rotating the torsion bars with respect to the indices on the front lower A-arms and rear mount within the cross member.  The bars are provided with a different number of splines (35 front, 34 rear) at each end, essentially a vernier scale, allowing precise adjustments to be made.  When removing the bars, take care not to switch them over.  The bars are marked by the following code: Left by a yellow mark and the letter S or L: right by a blue mark and the letter D or R. You shouldn't have to worry about this since the bars don't need to be fully removed to be adjusted, but I included it here just in case. 

Using a marker, grease pencil or scribe, mark the position of the factory indices on the A-arm and cross member in relation to the splines on the bars.  By employing the torsion bar removal tool or your substitute (you cheapskate), withdraw the torsion  bars to the rear so that the splines are completely free.  Complete the ride height adjustment by rotating the torsion bar by one tooth at each for every 1.5 mm to 2.0 mm of required adjustment.  Viewing the bars from the rear, rotate the right side bar counterclock  wise to lower the car and clockwise to raise the car.  You adjust the left bar in the same manner, but rotate the bar clockwise to lower the ride height and counterclockwise to raise it. 

Use this formula to correct ride height: (amount of required correction in inches) divided by .059  (number of splines rotated).  Round off the number of splines to be rotated, such as 10.4 is read as 10. 

Reinsert the bars, remembering to permanently mark the original factory indices, and temporarily mark your new splines corresponding to the factory indices.  These may be marked permanently once you've verified the new ride height, but always distinguish them from the original factory reference marks.

Front and Rear Sway Bar and Rear Coil Spring Installation
The sway bars come with installation instructions and complete hardware. The front is a simple matter of unfastening the original and bolting in the Shankle bit.  The bar hardware should never be tightened while the suspension is in the droop position during installation.  Only tighten it once the full weight  of the car is on it, otherwise you will pre-load the torsion bar, causing uneven handling.  This applies to both bars. 

The rear bar is a bit more difficult to install.  After having lifted the car and supported the chassis with stands, remove the rear wheels.  Next, unfasten the shift linkage at the transaxle (on later GTV-6s and Milanos this is not necessary) and disconnect the bottom  mounts of the shock absorbers.  Unbolt two outer ends of the Watts linkage and the sway bar mounts and move the coil springs-both on GTV and right only on Milanos. disconnect the parking brake cable and support the transaxle with a jack;  also disconnect the electrical wires to the transaxle.  Remove the single bolt fastening the transaxle to the body and lower the transaxle while watching the brake line to ensure that it is not stretched.  You may now remove the sway bar from the car.  Installation is the reverse of removal with the exception of substituting the Shankle coil springs for the originals and following the instructions regarding the Teflon lubricant and anti-squeak tape provided with the bar.

 

In Closing

These modifications have a transformed an extremely well handling car into a car that can generate an amazing amount of lateral g's.  How many g's? You'll have to wait to the end of the series like the rest of us to find out.  It is then that we will present all the dyno, skidpad and braking results.  Let's just say that most people would not believe us. Now the chassis is severely limited by the amount of tire on the car.  That's our next article.