Small Change Saves Big Bills (Post #133)

This exploded diagram of a 1900 Alfa's rear suspension from the official Alfa Model 1900 Parts Catalog solved a mystery, saved me a lot of trouble, and once again proved that you cannot take too many photos or make too many sketches when you are in the disassembly phase.

I took The Alfatross' rear suspension apart about 25 years ago when I still had not learned that lesson. I bagged all the parts and labeled them but--digital photography being at that time not even a glimmer in anyone's eye--did not have the means to photograph everything in its original location on the car.

When I reassembled the rear suspension about 18 months ago I re-used almost all the original cleaned and restored parts except for the drop stop straps.  The originals were made of some kind of fibrous material that was worn, frayed, tattered, and unsafe so I replaced them with widely available new reproductions that come with neatly cut holes ready to install. 

All I had to do was bolt the straps to the chassis under the big rubber bump stops, wrap them around the axle, and connect the ends. Among the rear suspension parts I had two small steel plates with holes matching the spacing on the straps, but mistakenly assumed [Mistake No. 1: don't assume anything.  Spend the time necessary to think it through.] that the straps were supposed to be secured end-to-end, which would mean that I was really supposed to have four little plates, not just two [Mistake No. 2: The more assumptions you have to make, the more unlikely an explanation is.] So I cut and drilled two steel attachment pieces, each with four holes to fill that function--and thought I was being very resourceful.

The "over-improved" drop stops utilizing
fabricated plates to connect the strap end-
to-end instead of overlapping. The result of
a failure to apply Occam's Razor.

The drop stop clamp plates.  Note the distinctive
ridges along the edges.

The Parts Catalog drawing of the drop stop shows clearly
that the strap ends overlap each other and (not so  clearly)
that they are secured with  two sets of bolts, washers, and
nuts passing through the holes in the straps and clamp
(no. 29). 

While replacing the rear suspension springs in order to lower the ride height I had occasion to look at the exploded diagram in the Parts Catalog again. This time, I noticed the small window in the upper right corner showing all the parts for both the drop- and bump-stops and finally realized that I had the right parts all along, I just wasn't putting them together right!  Not only that, I went to a lot of unnecessary trouble to do it all wrong!

Correcting this seemingly small mistake shortens the strap length and reduces the distance the rear axle can move downward by more than an inch. I am sure the Alfa engineers who designed the suspension system set the drop stop distance where it is for a reason, and allowing the rear axle to move an inch or more downward could cause damage to other components under certain circumstances, so I am relieved to correct this mistake in time.  It also means that the exhaust system can be attached an inch closer to the chassis. 

Correct attachment with strap ends overlapping and held together
with 10 mm bolts passing through the steel clamp plate, straps, washers, and
secured with nuts. 

So now, having removed or detached, replaced or reconnected the fuel pump, fuel lines, brake lines, emergency brake lines, axle supports, drive shaft, rear springs and drop stops in order to get the ride height sorted out . . . I can finally get back to where I was a month ago: attaching the new exhaust system.  

High Anxiety (Post # 132)

The Alfatross in about 1966.  The ride height is correct
and the tires fill the wheel openings nicely. Pat Braden.

I realize that the thread for The Alfatross' blog right now pertains to fitting the new exhaust system, but in order to continue with that we have to go back to fooling around with the suspension system because the exhaust passes underneath the rear axle. In order to figure out how close to the chassis to fit the exhaust, we have to know the vehicle's ride height and how far the rear axle can drop before being restrained by the "drop stop" straps. So there are two elements in The Alfatross' current rear axle configuration that have to be modified: the springs and how the drop stop straps are connected.

The Alfatross' ride height after fitting reproduction
springs front and rear--are we going off-roading or what?

The fact that the Alfatross' springs made it ride too high, particularly in the rear, was as obvious as it was puzzling. When I disassembled the suspension system 3 years ago I discovered that one of the front springs was broken, but the original rear springs were in perfect condition.  I knew I would have to find or make new front springs but figured I could re-use the rears.

The ride height is much better after using shims to lower
the front suspension and fitting springs re-designed and
manufactured by Hyperco.

I heard that other 1900C SSZ owners were experiencing similar ride height problems. Only later, after David Smith sent me a copy of the Alfa Romeo Model 1900 Parts Catalog, did I discover that there are at least 8 different rear spring types for different Model 1900 variants including 1900C, 1900L, 1900C SS, 1900 ambulance and, finally, 1900 C Super Sprint dalla vettura no. 10,001 Coupe Zagato! Up to that point I thought there were only two spring types, one for regular production Alfas and another for coach-built lighter cars like Zagatos. Photos of The Alfatross from the 1960s show it with the kind of original ride height I am looking for.  With the probability of finding OEM springs being vanishingly small the only alternative was to have new ones designed and manufactured. 

I got in touch with Peter Marshall who supplied me with copies of period technical drawings and specifications for front and rear springs specifically designed for Zagato-bodied 1900s.  Hyperco (http://www.hypercoils.com/) used that information to reproduce the new front and rear springs that I installed before the Arizona Concours d'Elegance in January 2016.  I didn't like the ride height, it was too high, but didn't have the time or energy to rework the entire suspension system until this summer. 

Shimming the front suspension was fairly easy and lowered the front ride height without modifying the springs, but the only way to lower the rear suspension was to manufacture "new" new springs.  I have no idea how to make a spring, but I now know that it takes a lot of data-gathering and analysis before any actual spring steel gets bent into a spiral--and you won't know if you got it right until you fit them to the car!  Hyperco engineer Mark Campbell used the weights and dimensions I sent him to fabricate a pair of "new" new rear springs.  Now that the old exhaust system is off the car it was time to install them. 

The process of separating the rear axle from the car so that the old springs could be removed and the new ones installed turned out to be a lot easier than the first two times I did it, which surprised me because this time I did it by myself.  I guess it was a good example of "practice makes perfect".  I hope I never have to do it again as long as I live, but this time I wrote down the 14 steps it takes--just in case I do.  After all, I didn't think I would have to do it more than once and it has already been 3 times!

The new Hyperco rear axle spring at left
compared to the taller reproduction spring
fabricated exactly according to Zagato
specifications--but still too tall!

The ride height before installing the new springs.  The top
of the wheel arch is 29 3/8 in. from the bottom of the tire.

After fitting the new new rear springs the ride height is 3
inches lower--just about right!

I think that the ride height in the rear will "settle" further over time. In any case with a full tank of gas, both front seats back in the car and a driver and passenger the height will be lower still.

So now I can get back to finishing the exhaust system, right?  Not so fast! What about those drop stops mentioned in the first paragraph?  Are they too insignificant to mention? No!  They are so important they deserve a post of their own--(Post #131) . . . .