The Alfatross

The Alfatross
The Alfatross in 1965 and 50 years later in 2016

Saturday, August 1, 2015

Suspension Animation (Post # 89)

Not suspended animation, suspension animation--the state of working vigorously on the suspension system. The Alfatross' front suspension with double A-arms, telescoping shock absorbers, and coil springs and its worm-and-sector steering system are pretty simple and straight-forward. But that doesn't mean they are easy to refurbish.  


The basic A-arm configuration.  Upper and lower control
arms connected by the steering knuckle, four pivot points
per arm, each requiring a bushing. 

Following disassembly Jeff Kramer and I determined that some of the the 16 copper-alloy sleeve bearings (sometimes called bushings) in the A-arms were worn and should probably be replaced. In the spirit of "In for a penny, in for a pound" we elected to replace them all as well as the four sleeve bearings for the kingpins.  






One of the original sleeve bearings, showing wear and 

corrosion.


New sleeve bearings are readily available on line, so parts were not a problem. This time the problem was ingenuity: getting the old sleeve bearings out, pressing the new ones in, reaming the new ones to fit the pins on the steering knuckles and A-arm pivot points, and align-reaming the new bushings for the kingpins. Modern suspension systems don't use sleeve bearings, so your average gearheads, like us, have never done this type of work. How hard can it be, we thought, and dived in, cheerfully oblivious to what we were getting ourselves into

The first thing we needed was a selection of "stepped" bushing drivers to press the old sleeves out, so once again we called on machinist Jeff Robison for his help making them to the right dimensions. This is where we got a surprise. One would expect the dimensions of the suspension members of an Alfa Romeo to be metric, but they were all Imperial. We had already noticed that the brake system and shock absorbers were made by Girling.  Now it seemed that the suspension system was also British made.


A selection of some of the tools we had to buy or fabricate to get the job done.  The Chadwick & Trefethen reamers are at the top.  Jeff Robison made the three drivers on the right, the brass "sleeve expander" on the left, and the aluminum collar in the center.

Pressing out the old bearings turned out to be the only easy part of the job. By "easy" I mean relative to putting a man on the moon.    



One of the 16 sleeve bearing joints needing replacement. 
Press out the old one, search the Web for replacements,
press in the new one, ream the new one to fit the specific
pin it will receive. Repeat 16 times--and don't screw up!


A stepped driver in position on an A-arm, 
ready for pressing. the first step fits inside 
the bearing.  The second step catches on the
lip of the bearing and presses it out. The 
third step limits the travel.






The original sleeve bearings seem to have been
technically superior to the new ones.  Note that they
are "split" instead of being a solid tube,  that the
split has a "dove-tail" tab to limit expansion, and that
they are bi-metallic: steel on the outside and copper
alloy on the inside.

All of the original sleeve bearings bore this logo: 
PV LTD. Anybody recognize the manufacturer? 
The LTD seems to suggest British origin.



Two sleeve bearings became loose during the
reaming process and had to be tightened up
using the "sleeve expander" manufactured by
Jeff Robison. Problem solved.

Hand-reaming the newly installed sleeve
bearings.  Each bearing took about 30 minutes
to ream to fit the specific pin it would  receive.
I hope I never have to do this again!



Reaming the sleeve bearings in one of the spindles with a self-aligning Chadwick & Trefethen reamer made specially for this purpose.  Don't leave home without it!

The tie rod ends held even more surprises.  Again there was no indication of who made them, but the dimensions of the threaded elements and nuts were all Imperial, so they probably originated in Great Britain. Some of the originals were re-usable but others were not and they are not rebuildable either, so new units were necessary.  Several on-line vendors offer tie rod ends, but none of them have the same dimensions as the originals.  

We ended up with a set of 6, 3 of which had right-hand metric threads on the tie-rod ends while the other 3 had left-hand Imperial threads on their tie rod ends.  Go figure.  So now we are going to have to make our own tie rods with metric threads on one end and Imperial threads on the other!   

The original tie rod ends, also manufactured to Imperial
dimensions.  They bore no logo or manufacturer's name, 
and could not be rebuilt.
After conferring with Dan Allen I now suspect the tie rod ends that were on the car when I bought it in 1969 may not have been original. He sent me the photo below of a tie rod end from a Matta, an Alfa Romeo-produced vehicle similar to the American Jeep that shared many parts with the 1900. With the right spanner you could remove the top to clean and recondition it. Dan thinks Alfa 1900s produced in the mid-1950s probably carried this type of tie-rod end. If anyone out there has definitive information about this subject, I'm all ears!



A tie-rod end from an Alfa Romeo Matta.
Dan Allen.