Re: trailing arms/Lemforder/Engineering/steering boxes

[yvesbou@mail.francomedia.qc.ca (yves boulanger et liette robin)]

>Date: Thu, 19 Feb 1998 13:29:53 +1100
>From: "Reid, Warren" <Warren.Reid@dsto.defence.gov.au>
>Subject: 105 trailing arm interchangeability
>
>Can anyone tell me if all the rear suspension trailing arms are the same
>(interchangeable) across the 105 series?
>

>Also rubber bushes v's urethane bushes, any opinions on
>drivability/harshness?
>
>Thanks in advance

(This was written and sent before the "changeover". I believe it was lost)

I never heard about different dimensions for the trailing arms themselves
but a change was made to a larger diameter and softer forward bushing in the
late sixties. I think they were introduced with the 1750; you don't state if
your GTV is a Giulia or a 1750. The earlier, smaller bushings allow a more
accurate positioning of the rear axle, and reduce rear axle steering effects
under power - at the price of somewhat increased haqrshness.

Regarding polyurethane bushings: I am a technical advisor for a transit
fleet and we had a bad experience with them a couple years ago. They were
sold to us as "the cure" for the rapid deterioration  (6 months!) we were
experiencing with rubber bushings ever since the first GM New Look bus hit
the road in 1960; their life was no better than the rubber ones but we ended
up damaging adjacent components.

A rubber bushing is normally bonded to inner and outer steel sleeves; if we
look at a forward trailing arm bush, the outer sleeve is pressed in the arm
while the inner one is held fixed to the chassis by the bolt. As the
suspension is compressed, there will be torsion in the rubber to accomodate
for the rotation of the arm around its pivot (bolt). But if the car goes
around a corner, body roll will also make the trailing arms rotate with
relation to the body, around an axis that is parallel to the arms. The
bushings have to flex laterally to accomodate this.

With the poly bushings, hardly any flex or torsion can accomodate these
motions. Poly bushings typically have an inner sleeve that is allowed to
rotate in the bush, to accomodate rotation of the arm around its bolt. But
the bushing is too stiff to accomodate any other type of motion, and during
body roll, the rotation of the arm will most likely be accomodated by flex
of the arm itself, which is an open C section. This imposes loadings on
suspension components that they were not designed for; eventually something
is going to give. Pray and hope that it's the bushing. Bus trailing arms
have forged loops, and the poly bushings split some of them open. We also
had rust on the inner sleeve, which then eroded the inside diameter of the
bushings.

I'd keep poly bushings for properly designed racing applications, or for the
few cases where only rotation is necessary - such as the body mounts for a
sway bar.

I already expect some people to rub their hands saying "See? Once again, the
original designer knew what he was doing..."

Sorry folks, that's just the way it turned out this time.

Y. Boulanger, M. Eng.

>Date: Thu, 19 Feb 98 04:34:20 UT
>From: "Alvin Porter" <alpo4@classic.msn.com>
>Subject: Wanted: Source for Lemforder ball joints
>
For all I remember, Lemforder is a branch of ZF (US headquarters:
(847)634-3500). Lemforder also had a plant in Maine. For older Alfas,
Ehrenreich was also a supplier of balljoints. Funny how much German stuff
there is on Alfas... (ZF, ATE, Fichtel und Sachs, Bosch and so on..., even
the horrendous Goodyear radials Alfa used in the 70's)

Subject: steering boxes and their removal on 105 cars...

The steering box that is connected to the column by a removable coupling and
universal joint was introduced at some point of 1973 production (1974 model
year for US market). It was part of a collapsible column set-up, and I don't
know if it was also used on European spec cars.

I have taken out the earlier version (with permanently attached column) on
two occasions; since in both cases I was retrofitting a later-style steering
box, I dismantled the box in place. Remove the four bolts from the flange
attaching the column to the box, remove the top cover of the box, and
"unscrew" the steering column shaft out... of course, all the balls will now
fall out. If you plan to reuse the same box, it will need to be completely
cleaned before reassembly. I hope you haven't lost the balls.

The only other way I could figure to get the steering box out, involved
taking the engine out. Any better idea?

Y. Boulanger