[DeTomaso] Was Removing Poly Bushings - now Squeaks

[Larry Finch]

 I recently spent some time talking with two vendors about their poly bushings.

First, it is important to realize that once installed, the clamping force of the mounting bolt
locks the bushing's metal center sleeve to the body mounting tabs so the sleeve does not rotate.

Second, where things move, things can squeak.

Read on, keeping the two above points in mind.
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There are two distinct styles of poly a-arm bushings currently available;

One uses a round center steel sleeve.

One uses a hexagonal center steel sleeve.

With the round sleeve style, movement can occur in two places:
At the juncture of the poly and the center sleeve AND at the juncture of the poly and the a-arm.
Which juncture sees the most movement is anyone's guess.
But both junctures can see rotational movement from a-arm or poly movement.

Also with this style, since the poly is free to rotate at both junctures, the outside faces of the poly
are free to move in relation to the body mount tabs. This face movement is where Mike thinks the
common squeak comes from. Each bushing has two faces.
So each round steel sleeve style bushing has FOUR squeak zones.
Total squeak zones for the four a-arms using the round sleeve style = 64.
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With the hexagonal sleeve style, movement can ONLY occur in one place:
At the juncture of the poly and the a-arm. 

Why? Because the poly cannot rotate on the hexagonal sleeve as it can on the round sleeve.
With the poly not free to rotate on the hexagonal steel sleeve, that movement zone is eliminated.
Second, as the hexagonal sleeve is clamped firmly to the body mounting tabs, the faces of the poly
hexagonal bushings do not rotate against the body tabs.  Result: two less junctures for squeaking.

So each hexagonal steel sleeve style has ONE squeak zone.
Total squeak zones for the four a-arms using the hexagonal sleeve style = 16
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Now of course grease can be used to address the squeaking of poly bushings.
Some a-arms are modified for the use of zerk fittings so grease can be applied.
Mike suggested the faces of the poly bushings be greased prior to installation.

With the two piece hexagonal bushings, (And I assume the round sleeve style) each piece has a chamfer
on the inside edge. This creates a void that can receive grease from the installed zerks. Under pressure,
this grease easily migrates to the poly and a-arm juncture and prevents squeaking at that juncture. 

Since that juncture is the ONLY movement area with the hexagonal style, they are greased at the only point
of movement. And can be periodically regreased as needed.

While this can also be done with the two piece round sleeve bushings (If they are chamfered) to introduce
grease to the juncture at the a-arm, it does not allow grease access to the the second squeak zone: the
juncture of the poly and the inner round sleeve. Thus that juncture is prone to squeaks. One could drill
a grease passage from the zerk all the way through the poly bushing to the center sleeve. Whether that
passage would remain open and in alignment with the zerk over the passage of time is anyone's guess. 

Likewise, while grease can initially be applied at the junctures of the poly faces and the body tabs,
all 32 such junctures cannot be regreased without considerable effort.
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The hexagonal style is sold by Dennis Quella. I believe all the other vendors use the round sleeve style.

2511 has Quella's poly bushings. It has seen over 35,000 miles of use since my purchase eight years ago,
the a-arm zerks are regularly regreased and I have yet to hear a suspension squeak.

YMMV

Larry