Rear Leaf Spring Shackles - Polyurethane Upgrade

Fresh Air Inspector

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Hello All,

Please let me know if I should be posting this in the Police Forum as my car has the AHB package.

Need some feedback - hopefully someone has done this already.

I'm in the midst of installing the ESPO polyurethane bushings in my rear suspension. The bushings for the shackles have a flat face where they meet the sides of the shackle. This is very different from the original which is dished to match the shackle face. I've attached pictures; #1 - shows the original style on the left and the polyurethane on the right, note the convex surface on the original versus the flat face of the polyurethane. #2 shows the inner surface of shackle with the convex recess for the factory bushing. I assume the polyurethane bushings need to be modified to match the factory ones. Polyurethane doesn't compress or deform very well.

Has anyone installed these ESPO bushings? If so, did you modify the bushings to match the factory ones? What tool(s) did you use?

Looking forward to the feedback.

Shackle Bushing - 1.JPG


Shackle Bushing - 2.JPG
 

AMC Diplomat

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I used their polyurethane ISO spring pads. They looked a little small, but by the time I had everything torqued to spec, they had conformed to the space exactly. I imagine their shackle bushings do the same.
 

Aspen500

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They can go in as-is. Don't forget the poly bushing lube. One suggestion. Wear nitryl gloves. That bushing lube is basically impossible to wash off your skin. Don't ask how I discovered that, lol.
 

Kern Dog

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I can absolutely attest to the value of that Polyurethane lube.
It is a really unique and strange substance that seems to both lubricate and stick to almost anything.
 

Fresh Air Inspector

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Hello All,

Appreciate the feedback.

I'm still can't get my head around the differences between the Polyurethane bushings and the originals. So, I have started to modify the bushings to match the originals. I'm using a Dremel tool with a cone shaped abrasive stone to trim the bushing. I'll share some pictures when I'm finished.

The lubricant provided with Polyurethane bushings is a grade 2 synthetic grease (NLGI 2). Yes, it is extremely sticky stuff that requires gloves. It is available via Amazon in various sizes, the link below is for a pair 3 oz. tubes.


Hope it helps.
 

AMC Diplomat

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No need to modify them. They squish when torqued and they take the shape they need too.

Same thing with the front sway bar bushings. Those showed up like hard pucks, but when torqued they took the shape they needed to.
 

Fresh Air Inspector

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Hello AMC Diplomat,

As always, your feedback is welcome and appreciated. I still have a hard time getting my head around using the polyurethane bushings 'as is' and having to 'squish' them to install. To me it will distort the bushing and significantly increase the friction between the shackle side plates and the bushing.

I decided to slightly modify each bushing. Prior to modifying the bushing I measured the distance between the bushing and the side plate, it was approximately 6 mm (1/4"). Managed to reduce this to approximately 3 mm (1/8"). I won't know if this makes any difference until I bolt everything up. Even then I won't be able to compare an installed original unmodified bushing to a modified one. I guess I'll have to live with the assumption that my modification made a difference. :)

If anyone would like to know the details of how I modified the bushing please let me know and I'll detail it including pictures as part of this thread.

The picture shows three bushings; the modified Polyurethane one on the left, unmodified one in the middle and on the right, a standard aftermarket bushing (Dayco).

Shackle Bushing - 3.JPG


Hope it helps.
 
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