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CarCare101: Project Miata: Prothane Poly Bushing Install

Bruce Nunnally

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So in the last post we completely blew apart Project Miata’s suspension. We did so because everything that could wear out had… some time around about a 100,000 miles ago. So before we can get our suspension back under Project Miata we need to get all those worn out parts replace. Starting with some shiny new Prothane Polyurethane Bushings at all 4 corners.



Step 1 – The Scrub Down:

We’re going to start by giving everything we are going to be reusing a good scrub down. A Parts washer would be great, but I don’t have one so I’ve found that Dawn’s foaming soap works wonders on getting old grease off parts as well as off of you. A scrub brush and a pressure washer really helps too. Though I don’t reccomend taking the pressure washer to your own hide.


Step 2 – Removing the Old Bushings:

This can be a nightmare if you don’t have the right tools. Turns out a quick trip to your local hardware store will procure the necessary 3ft lenght of all thread, hand full of fender washers and several nut’s that you’ll need. As a famous little green space muppet would say “Size matters not”. Just make sure the all thread will fit inside the bushing.

To make this work you just grab a couple of random deep well sockets from your tool box and assemble your new tool as shown.

Note: On the socket side use two nuts to ensure they won’t spin down the all thread. You want the wrench side to be the side that moves.


Step 3 – Bushing Removal Part 2:

So by now you’ve figure out that our backwoods bushing puller will only remove one bushing at a time. The other bushing is still stuck in the control arm.

To get the other one out you need to disassemble the tool and change one of the random deep well sockets to a random big *smurf* deep well socket. Make sure the socket is large enough to clear the entire bushing and rest only on the surrounding metal. It also needs to be deep enough to contain most of the bushing as it gets pressed out.

It should look something like the above photo when reassembled.

Wash, rinse, repeat until all bushing have been removed.

Note: Don’t forget the bushing in the rear uprights!


Step 4 – Clean Up:

So now that all the bushing popped out with out a single hitch thanks to our fablious backwood bushing puller… yeah right that will never happen…

So now that we’ve cussed and cajoled all those bushings out. It’s time to break out the die grinders and go to town cleaning up the control arms, make sure you get all the old rubber that fused to the bushing pockets cleaned out, otherwise the new bushing’s won’t want to go in.


Step 5 – Rust and Grime:

So now it’s time to grab another die grinder and a wire brush or sponge stone and power off 20 years of rust and grime to prep everything for paint.


Step 6 – Paint:

Spray bomb time! This was shot after 1 coat. We endend up putting 3 coats down before we were satisified.


Step 7  - Bits and Pieces:

So here’s what you’ll need to install the prothane bushings. Ignore the parts on the left we’ll get to those in a bit.

To start you’ll want to go through your Prothane Bushing boxes and sort out which sleeves go with what bushings and where they go on which control arm. They all look the same and it’s quite confusing to try and figure it out on the fly.


Step 8 – Super Lube!!!

No this isn’t for use in the bedroom. It’s slicker than greased owl *smurf* and sticks to everything. Wear gloves when messing with this stuff it does not wash off easily. Prothane includes a couple of packs in each box. We ordered a tube for a grease gun from Jegs as well.

Note the siping inside the bushing. This is intended to fill with Super Grease when you slide the bushing over the sleeve.


Step 9 – Sleeve -> Bushing -> Control Arm:

Cover the outside of the bushing with more Super Grease and insert the whole shebang in to the appropriate control arm.

Since we are using polybushings and plenty of lube, everything should slide in by hand provided you took the time to clean out the pockets on the control arms ahead of time. If by chance one or two are a tight fit you can use a c-clamp to press them into place.

Note: DO NOT install the sleeve yet. We will do that bit later.


Step 10 – Drilling for the Zerk Fittings:

Wait… what?

Zerk fittings? For like a grease gun?

Yup exactly. I know it’s kind of old school but it works. Unless you are in to vintage cars or work around farm equipment you probably have never used one of these.


Step 11 – Tap for the Zerk Fittings:

The next step is to tap for the Zerk’s threads. Also check to make sure the hole was drilled all the way though one side of the bushing. Otherwise the sleeve will not say lubed. The idea is to create a passage for the grease gun to force the Super Grease all the way down to the sipes in the bushings we showed you earlier.


Step 12 – The Right Zerk Fitting:

Zerk fitting will allow us to keep our poly bushings well lubed with Super Grease, that way they will never squeak or fuse to the control arms and bind up. The teflon tape you see on the threads of the zerk fitting is simply acting as a weak thread locker to ensure the fittings don’t vibrate loose.


Step 13 – Wash Rinse Repeat:

And that’s all there is to it. Now you just have a couple dozen left to do!

A couple of parting word of advice…

In order to make use of the Zerk fittings you’ve got to make sure you can get access to them. That’s why we have a plethora of diffrent Zerk Fittings we bought to choose from.

So before you start drilling holes, check to make sure you’ll have plenty of clearence for the fitting during suspension travel. And that you can get access to it with a grease gun. This is espically important on the rear upper control arms.

Don’t forget to lube up and insert the sleeves after you install the Zerk fitting


Prothane Poly Bushing Install - Step 01: The Scrub DownProthane Poly Bushing Install - Step 02: Removing the Old BushingsProthane Poly Bushing Install - Step 03: Bushing Removal Part 2Prothane Poly Bushing Install - Step 04: Clean UpProthane Poly Bushing Install - Step 05: Rust and GrimeProthane Poly Bushing Install - Step 06: PaintProthane Poly Bushing Install - Step 07: Bits and PiecesProthane Poly Bushing Install - Step 08: SUPER LUBE!!!Prothane Poly Bushing Install - Step 09: Sleeve -> Bushing -> Control ArmProthane Poly Bushing Install - Step 10: Drilling for Zerk FittingsProthane Poly Bushing Install - Step 11: Tap for the Zerk ThreadsProthane Poly Bushing Install - Step 12: The Right Zerk FittingProthane Poly Bushing Install - Step 13: Wash Rinse Repeat

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