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[NA & NB] Zerk fittings when installing poly bushings

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suspension
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58K views 34 replies 24 participants last post by  TicTac  
#1 ·
Hi guys,

I tried to find a dedicated thread about zerk installation on Miata arms, my search was unsuccessful. -If you know of a dedicated thread just drop the link here.

If you already had a look, you probably found Emilio's page.

I was not so happy about the location of zerks on rear arms.
The lower are, in my opinion, too exposed to be safe.
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The rear upper arms are known to be a problem because of suspension travel.
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For both rear arms, I have come out with my solution.

Here it goes :

I chose to use an already existing cavity, probably used in plant to hold various sheet metal parts before welding.

Here is the top rear arms, on the left hand, you can see the cavities I was referring to.
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I chose to put the zerks in these holes.
My zerks come from here : http://cgi.ebay.co.uk/ws/eBayISAPI..../eBayISAPI.dll?ViewItem&item=230557333229&ssPageName=STRK:MEWNX:IT#ht_500wt_922
specs : M6 thread. 7mm hex key.

To accommodate their size, I had to enlarge the holes to a good 10mm, 11mm to 12mm are even better but I had no 11 or 12mm drill that day.

Drilled at 10mm + 5mm hole for the zerk, both must be perfectly centered. (the picture makes it look like it's off, but it isn't)
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M6 tapping
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Zerk installed
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From the inside (of course, deburr as required)
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As my arms were powder coated before I had the chance to install the zerks, I removed paint in the process... No problem, a little rattle can and away it goes.
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On the bushing side, I slightly modified them to make sure the grease goes through perfectly.
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The tool :D
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Here is what it looks like once modified & installed
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The rear upper arms were done as follows :
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With the nipple caps, my 7mm hex key could just fit, this is why I recommend to drill a bit larger than 10mm.
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Looking perfect to me !
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If you need a scale : look here

Yes, the grease pump still fit on the zerk, just picture it as if it was one of the caps
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The rear lower arms were done following the same idea, to avoid any possible damages with objects on the road.
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The other locations are pretty straight forward looking at this picture or on 949 website.
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One last thing : don't always try to locate the zerk in the center of where it goes, but look at where is the junction between two bushings. It is sometimes offset a few millimeters ;)

Useful links :
zerks on ebay UK
Caps on ebay UK
949 Racing zerk page
My friend's Dustin official "red neck bushing removal tool" thread

Hope it helps!
 
#30 ·
its kinda frustrating... you find a great how-to thread from a couple years ago, only to realize most of the OP's picture links are dead. For threads like this, it'd be nice to see the images hosted somewhere permanent.
 
#35 · (Edited)
Just finished this project, and this thread helped me so I thought I would contribute some lessons learned. (This applies to Energy Suspension bushings).

***** Disassembly *****

It took heroic efforts to loosen some of the 18 year old suspension nuts.

The "long bolt" on the front upper arms was particularly bad to remove on one side, and it is blocked by a brake line bracket making it impossible to get a socket on it. A 21 mm box wrench was required...and I ended up denting the wrench faces on the open end of it. Using the ratcheting end, I had to hang off of the car with both arms like a monkey while using my foot on the wrench to do a full one-leg press on it to get it to crack loose, then beat on the wrench with a 3 lb hammer to work it loose. (That was after the PB blaster and trying to heat it...). We ended up demolishing that nut and a couple others on the rear.

The castle nuts weren't much better, and we had to grind one of them off. The ball joints also took heroic efforts to break loose, even with a ball joint separator tool and beating on the knuckle and/or separator tool with a 3 lb hammer. Both lower ball joints became missiles when they broke loose...shooting literally about 10 ft across the room. (Don't stand in front of that if a friend is working on it!)

After going through all of that trouble, there's no reason to not replace all of the ball joint and tie rod boots with OEM ones. (I ordered the Energy Suspension ones first, then decided to use the OEM ones since they contain an internal metal retaining ring). The ES ones came in handy for temporarily covering the joints while working on the arms, but I wouldn't want to use them in the final assembly.

I decided to replace several of the nuts and a couple of the corroded bolts. The long bolt nut part number was not represented correctly on the Miata parts diagram, and was not available from Mazda parts places that I checked. I ended up ordering this from Belmetric (conical locking flange nut). I had trouble finding places online that sell metric nuts with the smaller wrench sizes (which are known as "JIS" sizes) but Belmetric had a couple sizes that I was looking for.

I decided to apply anti seize on all parts prior to reassembly.


****** Painting *****

Cleaned up the arms using a wire wheel, sandpaper, and metal files. Used mineral spirits to get the grease off, and then got some Duplicolor wax and grease remover to remove any residue from the mineral spirits. (That wax and grease remover evaporates much more quickly than mineral spirits and is hard to work with due to the rapid evaporation, but seemed to do the job).

Used just over 1 can of POR-15 Top Coat spray paint for 2 coats on the arms. I originally ordered this after seeing the statement on the can (i.e., that it doesn't require primer). The fine print says to use their special prep cleaner and wash for best results, which would add significantly to the cost of the (already expensive) paint job. Although this concerned me not to use the suggested prep, I decided I would take my chances with just my own prep, and (while premature) I think the paint adhered well to my prep and it appears to be tough stuff.


****** Assembly ******

As reported elsewhere, a good thing to use for the OEM ball joint boots are PVC pipe adapters. A few whacks from a 3 lb hammer will get them seated. After some research I used Red Line CV2 grease for the ball joints. Hopefully it will be good enough.

The tapping of holes for zerks sounded difficult (I had never used a tap), but it proved to be one of the easier and more fun parts of the job. It takes maybe 5-10 minutes per hole to drill and tap.

I got two kinds of M6 zerks, but found them to be slightly different sizes. The first ones I got were stainless, from FittingsAndAdapters.com. These worked well for most of the holes except for the ones on the rear upper control arms, where I drilled the holes concentric with the existing holes in the support brace. (Used a 1/2 inch bit to enlarge the holes in the support brace). These zerks weren't quite long enough and the grease gun didn't get enough bite on them. I also had ordered some M6 (non-stainless) zerks from Fastenall, which were slightly taller by about 2-3 mm, and they worked better.

I found that using a utility knife to cut notches in the bushings to accomodate the zerks was much easier, quicker, and cleaner than using a drill or grinder. It takes about 5 seconds to cut a notch.

The front upper control arm bushings could be a problem as they do not have the little grooves to allow the grease to flow, and they fit very tightly. I think there may be just enough gap there for a tiny amount of grease to flow under high pressure, but on 3 out of the 4 bushings front upper bushings, the amount of grease that pushed out was almost too small to see.

I found that after assembling and torquing some bolts, that the bushings rubbed against the car, causing the bushings to rotate within the control arms. (This was perhaps not helped by the fact that I lubed outside the bushings as well as inside, at first). For example, the gap between the rear outer lower bushings was not wide enough to accommodate the wheel knuckle. Also, the rear upper inner bushings and rear lower inner bushings were also rubbing and binding somewhat. I decided to trim all 10 of these bushings (per rear corner - or 20 bushings total) to make them a little shorter (maybe 0.5 mm per bushing) but also to round the shoulder so the outside is shorter than the center. The best way I found to do this was to use a drill press with a drum sanding wheel and hold the bushing inside a 1.5 inch PVC pipe to keep the bushing aligned, then rotate the bushing inside the PVC slowly with my gloved hands. Still it was a slow process - maybe 10-15 minutes per bushing just shaving them. In hindsight it would have been better to shave all of the bushings up front before greasing them, but as I wasn't aware that they needed to be shaved, they were already greased and it got messy pushing the bushings out repeatedly.

I created a pair of jigs that aided in a couple of tasks. Took some wood (3/4" x 3 x 3) and used a 1 1/4" spade bit to counter-sink maybe 1/8 or 3/16", and put a small/shortish bolt through the center from the other side (also counter sunk to make the head flush). The jigs can then be placed on both sides of a bushing / metal sleeve combo and inserted into a vice or square-faced clamp to push them into position while allowing the metal sleeve to protude slightly (which you want for some of them). More useful than that however, is that they allow you to push the bushings back in after they have been primed with grease (which pushes them out a bit) and the countersunk areas allow the excess grease to escape while the non-countersunk part pushes on the bushing. The screw is just to keep the jig kind of centered on the metal sleeve.

Hope this helps someone.