65 shimmy, bad bushing
 

I just bought a 96 miata for 1900 off of ebay. It runs very good except for a random miss and a shimmy at 65. I had thought the shimmy might be due to a poor balance job, I recently put new tires on it, but when we put it up on the lift we found the drivers side rear knuckle to be loose. The tire has play if you grip it at 9 oclock and 3 oclock and shake it.

I work at a Honda dealership and get parts at discount as well as labor at $10 an hour. They are telling me that, If I can get a new bushing for the upper arm, and if the bushing there can be pressed out, then thats the way to go. Otherwise Im going to need to replace the entire knuckle.

Anyone have input on this? Im not knowledgable on suspension, so am not sure Im even using the correct terminology.

You can easily replace all the rubber bushings that are propably long gone by now. You can replace with new OEM style rubber bushings, which appears to be quite a task or get replacement polyurethane bushings. It took me about 2 hours to replace all my rear bushings here recently. All I had was the $40 bushing tool from harbor freight and it wasn't too big of a deal. I don't know what your goal is for the car, but a whole new set of front and rear bushings will greatly help to tighten the suspension up. Last time I checked you could get the F/R bushing kit for around $150 without the diff bushings. Don't get the diff poly bushings unless you have serious track goals for the car, they are not fun on the street. I ended up pulling the poly diff bushings out and putting rubber ones back in due to diff noise.

This is great news. do you happen to remember where you got your bushings?

the kit is $170 off ebay. it's also the master kit so includes end link and diff bushings.

http://www.ebay.com/itm/Prothane-199...-/270990407399

A friend of mine bought it and I can confirm that it's exactly the same as I got from 949racing. 90-97 kit also fits NBs, you just can't use the endlink bushings (and why should you...? stock endlinks suck anyways).

The ONLY issue with the prothane kit is that if you follow the instructions, the outer bushings on the rear lower control arms will be too tight for the knuckle to fit. All you have to do is put the "skinner" bushing inside (they have different lip thickness) and not inside like the manual suggests.

I got mine off of ebay a while back. I thinnk it was around $180 for the full master kit.

As for the random miss, have you checked or replaced the plugs? Hows the compression? Coil packs are known the give problems from time to time. Might pick up a spare set and swap them out if nothing else is fruitful.

Add boost.

I finally figured out what was causing the miss. I had bad wiring on the CAS.

Can anyone here tell me their experience with urethane / nolathane versus OEM rubber style...?

At some point I will need to replace bushes and my only experience was with an rx3 back in the day. It helped make the ride pretty unforgiving and promptly made all the other rubber bushings / ball joints etc fail.

For a DD and track day car is Urethane okay or more track orientated...?

For example the description above of the diff bushings (and others saying similar) make me think I would not do those...