I have an FC that is geared toward rally?rallycross racing for my build I am re doing the rear suspension. I have an extra one so I've torn it down and going through the process of sand blasting them down and powdercoating them.

now my question is while I have this extra rear suspension I'm wondering about what bushings to use.

factory new rubber
possible mazdaspeed comp rubber
poly
delrin (http://mazdatrix.com/rmounts.htm)

now would I want it not that stiff as delrin because of the off road harshness?

what do you guys think?

 

If it were my car, I would go with delrin on everything except the bushing for the rear control arm (where the toe adjusting bolt goes through). Use a rubber type (or similar that is flexible) bushings here (i used spherical bearing bushings in my build for this, not happy with them, plus, if you are going to get the car dirty, dirt will find its way into spherical bearings and you will be replacing them left and right).

As far as road harshness vs. solid type bushings. All your road imperfections NEED to be absorbed by your shock absorber and springs, if you have forces trying to go into the bushings directly and you think you are going to break things because of this, you have other problems.

Maintenance wise, delrin/solid type bushings are going to give you less headaches in the long run. If by hashness you mean the car will be vibrating like vibrator, your building a rally car, that should be your last worry.

 

yeah I wasn't thrilled with using a solid bushing for that toe bolt adjuster. I have to wait a few weeks before I hear back from mazdaspeeds' contingency program so I will get a catalog of their parts at discount. I just registered last week so it may take another week or two to be official.

to buy a poly susp bushing kit its about 120 dollars which is tempting to do that then buy mazdaspeed comp diff front diff mount (I still have the stock one....)
the delrin rear swingarm kit is about 180.

I'm keeping my rear diff mounts and rear subframe mounts factory rubber. I will be weld reinforcing the diff and then making a snubnose protector with some lowes/home depot goods lol.



do you have photos of the spherical bearing that you used in your setup? I'm curious to see how it came out

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s5-convertible-tii-extras-swap-project-pictures-877625/page3/

I think the best picture I have is them already mounted to the subframe, but you can see them somewhat. It's the MMR design.

The only rubber bushing I have in the rear is the mazda competition front diff mount. If you have fabrication skills (seems like you do), and while the subframe is apart, you should reinforce the mounting point for the front of the diff on the subframe (where front diff mount meets subframe). I have seen a few people that have broken this section and reinforcing it with some steel plating or similar will help. Another section to possibly reinforce would be the mounting point for the two small stock "camber links" on the subframe (connects subframe to swing arm). I noticed these are easy to bend, but not aware of anyone breaking them.

 

already have that subframe diff mount reinforcement underway

I dropped it off at my welder friends' place but I wont be assembling anything really till dec or late nov.

I can weld okay but when you know people who do it at outstanding quality for a living it makes it easier and better when you just can pay them in beer.