Solid Differential bushings
 

Has anyone made or tried solid (Delrin UHMW) differential bushings?

Have lots of clutch chatter so I thought I would make a set.
Probably will be noisy and rough but this isnt a daily driver.

I apparently have'em, but I can't guide you any because this car is still new to me....
https://www.miataturbo.net/forum/t24080

I made and installed some in the diff for my Locost 7, but never finished it so I can't help. Pretty easy to make, though. Mine were UHMW. Sorry I can't help more.

ISC racing makes some for Prod-class Miatas:

Miata_Brake_Dif

I bought them from ISC, as well as a full delrin control arm bushing set...but the only ones I have installed so far are the front control arm bushings. Good guy to work with...I like giving him my money because he's a little dude with a lathe in a barn somewhere from the looks of it ...haha

I have MMRs waiting to go in, I've been wondering the same thing.

I should have them in this evening. Ill post after that

I got the diff bushings in. THey are UHMW with a 1" steel insert. Every thing has a slight interference fit so theres no play at all. The original mounts would sag an inch plus when I lowered the jack from the diff. The clutch chatter is much better. I would say the car feels better in general and shifting is consistant. On the freeway I get some vibration transfer above 65. Other than that it isnt harsh at all. The vibration may be another problem so Ill have to check bearings etc. Other than the freeway vibration Id say all good and no bad. I have a really rough road leading to my house and Id expected it would be awful. The car actually seems better over bumps.

I was able to change them without removing the diff. Undid the bushing plates and lowered the diff carefully to spare the shifter boot. An air chissel with blunted tip (swore Id never own one) can be used to drive the bushings out. Then if the hard bushings dont have too much interference you can pull them in by hand and use the jack and then bushing lower plates to seat them fully.
If you dont have to make the parts an hour job so long as the new bushings aren't super tight. I had about .001 interference and a start taper.

Sounds like a worthwhile mod. So the car overall feels a bit more "solid"?

I used MMR mounts for two years in my STS2 car. It almost completely eliminated shudder and hop and only a slight buzz was added to the chassis noise. I used them along with MazdaMotorsports engine mounts. The chassis wasn't buzzy like using solid engine mounts.

FWIW, I'm putting together another non-turbo street car and will use the same motor and diff mount setup.

A friend made a few sets out of solid steel - they were a pretty slick design. We tried them on a couple of cars without mishap, but never brought them to market. I might be able to get a bunch made up if there's interest.

I have a set of Delrin bushings. nothing compared to solid motor mounts. i don't really notice them other than the car is more "rigid"

FM is selling some Solid Diff Bushings right now. I think it is in the group buy section, they need 10 people or something....

edit..
just saw the post from Keith at FM... guess they decided to put it up on the site.

I have these from FM
Flyin' Miata : Chassis : Bushings : Energy Suspension differential bushings
According to them they are a good compromise between the stock or MSM mounts and the Delrin types. Much stiffer than rubber, but not nearly as noisy as delrin.

I can hear the differential R&P whine a bit now but it is not bad at all, no big deal for me. And this is in a DD with a hard top (quiet). I would do the same thing again if I had to do it over. FWIW I also have Mazda competition engine mounts.

Ah snap, just saw the not for a DD part. Disregard.

^ Good to hear good things about these, as I have them waiting to be put on my car :D

I have a set of MMR Bushings...really not bad at all. Some slightly vibration/ass massaging at certain RPMs but that is about it