Until the car see major braking and acceleration forces, the thrust issue is insignificant. Again, if the bushing is made and installed properly, there shouldn't even be contact, and it definitely shouldn't change with bolt torque. I design my bushing so that the sleeve is 0.010" longer than the bushing stack up when everything is installed. Bushing flanges should never be preloaded. No one else has made similar observations because they have good, properly installed bushings, and this doesn't occur. Also, testing it while the car is on jack stands the way you guys are doing in no way represents the real world for the specific data you are taking from this. You are loading the thrust faces like they should never be loaded, while not loading the arm laterally at all. While in use, in a 1G turn, the bushings will see over 1000lbs radially. There is no doubt the radial friction is far greater than any axial thrust loads while in use.

This is definitely an issue with poly bushings on the LCA rear facing bushing halves while under hard braking, as evidenced by the thrust face tearing I have documented in the mega thread. Short of custom machining the bushings, there is no way to fit a thrust element in there, as I have mentioned.

The sales pitch on the Nylatron bushings sounds good, but the primary benefit of moly impregnated Nylatron GSM over standard Delrin seems to be that it has less friction and more wear resistance (and therefore implied that it should not require any lubrication maintenance). From some layman's googling, it looks like standard Delrin actually has superior properties over standard Nylatron in most of the ways that concern us for this application (compression/rebound, friction/wear, and possibly water absorption/expansion?). The moly impregnated version of Nylatron used in these bushings should have slightly less friction/wear and be lighter (although I can't imagine the weight difference being substantial enough to affect 99% of builds) than standard Delrin, but is it substantially better than a properly greased/lubed Delrin bushing? I assume it would still be as susceptible dust and moisture intrusion as Delrin is, which is most of the reason for adding the grease fittings to Delrin bushings anyway, right? The idea of a set-it-and-forget-it "nearly perfect" bushing appeals to me, but can the Nylatron really deliver any better than Delrin--and without adding grease fittings?

Sean this might be a dumbass question but at what point is a bushing set worthwhile for a car that has had very little attention to it's suspension over the years. My 99 Miata has near new BC BR coilovers but everything else is worn out, stock standard stuff. I want to get the lot up to par but don't know if this kit is overkill or not for a hillclimb/autocross car...

There are a lot of variables, what are you doing with the car, preferences, current condition, etc. And you're asking me about a competitors kit....

Good point.

Here's the situation: Standard car, suspension has been serviced but never overhauled since factory. Kid chucks brand new BC BRs on it, then sells to me 1000km after losing interest.

My plan is for the car to be a weekend hills car, that can drive to the track, put in a half day worth of laps then drive home. I can handle a hard car to drive on the street but don't see the point in a ridiculously stiff setup as it doesn't make me any faster on the track (the opposite actually).

Assuming all of this, would one of your bushing kits be worthwhile?

The Sadfab kit is a substantial improvement over stock blown out bushings in any environment and makes a huge difference on track in my opinion even when compared to poly.

You can see my review here:
https://www.miataturbo.net/suspensio...ing-kit-88399/

Awesome, thanks mate. This is exactly what I was looking for. I don't want to just replace stock for stock then find out I want to upgrade later anyway.

FWIW the bushing material doesn't add to the stiffness of the car, springs do. Bushing will increase NVH, but not as bad as most think. Going from stock to say 500/300 springs will increase the stiffness and NVH of the car wayyyy more than going to solid type bushings.

If I had to make up some bullshit to put into perspective, Id say going from rubber to delrin/nylon is like adding 100lbs of spring. A dual purpose car usually gets 2-300lbs of spring rate added, real race cars can be almost 1000lbs.

I run delrin on the street with no issues.

For what it sounds like you do, probably not worth it.

Ehhh, debatable. To be fair I didn't see that "weekend hills car" translated to "hillclimb" car. I read "weekend hills" to be the ubiquitous "canyons, bro".

He stated canyons and track use, and also doesn't mind a small increase in NVH. So yes it's a worthwhile modification. End of debate.

Replacing 25 year old dried-out bushings is worth doing for any car that isn't just a plain beater, IMHO. The SadFab kit is the least expensive way of doing that that doesn't have all kinds of nasty drawbacks (like the need to constantly relube polys, or delrin binding in the alignment slots).

--Ian

I don't think there's ANY nvh increase from this. It just makes everything work better.

I have a kit for my dedicated street-only car.

See this is why I'm on this forum and not those other hairdresser forums.

When I say streetable car, I've done the whole AE71 Toyota with chopped Falcon springs for a laugh, or a 5 puck clutch in my Evo 5, all 100% fine for the street. I'm happy with trade offs, I just don't want a spastically jarring ride for no reason. Delrin sounds fine for what I'll do in this car.

damn i clicked into the thread hoping to find good info on the A1 ground control bushing option haha.

anyway, has anyone here used this set? curious how it can use all nylatron bushings rather than the usual poly in the "misaligned" areas. is nylatron a little more pliable than delrin?