Do all poly bushings require zerk fittings?
 

After 122K chassis miles my FD just feels too soft handling and steering-wise. I'm interested in a full bushing replacement and am weighing poly vs OEM. I've done some searching but this is far from my area of expertise so would still like a more definitive answer, if I go for poly bushings is it also imperative to install zerk or grease fittings? Are they required on some (control-arms for example) and some not (steering rack would seem an obvious "no" but what about say, trailing arms)?

How about for Durometer rating? I hear that Powerflex can special mold some yellow70A bushings rather than the regular purple 80A, and I read somewhere that if the bushings are soft enough, grease fittings are not needed. Can anyone confirm or rebuke that statement?

Thanks lots, I'm excited to tighten up the car's feel!

I installed purple ones on the tow links and trailing arms only, no zerks. they squeak very annoyingly, no idea if zercs would solve that.

I was afraid of that, but honest feedback is what I wanted. Thanks!

The Mazdaspeed 40% stiffer rubber suspension bushings and engine/rear end mounting bushings are a VERY attractive alternative to poly.

I've been veeeery tempted by those. The only downside I see to Mazdaspeed is the cost. But after all this back and forth "Should I? Shouldn't I?" there's a point at which I think "do you want to do this right or what?!"

I think I'll end up going Mazdaspeed if I can, even if it means buying and installing one set at a time as I save up.

Again, Thanks!

I have a combination of the Powerflex purple, J-Auto pillows, M2 Heim-joint trailing and toe arms, and Mazdaspeed comp bushings in the 360-degree locations, which I installed on my recent rebuild. I like the combo. I used the high-end waterproof poly grease on the Powerflex bushings and greased the living hell out of them, inside, outside and along the metal internal rod. No squeaks at all so far but time will tell.
Mike

There's an extremely thorough write up on a miata forum about this. What I got it from it was yes, zerks are needed and the inside of the bushings needs modified to uniformly accept the grease. Honestly, I don't see a reason to not install zerks. The arm is off and right there with the bushing out. It would be a few minutes to install the fitting. Even greasing them to infinity and beyond, it will wear out eventually. I guess it just depends if you want to play the time game or not. Even if you never use the zerks at least you have the option down the line. Once they start squeeking, you can ignore it or do something. If you have zerks installed then a solution presents itself.

Thanks all for the responses, I've talked to Ray Crowe who gave some sage advice and suggested against replacing all of them at once as I was going to do, but instead prying on each and looking for play to find just what bushings need replacing. I'll be doing that first off. I'll also be having mine pressed in by a shop that, fingers crossed, knows what they're doing and can prevent damage while pressing.

Well keep in mind, once you beef up the other bushings the old ones will have more of a load on them and fail premature...... or right on time. As much life as we got out of our bushings, I would say mazda got their money worth out of them. Just something to think about......

I redid every bushing, front and back, myself on my recent rebuild. It is enough work getting everything apart, back together, and then realigned to do it bushing by bushing. I totally agree with cr-rex, they all go out around the same time give or take a few thousand miles and anyone that is left over will go out quicker due to the added stress. I have redone mine 3 times since I have had the car which I bought brand new in 1994 and I have only 78,000 original miles.
Mike

Good points both, thanks for that. Guess I've got lots to consider then.

Mike (and others who've gone through the full refresh), gotta ask, how big of a difference did it make? Big revelation or minor improvement?

I think it depends on what shape the suspension is in when you start. I had a lot of play on the rear pillows but the other bushings were not as bad. Also, mine is a street car with only a little track time once every 1-2 years for fun. I saw a significant improvement in cornering, Straight line not so much. Also, I switched from old Tokico shocks with Racing Beat springs to FP Spec Ohlins coilovers set for more street 8/10kg. That made a huge difference on rough roads.
Mike

Where can i get those? I would like some stiffer engine mounts without having to go Poly.

I purchase my Mazda or Mazdaspeed parts through Mazda Motorsports, but you have to sign up for their sponsorship program (race at least 2 races a year).

https://store.mazdamotorsports.com/w...0001&langId=-1

I typed F128-39-040-050A into google search bar and I found there is a pair for sale on Ebay for $780 (about the same price as stock pair btw).

Running all poly at the moment and if i were building a street car, would use mazda comps for the control arms and keep the diff and engine mounts poly.

Zerks arent that hard. Key is you need to get the lube to the inner race. Some instruction...

https://rallyways.com/5564/part-1-po...-installation/

Polyurethane bushing grease fitting install - Nissan Road Racing Forums

Directly from Mazda motorsports is not an option here unfortunatley. :(

I have the IR Performance poly engine mounts. I like them a lot. They are stiffer than stock but are not as rigid or stiff as typical polys that I have experienced with others cars(whole car shakes some at idle). Ihor from IR Performance added a second small softer poly bushing below the subframe than takes up some of the vibration typical of poly mounts. Good compromise and smart idea I believe. Fair price too, check out their website.
Mike

I know you were asking about suspension bushings, but just FWIW, I remembered that Racing Beat does sell the MAZDASPEED differential bushings... Competition Differential Mount for 93-95 RX-7 - Racing Beat