I have been running the Unobtanium nylon bushing set (all the suspension bushings are installed, but I am using the stock diff mounts) for a while and I recently decided to switch back to stock bushings to make my car a little more comfortable to drive. With the stiffer-than-stock springs (currently 450F/350R), metal-on-metal at the lower spring seats, heavily-damped shocks (GAB super-R), solid bushings, and rollbar connected to the rear shock towers (loud inside car) my car has become pretty loud and punishing to drive. Maybe I am just getting old, but I am looking to soften it up and make it a little quieter.

I have also grown fond of softer suspension tuning than I was before -- a softer, more forgiving car is easier to drive fast so long as it doesn't bottom out or wack-out the suspension geometry at the extemes (the FD suspension is pretty well-behaved in this regard). A stiff, ultra-low (and ultra-low travel) race-style suspension is probably faster in the hands of a true race car driver, but I think I can get more out of a friendlier suspension setup that I feel more confident in driving near the limit.

I bought used arms with the stock bushings still installed for all the spots where the Unobtanium bushings go, except for the trailing links (I might leave those or get some aftermarket arms to keep wheel hop in check -- my car has had zero wheel hop since I switched to the nylon bushings and aftermarket toe links). Tonight I installed the rear upper arms, which have 3 rubber bushings (or nylon bushings) and one pillow ball. I have some clunks in my rear suspension, and I figured that my Unobtanium bushings had developed some slop since I never re-greased them after the initial install.

What I found was that the two Unobtanium bushings at the body side of the upper arm were still very tight -- no slop at all. I couldn't even move the pins with my fingers even though I know the suspension moved freely with the arms installed. The bolts were tight, so I am sure the pin was stationary while the bushing moved around it. I had used some anti-sieze grease for the initial install (~3 years and 15K miles ago?) and had never regreased them. The nylon bushing at the bottom of the rear shock did have a little play, but I had cleaned those out once and never regreased them (I know, but I was feeling lazy at the time). I am not sure if the play was caused by lack of lube, or if they just wear out in that position, and I don't think we can draw any conclusions from my experience other than an unlubed nylon bushing will develop play at the bottom of the rear shock. What I also found and was not expecting was that the pillow ***** in the upper arm had developed a fair amount of play, even though they were only ~20K (?) miles old. Those come with a little grease on them, and the outer surface of the grease was still very clean, which tells me that it wasn't bad dust seals that caused them to loosen. I have become aware that the manual recommends that you add grease to them even though I did not (since they were already greased) when I installed them, but I don't think that was a factor. It's hard to draw a strong conclusion from that, but my hunch is that the nylon bushings contributed to the pillow ball wearing out so quickly.

The car is a little softer and a little quieter now, but it looks like I need to replace the pillow ***** again. I still need to replace the other nylon bushings. I raised the ride height and softened the shocks, too (settings were 3F/2R, now 1F/1R, but I think I'll up the fronts to 2 again after driving it). The stock rubber bushings seem to last a long time. I recommend sticking with them unless you are willing to give up a lot of comfort for a little precision. When I first installed the nylon bushings, I think I underestimated the change in ride comfort. They make the impacts more severe, but it doesn't seem like that big a deal on the first drive. After a while, it adds up to interior rattles and a fatiguing ride over any pavement that isn't smooth. The added precision is nice, but it just isn't worth the compromise in ride comfort to me anymore.

-Max

 

I have not run an entire set of nylon bushings but my feelings on a daily driven car would agree with you I'm sure.

As for the pillowballs, my car eats them too. Seems the one pillowball in the upper arm always wears out first.

 

Max great great info. Glad to see your car back on the road!

 

Drat! I was hoping I'd get more life out of them with the rubber bushings in the other positions. I'm still hopeful...

-Max

 

Max,

i second the comment that it is great to have you out on the road again.

you made the right move as to bushings... in my view the fd does need two bushings to be changed out...

in the rear of the car the lower longitudinal links have large rubber bushings that convey most of the braking and acceleration forces. it is the wrong design for the function. i run a nylon bushing w a steel insert. Rotary Exteme, Pettit, and perhaps other vendors sell a chrome moly tubular link w a spherical rod end replacing the bid gob of rubber. most fds that haven't done this mod are going toe in/toe out under braking and acceleration.
since the link transfers breaking and acceleration forces and doesn't support vehicle weight you won't change the NVH.

the other bushings is the differential bushings. again, they are big round rubber bushings. when you jack your car up under the differential note how the jack moves the diff over an inch up before the car moves! bad bad bad. i run nylon.

the rest of the car should run on OEM bushings as there is little slop due to the modest amount of rubber employed.

keep us updated as to your R85 setup... 74 lbs/minute tanslates into 570 rwhp when properly cared and fed. it's a good thing you have those CCWs.

howard coleman

 

Howard,

Are you talking about the toe control linkage or the trailing arms?

 

trailing arms

 

That's an interesting theory. How much time did the car spend on the track during those 15k miles? Hard use is hard use, of course. A race car with a spherical bearing suspension would likely have had them all replaced at least once in that interval.

As I showed in my cut-away photo, there is a Nylon "cup" inside the rear pillow bushings, and it's possible that under hard use, the cup deforms regardless of what the inner bushings are made of. The Nylon is certainly stiff, perhaps stiffer than the grade used in the pillow bushings. Hard to say.

To be fair, would you characterize the rest of your suspension choices and your 18" low profile tires as particularly forgiving? I don't think ride harshness can be solely attributed to the bushings, although you are right that they will not soak up the bumps or noise like the stock rubber bushings will.

I'm sure they transfered more noise, but having ridden in and driven three cars with them, I wouldn't say that they made the ride harsh. All three had "lesser" suspensions; one with stock shocks and springs (R1, FWIW), two with Koni yellows and Eibach or RB springs. None had anything more "aggressive" than a 40-series tire. Maybe that's the difference, maybe not. Hard to say.

You know Max, I didn't even know you had my bushings on your car.

 

In my opinion the perfect compromise btwn the nylon and stock bushings would be the Mazdaspeed bushings, which if you're buying oem bushings, wouldn't be that much of a difference in price. Just my 2cents. Here is an example of what I'm talking about in this thread:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/beefier-trailing-arm-bushings-oem-395279/

 

Max,

I've done the same thing primarily due to a quest for an easier to drive track car and a more comfortable/forgiving ride. Also had a failure in one of the rear bushings, but this was due to a rear brake failure and overheating.

I swapped the control arm and A-arm bushings for the Mazdaspeed units and am very pleased (retained the shock mount and diff bushings). The car is more predictable in turns and transitions. Brekaway is much more progressive compared to the twitchy felling I experienced with the bushings. That is not to say that Jim's bushings are bad, but I may not be a good enough driver to fully take advantage of them. The car was much more sentitive small changes in alignment setting as well- as one would suspect.

I have some brand new pillow ball bushings if you want them. Still in original Mazda packaging. I'll sell them for 1/2 of what I paid from Mazda Comp.

Gene

 

Jim, the car only spent a few hundred (300? definitely less than 1000) of those miles on the track. It was very interesting to see the stock pillow ball that you cut away. I always thought those were metal on metal, but it's clear now that they are metal on plastic/nylon. I wonder if some metal on metal spherical bearings would last longer (or shorter)?

In general in the automotive aftermarket world, it is not uncommon to find that stiff bushings cause other parts of the suspension (or wheel bearings) to wear out more quickly than normal. It's my hunch that for the FD's rear upper arms, stiffer bushings at the body cause the pillow ball to wear out faster, based on what I have observed on my car. It isn't conclusive proof by any means, but if I had to bet on it I would bet that this is true. As with anything I choose to run on my car, it is 100% my responsibility to deal with the side effects.

My street tires are 40 series on 17" wheels, and the ride is still more harsh than I would like. My spring rates are stiffer than stock (450F/350R), but less stiff than most coil-overs. The super-R shocks are pretty "stiff", I would say, but they are much more comfortable at the lowest settings (1 or 2 out of 8). I think switching back to the rubber bushings in most of the bushings positions will help tame the harshness.

This isn't an attack on the Unobtanium bushing set. They are nice in that they make the suspension feel very precise, and with the exception of the one I foolishly un-lubed, the ones I have checked so far have held up extremely well (much better than I expected). But I have decided to give up some precision for a little more ride comfort and hopefully reduced wear on the pillow *****. I just posted this thread to share my experiences, see what other people had found, and perhaps help someone that is considering a bushing swap to know what to expect, good or bad. I don't think I have made any unreasonable claims about them in either direction.

Gene, I want your extra pillow *****. I sent you a PM. Thanks.

-Max

 

Max, Howard, Jim and Gene.
A flashback to the go old days on the "Big List".......

 

When I said that I thought it was an interesting theory, I meant just that... it is an interesting theory, and something I hadn't thought about. I don't know how we'd go about proving or disproving it, especially since Damon doesn't have my inner control arm bushings but also has accelerated pillow bushing wear.

It'll be interesting to find out, especially since I have 30 and 35 series tires and JICs with stiffer springs and pillow mounts, as well as a combination of OEM, Nylon, and aftermarket (FEED) pillow bushings.

I know that, and I hope you didn't think my post was intended to be an attack on you.

I don't either. Thanks for sharing your experience.

 

Missed this post.

Was thinking the same thing, though present days are pretty damn good too.

Gene

 

I think a big part of my discomfort is the noise. I've tried to pay better attention to what is so fatiguing about my car as I have been driving it lately, and while I can live with some of the suspension harshness, the high level of noise drives me crazy. Softening the shock settings and/or the rear upper a-arm swap has actually helped a lot. But I need to up the shock settings again to get the suspension to work correctly. The front was bouncing around a turn I took this morning pretty badly -- hopefully I can just go back up to 2 instead of 3 which is what I was running before.

Part of it is exhaust noise, and although I have tried to choose quiet stuff already (cat, old-style RS*R/RB cat-back), it still drones pretty badly. I've got a number of wacky ideas (short muffler and/or bigger, heavier cat in midpipe to replace my small HF cat, perhaps some other mass-adding exhaust coatings/covers, sound deadening material in the doors, spare tire well, floor above exhaust, engine-bay exhaust coatings/blankets, quieter intake) to make it quieter, but I think I need to try some out and see how much they help before recommending them. I think I will start by doing some dB-level measurements on a familiar stretch of road so that I can actually measure my progress.

The roll bar connected to the shock towers makes the car very noisy inside on anything but the smoothest roads. If you have a similar setup, I would start by looking at some upper shock mounts that have some rubber in them. And/or some rubber pads between the upper mount and the body. The stock car has those thin white plastic-looking "gaskets" (for lack of a better term). I did not install those, and I don't know if they were even designed with the goal of reducing the amount of noise transmitted to the body from the shock top, but it seems like a good place to start to quiet things down. I also need to install some padding on my roll bar, so I will be looking for something that seems like it will reduce noise (some padding has a soft rubber-like feel in its surface layer, I think -- that should help with the noise).

There is a lot of other "impact noise" in the suspension as well, and I have a lot of interior rattles now, too. Running over rough pavement (deteriorated asphalt) makes me cringe and slow down now like it never has before (maybe I should have slowed down before! ). I am hoping the switch back to rubber bushings will reduce some of the noise from the suspension, and I should probably spend some time tracking down and fixing my interior noises.

Perhaps it is asking a lot, but I would love to have a car that was reasonably comfortable to drive, that I could feel confident in pushing to (or near) the limits in the turns, lay down some serious power on my way out of a turn or just going straight, won't spew noxious fumes in mass quantities, and won't make me deaf or attract too much attention from law enforcement. I'm not sure how it will end up, but I am willing to give up some ultimate performance and try some not-so-sports-car-like things to see how much more livable I can make my car. I remember doing a track day with a guy who had sound deadening installed in his new Z-06. I thought that was very odd at the time, and against the purpose of the car, but I understand the motivation now all too well and plan to do some of the same in my car. I just want a little comfort so that I can eat my ham sandwich and explore Twinkie aerodynamics in peace on the straightaways.

-Max

 

I ordered the trunk floor cover and a carpeted pass-through panel before I even picked up my Z06 because I'd read about the interior noise. ~3,200 miles on the way home was proof enough that something needed to be done. With the panels in place, it was much more pleasant inside and even the stereo sounded better, so I know what you're talking about. I'm making some of the same changes myself, not that I'll be driving my car any time soon.

 

I've driven a stock Z-06 and it is pretty loud, even when off the gas and just cruising on the highway. It sounds like you made a good choice with your accessories. But I sure wish I could make my car *only* that loud.

-Max

 

Max, I hate squeaks and rattles too. Over the winter I spent a few weekends fixing noises that I notice when I drive everyday. I replaced some clips on the b pillars, added some foam weatherstrip around the divider to keep it from rattling over the bins, found the rattle in my dash (my missing shock adjustor was in its bowels!), built new swaybar mounts and added thrust bearings to the swaybar. I also disassembled the divider and packed it with insulation. That made a nice improvement in keeping noise from the hatch in reaching me. Replacing my original stock rubber shock mounts with new stock ones also quieted the car some. I feel that most of the noise I get now comes from the hatch area through the floor and the rear shock towers. I plan to add sound insulation to those locations and see what happens. I already have sound insulation in the doors (big improvement!).

 

I replaced the arms on one side of my front suspension over the weekend and have some new findings to report:

- upper ball joint was bad
- some play (not major) in Unobtanium upper control arm bushings
- lower ball joint was fine
- Unobtanium lower control arm bushings had no play
- a little play in the rod ends from my Tri-Point sway bar, but not enough to prompt me to replace them yet

I had a spare set of upper arms with stock rubber bushings to swap in, but the ball joints on those are loose, too. So I ordered new ones from Malloy. $510. Ouch, but it's worth it to get rid of the clunks and vagueness.

I also swapped in some used lower control arms with the stock rubber bushings. I might switch back to the arms with the Unobtanium bushings, though, if the car feels too mushy.

As part of my quest to make the car quieter and more comfortable, I also ordered some sound deadening stuff from McMaster-Carr (part # 9709T19, plus some of the 3-ply aluminum stuff since it seemed to have better specs, though I now doubt the numbers after looking at them both). They are both dampeners rather than absorbers or barriers. I am sure the doors could benefit from some dampener material, but I think I might like to get some absorbtion and barrier action in there, too. For the rear hatch area, it seems like all three would be helpful there as well. I might lay down some of the dampener I already bought. I have heard from a reliable source that hot water heater blanket makes a good absorber, and that shower curtain stuff makes a good barrier, both of which are available cheap from Home Depot. I guess the magic configuration (if you have the room) is to make a sandwich of absorber-barrier-absorber. Sounds like a good recipe for the cargo area divider and the spare tire well (since the spare wheel no longer fits over the brakes at either end of my car). Installing the absorber stuff inside trim panels is said to be helpful, in addition to using it on the hatch floor, etc. I still want to do some measurements and see how much difference it makes, but it's so hard to find the time that I might just start installing and hope for good results.

-Max

 

Max, given the large area of potential sound leaks in the FD, I would think the damping material would be more effective than barrier material. It's hard to predict such things with zero test data in front of me.

FWIW, David Hayes had a thread in the Interior forum regarding the application of a damping compound to the chassis. He did sound measurements before and after (and I "hounded" him to do them right! ) and posted the results. You should take a look at what damping can do, especially given the thin sheet metal used in our cars.

 

Thanks for the info, I will check that out.

And I got some more info on the Home Depot supplies tonight -- the "yellow with foil backing" hot water heater stuff is a good absorber. And it isn't shower curtain stuff, but rather some shower barrier stuff you put in the walls that is supposed to be a good sound barrier. However, I think a heavy vinyl shower curtain is also a good barrier.

-Max

 

Found the thread. Interesting stuff. 13 dB!

I'm going to see how I do with Home Depot and McMaster Carr before I try anything expensive.

-Max

 

Post the link!

 

Oh yeah, I meant to do that the first time. Here it is:
https://www.rx7club.com/interior-exterior-audio-26/quietcoat-sound-dampening-195306/

-Max

 

These are the two nylon bushings that I'm looking for. I already have Jim's solid diff mounts. Jim would you have an extra pair for the longitudinal links?