Suspension bushings...what to expect?

So...one of the things that I do not like about the Molvo is that it can be "crashy" on rough roads.

I don't recall my NA Miata being this harsh.

Running pretty much stock suspension: KYB shocks with the front springs moved to the rear and stiffer springs in the front to  deal with the  V8 engine weight. Front springs are Monster Miata parts.

The  chassis is stiff. I added stiffening members under the car and hidden in the sills. Plus a solid roof structure. You can actually jack the front and rear of the car  on one side from in front of the front wheel.

What I suspect is causing the ride harshness is the Energy Suspension bushings. (black) I have a feeling that I should have left the factory rubber bits in place for a nicer ride. Has anyone else who installed these black poly bushings lived to regret it?

I am thinking I want to go back to factory bushings, but have not found a "master kit" that includes all of the required parts. Any leads? I am aware of the FM rubber busing kit from a German supplier, but this is advertised as a stiffer rubber .

Not in a big rush as it is now driving season and I have no interest in pulling the car apart, but I do have a list started for next winter.

Pete

Properly functioning poly bushings (without a bonded crush sleeve, like Polybush has) act more like a bearing. They don't really absorb anything, so do you get some increased NVH from them although you don't get a "spring rate" from them like you do with rubber. More importantly, if they lose their lubrication they will become high friction and very uncomfortable. Lots of crashing. The lube included with Energy Suspension bushings is not long-lived. Honestly, the best thing I can say about the ES parts is that they're very affordable.

I'm personally not a big fan of poly bushes. I pulled a set out of the Targa Miata after the first long test and went back to rubber. I have used SuperPro bushings fairly successfully in the past. 

I don't know if anyone sells a master kit of OE bushings, but it's relatively easy to put one together and order them from your local dealership or Mazda parts supply house. That's what I did with 338. It's not a cheap date, though. I can help you generate a list of all the parts if that helps.

The stiffer rubber from FM (IL Motorsports, which is functionally the same as the Mazda Competition kit) will likely still ride better than poly. I chose to go with OE on 338, I'd run the IL Motorsports on my other cars like the turbo street car.

Thanks Keith. I had a feeling that you would chime in and that you might have that to say. 

I did not install grease nipples when I did the bushing change and you might be right in that it is getting harsher. Guess I have a mandate for next winter.

I don't think grease nipples work on poly bushings, because you need to get the grease between the steel crush sleeve and the bushing. You can drill a hole through the bushing but that only works as long as it doesn't rotate on you. The only real solution is the right lube and lots of maintenance. Or rubber bushings :)

Let me know if you need that parts list for OE bushings.

In reply to Keith Tanner :

If you have such a list it would be useful. Thanks. 

Pete

I'll put it together. I'm about to hit the road for a few days, so feel free to remind me.

In reply to Keith Tanner :

Said to the man who forgets where he put the wrench 2 seconds ago!

I shall try. 

In reply to NOHOME :

I put the IL Motorsport bushings in my previous NB and they were quite nice. They are stiffer than stock but not a lot. They tightened up the handling nicely.

Keith Tanner said:

I don't think grease nipples work on poly bushings, because you need to get the grease between the steel crush sleeve and the bushing. You can drill a hole through the bushing but that only works as long as it doesn't rotate on you. The only real solution is the right lube and lots of maintenance. Or rubber bushings :)

Let me know if you need that parts list for OE bushings.

With the two-piece poly bushings (one going in each side, meeting in the middle) you can get grease to the steel sleeve through the gap between them.  For the single-piece ones if you drill a hole then the zerk does a pretty good job of locking the bushing relative to the mounting arm.

That said, my experience with trying to grease them through zerks is that it finds the path of least resistance, lubing part of one side, but the other remains dry.  It helps, but it's nowhere close to as good as fully disassembling and re-greasing them.

One thing that does work well with polys is the 2-piece sleeves made with oilite/bronze bushings.  949 has a set of them for Miatas, but I dunno if you can get them for other cars.

DeadSkunk (Warren) said:

In reply to NOHOME :

I put the IL Motorsport bushings in my previous NB and they were quite nice. They are stiffer than stock but not a lot. They tightened up the handling nicely.

I just replaced the bushings on our NB with IL Motorsports, and I'm happy with them as well.  Great compromise for a street car.

In reply to codrus (Forum Supporter) :

What I've done to get grease all the way around was to machine groves in the steel sleeves and then to grind a slot to connect them and the hole in the bushing. Now when I grease the bushing the grease has a "tunnel" to travel to all parts of the bushing.

I regretted the poly bushings on my Impala SS.  Noisy no matter how much I lubed them, harsh ride, NVH, and they didn't last as long as rubber.  They finally sanded themselves oversize from rust on the shaft and I replaced with rubber.

Random side note on a totally un-relatable car:  For a while I had some solid steel bushing arms on a 66 Bonneville while I sorted out the suspension.  Granted, the springs were somewhere between soft and marshmallow, but I didn't find them to be offensive.  I had some off-the-shelf Afco racing uppers that were close to the right geometry, so I slapped them on for a while.

I've been itching to try Delrin.

NOHOME said:

What I suspect is causing the ride harshness is the Energy Suspension bushings. (black) I have a feeling that I should have left the factory rubber bits in place for a nicer ride. Has anyone else who installed these black poly bushings lived to regret it?

Yes - every time.  In retrospect, it should be intuitive that pushing a poly bushing in easily by hand after cussing and burning out stock bushings for hours would result in sloppier performance.  Poly bushings wander around on center and then when the car takes a set they bind up suddenly, resulting in darty handling.  I've never been happy with poly for any busing that is supposed to deflect in more than one direction. 

You do need to be careful about where you install them to avoid causing bind - avoiding them where a bushing is supposed to deflect in more than one direction is a good rule of thumb. If you have a triangulated 4-link suspension with cylindrical bushings for example, the worst thing you could do to that suspension would be to allow the bushings to deflect even less.

One place I used them with great success was in the front of my AE92 however. It used to eat front LCA bushings like candy, especially the big ones at the back of the arm. Switched to SuperPro poly bushings and haven't had to worry about them since.

Also steering rack bushings are a good place to go for very hard materials.