Are the polyurethane bushings harsh ? ( For a daily or occasional street driver )

Or are the stock bushings just fine if replaced when worn ?

I hear some say they are harsh and noisy and others say they're the best thing to do to improve ride and performance.

 

From what I've heard you should go Poly in the front, but Rubber replacements in the rear. I haven't replaced mine *yet* so I can't tell you what that feels like, but folks were saying that doing the poly front/rubber rear is the best way to imporve ride/performance where busings are concerned. The main problem I have is *finding* rubber bushings! The poly ones are everywhere.

Jon

 

I'll be replacing the front bushings [or what little is left of them] with polyurethane to see how it rides. Of course, I won't have any standard of comparison, but I'll let you know how it rides after I get my 7 streetable.

 

I have poly all around. It's not too stiff (I have tokico illuminas, so I can soften the settings). Poly bushings in the front can affect toe in and camber under extreme driving because poly will not compress like rubber. It may also tighten up some slack in your steering. You will definitely feel more vibrations caused by alignment problems or unbalanced wheels.

I've heard tech talk about keeping rubber in the rear instead of poly. I'm not an expert, so maybe someone else can chime in with a good explanation.

Overall, I'm satisfied. I'll never have to worry about worn bushings again.

 

Its ok to use poly in the back except for the upper trailing arms. It's best to leave the old bushings in the uppers unless they're falling apart. If so replace them with rubber.

 

I got the poly w/ my RB sways. Hard to say what makes the ride stiffer but it was mo better. Did the same w/ my Miata & Jacson Racing sways. Never regretted that upgrade - makes a world of difference in cornering stability (flatness).

 

here's my experience with my upgrade...

https://www.rx7club.com/1st-generation-specific-1979-1985-18/waking-her-up-282098/

 

Can anybody shed light on this? Is it because the solid rear axle making 1st gen's tail happy?

 

From my understanding that is the reason. Apparently the polly bushings do not allow for as much flex as the watts link was desinged to have, causeing the watts link to bind earlier and cause sanp overstear. Something that isn't wanted in a well ballenced car. Overstear is nice, just not nice when its sudden and sometimes unexpected. Also I've heard its fine to replace everything in the rear except the wats linkage bushings with polly.

 

The reason you want to leave as much compliance in the upper trailing arms is because they are not parallel to the lower trailing arms. Because they aren't parallel, under cornering load they move in different directions and tend to bind. Poly bushings cause even more binding. When the suspension binds, it ceases to travel, causing a loss of traction and control.

That's my understanding anyhow.

 

Yes.The unequal trailing links and off-center Watts link causes inherient binding in the rearend,even when totally stock.The poly bushing's lack of "give" makes this worse,so its best to leave the rear end alone.Many guys even swiss cheese good condition stock rubber bushings to help aleviate the binding.
I run 100% poly bushings up front and out back is stock excpet poly's in my sway bar(I have 245 rear tires,so it still isnt too tailhappy with the stiffer swaybar.)
The poly fronts are not harsh at all.Id be more worried about too stiff a choice of spring,causing a harsh ride.I run 175lbs all the way around,its firm but nice.