1985 720 poly bushings

[85"720]

Where should I put poly bushings and where not to?

[datzenmike]

Actually I wouldn't use them at all. Most definitely not on a tension rod but maybe on a sway bar. Most suspension parts use rubber which clings to both moving parts. When there is movement the rubber deforms but maintains contact. Poly is too stiff and there is little give. When this happens there is going to be chaffing and wear and squeaks. Poly is a racing thing where noise, wear, maintenance and harsh ride are not a problem or worry. On a street vehicle it's a pain and a waste of your time and money. Replace old rubber with new.

[85"720]

Thanks for the input

[yello620]

I would put poly everywhere there is currently a rubber bushing in a 720, both front and rear. Buy quality bushings and install them with the proper lubricant and ENJOY the ride. I personally prefer the ride quality and handling control of a vehicle that has a poly everywhere. Yes, they are slightly stiffer to ride in, but the increased feeling of control is so much better.

 

This race car only talk is pure crap. I have poly in all three of my cars(including my wife's BMW) and would not even consider going back to rubber. And not one of them have a squeak due to the poly bushings.

 

Be warned, once you install all poly in one vehicle, you will want to do it to every vehicle you ever own.

[85"720]

Even if I change the old bushings with rubber. Would I feel a difference or just with the polys

[ggzilla]

New rubber bushings make it feel like new!

 

New poly bushings make it feel different from new.

[datzenmike]

If the rubber is cracked or just old yes, new will return to new car ride. Poly is ok if you know and understand the 'side effects'. Some suspension 'softness' is desirable on a street car and isolates you from road noise and vibration.

 

 

It's not crap. Stiffer less compliant suspension is more at home on a race course where high speeds and cornering is the norm. Many can't appreciate the stiffening poly adds to a compliant suspension on a daily driver car. Like a rear spoiler. Looks like a race car but not functional on a street car.  

[NissanEgg]

Actually I wouldn't use them at all. Most definitely not on a tension rod but maybe on a sway bar. Most suspension parts use rubber which clings to both moving parts. When there is movement the rubber deforms but maintains contact. Poly is too stiff and there is little give. When this happens there is going to be chaffing and wear and squeaks. Poly is a racing thing where noise, wear, maintenance and harsh ride are not a problem or worry. On a street vehicle it's a pain and a waste of your time and money. Replace old rubber with new.

^False info here. "Bench Racing" at its finest here.   These are not a "race" item.  The poly is not a waste of time or money.  Poly is actually cheaper than the rubber parts for the 720, and lasts longer than the vehicle will.  That alone saves time and hassle of having to redo the rubber later.

 

When lubed right and installed right, there is no noise and little-to-no bind. 

 

Replaced them all in my 85 720 a few months ago.  Truck came back to life in the suspension department with no more squeaks(mainly from the rear leafs).  The front end alignment came back into specs after doing the bushings in the control arms and tension rods.  Truck does NOT ride any harsher than the busted old bushings.  Steering feel is greatly improved.

[Tinman]

Oh my god!  I put poly bushings into my truck 15 years ago and was the best thing I did to it! 

My 720 rides great and handles like a good car.  No more soggy suspension.

 

No squeaks or rattles and it goes exactly where I point it.  Seriously, forget the rubber.  I'd agree that rubber is best on cars that already have a good suspension, but on the 720, poly is a vast improvement!

With the shell on the back to weigh down the rear, I can really enjoy driving through winding canyon roads at "speed" while feeling confident doing so.

[datzenmike]

There are exceptions to every rule and a personal preference can't be wrong. If handling and steering were restored then replacing with rubber would have worked also. All the poly I've seen or had might as well have been carved out of wood... they were rock hard and the rear spring bushes became oval shaped. If you have tension rod bushings you'd better inspect the tension rods for fatigue cracks from flexing around them. There'll be no warning if and when they snap.

[NissanEgg]

There are exceptions to every rule and a personal preference can't be wrong. If handling and steering were restored then replacing with rubber would have worked also. All the poly I've seen or had might as well have been carved out of wood... they were rock hard and the rear spring bushes became oval shaped. If you have tension rod bushings you'd better inspect the tension rods for fatigue cracks from flexing around them. There'll be no warning if and when they snap.

The stock rubber bushings even when new are so soft that they deflect alot under braking and big bumps, which causes a good amount of caster and camber change, which consequently affects toe.  When you take the deflection out, or minimize it, you also minimize the caster, camber, and toe change under braking and bumps.  This makes the steering feel more precise with no negative side effects.

[85"720]

I did the swaybar with poly. Drives better. Would it be good to put in poly leaf spring bushings or rubber I think thats the only places I would put poly at.