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Polyurethane bushings... by kevin
Started on: 11-24-2019 10:01 PM
Replies: 13 (333 views)
Last post by: cebix on 11-27-2019 02:34 PM
kevin
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Report this Post11-24-2019 10:01 PM Click Here to See the Profile for kevinClick Here to Email kevinSend a Private Message to kevinReply w/QuoteDirect Link to This Post
Fellas,
I’ve heard this before, but it is worth asking the experts😊. When you are upgrading your front suspension to polyurethane, I understand that you should NOT tighten the ‘A’ arms just before putting the Fiero on the ground? What? The reasonIng I read is that the Fiero will not settle to the level you want? Why? Because you have now added polyurethane bushings and therefore there is another method to use to get the Fiero to sit at the level you want?
Please help.
Cordially,
Kevin
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Patrick
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Report this Post11-24-2019 11:25 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickReply w/QuoteDirect Link to This Post
 
quote
Originally posted by kevin:

When you are upgrading your front suspension to polyurethane, I understand that you should NOT tighten the ‘A’ arms just before putting the Fiero on the ground?


I'm not 100% sure, but I thought that applied to new rubber bushings (because the inner and outer sleeves are bonded together by the rubber, and with resistance the rubber "twists").

In any event, it shouldn't be all that difficult (if it's been done incorrectly) to loosen the control arm bolts and re-tighten them after the suspension has been put under load.

[This message has been edited by Patrick (edited 11-25-2019).]

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cvxjet
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Report this Post11-25-2019 12:50 AM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetReply w/QuoteDirect Link to This Post
The rubber bushings are BONDED to both the inner and outer metal pieces...So you do not want to over rotate them- that would shear them and create a number of problems (Noise and extra wear among others)

The poly bushings are not bonded at all, so You can torque them and then lower the car- make sure they are well lubricated.

A friend of mine runs a 1966 Mustang w/ Nascar V8 (8000 rpm and 750 hp Plus pushrod rear suspension among other mods) in the Optima Ultimate Street Car Challenge....Years ago he moved away from Poly and went back to rubber....His main business is aftermarket custom Suspension setups for 1st Gen Mustangs.....(Look up "Mike Maier Mustang")
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wftb
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Report this Post11-25-2019 10:00 AM Click Here to See the Profile for wftbClick Here to Email wftbSend a Private Message to wftbReply w/QuoteDirect Link to This Post
Most factory performance versions of popular new cars will usually feature some of these things:
1. shorter stiffer springs to lower the car
2. Harder rubber suspension bushings
3. Stiffer anti roll bars front and rear
4. The latest and best available dampers (spool, magneterholic? sorry about the spelling)
5. A selection of settings for stability control electronics
6. Torque vectoring front/rear differentials

So you can get #s 1 and 3 for a Fiero. Harder rubber bushings were available at one time for the racing versions of the Fiero but not any more. My experience with the poly bushings available was that they tightened things up for about 2 years and then got sloppy, especially at the front. I really think that for stock control arms, new rubber is the best available option.

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theogre
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Report this Post11-25-2019 12:39 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreReply w/QuoteDirect Link to This Post
Was common to leave bolts loose until you load the suspension.... For Many years, even Decades, now... Most Rubber bushings Are Not "Bonded" to inner or both metal parts and will move to "settle" over driving a bit.
Because car makers don't want to wast time for installing control arms to start w/ and most if not all aftermarket don't want problems w/ bushings install by DIY and most Shops.
Car may sit higher but most times is new shocks/strut because most use Gas units that add to total spring rate for a car. Rubber windup might help that but go away after moving and more after driving a bit.
Moog has/had said none if theirs are bonded and most other are same w/ or w/o mentioning on FAQ etc.

Many think sit higher after but does that w/o replaces parts and most don't see it. Why? Jack up then done the tires etc move in and down when jacked then tires try to hold this positions when hits the ground. Move the car, even just a few feet, removes the tire side load and should be normal again.

If you want to load up suspension note that can be a Major safety hazard. Jacking a wheel w/ car jacked too can cause car to move on the main jacks, jack stands, or shop lifts.

Polly has many problems and can "wear out" and never make "polly noise." And this is even when people lube them as much as possible w/ polly safe lube. Most Dino and Syn Oil/grease make more problems.

Moog and many others use harder rubber and other things to fix problems w/ OEM suspension parts.
See my Cave, Suspension Parts and rest of section.

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Patrick
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Report this Post11-25-2019 03:30 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickReply w/QuoteDirect Link to This Post
 
quote
Originally posted by theogre:

For Many years, even Decades, now... Most Rubber bushings Are Not "Bonded" to inner or both metal parts...


So you're saying the inner metal sleeve of a new control arm bushing rotates within the rubber? If so, what prevents the rubber from being worn away from the constant chafing as the control arms pivot up and down?

Just as an example... the rubber of this particular bushing looks bonded to the metal sleeves to me.

[This message has been edited by Patrick (edited 11-25-2019).]

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theogre
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Report this Post11-25-2019 07:29 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:
So you're saying the inner metal sleeve of a new control arm bushing rotates within the rubber? If so, what prevents the rubber from being worn away from the constant chafing as the control arms pivot up and down?

Just as an example... the rubber of this particular bushing looks bonded to the metal sleeves to me.

CLICK FOR FULL SIZE
Again Moog and others Do Not bond metal to rubber for most CA and other types.

The rubber is "pressed in" then inner is pressed into the rubber or inner and rubber is "pressed" into the outer shell.
Either will generate huge compression forces in the rubber. Moog et al has tools to do this and work in thousands to hundreds of thousands of PSI to make them if needed.

Rubber rotates only when enough movement on outer shell forces the rubber to "slip" to a new spot.
Other wise inner and outer winds up the rubber in normal working zone and won't "wallow out" the rubber center unlike many polly installs.
IOW The inner and outer metal Does Not move against the rubber in normal operation.

Once set to "normal" the rubber may never move again and high pressure in the rubber can "Bond" them or seem to. Rust etc attacking the bushings may "bond" them too.

When you hit a pothole, curb, or whatever, the rubber can move in rotation, radial, and axial then move back when you drive. That feature protect the CA BJ and about everything else.

Polly Can Not do the same as rubber and rotational and static loads can "wallow out" the inner hole. How fast depend on exact Polly compound and several other things. Low/no "polly safe" lube won't help.
"Polly Noise" is made when polly ends, center, or both moves/rotates on frame or inner tube. But don't think no noise = no problem.

On top of the above...
Polly inner tubes doesn't have "teeth" to prevent easy movement/rotation like Rubber often does.
If the bolts are even a tiny bit "loose" the polly inner tube will move. This is why some hate Polly Dog Bones. The slotted holes will easily allow polly to move and slam each end breaking the bracket or far worse.
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Patrick
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Report this Post11-25-2019 07:59 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickReply w/QuoteDirect Link to This Post
 
quote
Originally posted by theogre:

IOW The inner and outer metal Does Not move against the rubber in normal operation.


Okay, got it.
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cebix
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Report this Post11-26-2019 12:50 PM Click Here to See the Profile for cebixSend a Private Message to cebixReply w/QuoteDirect Link to This Post
I must say my poly bushings hold up well after about 3 years. It's not that long of a time, I know. But no noises, no play.

However on my '85 duke auto I drove for a year or two with a poly dogbone. It was just crazy at idle, you could vibrate your head off idling in D. I switched that back to rubber and it's way smoother. Will see how the poly holds up in the suspension after a few years. The roads here aren't that great. I've got all control arms in poly as well as the stabilizer bushings and links plus the cradle bushings.
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Dennis LaGrua
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Report this Post11-27-2019 06:23 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaReply w/QuoteDirect Link to This Post
I would recommend poly bushings as well as the suspension arm bolts can be tightened with them in place. The handling will improve but the ride will be slightly harder. I don't buy that the rubber bushings now have movable inner sleeves. . Theocre could be right on some brands but I've never seen them constructed that way.

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Tony Kania
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Report this Post11-27-2019 10:41 AM Click Here to See the Profile for Tony KaniaSend a Private Message to Tony KaniaReply w/QuoteDirect Link to This Post
44,000 miles and a dozen years on my full poly. No squeaks.

I like the ride. My GT is not my daily, yet it is extremely comfortable on long rides. I would not put poly on my Toyota Avalon.
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cvxjet
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Report this Post11-27-2019 12:02 PM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetReply w/QuoteDirect Link to This Post
 
quote
Originally posted by cebix:

However on my '85 duke auto I drove for a year or two with a poly dogbone. It was just crazy at idle, you could vibrate your head off idling in D. I switched that back to rubber and it's way smoother. .


I switched only one end of my (V6) dogbone to poly- the other end is still rubber for good isolation........

On my 99 Firebird the rear arm bushings were fully bonded- I found out because I was towing my jet boat and had air-springs I installed for the first couple of summers (Then moved the boat back on the trailer to drop the tongue weight down from 250 to 120) I had to drop the axle pretty far to pull the steel springs so I could insert the air-springs. The bushings separated and started making noise so I replaced the trailing arm assemblies.....(Should have loosened the arm BOLTS before lowering the axle)

[This message has been edited by cvxjet (edited 11-27-2019).]

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theogre
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Report this Post11-27-2019 12:38 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreReply w/QuoteDirect Link to This Post
 
quote
Originally posted by cebix:

I must say my poly bushings hold up well after about 3 years. It's not that long of a time, I know. But no noises, no play.

However on my '85 duke auto I drove for a year or two with a poly dogbone. It was just crazy at idle, you could vibrate your head off idling in D. I switched that back to rubber and it's way smoother. Will see how the poly holds up in the suspension after a few years. The roads here aren't that great. I've got all control arms in poly as well as the stabilizer bushings and links plus the cradle bushings.
Auto trannies put Drive train loads on dog bone(s) all the time when in D or R.
Before 87 should have 2 trans mounts and could be front rear or both is bad making a lot of vibration.

[This message has been edited by theogre (edited 11-27-2019).]

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cebix
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Report this Post11-27-2019 02:34 PM Click Here to See the Profile for cebixSend a Private Message to cebixReply w/QuoteDirect Link to This Post
 
quote
Originally posted by theogre:

Auto trannies put Drive train loads on dog bone(s) all the time when in D or R.
Before 87 should have 2 trans mounts and could be front rear or both is bad making a lot of vibration.



I'm sure it was the dogbone. Two tranny mounts and one engine mount were all new and I think that's all of them.

[This message has been edited by cebix (edited 11-27-2019).]

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