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Gunnar
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Post subject: What means "PU bushes bind"? Posted: Sat Feb 14, 2004 9:32 am |
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Joined: Sat Aug 18, 2001 8:35 am Posts: 220 Location: Germany
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Often I can read about Polyurethane bushings they "bind".
What does this mean? A look in the dictionary brought a lot of meanings but not one that sounded applicable to PU bushes.
Can somebody give me clarification?
Gunnar
_________________ Until November 2004 I had a:
Red 99 Camaro Z28 Euro-Model, M6, T-Top, Movit/ Porsche GT3 front brakes, Alutec Kyro 8,5x19" wheels, Geiger (H&R) springs, oil intercooler, Dynomax twin exhaust,
BUT THAN I MADE A MESS OF IT and now its gone!
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ChrisV6
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Post subject: Posted: Sat Feb 14, 2004 10:47 am |
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Joined: Sat Oct 13, 2001 4:53 pm Posts: 1041 Location: Erlangen <=> Coburg
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From my little experience PU starts to "glue" to the metal (sway bar, bolts, whatever) if its ungreased.
IMO that means "binding".
Try to turn a sway bar in PU bushings with unbolted end links... then you know what i mean
_________________
2001 Pontiac Firebird Convertible 3.8l V6 - daily cruiser
1994 Pontiac Firebird 3.4l V6 - new engine one the way
1990 Chevy Beretta GTZ, back on the road in the year 2057
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Garry
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Post subject: Posted: Sat Feb 14, 2004 12:30 pm |
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Joined: Sat May 26, 2001 9:59 pm Posts: 7823 Location: Bad Hersfeld, Germany
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Stupid question - I take it that's a bad thing - if the bushings were greased when they came on, do they have to be greased every now and then? I have PU on my sway bars ...
_________________ Garry Glendown * '99 Firehawk Convertible
"Horsepower is how fast you hit the wall and torque is how far you take the wall with you." "Speed doesn't kill - suddenly becoming stationary on the other hand ..."
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BenZ28
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Post subject: Posted: Tue Feb 17, 2004 3:37 pm |
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Joined: Mon Sep 10, 2001 3:53 pm Posts: 2485 Location: Mainz, Germany
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Garry:
I think they have to. My front sway bar is already making very slight squeaks...
Ben
_________________ 1999 Camaro Z28, black, T-Tops, M6
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JackZ28
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Post subject: Posted: Wed Mar 03, 2004 9:46 am |
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Joined: Mon May 28, 2001 6:03 pm Posts: 8686 Location: Houston, TX
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Garry
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Post subject: Posted: Wed Mar 03, 2004 9:59 am |
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Joined: Sat May 26, 2001 9:59 pm Posts: 7823 Location: Bad Hersfeld, Germany
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Stupid question #2: How? They went on pretty tight, the only way I can imagine to grease them would be to pull the sway bars ... !?
_________________ Garry Glendown * '99 Firehawk Convertible
"Horsepower is how fast you hit the wall and torque is how far you take the wall with you." "Speed doesn't kill - suddenly becoming stationary on the other hand ..."
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Roy
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Post subject: Re: What means "PU bushes bind"? Posted: Fri Mar 05, 2004 3:27 pm |
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Joined: Sun May 27, 2001 2:52 pm Posts: 5556 Location: Mehlingen,Rhineland Pfalz, Deutschland
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Garry
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Post subject: Posted: Fri Mar 05, 2004 3:40 pm |
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Joined: Sat May 26, 2001 9:59 pm Posts: 7823 Location: Bad Hersfeld, Germany
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Hm ... so Poly bushings are a "bad thing" ... Wonder if there are any rubber bushings that even fit the BMR sway bars ...
_________________ Garry Glendown * '99 Firehawk Convertible
"Horsepower is how fast you hit the wall and torque is how far you take the wall with you." "Speed doesn't kill - suddenly becoming stationary on the other hand ..."
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ChrisV6
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Post subject: Posted: Fri Mar 05, 2004 5:04 pm |
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Joined: Sat Oct 13, 2001 4:53 pm Posts: 1041 Location: Erlangen <=> Coburg
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I read that page also, even before i bought my pu bushings.
Who is this guy? Does he have some kind of good reputation?
He seems to know his stuff, even though his proofs against this stuff are not better than the proofs in the advertisment for it.
Damn, i´m unsure.
I still think evil PU bushings are at least better than 10 year old cracked rubber bushings...
_________________
2001 Pontiac Firebird Convertible 3.8l V6 - daily cruiser
1994 Pontiac Firebird 3.4l V6 - new engine one the way
1990 Chevy Beretta GTZ, back on the road in the year 2057
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BenZ28
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Post subject: Posted: Fri Mar 05, 2004 5:47 pm |
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Joined: Mon Sep 10, 2001 3:53 pm Posts: 2485 Location: Mainz, Germany
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Roy:
Do you have poly bushings on your car?
Ben
_________________ 1999 Camaro Z28, black, T-Tops, M6
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RTZSS
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Post subject: Posted: Fri Mar 05, 2004 7:45 pm |
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Joined: Sat Nov 23, 2002 11:45 pm Posts: 829 Location: Stuttgart, Germany
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Oh well, I just got my BMR adjustable LCAs and PHR yesterday with PU bushings. I have seen a hell of a lot more good feedback supporting PU than I have of those speaking against it. I suppose they will just have to do for me.
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Roy
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Post subject: Posted: Sat Mar 06, 2004 6:21 am |
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Joined: Sun May 27, 2001 2:52 pm Posts: 5556 Location: Mehlingen,Rhineland Pfalz, Deutschland
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BenZ28 wrote: Roy: Do you have poly bushings on your car?
Ben
Ben I Have no Poly bushings on the rear LCA's or the Front , but maybe that is why my car handles so bad on the tracks. PU has very limited uses . Unless your drag racing PU has no place in rear lower control arms of F bodies, Fox bodies are okay with their single axis roataion on the Rear LCA.
The main Problem with PU for Performance applications is its tendencies to lose its shape over time . This is called Cold flow in its most basic sense.
PU works great for sway bar bushings. just a little noisey.
_________________ Roy My vids on Youtube My vids on Streetfire
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BenZ28
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Post subject: Posted: Sat Mar 06, 2004 11:24 am |
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Joined: Mon Sep 10, 2001 3:53 pm Posts: 2485 Location: Mainz, Germany
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Well, the only place where I have poly bushings is on the swaybars... so that should be OK.
And you're right: Your car handles really bad. I've experienced it personally.
Ben
_________________ 1999 Camaro Z28, black, T-Tops, M6
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Roy
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Post subject: Posted: Sat Mar 06, 2004 12:24 pm |
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Joined: Sun May 27, 2001 2:52 pm Posts: 5556 Location: Mehlingen,Rhineland Pfalz, Deutschland
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Ben
There great for swaybar bushings,
About the best things for lower control arms would be a spherical rod bearing and a PU bushing.
I currently run 1LE Bushings in my lower controls arms , They are made of a higher durometer rubber and are solid as compared to to regular z28 and v6 arms.
_________________ Roy My vids on Youtube My vids on Streetfire
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Gunnar
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Post subject: Posted: Fri Apr 02, 2004 10:58 am |
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Joined: Sat Aug 18, 2001 8:35 am Posts: 220 Location: Germany
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Oh Roy,
I have not checked the forum for a while and now the link does not work anymore explaining what BIND means.
By any chance, can you copy this into this chapter?
I have decided to go for LCAs with PU/spherical rod end combo.
This should give a good compromise between handling and noise.
Gunnar
_________________ Until November 2004 I had a:
Red 99 Camaro Z28 Euro-Model, M6, T-Top, Movit/ Porsche GT3 front brakes, Alutec Kyro 8,5x19" wheels, Geiger (H&R) springs, oil intercooler, Dynomax twin exhaust,
BUT THAN I MADE A MESS OF IT and now its gone!
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Garry
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Post subject: Posted: Fri Apr 02, 2004 12:42 pm |
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Joined: Sat May 26, 2001 9:59 pm Posts: 7823 Location: Bad Hersfeld, Germany
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Still works for me - must be something with your provider ... !?
Quote: Suspension/bushing bind:
Bind occurs when the the pivot points of the suspension cannot move as intended. As it relates to third- and forth generation F-body car, bind is when the pivot points do not move smoothly under load (stiction, or static friction) or when the suspension moves outside its (or one or more of its components) design parameters (in this case, range of motion restricted by the lack of compliance in the polyurethane bushings)
Under hard cornering, bind can create dangerous handling conditions.
Polyurethane bushings:
Polyurethane (or 'poly' or 'plastic') bushings are popular, as they noticeably 'tighten up' the suspension, and the aftermarket arms look cool, but most purchasers to not understand how they work, or the problems they create. This is an old issue, but the recent popularity of poly-equipped aftermarket control arms has drowned out the proven drawbacks of this material, including stiction, binding, squeaking, harshness, and need for regular greasing.
Poly is used in place of the rubber portion of the factory bushings. Unlike the rubber bushings, they are not bonded to the inner and outer sleeve, and movement of the control arm will cause the internal surfaces of the sleeves and bushing to slide to accommodate the shearing forces. The two main issues:
Stiction (Static Friction): Under light loads, they may squeak as the arm moves. Regular greasing reduces the squeaking, but under high loads, especially cornering on uneven pavement, the "sticky" properties of polyurethane causes the plastic to "grab" the steel liner, adding harshness to the ride, as the steel sleeves can't slide smoothly over the poly bushing surfaces. At worst, when the suspension then cannot move as designed, the handling of the car will be affected and this can create unexpected and dangerous oversteer.
Binding: To complicate matters, the trailing arm type rear suspension in the late model f-body cars has bushings that flex or 'deflect' as a normal and required part of their function. As the solid 'live' axle moves to comply with an uneven surface, it (and the LCA mounting points) rotate in relation to the chassis. To illustrate:
Normal axle movement (missing the picture here)
1. The factory rubber bushings in the lower control arms accommodate this rotation/twist by design; 2. Poly bushings force the lower control arms to twist. 3. Tubular or boxed control arms - with poly bushings - force the LCA mounting brackets on the chassis and axle to bend; 4. Now that the car relies on twisting metal for suspension, it may at times bind, as the axle cannot move smoothly comply with bumps. The resulting oversteer condition can result in loss of control on high speed corners - not what you want in a high-power rear-drive car. 5. Subframe connectors (SFCs), added to brace the chassis, reinforce the forward LCA mounting points, but the twisting force is still there on the arms and rear mounts; poly bushings may seen to ride firmer after the addition of SFCs due to the more solid mounting of the LCAs. 6. Even for lower speed handling, the poly bushings increase the rear roll stiffness - something you should be tuning with the spring rates and sway bars. 7. Greasing the poly bushings does not help this issue.
_________________ Garry Glendown * '99 Firehawk Convertible
"Horsepower is how fast you hit the wall and torque is how far you take the wall with you." "Speed doesn't kill - suddenly becoming stationary on the other hand ..."
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Roy
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Post subject: Posted: Sat Apr 03, 2004 5:18 am |
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Joined: Sun May 27, 2001 2:52 pm Posts: 5556 Location: Mehlingen,Rhineland Pfalz, Deutschland
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Gunnar
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Post subject: Posted: Tue Apr 06, 2004 9:46 am |
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Joined: Sat Aug 18, 2001 8:35 am Posts: 220 Location: Germany
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Hello Roy,
I am happy as a Happy Hippo, because today Thunderracing answered that they want to ship parts to me:
Unfortunately they do not sell LG parts, but I think Global West suspensions will do the same job. I was also keen on their front upper A arms with Delalum bushings.
If LMperformance had answered I would have gone for LG or Spohn.
The plan now is
Sway bars, STB, reloc brackets from BMR
Panhard, LCA, front upper a arms from Global West
Lower a arms from PA Racing
SFCs, Bilstein shocks from SLP
Time to go home!
Bye !
Gunnar
_________________ Until November 2004 I had a:
Red 99 Camaro Z28 Euro-Model, M6, T-Top, Movit/ Porsche GT3 front brakes, Alutec Kyro 8,5x19" wheels, Geiger (H&R) springs, oil intercooler, Dynomax twin exhaust,
BUT THAN I MADE A MESS OF IT and now its gone!
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JackZ28
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Post subject: Posted: Tue Apr 06, 2004 7:56 pm |
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Joined: Mon May 28, 2001 6:03 pm Posts: 8686 Location: Houston, TX
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Gunnar
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Post subject: Posted: Wed Apr 07, 2004 11:14 am |
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Joined: Sat Aug 18, 2001 8:35 am Posts: 220 Location: Germany
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Problem with PU bushes:
This is exactly what I suspected: When you go over a bump with one wheel only, one spring is depressed, the LCA is lifted but also twisted, because there are no ball joints, neither on the body nor at the axle. With rubber bushes the twist is easily caught, but with PU bushes the load/ stress is guided into the hinges on the body (ie flexing them) and into the (relocation) brackets on the axle.
I think, even a combination of PU and spherical rod end will not eliminate all bind.
The twist is prevented by the rod end ball joint, but still some bending will be there as the rear axle is not just moving vertically upwards because of the bump, but also (slightly) sideways (controlled be the panhard rod). Its not easy to express my idea without a sketch.
But this is also where my problem lies: I do not have the courage to go for full rod end LCAs, because of the reported considerable additional noise (whatever considerable means!). John Silas (SRZ) however cannot tell any noise difference between PU and full rod end equipped cars.
Jack, about the oil intercooler: This is no high-tech. My mechanic told me that 5litres of oil are a joke for a 5,7litre V8, so he put an adaptor on the oil pan, replaced the oil filter and put an intercooler in front of the radiator. For fitting he unfortunately needed 9 hours, which were increasing total cost to 800EUR. As there is no thermostat, the oil needs longer to warm up, not a good thing in cold wheather….
_________________ Until November 2004 I had a:
Red 99 Camaro Z28 Euro-Model, M6, T-Top, Movit/ Porsche GT3 front brakes, Alutec Kyro 8,5x19" wheels, Geiger (H&R) springs, oil intercooler, Dynomax twin exhaust,
BUT THAN I MADE A MESS OF IT and now its gone!
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