Poly bushings vs. OE rubber bushings
08-21-10, 12:16 AM
#1
Dstamp
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Poly bushings vs. OE rubber bushings
I am looking at doing some suspention work to my rx-7 this requires me to replace the old bushings that are worn out. I have read on many forums that poly bushings are rubbish, but on ausrotary.com they are saying that poly bushing inprove the geometry of the suspention. What is the difference between the two?
08-21-10, 02:26 AM
#2
Poly bushing are stiffer and allow less movement compared to stock bushings.
When replacing the bushings in the rear, always let the car sit on the ground (or on ramps) as
to get the weight on it before the final tightening.
I had a Poly set from ReSpeed at a great price. Let a friend install them on his car and he said
they were night and day difference between his worn stockers and the polys.
When replacing the bushings in the rear, always let the car sit on the ground (or on ramps) as
to get the weight on it before the final tightening.
I had a Poly set from ReSpeed at a great price. Let a friend install them on his car and he said
they were night and day difference between his worn stockers and the polys.
08-21-10, 08:15 AM
#3
As Jeezus said, ploy bushings are stiffer and the correct installation is important.
In all cases for the first gen, the bushings do not change the geometry. Suspension geometry is derived from the pickup points of the suspension system and design. On the front they are inner pivot of the control arms, ball joint, upper strut mount and the front stay rod mounting point. In the rear they are from the control arm pickup points on the chassis and the rear end housing as well as the watts pivot point.
Some bushings for other brand cars have the center hole in the bushing offset from the outer diameter. This is the only case where the bushing changes the geometry.
Some bushings can add to the spring rate of the vehicle and on the first gen these would be the stay rod mounts. Since the bushings are twisted when the suspension travels.
The whole idea behind poly bushings is to reduce compliance. See when a automotive manufacturer builds a car for road use rubber bushings are used in order to dampen road feel and vibration from the driver. This means the designed geometry of the suspension suffers from the pickup points changing when stressed. Poly bushings do not give as much as rubber therefore the pickup points do not suffer as much. In plains terms this simply equates to a firmer feel of the road as the suspension system does its job.
In motorsports these bushings are replaced by metal to metal bearings (well normally a teflon liner between the metal bits) that eliminate 99% of the compliance.
-billy
In all cases for the first gen, the bushings do not change the geometry. Suspension geometry is derived from the pickup points of the suspension system and design. On the front they are inner pivot of the control arms, ball joint, upper strut mount and the front stay rod mounting point. In the rear they are from the control arm pickup points on the chassis and the rear end housing as well as the watts pivot point.
Some bushings for other brand cars have the center hole in the bushing offset from the outer diameter. This is the only case where the bushing changes the geometry.
Some bushings can add to the spring rate of the vehicle and on the first gen these would be the stay rod mounts. Since the bushings are twisted when the suspension travels.
The whole idea behind poly bushings is to reduce compliance. See when a automotive manufacturer builds a car for road use rubber bushings are used in order to dampen road feel and vibration from the driver. This means the designed geometry of the suspension suffers from the pickup points changing when stressed. Poly bushings do not give as much as rubber therefore the pickup points do not suffer as much. In plains terms this simply equates to a firmer feel of the road as the suspension system does its job.
In motorsports these bushings are replaced by metal to metal bearings (well normally a teflon liner between the metal bits) that eliminate 99% of the compliance.
-billy
08-23-10, 09:02 PM
#4
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One of the best <$200 mods I have ever done. I replaced every bushing with polyurethane and the car was an entirely new and better ride. Response, feel, comfort and noise were all improved with replacing the stock rubber with poly. Made me much more confident with the car since I could feel so much more.
08-25-10, 10:21 AM
#5
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Rubber bushings allow movement in several different directions.
Poly bushings allow movement only in the direction that the system was designed for. This eliminates unwanted deflection during braking, cornering, bumps, etc.
Great mod. Get them from www.re-speed.com (because the price is good and he helps out on these forums)
.
Poly bushings allow movement only in the direction that the system was designed for. This eliminates unwanted deflection during braking, cornering, bumps, etc.
Great mod. Get them from www.re-speed.com (because the price is good and he helps out on these forums)
.
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08-26-10, 12:27 PM
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Road racers say it helps in the corners to remove the rear bar.
Dstamp, upgrade to an RE-Speed front sway bar and an adjustable rear bar. A few are available on Mazdatrix.com. The RE-Speed bar is considerably lighter and stiffer than the RB bar. I've had both. With the RB bar, RB springs and Tokico blues, the front end would still roll a bit. I had to drive home with a completely stock front strut assembly and my RE-Speed bar, and the car hardly rolled at all, even when pushing hard around clover leaf on ramps. It's worth the money.
Dstamp, upgrade to an RE-Speed front sway bar and an adjustable rear bar. A few are available on Mazdatrix.com. The RE-Speed bar is considerably lighter and stiffer than the RB bar. I've had both. With the RB bar, RB springs and Tokico blues, the front end would still roll a bit. I had to drive home with a completely stock front strut assembly and my RE-Speed bar, and the car hardly rolled at all, even when pushing hard around clover leaf on ramps. It's worth the money.
08-27-10, 09:38 PM
#10
Lives on the Forum
I started off using all of the Racing Beat parts. Outgrew that stuff real fast. Sold it. Moved up to Respeed products. No regrets.
Like Chris said, roadracers pull the rear bar for added stability in fast sweepers, but us autocrossers leave it on because it aids in the quick tight handling stuff.
I use the Respeed front bar (stiffer and weighs a ton less than the racing beat bar) along with an adjustable rear bar on the stiffest setting. Unbeatable setup.
I'll dig up a video for you to check out... Here you go:
http://www.youtube.com/watch?v=rWpEYAKo0fU
Like Chris said, roadracers pull the rear bar for added stability in fast sweepers, but us autocrossers leave it on because it aids in the quick tight handling stuff.
I use the Respeed front bar (stiffer and weighs a ton less than the racing beat bar) along with an adjustable rear bar on the stiffest setting. Unbeatable setup.
I'll dig up a video for you to check out... Here you go:
http://www.youtube.com/watch?v=rWpEYAKo0fU
