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Poly bushing lubrication
- Thread starter Lin
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tahoe healey
Yoda
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What about the "rubber" bushings. Will it speed up the deteriation of the rubber to lubricate them or protect them? I replaced bushings 3 to 4 years ago and they need replacing again. I used Moss last time. I'm replacing them with some form British Car Specilaist in the next few weeks. Hopefully they don't get them form the same supplier.
Keoke
Great Pumpkin
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Hello TH, /ubbthreads/images/graemlins/nonono.gif No do not put any petroleum based lubricants on rubber bushes. /ubbthreads/images/graemlins/yesnod.gif Yes it will speed up deterioration of the rubber. There still may be some rubber lubes available but I have no source for them at the moment.---Keoke- /ubbthreads/images/graemlins/cowboy.gif
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Hi TH & Lin,
Original type rubber bushings are designed to be clamped tightly on their outer surface & bonded to a metal inner sleeve that is clamped to it's own pivot. There is no actual rotational motion between the outer mount surface & the bushing. Likewise with the bushing's inner sleeve & it's mounting/clamping surface. All of the rotational motion is intended to be taken by the rubber's flex in a twisting motion. This means that no lube is needed & is in fact not desirable. This type of bushing actually acts as a rubber torsion/twist spring.
Poly bushings are not designed to twist/flex, but to rotate against their inner & outer surfaces as a bearing. Therefore, they need to be lubed. They should also be re-lubed as needed.
On a related subject, a quote from Jim Hockert somewhere on the web:
----------------------------------------
"I believe that changing out the OEM type suspension bushings for a harder material is not beneficial to the car or driver in the case of big Healeys.
The reason is that the design and manufacture of the front suspension causes the bushes to bind as the suspension travels up and down. That is the reason that you hear squeaks, clunks and thumps when poly bushes are installed. They bind up, then release with a 'pop'. That is also why the ride is so harsh with poly bushes.
The castor on the front suspension is built into the chassis by having the horizontal centerline of the rear suspension bracket one-half inch closer to the top of the chassis (lower) than the horizontal centerline of the front suspension bracket. This provides two degrees of positive castor for the suspension. Unfortunately, in the manufacturing process, the brackets are installed at a 90 degree vertical angle to the chassis instead of 88 degrees. In addition, the shock tower is 90 degrees vertical to the chassis instead of 88 degrees. Thus, both the upper and lower A-arms do not travel in plane with the castor angle causing the suspension to bind
slightly as it works. The OEM rubber bushes absorb the binding and actually snug up somewhat in a tight turn.
The best solution, absent blueprinting the suspension and changing the angles of the brackets, is to replace the rubber bushes with OEM type bushes as a regular maintenance item.
Jim Hockert
Dallas, TX"
--------------------------
At the very least, I would use the "softer" type poly bushings if you can't live with the stock rubber bushings on a Healey. I'm sure that folks who consider these problems secondary to the benefit of harder bushings will not agree. On a race car a bit of binding likely doesn't matter very much.
D
Original type rubber bushings are designed to be clamped tightly on their outer surface & bonded to a metal inner sleeve that is clamped to it's own pivot. There is no actual rotational motion between the outer mount surface & the bushing. Likewise with the bushing's inner sleeve & it's mounting/clamping surface. All of the rotational motion is intended to be taken by the rubber's flex in a twisting motion. This means that no lube is needed & is in fact not desirable. This type of bushing actually acts as a rubber torsion/twist spring.
Poly bushings are not designed to twist/flex, but to rotate against their inner & outer surfaces as a bearing. Therefore, they need to be lubed. They should also be re-lubed as needed.
On a related subject, a quote from Jim Hockert somewhere on the web:
----------------------------------------
"I believe that changing out the OEM type suspension bushings for a harder material is not beneficial to the car or driver in the case of big Healeys.
The reason is that the design and manufacture of the front suspension causes the bushes to bind as the suspension travels up and down. That is the reason that you hear squeaks, clunks and thumps when poly bushes are installed. They bind up, then release with a 'pop'. That is also why the ride is so harsh with poly bushes.
The castor on the front suspension is built into the chassis by having the horizontal centerline of the rear suspension bracket one-half inch closer to the top of the chassis (lower) than the horizontal centerline of the front suspension bracket. This provides two degrees of positive castor for the suspension. Unfortunately, in the manufacturing process, the brackets are installed at a 90 degree vertical angle to the chassis instead of 88 degrees. In addition, the shock tower is 90 degrees vertical to the chassis instead of 88 degrees. Thus, both the upper and lower A-arms do not travel in plane with the castor angle causing the suspension to bind
slightly as it works. The OEM rubber bushes absorb the binding and actually snug up somewhat in a tight turn.
The best solution, absent blueprinting the suspension and changing the angles of the brackets, is to replace the rubber bushes with OEM type bushes as a regular maintenance item.
Jim Hockert
Dallas, TX"
--------------------------
At the very least, I would use the "softer" type poly bushings if you can't live with the stock rubber bushings on a Healey. I'm sure that folks who consider these problems secondary to the benefit of harder bushings will not agree. On a race car a bit of binding likely doesn't matter very much.
D