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Lightbulb Front LCA Rubber Bushing

I have the standard grossly eccentric rubber bushings on my front LCAs, along with the obligatory deeply grooved torsion bars. I have already ordered a set of PB bushings to fix the issue (boy those are nice looking parts!).

But then, after reading the PB installation instructions, I had an idiotic thought, and I followed through.... just to see if it would work.....

I used a punch to mark the relationship of the rear outer bushing to the control arm (a couple of small dimples). I then used a dremel to melt / drill a small depression in the very eccentric rubber bushing, 180 degrees off from my previous marks.



I then heated the control arm with a propane torch. Not a whole lot - just enough to get a slight wisp of smoke. I then used a big screwdriver to turn the bushing 180 degrees. The bushing stayed stuck to the outer sleeve and rotated about the control arm.



I cooled the control arm with compressed air. I then heated the outer bushing sleeve with the torch, again just a wisp of smoke, and rotated the uter sleeve back 180 degrees. This time, the bushing stayed stuck to the control arm.

I was also exerting axial force to make sure the whole mess didn't wander off the control arm.



So, the bushing itself has been rotated 180 degrees. It's still eccentric, but in the correct direction - when it's loaded, it will tend to become concentric. Considering the A-arm design, Porsche probably should have installed an eccentric bushing to begin with.


So, is this a reasonable repair? Looking for input here... sure was fast, and sure was cheap... and I'm thinking it can't be this simple to fix these darn things.
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Old 10-08-2007, 12:27 PM
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Well, no detractors so far ... looks like I'll give it a whirl. I plan on going to bigger torsion bars in a year or so, I'll unbolt the arms & inspect the results then. Can't be any worse than it was when I took it apart...
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Old 10-09-2007, 01:38 AM
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Are the mounting holes on the fwd bushing holder different top/bottom,the larger face uppermost for fitting to x member?

Last edited by red83911; 10-09-2007 at 03:06 AM..
Old 10-09-2007, 02:32 AM
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I didn't touch the front bushing at all. There are spacers on the front bushing - they go against the suspension pan.

I rotated the rear rubber bushing only. The outer can ended up back in its original orientation relative to the A-arm (look for the different dimple positions in the succesive pictures)

The rear outer can has a spacer welded to it. This spacer is bigger on the top than on the bottom (it's conical sort of). It still is that way.

Did that answer the question, or did I misunderstand?
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Old 10-09-2007, 05:56 AM
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sorry I mixed up, but now see what you have done.
Old 10-09-2007, 06:38 AM
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Nice Work!!

Many of us have had the thought of rotating the bushing, but couldn't figure how to control the slippage of the inner and outer grips.

btw, these Silentbloc bushing are, by design to grip, NOT adhered to the carriers.

the egr data sheet:



your using heat to help control the grip.... --Again, nice work!

edit: btw, I would have started with heating the outer first, as the inner is easier to break free.
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Last edited by island911; 10-09-2007 at 07:26 AM..
Old 10-09-2007, 07:22 AM
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I suspect that is not a reasonable repair. The bushing was once soft, and has no doubt now hardened over the years & decades.

OTOH, if it rotates with no stiction, then you should be doing about as well as the Elph. bushings.
Old 10-09-2007, 01:14 PM
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The bushing still seems to allow 20 to 30 eyecrometered degrees of elastic rotation without slipping - that should cover the range of available suspension travel. It's from an 88, so 19 years old....

Well, they're going in. I'll have a look see in a year or so.... wish me luck!
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Old 10-10-2007, 02:01 AM
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sounds pretty good

Let us all know how it feels after you run the car some.
Old 10-10-2007, 10:34 AM
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So far so good - 1st drive was very nice. All the impact harshness is gone from the front end - though the rear end's harshness is now doubly annoying. Will probably strive to swap the LH & RH torsion bar covers sometime in the spring....
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Old 10-17-2007, 02:05 AM
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I think I read on this forum... someone is making a front LCA bushing replace kit. It is not the PB type but some sort of all "rubber" type. I wonder how that is going... I need to find the thread again.
Old 10-17-2007, 06:07 AM
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found this on another thread....not sure of the progress or exactly how these get installed....


In response to this topic raised a couple weeks ago on this forum, our company has started work on having these manufactured. We have secured a couple of new factory control arms to provide samples of these bushings for analysis and reproduction. They will be produced with the same rubber compound as the originals. I'll post info as soon as we have some idea of when these will be available, but this type of project generally takes 4-6 months before stock is availabe for sale. We do not sell direct to the public but our products will sold through retail companies like Pelican Parts if they decide to carry them. Be patient they are coming.
Old 10-17-2007, 06:24 AM
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The rear covers don't have the bushing in them, swapping won't help there. I put some Parker O-ring lube in my rear (factory) bushings to reduce friction. So far so good, no major difference.
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Old 10-17-2007, 06:25 AM
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Chuck Moreland of ER also rebushes LCA arms with rubber bushings. He quoted me $500 and 4 week turnaround for both arms....longer than I was wanting to wait. If this doesn't work out, maybe I'll scour for a set of used A-arms, get them rebushed, and then install 'em. Or, I'll just go the PB route, since I already have the parts, and see how those work out.
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Old 10-17-2007, 06:29 AM
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Quote:
Originally Posted by burgermeister View Post
Chuck Moreland of ER also rebushes LCA arms with rubber bushings. He quoted me $500 and 4 week turnaround f....
NO WAY !!!! LOL
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Old 10-17-2007, 08:16 AM
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Turnaround time is now down to about 1 week, and includes power coating.
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Old 10-17-2007, 10:44 AM
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I had an opportunity to check up on my rotated bushings today. They are very nearly concentric (when unloaded) after almost 1 year and around 7000 miles. Bushing can to A-arm gap on the bottom measures 6.9mm, gap on top 6.5mm.
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Old 08-15-2008, 06:27 PM
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burger how about the 'impact harshness' you mentioned? i THINK this is what i feel in my car and would think new rubber would be required to adress it.
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Old 09-26-2008, 04:59 PM
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Impact harshness has been gone since I rotated the bushings. I think what I felt was the torsion bars smacking the A-arm, which they did frequently judging by the 1+mm deep grooves in the bars. I swapped spring plates side-to-side in the rear for the same reason - get the fat part of the bushing on the load bearing side. It too improved my ride noticeably.

My bushings were still pretty elastic - not at all brittle or hard.

My car is set around 10 - 15mm lower than the actual Porsche-spec torsion bar center measured euro height, which also contributes to a better ride on MI roads. It works out to be around 26.75" at the front fender on my car.

The lack of fore-aft compliance in the suspension means these cars will always ride somewhat harshly compared to newer ones.
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Old 09-27-2008, 09:10 AM
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good reminder... turning the front bushings.. I haven't really dug into the whole suspension thing much... is this a big deal (front bushing rotation)? Do I lose my corner weighting/alignment/etc. ? I might bite the bullet and get the arms redone to the "original" rubber. I like the PB deal... but still afraid re. harshness... not that I don't have that now.
Since I'm close to Chuck I should go down there.
Old 09-27-2008, 09:39 AM
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