Front control arm bushings
05-25-2007, 07:17 AM
#16
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Jean,
As I said the standard RS arms have a slightly harder bush in the rear compared to non RS as the only difference .
The Polyflex bushes are very well made and I believe can be made in even harder Poly if required .
I too have seen other bush makes which were very dubious.
Perhaps one of the guys using Poly bushes in competition will tell us how they are perfoming.
I have used a set in my road 964 for three years with no wear issues at all !
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
As I said the standard RS arms have a slightly harder bush in the rear compared to non RS as the only difference .
The Polyflex bushes are very well made and I believe can be made in even harder Poly if required .
I too have seen other bush makes which were very dubious.
Perhaps one of the guys using Poly bushes in competition will tell us how they are perfoming.
I have used a set in my road 964 for three years with no wear issues at all !
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
05-25-2007, 08:17 AM
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Geoff
The front RS arm is different too, it is the part I posted.
I am sure these bushes are very good, for a track car. I was not recommended to use them for a street/track car. The polybushes in competition are certainly a must, but that is another topic I think.
The more important thing is that the cost to replace them (unless you are as good DIYer as Chris) might be not justified and you can go for RS arms at once instead, that will last for another 10 years and been tested and proven by the factory..
Just a different opinion.
The front RS arm is different too, it is the part I posted.
I am sure these bushes are very good, for a track car. I was not recommended to use them for a street/track car. The polybushes in competition are certainly a must, but that is another topic I think.
The more important thing is that the cost to replace them (unless you are as good DIYer as Chris) might be not justified and you can go for RS arms at once instead, that will last for another 10 years and been tested and proven by the factory..
Just a different opinion.
05-25-2007, 11:03 AM
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Jean brings-up a good point -- from a time and materials standpoint, labor alone might negate any advantage of rebuilding lower control arms vs. buying two new one and bolting them in. There is quite a bit of time spent preparing control arms for aftermarket bushings.
05-25-2007, 12:08 PM
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Steve W. voiced his concern about the aftermarket bushings without installing zirc fittings and grease channels to lubricate them... I don't have time to find the thread, but it was a recent one over on the 993 NA board.
Chris, any thoughts about lubrication of the bushings? thanks for posting the pictures.
Chris, any thoughts about lubrication of the bushings? thanks for posting the pictures.
05-25-2007, 04:36 PM
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One certainly could drill and tap for a zirc fitting, which I have given some thought to in terms of placement not in the plane of typical load paths. In other words, I would hate to drill into the casting only to later find it fail. Plus you would have to groove the bushing to all grease to disperse.
At the end of the day, the a-arm is very easy to remove, regreasing the bushings wouldnt take much time at all. Probably the same time as an oil change. Realignment would not be necessary as it would be possible to leave the lower balljoint connected. Just drop the inboard mountings.
At the end of the day, the a-arm is very easy to remove, regreasing the bushings wouldnt take much time at all. Probably the same time as an oil change. Realignment would not be necessary as it would be possible to leave the lower balljoint connected. Just drop the inboard mountings.
05-25-2007, 05:19 PM
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Interesting discussion. Since I have no need to track-equip my 993turbo, but on the other hand, I am not totally satisfied with the road-handling as it is now I might start with just changing the inner steering ball joints and see what that gives me.
After that, I think it's time for me to have a look at control arms and bushings.
It seems maybe that bushings replacement requires quite a lot of time and garage-equipment which might pose a serious problem for me......
After that, I think it's time for me to have a look at control arms and bushings.
It seems maybe that bushings replacement requires quite a lot of time and garage-equipment which might pose a serious problem for me......
05-25-2007, 05:33 PM
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I think there's a rubber insert in the stock inner steering ball joints; as this ages and softens the toe varies more than it should. I've heard of the gap being welded to take the rubber out of the equation.
05-25-2007, 05:43 PM
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Seems that there are quite a few reasons why a car with more than 100000km on the meter could experience some nervousness on the road. First things first, new inner ball joints.
The RS control arms...anyone knowing how much they cost?
/Thomas
The RS control arms...anyone knowing how much they cost?
/Thomas
05-25-2007, 07:28 PM
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Guys,
There seems to be a little confusion on this subject.Maybe a read of the bushes article appearing in 911 & Porsche World in the June 2004 issue , page 102 ,called Bush Administration , which has install pictures ,could be helpful.
The essential detail is that on a standard wishbone the front bush, which is whats called a void bush , is bonded directly to the wishbone.
A void bush is a bush that has longitudinal holes cast in the rubber. The idea is that makes the front of the wishbone transversley, sideways flexible. In other words if the front wheel hits a bump it has the ability to change the wheel toe geometry.
Fine idea until the bush goes soft and then the front wheels move too much .
To know the bush stifness is to use a pry bar on the wishbone front support and guess !!
Both standard and RS 993 wishbones use the same front bush .
The rear wishbone bush is a solid rubber bush bonded to the wishbone .
The RS has a harder rear bush than a standard 993.
The Polyflex bush is made from a ,correctly judged for road use ,poyurethane.
A talk with Polyflex can lead to uprated Polyurethane material for race use.
The P&911 article mentions durability testing . We used my 964 and two everyday use 993 RS cars. My 964 is now three years on and the bushes have shown no sign of wear. The two 993RS cars still are running the same bushes.
I have seen bronze and other metal bushes in use. That can be a very dangerous situation as many of those bushes will wear very quickly and instances of wishbone siezure on the track have been recorded - a temporary 3 wheel racer !!!
Hope that helps.
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
There seems to be a little confusion on this subject.Maybe a read of the bushes article appearing in 911 & Porsche World in the June 2004 issue , page 102 ,called Bush Administration , which has install pictures ,could be helpful.
The essential detail is that on a standard wishbone the front bush, which is whats called a void bush , is bonded directly to the wishbone.
A void bush is a bush that has longitudinal holes cast in the rubber. The idea is that makes the front of the wishbone transversley, sideways flexible. In other words if the front wheel hits a bump it has the ability to change the wheel toe geometry.
Fine idea until the bush goes soft and then the front wheels move too much .
To know the bush stifness is to use a pry bar on the wishbone front support and guess !!
Both standard and RS 993 wishbones use the same front bush .
The rear wishbone bush is a solid rubber bush bonded to the wishbone .
The RS has a harder rear bush than a standard 993.
The Polyflex bush is made from a ,correctly judged for road use ,poyurethane.
A talk with Polyflex can lead to uprated Polyurethane material for race use.
The P&911 article mentions durability testing . We used my 964 and two everyday use 993 RS cars. My 964 is now three years on and the bushes have shown no sign of wear. The two 993RS cars still are running the same bushes.
I have seen bronze and other metal bushes in use. That can be a very dangerous situation as many of those bushes will wear very quickly and instances of wishbone siezure on the track have been recorded - a temporary 3 wheel racer !!!
Hope that helps.
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
05-26-2007, 05:45 AM
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Originally Posted by Red rooster
Both standard and RS 993 wishbones use the same front bush .
The rear wishbone bush is a solid rubber bush bonded to the wishbone .
The RS has a harder rear bush than a standard 993.
The rear wishbone bush is a solid rubber bush bonded to the wishbone .
The RS has a harder rear bush than a standard 993.
Again, the front 993RS arm has different and harder bushings than the 993TT or 993N/A arm, all the rest is the same.
Good information about the bushings, thanks for the info.
Articles in Porsche 911 and a few other mags are not much more than advertising, I have a hard time seeing how they could test the quality, longevity and reliability of these bushings in such a short duration of time, so I trust better your personal experience with them.
Last edited by Jean; 05-26-2007 at 06:05 AM.
05-26-2007, 06:31 AM
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Jean,
Please believe me when I say that the standard and RS 993 wishbones have the same void bush at the front.
The stronger RS bush is the solid rear bush !
It suprised me when we did deflection/strength measurements .
That would make the RS wishbone a very limited value part in my eyes .
During the development of these bushes I went round to a few of the specialists I know around Oxford , UK and found one morning ,10 sets of replaced ,wishbone pairs stood with the rest of the garbage !
It may be that obtaining a set of wishbones to play with is still a zero cost situation !
I started this bush development largely because an inspection of the standard parts seemed to leave lots of room for improvement !
I have no commercial imterest in the bushes at all.
Hopefully others will take a look.
Geoff
--------------------------------------------------------------------------------
KS400200 , the oldest 964 on Rennlist , unless you know differently !
Please believe me when I say that the standard and RS 993 wishbones have the same void bush at the front.
The stronger RS bush is the solid rear bush !
It suprised me when we did deflection/strength measurements .
That would make the RS wishbone a very limited value part in my eyes .
During the development of these bushes I went round to a few of the specialists I know around Oxford , UK and found one morning ,10 sets of replaced ,wishbone pairs stood with the rest of the garbage !
It may be that obtaining a set of wishbones to play with is still a zero cost situation !
I started this bush development largely because an inspection of the standard parts seemed to leave lots of room for improvement !
I have no commercial imterest in the bushes at all.
Hopefully others will take a look.
Geoff
--------------------------------------------------------------------------------
KS400200 , the oldest 964 on Rennlist , unless you know differently !
05-26-2007, 07:15 AM
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Geoff,
I believe you if you say you tested them. I am not educated enough in this to know how they should be tested, but in your opinion why does Porsche have different part numbers for those units, and a few other suspension parts? I don't buy a marketing reason though!
Jean
I believe you if you say you tested them. I am not educated enough in this to know how they should be tested, but in your opinion why does Porsche have different part numbers for those units, and a few other suspension parts? I don't buy a marketing reason though!
Jean
05-26-2007, 08:42 AM
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Jean,
The part numbers are different because the rear bushes are different.
I am not trying to persaude anyone to use Powerflex bushes . Its obviously a completely personal decision . I have , absolutely no commercial interest in this at all .
I was just highlighting why they were developed in the first place and what they do . You wouldnt believe the effort I put in just to get them made !
I have them on my 964 and thats where they will stay . I take a look at every major service after the initial frequent checks , just to be sure that nothing has happened . On the road the front end feels a little tighter and ride comfort is the same .
Just an area for the memory ?
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
The part numbers are different because the rear bushes are different.
I am not trying to persaude anyone to use Powerflex bushes . Its obviously a completely personal decision . I have , absolutely no commercial interest in this at all .
I was just highlighting why they were developed in the first place and what they do . You wouldnt believe the effort I put in just to get them made !
I have them on my 964 and thats where they will stay . I take a look at every major service after the initial frequent checks , just to be sure that nothing has happened . On the road the front end feels a little tighter and ride comfort is the same .
Just an area for the memory ?
Geoff
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KS400200 , the oldest 964 on Rennlist , unless you know differently !
