Front Lower Control Arm Busing Removal
04-26-2017, 05:27 PM
#16
The original bushings... Fronts are made-in-place for the most part, so the rubber flexes but doesn't actually move. I'm not sure how an aftermarket bushing material can be similarly made-in-place. Neither the aluminum control arm nor the aluminum support are ready for a bushing that slips.
In the rear, the bushing is bonded to the control arm and sits in a saddle between a formed section that's part of the crossmember, and the aluminum support. There is no provision for a slipping-style bushing. In fact, the factory recommends that you allow the suspension to settle some, before final tightening of that rear support clamp if the clamp is loose when the car is lifted on the suspension.
I'll be very interested is seeing what is actually supplied, and how the supplier recommends installation.
In the rear, the bushing is bonded to the control arm and sits in a saddle between a formed section that's part of the crossmember, and the aluminum support. There is no provision for a slipping-style bushing. In fact, the factory recommends that you allow the suspension to settle some, before final tightening of that rear support clamp if the clamp is loose when the car is lifted on the suspension.
I'll be very interested is seeing what is actually supplied, and how the supplier recommends installation.
04-26-2017, 05:40 PM
#17
Rennlist Member
Thread Starter
Thanks for the feedback. I am going to tilt some of you guys with what I have to say below. Sorry about that. Just my opinion.
Anyhow, I already bought the lower powerflex bushings so I am basically committed. If I lose a bit of the "built in shock" characteristics of the factory bushings, so be it, I have aftermarket lowering springs and Koni shocks to make up for it. I man who is going to notice it driving on the street?
What I don't understand, and what ticks me off about the 928 is fact that Porsche, and it's supposedly "brilliant" team of engineers intentionally designed a car where the owner is expected to replace an entire a arm (expensive) just because the rubber bushings are worn out. Or, ball joints on the later cars that are not replaceable like most other car manufacturers? Then there is the rear suspension... Even these "interference motors" are nothing short of diabolic. Surely Porsche could have built in deeper valve reliefs in the pistons so they whole top end is not lunched. As for the small loss of power due to lower compression, you would never feel it. Aluminum cam gears that are crap and wear out...even aluminum ball joints...yikes!
I mean who builds a suspension that cannot be lifted off the ground to align the front end without screwing up things? A suspension that needs time to "settle" (if it settles) before the bolts can be torqued? Sorry, but I can only see this as a design flaw. As for the "built in shock" in the a arm bushings: This is just a fortunate side effect (or happenstance) of an otherwise greedy and evil design (ex: rubber bushings vulcanized onto the control arm so they are not rebuildable). If Porsche thought they could get away with making you buy a complete, 1 piece drop in front and rear suspension that was not rebuildable and costs 10k they sure would of.
Where exactly is the FUN in all this when a 928 buyer spends and spends and spends and can still never afford to get their car done? Never even drives it. Craigslist is riddled with old 928 caracasses that the owners cannot afford to fix. Sometimes I feel like I will never get this car done. End of rant.
Anyhow, I already bought the lower powerflex bushings so I am basically committed. If I lose a bit of the "built in shock" characteristics of the factory bushings, so be it, I have aftermarket lowering springs and Koni shocks to make up for it. I man who is going to notice it driving on the street?
What I don't understand, and what ticks me off about the 928 is fact that Porsche, and it's supposedly "brilliant" team of engineers intentionally designed a car where the owner is expected to replace an entire a arm (expensive) just because the rubber bushings are worn out. Or, ball joints on the later cars that are not replaceable like most other car manufacturers? Then there is the rear suspension... Even these "interference motors" are nothing short of diabolic. Surely Porsche could have built in deeper valve reliefs in the pistons so they whole top end is not lunched. As for the small loss of power due to lower compression, you would never feel it. Aluminum cam gears that are crap and wear out...even aluminum ball joints...yikes!
I mean who builds a suspension that cannot be lifted off the ground to align the front end without screwing up things? A suspension that needs time to "settle" (if it settles) before the bolts can be torqued? Sorry, but I can only see this as a design flaw. As for the "built in shock" in the a arm bushings: This is just a fortunate side effect (or happenstance) of an otherwise greedy and evil design (ex: rubber bushings vulcanized onto the control arm so they are not rebuildable). If Porsche thought they could get away with making you buy a complete, 1 piece drop in front and rear suspension that was not rebuildable and costs 10k they sure would of.
Where exactly is the FUN in all this when a 928 buyer spends and spends and spends and can still never afford to get their car done? Never even drives it. Craigslist is riddled with old 928 caracasses that the owners cannot afford to fix. Sometimes I feel like I will never get this car done. End of rant.
04-26-2017, 07:02 PM
#18
Rennlist Member
Your bushes dont look really worn out in your photos..and the upper rear ones go sour, they can be replaced.
Keep in mind how much danger your lower engine block will now be in as well.
Keep in mind how much danger your lower engine block will now be in as well.
04-26-2017, 07:43 PM
#19
Archive Gatekeeper
Rennlist Member
Rennlist Member
Quick question- Is either rubber bushing on the lower control arm pictured in post #1 failed? (ie- is the forward one's rubber separated from the arm or the mounting bracket?)
If not, I'd just run those arms as-is. The rubber on the rear is smooshed a bunch but as long as the rubber's still vulcanized to the arm at both ends, I'd save your money for whatever else is keeping you from enjoying the car.
If not, I'd just run those arms as-is. The rubber on the rear is smooshed a bunch but as long as the rubber's still vulcanized to the arm at both ends, I'd save your money for whatever else is keeping you from enjoying the car.
04-26-2017, 08:46 PM
#20
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
The key advantage of these three piece bushes is that there is no settling required. There is little resistance to movement by hand force. As such the arm can track easily and accurately it's designed pathway. This way stitchen is greatly reduced and dampers can be more accurately tuned.
What I don't understand, and what ticks me off about the 928 is fact that Porsche, and it's supposedly "brilliant" team of engineers intentionally designed a car where the owner is expected to replace an entire a arm (expensive) just because the rubber bushings are worn out.
I replaced all the rubber bits on my SAAB. After spending several hours at Turbo Todd's shop making custom tools to push out the old bushings, he really questioned why I didn't just buy the rebuilt arms with the bushings already installed.... I didn't have a good answer, he was right. The amount of time we wasted did not make up for the extra cost of all new parts.
Originally Posted by Fresh
Even these "interference motors" are nothing short of diabolic. Surely Porsche could have built in deeper valve reliefs in the pistons so they whole top end is not lunched. As for the small loss of power due to lower compression, you would never feel it.
Originally Posted by Fresh
I mean who builds a suspension that cannot be lifted off the ground to align the front end without screwing up things?
Originally Posted by Fresh
A suspension that needs time to "settle" (if it settles) before the bolts can be torqued? Sorry, but I can only see this as a design flaw.
My Saab has a detailed procedure similar to the 928 when replacing the rear bushings.
Originally Posted by Fresh
This is just a fortunate side effect (or happenstance) of an otherwise greedy and evil design (ex: rubber bushings vulcanized onto the control arm so they are not rebuildable).
So the real complaint is you are not qualified to rebuild them yourself and this is Porsche's design flaw???
Vintage Porsches are not for everyone, that is why God invented Mustangs and Camaros.
04-27-2017, 09:02 AM
#21
Rennlist Member
When you post a query please include your model and year- more often than not it is relevant. The bushing is the same for all model years but 86 and earlier have different arms [FYI]. The older the arm the more likely degradation has ocurred. From what I can of your photo I see no markings on the arm so perhaps that suggests you have the older model?
Either way what prompted you to suspect the arms were shot- not saying there is nothing wrong with them but intrigued as to what drove you to your decision to refurb.
Regarding your original query I removed the front end bushing using a press but for the rear most one I used my dremel to cut through the bush [see pic 1 below]- if it can be removed by a press so much the better but I was "exploring" at the time. I tried to be very careful and I caught the flange face ever so slightly but nothing of consequence. The trick is to know how deep to cut. Fiirst of all one has to cut through the outer rubber layer and then the inner steel layer. Once the steel layer has been completely breached you then tackle the rubber with great care. Where the inner bush sits on the stub of the arm the surface is serrated [see pic]. I cut through the inner rubber until I could see some kind of separation- after that I pried the cut surfaces apart and the bush came away quite easily [to my relief] and no sign of anything bonded just what looked like a press fit.
Now the interesting bit- as you will have seen from the above posts the consensus suggests that these bushes are bonded to the arm- I saw absolutely no evidence to support this front or rear. For sure the rubber is bonded to the inner steel sleeve. Whether or not it was bonded originally and that degraded who knows but I saw no evidence to support this.
As and when you get round to fitting the bushes do keep us posted with pics so we can learn something unless of course you decide not to fit the bushes at this moment in time.
Regarding your "rant" all I can say is welcome to the club! You can buy a 30 year old supercar for peanuts but you cannot run it for such and if that is your want flog the thing and go play with something else. Hopefully you will see the light and come to think like rest of us "nutjobs". It is not uncommon for people to purchase these machines and spend more in the first year of ownership than they paid for it. Buy one that has been properly looked after for top dollar and you will still have bills but way less than with a neglected mongrel.
Rgds
Fred
04-28-2017, 08:15 AM
#22
Rennlist Member
Thread Starter
Glad to see another person open to using non porsche bushings. Personally, I think the powerflex bushings are going to work great. These are supposedly huge in Europe with the BMW crowd. When it's done, I'll bet the thing handles like it's glued to the road. Granted, my 928, in the 6 months I actually got to drive it (so many years ago) handled fantastic. If the head gaskets hadn't blown, I'd probably still be driving it today. The car is indeed a feat of engineering, especially for its time....
Perhaps I was a bit harsh on Porsche and its engineers, but who can afford some of these parts? It's crazy after a while...
I am going powerflex in front (upper and lower) and probably poly bushings from 928 performance in the back, as I don't think powerflex makes them for the rear.
What is the worst thing that can happen? The car rides too rough? The bushings crap out? A front control arm flies off, the car rolls over 10 times then explodes? I been married 27 years. BRING IT ON! ..and if I'm unlucky enough to limp away, I can always beat the car back into shape with as 5 pound sledge and go back to using Porsche bushings... It's a good plan
But seriously, our 928's are not exactly skyrocketing in value like the air cooled 911's. Who gives a crap? Experiment on them.
Perhaps I was a bit harsh on Porsche and its engineers, but who can afford some of these parts? It's crazy after a while...
I am going powerflex in front (upper and lower) and probably poly bushings from 928 performance in the back, as I don't think powerflex makes them for the rear.
What is the worst thing that can happen? The car rides too rough? The bushings crap out? A front control arm flies off, the car rolls over 10 times then explodes? I been married 27 years. BRING IT ON! ..and if I'm unlucky enough to limp away, I can always beat the car back into shape with as 5 pound sledge and go back to using Porsche bushings... It's a good plan
But seriously, our 928's are not exactly skyrocketing in value like the air cooled 911's. Who gives a crap? Experiment on them.
04-30-2017, 07:09 PM
#23
Rennlist Member
Thread Starter
I also got the top wishbone bushings come in black. PFF57-704, which were $167 for the 4 bushings. These bushings are not so cheap, so I am hoping that they are really good and durable. With shipping you will pay a little under $400 plus shipping, which is pretty cheap. YOu can also get front and rear sway bar bushings. I did not get them yet. Might use others from 928 Performance, not sure yet.
When I put these in, I will make a video on youtube.com
04-30-2017, 07:17 PM
#24
Rennlist Member
Thread Starter
Why do you "need" to remove the existing bushes- is it simply because you want to fit the Powerflex items? For sure these things degrade with age but if my experience is anything to go by it takes a really long time.
When you post a query please include your model and year- more often than not it is relevant. The bushing is the same for all model years but 86 and earlier have different arms [FYI]. The older the arm the more likely degradation has ocurred. From what I can of your photo I see no markings on the arm so perhaps that suggests you have the older model?
Either way what prompted you to suspect the arms were shot- not saying there is nothing wrong with them but intrigued as to what drove you to your decision to refurb.
Regarding your original query I removed the front end bushing using a press but for the rear most one I used my dremel to cut through the bush [see pic 1 below]- if it can be removed by a press so much the better but I was "exploring" at the time. I tried to be very careful and I caught the flange face ever so slightly but nothing of consequence. The trick is to know how deep to cut. Fiirst of all one has to cut through the outer rubber layer and then the inner steel layer. Once the steel layer has been completely breached you then tackle the rubber with great care. Where the inner bush sits on the stub of the arm the surface is serrated [see pic]. I cut through the inner rubber until I could see some kind of separation- after that I pried the cut surfaces apart and the bush came away quite easily [to my relief] and no sign of anything bonded just what looked like a press fit.
Now the interesting bit- as you will have seen from the above posts the consensus suggests that these bushes are bonded to the arm- I saw absolutely no evidence to support this front or rear. For sure the rubber is bonded to the inner steel sleeve. Whether or not it was bonded originally and that degraded who knows but I saw no evidence to support this.
As and when you get round to fitting the bushes do keep us posted with pics so we can learn something unless of course you decide not to fit the bushes at this moment in time.
Regarding your "rant" all I can say is welcome to the club! You can buy a 30 year old supercar for peanuts but you cannot run it for such and if that is your want flog the thing and go play with something else. Hopefully you will see the light and come to think like rest of us "nutjobs". It is not uncommon for people to purchase these machines and spend more in the first year of ownership than they paid for it. Buy one that has been properly looked after for top dollar and you will still have bills but way less than with a neglected mongrel.
Rgds
Fred
When you post a query please include your model and year- more often than not it is relevant. The bushing is the same for all model years but 86 and earlier have different arms [FYI]. The older the arm the more likely degradation has ocurred. From what I can of your photo I see no markings on the arm so perhaps that suggests you have the older model?
Either way what prompted you to suspect the arms were shot- not saying there is nothing wrong with them but intrigued as to what drove you to your decision to refurb.
Regarding your original query I removed the front end bushing using a press but for the rear most one I used my dremel to cut through the bush [see pic 1 below]- if it can be removed by a press so much the better but I was "exploring" at the time. I tried to be very careful and I caught the flange face ever so slightly but nothing of consequence. The trick is to know how deep to cut. Fiirst of all one has to cut through the outer rubber layer and then the inner steel layer. Once the steel layer has been completely breached you then tackle the rubber with great care. Where the inner bush sits on the stub of the arm the surface is serrated [see pic]. I cut through the inner rubber until I could see some kind of separation- after that I pried the cut surfaces apart and the bush came away quite easily [to my relief] and no sign of anything bonded just what looked like a press fit.
Now the interesting bit- as you will have seen from the above posts the consensus suggests that these bushes are bonded to the arm- I saw absolutely no evidence to support this front or rear. For sure the rubber is bonded to the inner steel sleeve. Whether or not it was bonded originally and that degraded who knows but I saw no evidence to support this.
As and when you get round to fitting the bushes do keep us posted with pics so we can learn something unless of course you decide not to fit the bushes at this moment in time.
Regarding your "rant" all I can say is welcome to the club! You can buy a 30 year old supercar for peanuts but you cannot run it for such and if that is your want flog the thing and go play with something else. Hopefully you will see the light and come to think like rest of us "nutjobs". It is not uncommon for people to purchase these machines and spend more in the first year of ownership than they paid for it. Buy one that has been properly looked after for top dollar and you will still have bills but way less than with a neglected mongrel.
Rgds
Fred
04-30-2017, 09:13 PM
#25
Rennlist Member
Thread Starter
Quick question- Is either rubber bushing on the lower control arm pictured in post #1 failed? (ie- is the forward one's rubber separated from the arm or the mounting bracket?)
If not, I'd just run those arms as-is. The rubber on the rear is smooshed a bunch but as long as the rubber's still vulcanized to the arm at both ends, I'd save your money for whatever else is keeping you from enjoying the car.
If not, I'd just run those arms as-is. The rubber on the rear is smooshed a bunch but as long as the rubber's still vulcanized to the arm at both ends, I'd save your money for whatever else is keeping you from enjoying the car.
04-30-2017, 09:16 PM
#26
Rennlist Member
Thread Starter
Wow, that's interesting. That's the opposite effect most other cars have when you go from rubber to poly bushings. Now I'm tempted to try them on my 79...
How many other cars have you worked on? This isn't terribly uncommon. I recently updated all the rubber bits on the front of my friends F150 and the box of parts from Ford was new control arms. Could they be rebuilt? Sure, if I have the correct tools. Same with the 928 arms. If you have the knowledge & equipment they can be rebuilt. It's just easier to swap the arms.
I replaced all the rubber bits on my SAAB. After spending several hours at Turbo Todd's shop making custom tools to push out the old bushings, he really questioned why I didn't just buy the rebuilt arms with the bushings already installed.... I didn't have a good answer, he was right. The amount of time we wasted did not make up for the extra cost of all new parts.
Dear Lord, not this BS argument again. Make a list of every car made today that is not interference. Even the Chevy 350 in most GM vehicles are interference. Friend of mine busted up an engine real bad when he lost a timing chain in his ZO6. So maybe there is more to it than a couple simple valve reliefs.
The procedure is detailed in the WSM and is very easy to follow (yes I've done it). I could understand this issue if Porsche never bothered to share with the world how to do it.
See my post above, all suspension bits need to be at level before the bolts should be torqued. Any experienced mechanic knows this.
My Saab has a detailed procedure similar to the 928 when replacing the rear bushings.
Again, work on a few more cars and get back to me. It's very rare on modern day cars to rebuild suspension pieces. Shops order new units with new bushings installed. Yes they can be rebuilt if you know how (most shops do) it's just easier to swap the arms.
So the real complaint is you are not qualified to rebuild them yourself and this is Porsche's design flaw???
Vintage Porsches are not for everyone, that is why God invented Mustangs and Camaros.
How many other cars have you worked on? This isn't terribly uncommon. I recently updated all the rubber bits on the front of my friends F150 and the box of parts from Ford was new control arms. Could they be rebuilt? Sure, if I have the correct tools. Same with the 928 arms. If you have the knowledge & equipment they can be rebuilt. It's just easier to swap the arms.
I replaced all the rubber bits on my SAAB. After spending several hours at Turbo Todd's shop making custom tools to push out the old bushings, he really questioned why I didn't just buy the rebuilt arms with the bushings already installed.... I didn't have a good answer, he was right. The amount of time we wasted did not make up for the extra cost of all new parts.
Dear Lord, not this BS argument again. Make a list of every car made today that is not interference. Even the Chevy 350 in most GM vehicles are interference. Friend of mine busted up an engine real bad when he lost a timing chain in his ZO6. So maybe there is more to it than a couple simple valve reliefs.
The procedure is detailed in the WSM and is very easy to follow (yes I've done it). I could understand this issue if Porsche never bothered to share with the world how to do it.
See my post above, all suspension bits need to be at level before the bolts should be torqued. Any experienced mechanic knows this.
My Saab has a detailed procedure similar to the 928 when replacing the rear bushings.
Again, work on a few more cars and get back to me. It's very rare on modern day cars to rebuild suspension pieces. Shops order new units with new bushings installed. Yes they can be rebuilt if you know how (most shops do) it's just easier to swap the arms.
So the real complaint is you are not qualified to rebuild them yourself and this is Porsche's design flaw???
Vintage Porsches are not for everyone, that is why God invented Mustangs and Camaros.
04-30-2017, 10:51 PM
#27
Rennlist Member
Thread Starter
05-01-2017, 01:14 PM
#30
Nordschleife Master
... The car is indeed a feat of engineering, especially for its time....
Perhaps I was a bit harsh on Porsche and its engineers, but who can afford some of these parts? It's crazy after a while...
But seriously, our 928's are not exactly skyrocketing in value like the air cooled 911's. Who gives a crap? Experiment on them.
Perhaps I was a bit harsh on Porsche and its engineers, but who can afford some of these parts? It's crazy after a while...
But seriously, our 928's are not exactly skyrocketing in value like the air cooled 911's. Who gives a crap? Experiment on them.
Cayennes are the same way. You can pick up the early ones for next to nothing (compared with sticker price), but parts prices still reflect that sticker price, not what they sell for now.
911 prices seem to be leveling off. Some of the "bubble" seems to have settled down (not exactly 'burst'). 928 values are increasing. But (as is normal for this sort of thing), the ones seeing the most increase are the first and last, and mostly all original, low mile, pristine examples. When and if 928s are going to see rusty shells going for 4 or 5 figures remains to be seen.