Squeak from front suspension
06-10-2016, 12:35 PM
#16
Nordschleife Master
Something to try is to shoot some lithium grease into the bushing gaps one-at-a-time. Get the spray grease and use the extension tube to get it into the crack. If it quiets, or changes, then you've got your suspect.
Consider other sources, too. I spent months chasing a suspension noise that was a bent heat shield rubbing on the transmission. The drivetrain moves a bit over bumps and it really screeched.
Consider other sources, too. I spent months chasing a suspension noise that was a bent heat shield rubbing on the transmission. The drivetrain moves a bit over bumps and it really screeched.
06-10-2016, 01:11 PM
#17
Rennlist Member
Thread Starter
Something to try is to shoot some lithium grease into the bushing gaps one-at-a-time. Get the spray grease and use the extension tube to get it into the crack. If it quiets, or changes, then you've got your suspect.
Consider other sources, too. I spent months chasing a suspension noise that was a bent heat shield rubbing on the transmission. The drivetrain moves a bit over bumps and it really screeched.
Consider other sources, too. I spent months chasing a suspension noise that was a bent heat shield rubbing on the transmission. The drivetrain moves a bit over bumps and it really screeched.
In my case it is getting noticeably worse suggesting something is going downhill. I know what it is not so it boils down to upper ball jpints [doub tit] or lower arm bushings [more or less].
Rgds
Fred
08-10-2016, 04:07 PM
#18
Rennlist Member
Thread Starter
So, I was planning to look into this problem in more detail once the hot season subsides around late October but as we have had a spell of relatively mild weather and thus driving the 928 more than I normally do this time of year, the squeak has been driving me up the twist so this evening I decided to take a look at the lower A arm rear bearings.
Put the car up on my home brewed lift bars and having dropped the belly pan removed the rear bearing caps. On the driver's side I found some damage to the rubber as per the first photo below, there seems to be about 5 ribs of rubber and the rear most rib was damaged as can be seen on the photo.
On the passenger side the rubber was cleaner but as per the second photo I noticed that on one side where the bearing cap sits the rubber looked as though it had been "pinched" a bit. My assumption is that when the arm pivots something must move, whether it is the arm inside the rubber, the rubber inside the outer bearing cap or the rubber itself that stretches elastically [or a combination thereof].
My queries to those that may have an opinion:
1. Is the damage to the rubber on the driver's side indicative of something that would cause my squeak and is it likely to be "terminal"?
2. Is the "pinching" of the rubber on the passenger side of any significance?
As always any thoughts appreciated and any suggestions as to how best to keep the thing in service/reduce the squeak [perhaps along the lines of Glen's earlier comment to use some lithium grease- not sure I can get that in spray form here though]. I do have regular grease and some copper slip anti seize grease but not sure whether these would goose the rubber up some more.
I do have some spare lower arms that appear to be in better condition if the damage is reckoned to be terminal albeit I would prefer to avoid trying to install them in the current heat.
Thoughts most welcome.
Rgds
Fred
Put the car up on my home brewed lift bars and having dropped the belly pan removed the rear bearing caps. On the driver's side I found some damage to the rubber as per the first photo below, there seems to be about 5 ribs of rubber and the rear most rib was damaged as can be seen on the photo.
On the passenger side the rubber was cleaner but as per the second photo I noticed that on one side where the bearing cap sits the rubber looked as though it had been "pinched" a bit. My assumption is that when the arm pivots something must move, whether it is the arm inside the rubber, the rubber inside the outer bearing cap or the rubber itself that stretches elastically [or a combination thereof].
My queries to those that may have an opinion:
1. Is the damage to the rubber on the driver's side indicative of something that would cause my squeak and is it likely to be "terminal"?
2. Is the "pinching" of the rubber on the passenger side of any significance?
As always any thoughts appreciated and any suggestions as to how best to keep the thing in service/reduce the squeak [perhaps along the lines of Glen's earlier comment to use some lithium grease- not sure I can get that in spray form here though]. I do have regular grease and some copper slip anti seize grease but not sure whether these would goose the rubber up some more.
I do have some spare lower arms that appear to be in better condition if the damage is reckoned to be terminal albeit I would prefer to avoid trying to install them in the current heat.
Thoughts most welcome.
Rgds
Fred
08-11-2016, 07:55 PM
#19
Chronic Tool Dropper
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Fred--
Sorry for the delayed follow-up. My understanding is that there should be no slippage at all in the LCA bushings. Your picture shows that the rubber has failed. where it should be intact to make the rubber flex rather than slip when there's suspension movement.
Mark has the lower arms rebuilt by the company that originally manufactured the part for Porsche, so no worries at all about having the right stuff in the right places. Also don't know shipping logistics from US to where you are. So intact "other" used arms might be an OK stopgap until the right parts can get there. Replacement is amazingly easy, but demands a full wheel alignment once the car has settled again. Popular recommendation is to delay tightening the rear bushing clamps until the car is on the ground -- anytime the clamps are loosened.
Sorry for the delayed follow-up. My understanding is that there should be no slippage at all in the LCA bushings. Your picture shows that the rubber has failed. where it should be intact to make the rubber flex rather than slip when there's suspension movement.
Mark has the lower arms rebuilt by the company that originally manufactured the part for Porsche, so no worries at all about having the right stuff in the right places. Also don't know shipping logistics from US to where you are. So intact "other" used arms might be an OK stopgap until the right parts can get there. Replacement is amazingly easy, but demands a full wheel alignment once the car has settled again. Popular recommendation is to delay tightening the rear bushing clamps until the car is on the ground -- anytime the clamps are loosened.
08-12-2016, 03:57 AM
#20
Rennlist Member
Thread Starter
Bob,
Thanks for the follow up and confirming the modus operandi. Indeed the rubber is totally shot- I pulled the arm yesterday after marking the position of the alignment cams. I will transfer those positional marks to the replacement arm I have to put back in to get me in the right ball park while the suspension settles.
I am due an overall alignment after doing the rear cam pocket adjusters earlier this year, perhaps waiting until I get new rubber on the car if the alignment is not too far out [I got it pretty close after replacing the lower ball joints].
Realistically I now need new upper and lower A arms [sad to say] as do most examples that have not had such done after 20 pus years of use not to mention what else the rear end might need over and above what I have done already.
928 ownership is like painting the Forth Rail Bridge- when you get to the finish you start all over again!
Thanks/regards
Fred
Thanks for the follow up and confirming the modus operandi. Indeed the rubber is totally shot- I pulled the arm yesterday after marking the position of the alignment cams. I will transfer those positional marks to the replacement arm I have to put back in to get me in the right ball park while the suspension settles.
I am due an overall alignment after doing the rear cam pocket adjusters earlier this year, perhaps waiting until I get new rubber on the car if the alignment is not too far out [I got it pretty close after replacing the lower ball joints].
Realistically I now need new upper and lower A arms [sad to say] as do most examples that have not had such done after 20 pus years of use not to mention what else the rear end might need over and above what I have done already.
928 ownership is like painting the Forth Rail Bridge- when you get to the finish you start all over again!
Thanks/regards
Fred
08-12-2016, 06:48 PM
#21
Rennlist Member
Thread Starter
I fitted my spare lower A arm today - not the easiest of tasks working from axle stands but not too difficult either.
To complete the installation the workshop manual talks about tightening the rear most bolts to 88ft lbs after the system has settled and before that tighten such that two threads are showing. Previously I left the rear bolts finger tight, put the car back on its wheels and then tightened on a lift. At the moment I do not have a lift so wondered if it is ok to jack up on the underside of the A arm so they are taking the weight of the car- any thoughts?
Not sure I would want to drive around waiting for the car to settle with the rear bolts not fully torqued- maybe I am missing something given I have no clue what they mean by "two threads showing".
Rgds
Fred
To complete the installation the workshop manual talks about tightening the rear most bolts to 88ft lbs after the system has settled and before that tighten such that two threads are showing. Previously I left the rear bolts finger tight, put the car back on its wheels and then tightened on a lift. At the moment I do not have a lift so wondered if it is ok to jack up on the underside of the A arm so they are taking the weight of the car- any thoughts?
Not sure I would want to drive around waiting for the car to settle with the rear bolts not fully torqued- maybe I am missing something given I have no clue what they mean by "two threads showing".
Rgds
Fred
08-12-2016, 08:19 PM
#22
Chronic Tool Dropper
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Fred--
Those rear saddle clamp bolts are accessible. at least on my car. with the car sitting on the tires. Go ahead and let the car down, tighten the bolts, and drive to settle the suspension. Once settled, loosen and then tighten them again without lifting the car. Watch the clearance between the saddle and the clamp to see when the bolts are "loose" enough. "A couple threads" is maybe 1/4" and you may not want quite that much. Just enough to let the bushings move if they need to, not so much that you risk losing the indexing from the little sleeves. Then perform the alignment before installing new tires.
Those rear saddle clamp bolts are accessible. at least on my car. with the car sitting on the tires. Go ahead and let the car down, tighten the bolts, and drive to settle the suspension. Once settled, loosen and then tighten them again without lifting the car. Watch the clearance between the saddle and the clamp to see when the bolts are "loose" enough. "A couple threads" is maybe 1/4" and you may not want quite that much. Just enough to let the bushings move if they need to, not so much that you risk losing the indexing from the little sleeves. Then perform the alignment before installing new tires.
08-13-2016, 07:18 AM
#23
Rennlist Member
Fred--
Those rear saddle clamp bolts are accessible. at least on my car. with the car sitting on the tires. Go ahead and let the car down, tighten the bolts, and drive to settle the suspension. Once settled, loosen and then tighten them again without lifting the car. Watch the clearance between the saddle and the clamp to see when the bolts are "loose" enough. "A couple threads" is maybe 1/4" and you may not want quite that much. Just enough to let the bushings move if they need to, not so much that you risk losing the indexing from the little sleeves. Then perform the alignment before installing new tires.
Those rear saddle clamp bolts are accessible. at least on my car. with the car sitting on the tires. Go ahead and let the car down, tighten the bolts, and drive to settle the suspension. Once settled, loosen and then tighten them again without lifting the car. Watch the clearance between the saddle and the clamp to see when the bolts are "loose" enough. "A couple threads" is maybe 1/4" and you may not want quite that much. Just enough to let the bushings move if they need to, not so much that you risk losing the indexing from the little sleeves. Then perform the alignment before installing new tires.
08-13-2016, 04:58 PM
#25
Rennlist Member
Thread Starter
That looks like the computations that were going through my mind this afternoon in 45C heat as I was trying to fit the two front reinforcing bracket bolts that would not engage. 
Had to loosen everything to solve that one. Amazing how if you have not done these jobs for a while you forget the little tricks that make it work.
Although I indexed the adjusters, when I got the car back on the deck the alignment was a million miles out, especially the toe. Need to cross check everything tomorrow and/or adjust the front driver side toe some. I suspect I did something dumb like index one of the adjusters incorrectly but..?
Rgds
Fred
Had to loosen everything to solve that one. Amazing how if you have not done these jobs for a while you forget the little tricks that make it work.
Although I indexed the adjusters, when I got the car back on the deck the alignment was a million miles out, especially the toe. Need to cross check everything tomorrow and/or adjust the front driver side toe some. I suspect I did something dumb like index one of the adjusters incorrectly but..?
Rgds
Fred
08-13-2016, 06:28 PM
#26
Chronic Tool Dropper
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Fred--
The cam adjusters have a LOT of room around them, such that having the cams facing in the same direction as before will only get the alignment into the right area. The fine adjustments are extremely sensitive.
Adjust the caster so that the ball end of the balljoint is as far towards the rear of the car as the cam will allow. So you get the MINIMUM allowable caster as your starting point. I usually adjust the cam to rearmost position, snug but not tight on the nut, then tap the balljoint end gently with a mallette', then a little more snug on the nut but not tight yet.
Camber adjusts with a carpenter's level, ideally spaced vertically against the rim edges. MK does his with the level against the tire face, but that doesn't account well for bulge at the bottom of the tire IMO. A couple scrap pieces of wood the same thickness will do the job, with a couple elastic bungee cords to hold the level and the blocks in place. For factory camber, I then place a 5/32" (4mm) drill bit between the level and the top spacer block. Then adjust the camber cam to show vertical on the carpenter's level. You may end up tapping the end of the balljoint to the rear again as you adjust camber, before you tighten the two nuts to lock the balljoint in place on the LCA.
Adjusting toe-in is a little more fun at this point, because the car is raised from normal ride height. You'll want to add some extra toe-in initially to compensate for the change that happens as the car settles. Maybe 2º? guessing. Whatever method you use to measure toe (lasers, straightedge, strings, tape measure) is fine at this point.
The cam adjusters have a LOT of room around them, such that having the cams facing in the same direction as before will only get the alignment into the right area. The fine adjustments are extremely sensitive.
Adjust the caster so that the ball end of the balljoint is as far towards the rear of the car as the cam will allow. So you get the MINIMUM allowable caster as your starting point. I usually adjust the cam to rearmost position, snug but not tight on the nut, then tap the balljoint end gently with a mallette', then a little more snug on the nut but not tight yet.
Camber adjusts with a carpenter's level, ideally spaced vertically against the rim edges. MK does his with the level against the tire face, but that doesn't account well for bulge at the bottom of the tire IMO. A couple scrap pieces of wood the same thickness will do the job, with a couple elastic bungee cords to hold the level and the blocks in place. For factory camber, I then place a 5/32" (4mm) drill bit between the level and the top spacer block. Then adjust the camber cam to show vertical on the carpenter's level. You may end up tapping the end of the balljoint to the rear again as you adjust camber, before you tighten the two nuts to lock the balljoint in place on the LCA.
Adjusting toe-in is a little more fun at this point, because the car is raised from normal ride height. You'll want to add some extra toe-in initially to compensate for the change that happens as the car settles. Maybe 2º? guessing. Whatever method you use to measure toe (lasers, straightedge, strings, tape measure) is fine at this point.
08-13-2016, 07:36 PM
#27
Rennlist Member
Thread Starter
Fred--
The cam adjusters have a LOT of room around them, such that having the cams facing in the same direction as before will only get the alignment into the right area. The fine adjustments are extremely sensitive.
Adjust the caster so that the ball end of the balljoint is as far towards the rear of the car as the cam will allow. So you get the MINIMUM allowable caster as your starting point. I usually adjust the cam to rearmost position, snug but not tight on the nut, then tap the balljoint end gently with a mallette', then a little more snug on the nut but not tight yet.
Camber adjusts with a carpenter's level, ideally spaced vertically against the rim edges. MK does his with the level against the tire face, but that doesn't account well for bulge at the bottom of the tire IMO. A couple scrap pieces of wood the same thickness will do the job, with a couple elastic bungee cords to hold the level and the blocks in place. For factory camber, I then place a 5/32" (4mm) drill bit between the level and the top spacer block. Then adjust the camber cam to show vertical on the carpenter's level. You may end up tapping the end of the balljoint to the rear again as you adjust camber, before you tighten the two nuts to lock the balljoint in place on the LCA.
Adjusting toe-in is a little more fun at this point, because the car is raised from normal ride height. You'll want to add some extra toe-in initially to compensate for the change that happens as the car settles. Maybe 2º? guessing. Whatever method you use to measure toe (lasers, straightedge, strings, tape measure) is fine at this point.
The cam adjusters have a LOT of room around them, such that having the cams facing in the same direction as before will only get the alignment into the right area. The fine adjustments are extremely sensitive.
Adjust the caster so that the ball end of the balljoint is as far towards the rear of the car as the cam will allow. So you get the MINIMUM allowable caster as your starting point. I usually adjust the cam to rearmost position, snug but not tight on the nut, then tap the balljoint end gently with a mallette', then a little more snug on the nut but not tight yet.
Camber adjusts with a carpenter's level, ideally spaced vertically against the rim edges. MK does his with the level against the tire face, but that doesn't account well for bulge at the bottom of the tire IMO. A couple scrap pieces of wood the same thickness will do the job, with a couple elastic bungee cords to hold the level and the blocks in place. For factory camber, I then place a 5/32" (4mm) drill bit between the level and the top spacer block. Then adjust the camber cam to show vertical on the carpenter's level. You may end up tapping the end of the balljoint to the rear again as you adjust camber, before you tighten the two nuts to lock the balljoint in place on the LCA.
Adjusting toe-in is a little more fun at this point, because the car is raised from normal ride height. You'll want to add some extra toe-in initially to compensate for the change that happens as the car settles. Maybe 2º? guessing. Whatever method you use to measure toe (lasers, straightedge, strings, tape measure) is fine at this point.
At the moment I am puzzled as to why I am seeing so much toe in on the side I replaced the lower arm. Replicating the previous [eyeballed] settings was meant to get me safely to the alignment shop after the suspension settled.
I can get the toe back into shape iteratively just by eyeballing and test driving and pretty much the same for camber [having done it so many times previously]. As you say once one gets onto the Hunter machine one sees quite big changes for relatively small changes. for settlement the rubber can withstand quite some difference on camber and caster while it settles but toe has to be reasonable. for sure with caster it is better to have too much and camber I can usually eyeball as well - I do have a rig along the lines you mentioned.
Trouble with these things is that they are quite interactive- much more so than most appreciate. The driver's side toe looked hilarious- must have been around 15 degrees believe it or not- some of that would disappear with settlement but nothing close to what is needed.
If nothing else the alignment shop is quite close to my home.
Rgds
Fred
08-14-2016, 11:01 AM
#28
Rennlist Member
Thread Starter
Well I solved the mystery today and deserve a wooden spoon for stupidity!
I do not run a stock alignment, rather I try to take advantage of the car's capabilities given the suspension and wheels. One of the problems I had years ago was that I could not get the alignment I wanted because the adjustment range on one side of the car only allowed minus 1 degree of camber when I wanted minus 2 degrees. The answer was to fit one of the earlier lower A arms together with its support bracket- worked a treat. for some reason I had it in my mind that when I did this modification I did so on the passenger side- the opposite side to that I have been working. Today I took a close look at the arm I removed and saw that it did not have "PORSCHE" stamped on it- durrgh! The arm I replaced it with was the one I removed from the car but it seems my notion of which side was which was *** about face. Cannot believe I did this.
I do have spare arms of both kinds albeit the spare early arm is probably past its best but is in better condition than the one I pulled out.
So I have to start all over again- bugger! No joke doing this job in 40C plus heat never mind the fact that I am well past my best.
Ay least I took a little solace reading Stan's engine thread and seeing he made a couple of mistakes - helped me feel a little less stupid!
Rgds
Fred
I do not run a stock alignment, rather I try to take advantage of the car's capabilities given the suspension and wheels. One of the problems I had years ago was that I could not get the alignment I wanted because the adjustment range on one side of the car only allowed minus 1 degree of camber when I wanted minus 2 degrees. The answer was to fit one of the earlier lower A arms together with its support bracket- worked a treat. for some reason I had it in my mind that when I did this modification I did so on the passenger side- the opposite side to that I have been working. Today I took a close look at the arm I removed and saw that it did not have "PORSCHE" stamped on it- durrgh! The arm I replaced it with was the one I removed from the car but it seems my notion of which side was which was *** about face. Cannot believe I did this.
I do have spare arms of both kinds albeit the spare early arm is probably past its best but is in better condition than the one I pulled out.
So I have to start all over again- bugger! No joke doing this job in 40C plus heat never mind the fact that I am well past my best.
Ay least I took a little solace reading Stan's engine thread and seeing he made a couple of mistakes - helped me feel a little less stupid!
Rgds
Fred
08-14-2016, 01:25 PM
#29
Rennlist Member
Hang in there, Fred! You'll get it. Often times, its 2 steps forward, 1 step back.
Seeing what you are going through makes me feel better about working on the Red Witch, inasmuch that I can do it.
Thanks and good luck!
Seth K. Pyle
Seeing what you are going through makes me feel better about working on the Red Witch, inasmuch that I can do it.
Thanks and good luck!
Seth K. Pyle
03-14-2017, 04:29 AM
#30
Rennlist Member
Thread Starter
Just bumping this thread a tad-
The mystery squeak is gone or so it seems. If you followed this thred earlier you will know that I was previously running with the older style lower control arm. Decided I do not need as much camber as I ran with previously given there are no track days in my tea leaves so re-fitted the original GTS lower arm that looked in very good condition rather than try fitting shims in the upper control arm. It will be intesting to see how much camber I can get on this side given te first time I tried it I was limited to minus 1 degree- I can live with that now [plus the 928MS lower frame brace seems to reduce the need for as much camber]! I also opted to fit slightly narrower front tires [255 versus 265 previously].
The thing that tweaked my imagination was a post a while ago from GB wherein he stated it was not a good idea to fit any LCA in a position it was not originally fitted to, that and those arms are ancient. Like most home hacks I was not aware of this at the time but I am now!
The Rennlist membership fee pays off first time one posts on this list and even after 18 years continues to do so. I doubt I would still be in a 928 and getting in deeper by the year were it not for the camaraderie of this list.
Rgds
Fred
The mystery squeak is gone or so it seems. If you followed this thred earlier you will know that I was previously running with the older style lower control arm. Decided I do not need as much camber as I ran with previously given there are no track days in my tea leaves so re-fitted the original GTS lower arm that looked in very good condition rather than try fitting shims in the upper control arm. It will be intesting to see how much camber I can get on this side given te first time I tried it I was limited to minus 1 degree- I can live with that now [plus the 928MS lower frame brace seems to reduce the need for as much camber]! I also opted to fit slightly narrower front tires [255 versus 265 previously].
The thing that tweaked my imagination was a post a while ago from GB wherein he stated it was not a good idea to fit any LCA in a position it was not originally fitted to, that and those arms are ancient. Like most home hacks I was not aware of this at the time but I am now!
The Rennlist membership fee pays off first time one posts on this list and even after 18 years continues to do so. I doubt I would still be in a 928 and getting in deeper by the year were it not for the camaraderie of this list.
Rgds
Fred