Suspension Rattle, Chassis Ears, Need Advice
09-11-2020, 02:52 PM
#31
Congrats and thanks for getting back to us regarding your feat!!!
To be clear, that write up from The Bruce was entirely his doing. All thanks should be pointed in his direction.
To be clear, that write up from The Bruce was entirely his doing. All thanks should be pointed in his direction.
09-13-2020, 06:40 AM
#32
2009 C2S 159K miles
Google is your friend for torque values.... but here are some:
https://rennlist.com/forums/997-gt2-...uspension.html
https://rennlist.com/forums/997-foru...que-specs.html
I completed my job of replacing the rear wheel carriers, aka knuckles. Toughest job I ever did and did it without any assistant. Plenty of sweat-inducing situations. I pressed in my own new bearings into the new carriers but had to get a speed shop to remove and press in the hubs... they used a hydraulic press of course. To get my new bearings in, I put the carriers in my home oven and put the bearings in my freezer. Then using a bearing press kit rented for free from Autozone, used my impact gun and they went straight on in without any drama.
My noise was fixed with this replacement as I am 98% sure it was the bushing in the knuckle that was wearing and allowing the lower shock/bolt to make noise. I say 98% sure, because I read that the mounts, on top, are a source of noise, and I decided to go ahead and replace these too. So I am not 100% sure it was that lower bushing. When I used my chassis ears, I put a microphone clip on that lower bolt and it was noisy and super clear. I found I could induce the noise by literally shaking the car. Open the driver door and had a friend (stronger than me) rock the car by pushing up on the roof line. I did put clips on the top of the spring and anything else I could clip those things onto but did not get the metal-on-metal noise from the top. When I examined the old and new shock mounts, I could not see how they make noise as the shock piston is isolated by the foam and rubber parts and the car sits on the spring (on a cushioning seat) where I had the clip... but oh well, I succeeded in killing the noise.
FYI: for replacing the shock mounts, I did not need a spring compressor.. I had one rented just in case, but you don't need one at all.
BTW, the most difficult parts to the job included releasing the emergency brake cable "tube" from the carrier... I did this by freezing the tube. I sprayed fluid from an upside-down can of compressed air... the kind you use for blowing out dust from photography and other equipment. I placed a vice grip on it, then sprayed the inside of the tube while twisting the tube back and forth. The other challenge was re-installing the emergency brake shoes... sheesh! I found the Porsche parts katalog incorrect in that they noted the tube is a separate part, but on my car, it was pinch welded to the cable and was not coming off so I had to pull it out of the carrier.
Another toubling issue is there is a 997 part number cast into the carrier and it did not match the correct part number. This cast number does not match anything and does not come up on Google except for used parts on eBay. The dealer where I purchased the carriers from had no idea why this was so but assured me he sent me the correct parts. So I went under my car with a mirror, and sure enough, the existing carriers had this same, odd part number cast into the factory carriers.
I did not use a torque wrench on the suspension parts for re-assembly. I purchased a set of crows feet to get a torque wrench in there.... of course the set I purchased did not have the sizes I needed ..... very frustrating. Anywho.... I have removed and replace many control arms from my cars and my friends cars so... well... the car has not ejected any parts .... yet.
For torquing the axle nut to 340 ft lbs, there is a trick. I could not find a torque wrench that big and I was going to buy a torque multiplier tool... but that all costs money. The trick is to divide 340 by your body weight. For me, that was 1.7 ft. or 20.4 inches. So, with a breaker bar perpendicular to the ground, I stood on the bar at 20.4 inches, or thereabouts and let the bar settle. It will settle at 340 ft lbs. Coooool.
Regarding replacement parts, many have opinions on this one.... no perfect answer in my opinion. I did not use any "upgraded" parts, but I do use non-Porsche labeled OEM suspension parts like TRW etc. I have heard.... looking for others opinions here... that many of these performance parts use harder bushings and are prone to rattling way faster than OEM arms.
So, in summary, my rear is tight, noise free and I have new bearings in there. And for my high-mileage car that I plan on keeping forever (?), new bearings are a good idea as they will go in time.
Sorry I did not document all of this.... it took me about four days to do both wheels... I go slow... get stuck... research... sleep on it. I was a bit too stressed to take the time to document... there were many procedures that I wrestled with... no time or willingness to spend time taking pictures.... just too complicated for me.
Special thanx to Wayne and TheBruce for your great instructions... I studied them closely. https://rennlist.com/forums/997-foru...rut-mount.html
Peace
Bruce in Philly
Google is your friend for torque values.... but here are some:
https://rennlist.com/forums/997-gt2-...uspension.html
https://rennlist.com/forums/997-foru...que-specs.html
I completed my job of replacing the rear wheel carriers, aka knuckles. Toughest job I ever did and did it without any assistant. Plenty of sweat-inducing situations. I pressed in my own new bearings into the new carriers but had to get a speed shop to remove and press in the hubs... they used a hydraulic press of course. To get my new bearings in, I put the carriers in my home oven and put the bearings in my freezer. Then using a bearing press kit rented for free from Autozone, used my impact gun and they went straight on in without any drama.
My noise was fixed with this replacement as I am 98% sure it was the bushing in the knuckle that was wearing and allowing the lower shock/bolt to make noise. I say 98% sure, because I read that the mounts, on top, are a source of noise, and I decided to go ahead and replace these too. So I am not 100% sure it was that lower bushing. When I used my chassis ears, I put a microphone clip on that lower bolt and it was noisy and super clear. I found I could induce the noise by literally shaking the car. Open the driver door and had a friend (stronger than me) rock the car by pushing up on the roof line. I did put clips on the top of the spring and anything else I could clip those things onto but did not get the metal-on-metal noise from the top. When I examined the old and new shock mounts, I could not see how they make noise as the shock piston is isolated by the foam and rubber parts and the car sits on the spring (on a cushioning seat) where I had the clip... but oh well, I succeeded in killing the noise.
FYI: for replacing the shock mounts, I did not need a spring compressor.. I had one rented just in case, but you don't need one at all.
BTW, the most difficult parts to the job included releasing the emergency brake cable "tube" from the carrier... I did this by freezing the tube. I sprayed fluid from an upside-down can of compressed air... the kind you use for blowing out dust from photography and other equipment. I placed a vice grip on it, then sprayed the inside of the tube while twisting the tube back and forth. The other challenge was re-installing the emergency brake shoes... sheesh! I found the Porsche parts katalog incorrect in that they noted the tube is a separate part, but on my car, it was pinch welded to the cable and was not coming off so I had to pull it out of the carrier.
Another toubling issue is there is a 997 part number cast into the carrier and it did not match the correct part number. This cast number does not match anything and does not come up on Google except for used parts on eBay. The dealer where I purchased the carriers from had no idea why this was so but assured me he sent me the correct parts. So I went under my car with a mirror, and sure enough, the existing carriers had this same, odd part number cast into the factory carriers.
I did not use a torque wrench on the suspension parts for re-assembly. I purchased a set of crows feet to get a torque wrench in there.... of course the set I purchased did not have the sizes I needed ..... very frustrating. Anywho.... I have removed and replace many control arms from my cars and my friends cars so... well... the car has not ejected any parts .... yet.
For torquing the axle nut to 340 ft lbs, there is a trick. I could not find a torque wrench that big and I was going to buy a torque multiplier tool... but that all costs money. The trick is to divide 340 by your body weight. For me, that was 1.7 ft. or 20.4 inches. So, with a breaker bar perpendicular to the ground, I stood on the bar at 20.4 inches, or thereabouts and let the bar settle. It will settle at 340 ft lbs. Coooool.
Regarding replacement parts, many have opinions on this one.... no perfect answer in my opinion. I did not use any "upgraded" parts, but I do use non-Porsche labeled OEM suspension parts like TRW etc. I have heard.... looking for others opinions here... that many of these performance parts use harder bushings and are prone to rattling way faster than OEM arms.
So, in summary, my rear is tight, noise free and I have new bearings in there. And for my high-mileage car that I plan on keeping forever (?), new bearings are a good idea as they will go in time.
Sorry I did not document all of this.... it took me about four days to do both wheels... I go slow... get stuck... research... sleep on it. I was a bit too stressed to take the time to document... there were many procedures that I wrestled with... no time or willingness to spend time taking pictures.... just too complicated for me.
Special thanx to Wayne and TheBruce for your great instructions... I studied them closely. https://rennlist.com/forums/997-foru...rut-mount.html
Peace
Bruce in Philly
Does anyone have experience with upgrading control arm and suspension arms by replacing improved bushings? Example of an elephant racing company.
Thanks
08-05-2021, 11:21 AM
#33
Burning Brakes
I commented on the quality of a specific aftermarket manufacturer on here a couple of years ago. My experiences were first hand.
https://rennlist.com/forums/996-gt2-...rs-beware.html
As I said in the thread I've linked to above, use the factory Porsche Motorsport parts wherever possible, though for items like ARB droplinks, it's easy to buy something just as good as the Motorsport parts, but cheaper, (just don't use cheap Rose/Heim joints thinking they'll last, as more often than not, they won't)
For what it's worth, the caster rod bush "upgrade" referred to by Bruce earlier in this thread, is just plain nasty. Porsche fitted a spherical bearing to that component for a reason, it needs to articulate. Relying on a poly bush to "deform" to enable the caster rod to articulate is poor engineering practice.
And as for the comment about the upgraded bush stiffening the suspension and it being beneficial ...
https://rennlist.com/forums/996-gt2-...rs-beware.html
As I said in the thread I've linked to above, use the factory Porsche Motorsport parts wherever possible, though for items like ARB droplinks, it's easy to buy something just as good as the Motorsport parts, but cheaper, (just don't use cheap Rose/Heim joints thinking they'll last, as more often than not, they won't)
For what it's worth, the caster rod bush "upgrade" referred to by Bruce earlier in this thread, is just plain nasty. Porsche fitted a spherical bearing to that component for a reason, it needs to articulate. Relying on a poly bush to "deform" to enable the caster rod to articulate is poor engineering practice.
And as for the comment about the upgraded bush stiffening the suspension and it being beneficial ...
Last edited by Atgani; 08-05-2021 at 11:28 AM.