New mechanical sound in cabin, failing transmission mount?
02-23-2015, 10:44 PM
#31
R
The important thing is I believe we've identified the cause; and yes the grease injection is merely a bandaid, and a temporary one at that!
If a failing CV goes catastrophic, it can do a fair bit more damage than replacement cost!
I had an 87 factory turbo look that I purchased complete CV joints, while rebuilding with the existing half shaft and stub axle's. Is the 993 configuration so different that this simple repair can no longer be performed?
I do admit being fortunate enough to have the late Grady Clay helping me with tips like the use of schnoor and half-moon washers, but the job was fairly straight forward...
In 05, the cost of the CV's were about $85 ea. x 2 per half-shaft. That's $320 for a complete rebuild with new CV's, useing existing shafts and stub axle's.
Did this all change with the 964/993 iterations?!
Anyhow back to OT, I picked the car up from the mechanic. He injected new CV grease into the 4 CV boots and it seems to have improved things. I immediately drove it to SF and back for a meeting and during that 30 mile trip, I heard the noise very briefly once. I'm going to give it a little more time to allow for the grease to work its way back into the CV joint.
If a failing CV goes catastrophic, it can do a fair bit more damage than replacement cost!
I had an 87 factory turbo look that I purchased complete CV joints, while rebuilding with the existing half shaft and stub axle's. Is the 993 configuration so different that this simple repair can no longer be performed?
I do admit being fortunate enough to have the late Grady Clay helping me with tips like the use of schnoor and half-moon washers, but the job was fairly straight forward...
In 05, the cost of the CV's were about $85 ea. x 2 per half-shaft. That's $320 for a complete rebuild with new CV's, useing existing shafts and stub axle's.
Did this all change with the 964/993 iterations?!
Last edited by nine9six; 02-23-2015 at 11:21 PM.
02-23-2015, 11:37 PM
#32
Drifting
Thread Starter
The CV replacements cost about $80 for a kit, but the catch is the outer CV joints are not removable from the halfshaft (at least they aren't intended to be). Only the inner CVs are readily replaceable. What I'm unclear on is how much the difference in labor would be between replacing the inner CVs only vs. replacing both hslfshafts entirely.
Guess what else just happened to me, the belt indicator light just came on, but all three belts look fine and there are no codes showing when I read the CEL memory. Ugh! Perhaps it's just a failed sensor. Time for more forum searching...
Guess what else just happened to me, the belt indicator light just came on, but all three belts look fine and there are no codes showing when I read the CEL memory. Ugh! Perhaps it's just a failed sensor. Time for more forum searching...
02-24-2015, 12:08 AM
#33
The CV replacements cost about $80 for a kit, but the catch is the outer CV joints are not removable from the halfshaft (at least they aren't intended to be). Only the inner CVs are readily replaceable. What I'm unclear on is how much the difference in labor would be between replacing the inner CVs only vs. replacing both hslfshafts entirely.
Guess what else just happened to me, the belt indicator light just came on, but all three belts look fine and there are no codes showing when I read the CEL memory. Ugh! Perhaps it's just a failed sensor. Time for more forum searching...
Guess what else just happened to me, the belt indicator light just came on, but all three belts look fine and there are no codes showing when I read the CEL memory. Ugh! Perhaps it's just a failed sensor. Time for more forum searching...
After looking at the PET, I see the configuration of the half-shaft has changed, and not for the better, IMHO. That sucks!
02-24-2015, 11:13 AM
#34
Drifting
Thread Starter
Yeah, I can confirm the belt sensor is shot. The plastic wheel is nowhere in sight... The little metal axle for the wheel is pressing against the belt now, which must do wonders for the durability of the belt. It's a cramped space, but this one I'll DIY.
02-24-2015, 05:55 PM
#36
RL Community Team
Rennlist Member
Rennlist Member
That not a broken sensor, its an aftermarket upgrade opportunity. Use a tie wrap to hold the arm back and your're done!
02-24-2015, 06:18 PM
#37
Rennlist Member
Join Date: Nov 2010
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Yep, when I put my RS fan hub on, I cleaned, and improved my sensor (I know, I could've chucked it). Tiny bolt, lock washer and nylock nut.
Hey, what's that o-ring doing down there below your sensor, part of the inner wheel remnants? I'd zip tie that thing, just to be sure your wire doesn't get dragged into anything.
Hey, what's that o-ring doing down there below your sensor, part of the inner wheel remnants? I'd zip tie that thing, just to be sure your wire doesn't get dragged into anything.
02-24-2015, 06:53 PM
#38
Drifting
Thread Starter
I just noticed that washer while posting the photos. I'll investigate. The picture wiring was done this morning as I was rushing out the door to attend a meeting and fearing premature belt failure due to the failed sensor. 
I'm not wild about looping the wire around the other electrical wires, but after a round-trip drive from Marin to SF to Marin it seems to be holding fine. Unfortunately, since my wheel is AWOL I cannot simply replace the axle like you did OB, I have to source a new wheel or replace it outright.
I'll work at securing it more thoroughly once I'm home tonight. Perhaps I'll be able to loop the wire more tightly and just around the sensor assembly and not the other wiring bits as well. There really isn't much space to work with in there, even with my thin fingers.
Regarding the CV joint(s), my mechanic assures me that I'll be hearing A LOT more noise from the joint before it gets anywhere near the point of total failure. Still it feels like I'm driving on a ticking time bomb.
I'm not wild about looping the wire around the other electrical wires, but after a round-trip drive from Marin to SF to Marin it seems to be holding fine. Unfortunately, since my wheel is AWOL I cannot simply replace the axle like you did OB, I have to source a new wheel or replace it outright.
I'll work at securing it more thoroughly once I'm home tonight. Perhaps I'll be able to loop the wire more tightly and just around the sensor assembly and not the other wiring bits as well. There really isn't much space to work with in there, even with my thin fingers.
Regarding the CV joint(s), my mechanic assures me that I'll be hearing A LOT more noise from the joint before it gets anywhere near the point of total failure. Still it feels like I'm driving on a ticking time bomb.
02-24-2015, 11:45 PM
#39
Drifting
Thread Starter
I've done some more archive reading and my noise isn't a repetitive clunk as described by this member that had a failing CV joint: https://rennlist.com/forums/993-foru...end-clunk.html
I'd describe it more like a rattling tin can sound except the rattling matches the revving of the engine. I suppose a resonance in the power train might be a fitting description. When it happens it is quite loud. Other times I think I'm hearing it more subtly masked by the normal rev of the engine, but maybe that's just me being paranoid.
I did some reading up on DMF failure symptoms, but I don't think that's whats going on here either. I know the transmission fluid should be flushed because it hasn't been done yet during my ownership of the car, and I was planning on doing that during the next oil change that's planned in another 500 miles or so (changing oil on a 5k mile basis). Perhaps I should just go ahead and have that changed now and see if that clears up the issue.
I'd describe it more like a rattling tin can sound except the rattling matches the revving of the engine. I suppose a resonance in the power train might be a fitting description. When it happens it is quite loud. Other times I think I'm hearing it more subtly masked by the normal rev of the engine, but maybe that's just me being paranoid.
I did some reading up on DMF failure symptoms, but I don't think that's whats going on here either. I know the transmission fluid should be flushed because it hasn't been done yet during my ownership of the car, and I was planning on doing that during the next oil change that's planned in another 500 miles or so (changing oil on a 5k mile basis). Perhaps I should just go ahead and have that changed now and see if that clears up the issue.
02-25-2015, 01:03 AM
#40
If the sound matches the engine revs and not the wheel rotation, then I do not suspect your issue is the CV's; and the CV's are ancillary issues that need to be addressed as well.
02-25-2015, 01:29 AM
#41
Drifting
Thread Starter
Today it happened while idling. I was approaching making a left turn and moved up about a car's length before putting the clutch in. Then I noticed the rattle starting again. I gave it some gas to see if it would clear up and once I put it in gear and started accelerating the noise went away. It also happened again coming how. I just made a left turn and then was driving down a downhill slope with a gradual right turn. I had to step on the brake as there was traffic back up. I then let the engine compression regulate my rolling speed down the slope and the rattle started up again rather loudly until I gave it some more gas. It made the noise on the exact same part of the road under similar driving conditions a coupled days prior, so its at least consistent in that regard.
I'm not confident that it relates to making a left turn. It might relate more to lower revs of the engine and using engine compression. It seems like a resonance with the power train...
I'm not confident that it relates to making a left turn. It might relate more to lower revs of the engine and using engine compression. It seems like a resonance with the power train...
02-25-2015, 02:46 AM
#42
a couple of things to also check
1. LSD, mine at 195k is due to be replace. It makes a rattling noise in reverse or low speeds. I have not heard it during down hill. but it makes a noise like its bad engine/gearbox mounts. I had them replaced thinking that was the problem..not!
2. DM Flywheel, I remember reading where you can check the obd for errors, that wont trigger the CEL> or was it using another tool to check. somewhere here in the archives.. ( I replaced mine at 160k miles)
3. CV joints. if you can rotate the drive shafts like a motorcycle throttle, they are in need of replacing.. the amount of rotation, not the in and out between the gearbox and wheel, will let you know how bad they are..
my guess is the LSD!..
hope this helps.
1. LSD, mine at 195k is due to be replace. It makes a rattling noise in reverse or low speeds. I have not heard it during down hill. but it makes a noise like its bad engine/gearbox mounts. I had them replaced thinking that was the problem..not!
2. DM Flywheel, I remember reading where you can check the obd for errors, that wont trigger the CEL> or was it using another tool to check. somewhere here in the archives.. ( I replaced mine at 160k miles)
3. CV joints. if you can rotate the drive shafts like a motorcycle throttle, they are in need of replacing.. the amount of rotation, not the in and out between the gearbox and wheel, will let you know how bad they are..
my guess is the LSD!..
hope this helps.
02-25-2015, 01:50 PM
#44
1. LSD, mine at 195k is due to be replace. It makes a rattling noise in reverse or low speeds. I have not heard it during down hill. but it makes a noise like its bad engine/gearbox mounts. I had them replaced thinking that was the problem..not!
2. DM Flywheel, I remember reading where you can check the obd for errors, that wont trigger the CEL> or was it using another tool to check. somewhere here in the archives.. ( I replaced mine at 160k miles)
3. CV joints. if you can rotate the drive shafts like a motorcycle throttle, they are in need of replacing.. the amount of rotation, not the in and out between the gearbox and wheel, will let you know how bad they are..
my guess is the LSD!..
2. DM Flywheel, I remember reading where you can check the obd for errors, that wont trigger the CEL> or was it using another tool to check. somewhere here in the archives.. ( I replaced mine at 160k miles)
3. CV joints. if you can rotate the drive shafts like a motorcycle throttle, they are in need of replacing.. the amount of rotation, not the in and out between the gearbox and wheel, will let you know how bad they are..
my guess is the LSD!..
Last edited by nine9six; 03-04-2015 at 11:21 PM.