I posted this on the original thread, but to try and get better feedback I am starting a new thread about what I think may be wrong. Since I finished the job last week, I noticed a new sound that is concurrent with speed, as the car goes faster, its louder and higher pitched. Today I got the car back up on the ramps and removed the transmission mount to look at the front flex disc again. I noticed that it is showing a rub mark on the highest point of the edge on the outside rim. The original disk also had that same mark, though much more pronounced. Sticking my hand up underneath (actually the top of it) I could feel and see a spot where the sound deadening was worn away by the old disc. So I know now where the rub marks on the disc are comimg from. Just to be safe, I removed all 6 bolts and freed up the disc from both spyders and then set it back in, making sure to keep the alignment correct. I also wanted to make sure both spyders were correctly seated on either side of the disc. I made sure to torque them down as well to make sure the noise wasnt somehow coming from a loose fit between either spyder and the disc.
So while I was test driving the car, I came up with what I think may be the cause of the noise. The old center bearing support was sagging down by a quarter inch. The old transmission mount looked ok but may have had some sagging too. I replaced that mount with a new one which may be pushing the front disc up higher causing it to rub. But why would the new mount cause a rub? My guess is that if the motor mounts are on their way out or gone, that they may be allowing the motor to sit lower in the front and thereby pushing the back of the tranny up higher. Does this sound plausible? I think most of the rubber parts in this car are original and its 16 years old now. Before I go buying new mounts, I'd like some opinions from the group on this theory or other things to look at. At this stage I'm pretty sure the new flex discs are in correctly, the front one having been done essentially twice.
So while I was test driving the car, I came up with what I think may be the cause of the noise. The old center bearing support was sagging down by a quarter inch. The old transmission mount looked ok but may have had some sagging too. I replaced that mount with a new one which may be pushing the front disc up higher causing it to rub. But why would the new mount cause a rub? My guess is that if the motor mounts are on their way out or gone, that they may be allowing the motor to sit lower in the front and thereby pushing the back of the tranny up higher. Does this sound plausible? I think most of the rubber parts in this car are original and its 16 years old now. Before I go buying new mounts, I'd like some opinions from the group on this theory or other things to look at. At this stage I'm pretty sure the new flex discs are in correctly, the front one having been done essentially twice.
Did the job last week, can post a few photos for the group. Good and bad news. The good news is that the front flex disc was cracked and needed replacement, the rear was very stiff and dry, probably from living so close to the exhaust all these years and was probably original. The center bearing support was intact, but was drooping down by a quarter inch at least. The bearing seemed to spin fine, but that got replaced as well.
For the bad news, it didnt seem to fix the problem. There is still a drone when running down the highway. As I mentioned previously, the noise seems to appear only when temps are above 75 or so, and its been hot for the last week so no chance to see if it goes away with the cooler temps.
Here are some pix of the job for anybody's future reference. BTW, you do have to remove the rear exhaust in order to remove the heat shield in order to get access to the center bearing support. Clearance under the car is very tight, I had to make a homemade set of ramps to get the front up, my old metal ones would not clear the front plastic. I also replaced the front transmission mount, that has to be removed in order to get access to the front disc.
Home made ramps:
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The pesky heat shield. Held in by 4 nuts. Takes some flexing to get it out, but it will come:
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The rear exhaust. The clamp has three bolts, better have a grinder or wheel cutter to get them, they were completely rusted. Replaced with 3 stainless bolts going back in:
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The flange once the exhaust is out (looking toward the back):
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Looking a bit more forward, the transmission support bracket which holds the transmission mount. Four bolts to the frame, two to the mount. Comes out easy, just need to have a jack under the tranny pan with a board to spread out the load:
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Looking back at the rear axle.
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Looking up at the front flex disc. Tranny mount is still in place. You can see one of the cracks if you look closely. For some reason, the edges of this disk look to have rub marks on them, couldn't really tell where it was rubbing.
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Center bearing mount. New one on the left. You can see how the rubber is compressed on the right. New bearing in the upper right, fairly small.
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"The Boot". The old one was shredded and completely gone. This is where I screwed up and didn't order this along with the other parts, most of the sites don't seem to list it. 5 dollar part and even the dealer didnt have it in stock. Car had to sit for almost a week while I waited for it to come in. Got it from Bap geon. Just sits on the shaft and covers the splines.:
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Getting the old bearing off. This is the only shot I have of the process. If you have the new bearing (and you should), you dont have to be too gentle to the old one. I used some long pin punches on either side to move it down till it got off the machined surface. I had the splines in the vise covered with a rag so they didnt get buggered up. New bearing went on fairly easy, had to gently push it back down with a wooden drift till it seated.
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The U joint was tight, no slop I could detect. When installing the flex discs (which by the way were identical front and back), make sure that you put the washer on the "rubber side". So three of the bolts will have the washers by the nut, three will be by the bolt head. New bolts were hex key bolts.
No room to pre-install the front flex disk on the shaft, it has to slide up a narrow tunnel coming in from the rear.
On the rear shaft, slide the rubber bearing mount on the bearing first before you install the it. Leave it loose till you bolt in the flex disc. The rear flex disk has enough room in that you can mount it to rear shaft outside the car then push the splined end in and clear the rear axle spyder and then tap it in place and put the last three bolts in.
Even with the car on ramps in front and on jack stands in the back it was tight working. Takes a good amount of strength to loosen the 6 bolts on each disc. Be careful not to round over any nut, use a box end wrench. Sockets are a bit tough with the tight clearances.
Hope this all helps somebody down the road, any questions just ask. Total time was about 2 days, though it could have been done in one if I had the lousy little boot from the gitgo. On a lift in a nice cool garage with all the tools and parts in hand and having done it a few times before I can see this job taking 3 or 4 hours. Unfortunately I don't live in that world...
