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transmission thud


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Seems when standing still, or close to it and depressing my clutch i hear what seems loud(with window down) thud. Almost seems to make the noise before the clutch is even halfway depressed..before the gears are even engaged. Anyone have a similar issue or troubleshooting tips/advice on that one? Otherwise the trans shirts perfectly and the clutch has a lot of life left in it. Also, it doens't happen everytime..the noise occurs intermitently

1999 C4 110k

Edited by bmohr
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thats what i suspected, but Jeff at Sunset said he has only ordered one or two of those parts for his clients over the years...so very rare. But that was my initial guesstimate as well. Im going to jack it up and see whats what this weekend.

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I'm one of the people Jeff ordered a mount for. I had a similar type of thud.

When I was changing the clutch I noticed the mount was about 50% broken.

I also changed all of the clutch parts, the flywheel, and the RMS seal, at the same time. So I can't be

sure what was causing the thud, but it went away and clutch is much smoother and lighter.

The mount is pressed in so the transmission has to come completely out and set up

on a shop press.

It's also pretty difficult to see if it's broken without removing some brackets and stuff.

post-34457-1240776817_thumb.jpg

Edited by Foster
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If you had a thud and the mount that was removed looked like that I'd say you found the cause. I'm replacing Boxster mounts at a remarkable rate. I just did two last week that were COMPLETELY separated. I'll post the pix in the morning.

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okay, i've read your thread Foster. I notice very similiar issues, so I'm fairly confident I need a new mount. But just to recap, I need to know if I can remove and replace without taking the trans out completely. Can I just lower the front end using a jack and do the work from there? Also, do you need a speciality tool/press for getting the new mount in? I don't want to have to go my indy, i always try to do repairs myself and have been very sucessful swapping components and whatnot, but the tranny is one i haven't touched yet. Yes, i'm a tranny virgin:) I appreciate your tips and advice dr914jr and Foster.

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I asked Jeff the same question. He suggested cutting the metal part of the mount with a hacksaw blade and pounding it out.

Then rigging up some kind of puller to PULL it in.

I started to try that but it's really not worth it. That thing is in there TIGHT!

I can't see anyway to do it without taking the trans out and using a press.

You should also find someone willing a capable to install the new one before you start.

I went to 2 transmission shops and 2 indy Porsche shops and they wouldn't touch it for fear of cracking the trans case.

I finally ended up at a marine machine shop. I think they charged me $80. (I brought the trans to them)

I may have a few more pics. I'll post them if I can find them.

This is one job I would leave the the pros with the right tools.

Edited by Foster
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okay, i've read your thread Foster. I notice very similiar issues, so I'm fairly confident I need a new mount. But just to recap, I need to know if I can remove and replace without taking the trans out completely. Can I just lower the front end using a jack and do the work from there? Also, do you need a speciality tool/press for getting the new mount in? I don't want to have to go my indy, i always try to do repairs myself and have been very sucessful swapping components and whatnot, but the tranny is one i haven't touched yet. Yes, i'm a tranny virgin:) I appreciate your tips and advice dr914jr and Foster.

Unfortunately you'll really need to remove the transmission to replace the mount. The good news is that the transmission is quite easy to remove in a 996. And you'll really need to be careful to press the mount out so you don't crack the case. Another option would be to replace the entire tale cover that includes the integrated mount. Unfortunately that particular part just over $800.

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hey dr914jr...what have you been charging to do these mount removal and press in's? I spoke with my indy today and he said he hasn't done them yet, but would love to do it for me. He's got several style presses so it should be easy for him. He wasn't sure about pricing yet. I would like to have a reasonable estimate in my mind so I can guage whatever he comes up with. TIA!

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I'd say $630 in labor is perfectly reasonable. He should also inspect and replace as necessary the clutch and all the usual suspects while he's milling around. That could add another hour or two.

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  • 1 month later...

took off all underbody panels and inspected vehicle. While at it checked the trans mount. It had two different numbers on both sides. Are there actually two mounts? I had a 986.375.027 and a 996.375.550 or something close to that. Normal? Advise? Also, the mount, at least the one side I could see wasn't pulled away from the metal. I guess it looks like fosters pic above.

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  • 1 month later...
took off all underbody panels and inspected vehicle. While at it checked the trans mount. It had two different numbers on both sides. Are there actually two mounts? I had a 986.375.027 and a 996.375.550 or something close to that. Normal? Advise? Also, the mount, at least the one side I could see wasn't pulled away from the metal. I guess it looks like fosters pic above.

99637505505 Is the number sunset used when I ordered.

It is very difficult to tell if it is split when it's on the car, but if it were completely shot you would probably be able to tell.

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Could it be a failing transmission mount? :huh:

How does one change the transmission mount? Does the transmission need to be pulled to press the new mount in, or can it be done on the car with special tools?

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okay, i've read your thread Foster. I notice very similiar issues, so I'm fairly confident I need a new mount. But just to recap, I need to know if I can remove and replace without taking the trans out completely. Can I just lower the front end using a jack and do the work from there? Also, do you need a speciality tool/press for getting the new mount in? I don't want to have to go my indy, i always try to do repairs myself and have been very sucessful swapping components and whatnot, but the tranny is one i haven't touched yet. Yes, i'm a tranny virgin:) I appreciate your tips and advice dr914jr and Foster.

Unfortunately you'll really need to remove the transmission to replace the mount. The good news is that the transmission is quite easy to remove in a 996. And you'll really need to be careful to press the mount out so you don't crack the case. Another option would be to replace the entire tale cover that includes the integrated mount. Unfortunately that particular part just over $800.

I have been considering machining a special puller/press out of steel to do the extraction and pressing in of the mount, with the trans still on the car. Do you really think it is pointless to pursue this route? I'm figuring if there is enough space around the mount for the special tool it might be possible. But, of course I value you opinions on this.

If I remove the Transmission, mine is a Tiptronic, what is the procedure of removing a Tip instead of a Manual? Is it substantially more difficult? What do I have to look out particularly for?

If I remove the transmission, should I change the RMS? Is it more difficult to access the RMS with a Tiptronic? Most of the RMS tutorials I've seen are for Manual transmissioned cars.

Thanks to everyone for any advice!

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I think for me, taking the trans to a machine shop to replace the mount was the right choice.

It was only $80 and I may have spent that much and countless hours making a tool that might not work.

Pick your battles. ;)

Should you change the RMS? If it ain't leaking go with you're gut. I don't think there is a right answer.

If you're paying someone to do it, and they guarantee it then I'd go ahead and do it.

I changed the RMS, and I have the install tool I'm getting ready to sell if you're interested.

Edited by Foster
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