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mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Well I haven't been around much lately since my laptop has been in the shop so I'm sending this from my phone, hopefully it comes through ok.
So the car has been running great since I've had it back on the road and now its my daily driver. However a new thing has started. Vibrations at the gear shifter, bad. But it really only seems to act up when I accelerate through the gears. If I really ease through the gears it isn't bad though. And if I try to downshift, it does it again.
My first thought was a rear wheel out of balance but it isn't really something that happens at certain speeds. And if its in neutral it doesn't really do it when I rev it up. It does a little, but not bad. I have a lot of the parts for my upcoming 5 lug/5 speed conversion so I wouldn't be too upset if the tranny is starting to go but I do want to figure this out. Especially since I'm driving the car everyday.
Does any of these symptoms ring a bell with anyone?
Oh btw, if anyone has been thinking of rewiring the starter and alternator, I strongly reccomend it. And a thank you to Dan for the help over the phone, definitely calmed me down. Anyways my wires just melted so bad a couple days ago it melted off the neg cable from the battery. Wires were touching the exhaust manifold. Damn thing started smoking so much I thought it was gonna catch fire. Luckily I was at my station, everyone was more than excited for a possible car fire! But thankfully no flames. Anyways, as always, any help is appreciated.
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Any chance it's related to your recent torque tube rebuild? I know that's not what you want to hear, but troubleshooting 101 forces you to ask what has changed recently in the driveline, and that would be at the top of the list...

What about your trans mounts? Are they secure?

Have you checked that all six bolts in each of the CV joints are all still intact and torqued down?

Have you double checked that all of your lugnuts are torqued? It sounds stupid, I know, but I just had a buddy that told me a story about getting some strange vibration and couldn't figure it out, until he found out one of his rear wheels was only being held on by one lugnut. It happens!
_________________
erstwhile owner of just about every 924 variant ever made

Voodoocars · Joined: 06 Jun 2004 Posts: 10 Location: Coventry

Check that the centre exhaust box hanger or part of it is not too close to torque tube and vibrating on it - I had similar prob many years ago and even porsche dealer couldn't find it.I only found it by chance.

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Thanks for the input boys. I'm really hoping it's something as simple as a loose exhaust bracket. And I really really hope it's nothing to with the TT. That would suck. I'll keep u posted on what I found tonite. Fingers crossed!!
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Could be an issue with a CV Joint.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Ok well I looked over everything and its all tight. CV's, tranny, lugs, they're all good. I did however notice that the exhaust bracket that sits over the torsion bar is rusted through. And the rubber thingy (technical term) is missing too. So I revved up the engine and looked under and saw the exhaust vibrating big time right in that area. I'm thinking I need to replace the bracket with a new(er) one and get new rubber. Anyone have one?????
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

The rubber piece would be a vibration damper. You'll probably need to source one new from any of the usual places, as used ones are usually shot.
_________________
erstwhile owner of just about every 924 variant ever made

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Hope I can get the bracket too?
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Ok I think I'm gettin somewhere now. Just had a whole new exhaust from the header on back so I know its not vibrating.
So here's what I do know...from 2500-3000 the car shakes. While driving or car in neutral. And as soon as I get above 3200 it goes away though.
BUT... if I push in the clutch, it doesn't shake at all. I can rev it all the way up if I want to. But the second I let the clutch out, it shakes.
Does this sound at all like it could be the motor mounts gone bad? I'm kinda at a loss and need to get this resolved. Thanks for the help.
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Fifty50Plus · Posted: Fri Sep 25, 2009 5:42 am Post subject:

With your clutch pushed in, the TT shaft isn't turning to match the speed of the engine and no vibration you say. With the clutch out and the transmission in neutral, the TT shaft is matching the engine speed. If the vibration is only there in this state (or driving down the road) you have a problem with the TT bearings.
Chuck
edit: the shaking at 2500-3000 is a harmonic vibration of the TT shaft in a bad bearing most likely.
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Chuck- I just did a TT rebuild about 2 months ago and it has been working great since the new bearings. Man I hope something isn't wrong with it again, I really don't wanna tear this damn thing apart again.

Tonight when I was driving I was taking special note of when the shaking happens more. I also noticed that when I'm going at highway speed (60ish), the shaking is gone and I can accelerate great with no problem, 80, 90, easy. If I take it out of gear and try to put it back into 4th, it does go in but it REALLY shakes for a split second while going back in. I also put the car in neutral coming off the exit ramp with the clutch in and just used the brakes to slow down, shook like hell when the tach got to about 3000rpm again.

I guess I'm just really trying to rule out a problem with the TT as I really don't know what could be wrong with it this fresh after a rebuild. Is there something in the tranny that could be causing this? And are you sure it couldn't be the motor mounts? I had thought about putting a floor jack under the motor and relieving the weight from the mounts and starting it and see if that improves anything.

And if there is something wrong with the tranny somehow, this will just push along my 5 lug conversion much sooner, which wouldnt be a bad thing. But I wanted to wait til the winter to do that project as this car is my daily driver now and can't afford to have it out of commission more than a day or so at a time. Any more thoughts?
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Fifty50Plus · Posted: Sat Sep 26, 2009 12:01 am Post subject:

If it was a motormount, the vibration would always be there when you revved up the engine - rolling or not, clutch in or clutch out.
Another lesser possibility is a broken spring on the clutch disk or pressure plate. With the clutch pedal pushed in, the PP and clutch disk aren't matched to the engine RPM. Thus no vibration at 2500 to 3000 on the tach. But if the trans is in gear and you are coasting down with the clutch pedal pushed in, the PP, clutch disc and TT shaft will at some point go through the 2500 to 3000 RPM range and the vibration will occur.
The internals on a trans shouldn't have an RPM related vibration- I'm thinking first support bearing on the trans input shaft. Extremely unlikely.
Do your diagnostics again in the driveway. In neutral, clutch in and clutch out. When can you create the vibration? With the clutch pedal pushed in does the vibration go away? If so, problem is in the TT, clutch disc or PP.
Chuck
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

I just ran another test at my fire station. In neutral, clutch in.. no vibration whatsoever. Clutch in... vibration at 2500-3000 rpms. I'm not liking what you're telling me. I really don't see how a bearing could have gone bad already or the clutch. I put a new one in when I did the bearings. I'm off next week for five days so I guess it looks like I'll be tearing the thing apart again...
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)

Fifty50Plus · Posted: Sat Sep 26, 2009 2:16 am Post subject:

Could one of those little plastic/nylon thingys (technical term) that go inside the bearing and around the shaft have come out?
Bearings don't go bad at only a certain RPM and when bad, they make all kinds of noise all the time.
My bet is that it's the shaft and not clutch or PP.
Now if I were faced with the next steps, I would look long and hard for another possibility prior to yanking it all apart to check the shaft and bearings.
Chuck
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

mgatlag · Joined: 02 Aug 2007 Posts: 647 Location: Avon, IN

Man I hope I don't have to source any more parts for the bearings, they were a bitch to find what I did. I got lucky and was able to cut up an old TT that Vaughan wasn't using. And then I sent my left overs to a another member that needed then. Kinda wish I kept them now.
_________________
Michael
'77 1/2 924 N/A- 5 speed Audi box
'04 Ford Taurus - gone!!
'92 Jeep Cherokee Laredo - gone!!

Porsche... better than tea with Miss McGill
(Slap Shot)