Central Tube Auto Transmission Problem

alantica · 07-05-2009, 10:44 AM

88 N/A belongs to my son that is an everyday driver. He was hearing a slight vibration that seemed to originate from below the gear shifter. Just loud enough to be irritating. Looked under the hood and below the car and could not find a source. Noticed the transmission fluid was at minimum. Turned the car off and the fluid level went up to half way between minimum and max. Filled it up to max and he took it out for a test drive. He had driven it a mile when he heard a loud pop and smelled a scent like a burning belt. There was an increase in RPM's to 6000 then it dropped back down, he shut it off thinking it may have broken the timing belt. I towed him back home and checked all of the belts including the timing belt with no problems found. Cranked the car and could hear directly in the center a continuous banging noise as if something had broken.

Auto trans level is not quite up to max. I put the car up on jacks and removed the muffler piping from the exhaust manifold completely to the muffler. I can see no leaks or problems with transmission fluid piping. Cranked the car while up on jacks and put it in gear, there was a slow movement of the rear wheels, but not enough speed as normal even with an increase of fuel.

Normally I would say that the problem is a universal joint at the front of a drive shaft, but I cannot see anything because it is covered by a central tube. The point I am stuck at now is should I try and remove the central tube with the complications of the transmission and rear axle, regulator & CV joints? Or, is there a simpler way to get to it at the front of the central tube and see what is making the racket?

Another thought is the oil pump inside of the transmission, but that does not explain the burning smell at the front of the central tube. This car is going to stay as an automatic and not be converted to a manual. Thank you for any help or ideas that may provide a solution.

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944 Ecology · 07-05-2009, 03:48 PM

Your flywheel rubber damper plate has disintegrated.

zedsn · 07-05-2009, 04:54 PM

Very expensive part to begin with and labor intensive to install. These cars suck sometimes.

alantica · 07-05-2009, 09:50 PM

Thanks 944 Ecology & zedsn. Yes, cost is always a factor, but there are some things that money can't buy and fortunately his 944 is in great shape. 944 Ecology, are we looking at a complete rebuild or replacement? I've also been told on another forum that it could be the flex plate, but what you are saying is logical because of the location. Would this be a good time to consider swapping to a manual? Thanks again for your help!

zedsn · 07-06-2009, 02:59 AM

Hi, sounds to me like it is your flex plate from what you have described. I see used ones for 250 sometimes but they are usually starting to deteroriate. People have done 5 speed change overs and the car will be worth more and alot more fun to drive with a 5 speed. If you decide to go that route though it will be alot of work and you would be better off to get a complete 5 speed parts car to get everything for a changeover. If memory serves me right a new flex plate is 750+.

944 Ecology · 07-06-2009, 03:56 AM

Keep in mind that the flex plate is in the back of the car, attached between the torque converter and the drive shaft. That is not the one that is the problem.

The rubber damper plate is located in the front of the car, between the flywheel and the drive shaft. This is the one that has failed.

968rz · 968rz's Garage

Flex plates don't fail that often, I would look at the rubber damper. Those things fail at least once a life time. They are a PITA to replace (need to pull the exhaust, trans and t-tube) but it is doable in your garage with some Dad help.

zedsn · 07-06-2009, 07:41 AM

I mean the damper I supposed. I haven't heard the rear coupler called the flex plate have only heard it refered to torque tube coupler.

alantica · 07-06-2009, 11:04 AM

Thank's 968rz, 944 Ecology & zedsn. On another forum a guy mentioned the tube shaft coupling which makes perfect sense for the banging racket. The rubber damper plate explains the burning belt or rubber smell.

I am going out later this afternoon to look at what I have to do to take it apart and get in that area to replace the broke parts. Looking at the PET, pictures, diagrams, etc. right now and trying to figure out an attack plan.

I've already dropped the exhaust. It looks like the starter and a cover plate is going to have to be dropped to allow access. I also think the transmission, torque converter and other parts described before are going to have to be dropped to let me pull back the central tube, hopefully I am wrong.

Are there any areas in dropping these parts and completing repairs that I need to have special tools or are there places I need to look out for in moving small parts, springs, etc...

Thanks again for any help in advance. The cost may be as much as a couple of ounces of gold, but as much as my son & I love these cars, this knowledge is more valuable than a bucket of gold.