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Unhappy knock sound

1987 carrera
2 issues have ocurred in the last few days...1. I hear SOMETIMES a single knock sound from the back of the car when going over a bump just as going from the driveway into my garage at very low speed. It is only a SINGLE knock.
2. Yesterday I could not shift into 1st. gear but reving and going through other gears, it engaged and did not occur again...it was cold outside and the engine was not fully warm. The transmission shift is not loose at any of the 5 gears...
the 2 issues might or might not be connected...Any thoughts?
Old 04-12-2019, 06:52 AM
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Rear sway bushings and/or engine/trans mounts?
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Old 04-12-2019, 07:06 AM
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On the first issue, it sounds very much like a broken sway bar mount, which is extremely common on 3.2 Carreras.

Don't worry about the second issue unless it repeats frequently. Occasional balky gear engagement is normal. Sometimes you have to select second before you can engage first.
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Old 04-12-2019, 07:07 AM
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Issue 1. is most likely a broken rear sway bar chassis bracket.

Not sure about issue 2.
Old 04-12-2019, 07:08 AM
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If a front transmission mount is loose it could knock, and shifting would be affected.

It is an easy check to crawl under the car with a wrench and see if the are snug, or apply gentle pressure to the transmission with jack and see if it moves.

At lease rule out that one, and while you are under there, inspecting the sway bar brackets as others have mentioned is also easy since they are not hidden.
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Old 04-12-2019, 07:22 AM
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knock sound

Can the bracket be removed or is it welded?
Old 04-12-2019, 10:38 AM
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David - half the bracket is welded to the chassis. The other half is held on with two bolts. Rubber bushing in between, with the sway bar. If one of the bushings has failed, you could get a knock easily. You'll figure this out pretty easily, I suspect.

Got jack stands to go along with the jack?
Old 04-12-2019, 07:44 PM
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The bracket is welded. Get the WEVO if you need to replace it. Better than Porsche.

On the 2nd issue- when was your last gear oil change? I have observed that the g50 is very sensitive to the two year change interval. It also likes to be shifted when warmed up, especially 1st.

Last edited by mo-mon; 04-12-2019 at 09:04 PM..
Old 04-12-2019, 08:37 PM
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knock sound

I examined the rear sway bar area and found out that the bracket LOWER portion that receives the 2 bolts that are inserted from the lower u portion is separated from the base...
what are my options here? I do not know how to weld...my car is 87 carrera
Old 04-13-2019, 06:47 AM
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There are no options. It MUST be welded back. Any decent independent Porsche shop has fixed this problem a hundred times and re-welding is a very simple repair.

The Wevo mounts are excellent, but much more expensive and not necessary on a street-driven car. They're more for race cars that see much higher cornering stresses.
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Old 04-13-2019, 07:43 AM
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Yep

My 1988 911 had this problem.

New bracket welded on while engine rebuild was going on.

Went stock OEM bracket for my street car.
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Old 04-13-2019, 07:48 AM
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knock sound

How do you remove the old bracket that is broken?
Old 04-13-2019, 10:51 AM
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David

You can get more accurate advice if you attach pictures.

Assuming the broken bracket is, indeed, the one attached to the chassis (you use the term "lower portion" twice, but seem to mean two different parts), you can just have it welded up as it is. You have identified a crack or cracks where the bracket is attached to the chassis, right? Remove the lower (clamp) half so you can get the sway bar and its bushing out of the way, hammer or otherwise force the broken part back up so the two sides of the break or crack are together or close, and weld the joint.

Since you can't weld, take it to your local muffler shop (if you don't have other choices) and have them do the welding. Or what others have suggested.

If you want to put on a new bracket, and have to ask how to get the old one off, you might consider having a shop do the job. You get the old one off with the variety of cut off wheels, die grinders, air chisels or just chisels, vice grips, and other tools you have because you do things of this sort around the house and garage, or maybe, like a farmer, as a matter of course on work equipment.

Driving to an event long ago at night I ran over a rock in the road - big clunk. I stopped and looked under the car, but didn't see anything and continued on. Changing tires at the track the next day I noticed the sway bar hanging down on the driver's side - the rock had torn the bracket off. Drove to a muffler shop, had it welded back on. Later I reinforced both of these by welding a plate over them to box the bracket in. 30 years and a lot of track miles later both are still doing their job even though I'm not a really good welder and I have a crummy little MIG that acts up and makes the job harder.

So not difficult to fix in most cases.
Old 04-13-2019, 01:04 PM
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As a precaution, disconnect your motronic ecu before any welding on the car.
Old 04-13-2019, 01:20 PM
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