924Board.org

[Aussie931]

Hi all,

Just wanted to find out if anyone has experienced rattling coming from the rear of their car when driving over bumpy surfaces? The rattle I am experiencing is getting continually worse and I can't narrow it down. I have checked the suspension bushes, play in the hubs and secured everything that may be loose beneath the car and in the boot but it still remains. When I bounce the rear end while it is up on ramps I can't hear anything - it only happens when driving.
Any ideas would be greatly appreciated.
thanks.
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1979 Series 1 924 turbo

[Smoothie]

If you have disc brakes in the rear, check the "locating springs" on the brake calipers. They're an odd-shaped piece of spring metal that wraps around the piston housing with ends that bend out to hold the floating caliper part in place. When they break, you get a lot of rattling on bumps.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[938GTNick]

I'm now running on Koni Sports, since when any little rattles became amplified. Since I moved from AVS Sport Yokos to Bridgestone S02 N3, the more compliant sidewalls seem to have improved the ride. Anyhow, there must be an endless list of possible sources, but here are a few suggestions:

Check the hatch pins are nice and tight, with just a little tension against the seals.

The metal 'tubes' which fix the rear seat backs to the side mounts in the upright position have plastic endcaps which can wear away over the years, causing metal on metal rattling under torsional load. Try dropping the back seat and see if the rattle is still there. The end caps are inexpensive from Porsche.

I doubt it's this, but the most elusive rattle I cured was from the post securing the rear wiper arm to the blade. A new one from Porsche sorted it.

It took me ages to find that one! That was before I found the invaluable advice on this forum. I don't claim to know half as much as some of the senior members on this forum, so thanks guys !!
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924 Carrera GT
No. 434
(& No. 322)

[simsport]

My race car had a knock/rattle for ages and I just couldn't find it.
Then one day when underneath the car I noticed a small rub mark on the underside of the body above the fuel lines and before they pass behind the beam and bingo....that was it!

I also found the handbrake lines could be loose behind the beam, although on mine this wasn't the offending noise.

Cheers
Simon.
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Blown is always best!

[Aussie931]

Thanks all for the great suggestions. The locating springs sound like a goer as I occasionally notice the rattle when I apply the brakes. I'll have another look on the weekend and keep you posted.
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1979 Series 1 924 turbo

[20v924]

How about the spare tire securing bolt with that rattly plate.
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A person is smart. People are stupid

[Aussie931]

Seems as though I am out of ideas on the rattle. I checked the caliper retaining springs - they are OK, the pad anti-rattle springs are fine and I even pulled apart the hubs and repacked the inner & outer bearings with grease. After doing all of that, the damn rattle is still as strong as ever. If anyone has any more ideas I would love to hear them. The only lead I have is that the rattle disappears when I have my foot on the brake.
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1979 Series 1 924 turbo

[OutOfTheBox]

I've had numerous rattle problems.

1. Gear box mounts loose, I checked by getting underneath and pushing and shoving, but it wasn't until I got a spanner and checked that I found it.

2. Front engine mount snapped, also seemed fine from pushing and shoving, , I only found it when I changed the clutch, it had snapped inside the rubber bushing.

3. Rear seat rubbing against trim, only on dirt roads.

4. Exhaust.

It could be that your baffles inside your rear silencer have rotted, tap it with a rubber mallet, and you'll here all the metal rattling inside. This would explain the brake thing, but because you are off the throttle not anything to do with brakes.

The rear seat problem, I only got to the bottom of, by getting someone to ride in the back, and stick their ear against the different areas.

[OutOfTheBox]

maybe you should take it to a exhaust and tyre shop, they usually have a machine for testing shock absorbers, ask them to check your rear shocks then listen.

[WEASEL149]

I had the same kind of rattle from the rear of my 931 and checked everything.

It eventually turned out to be the heat shield above the rear muffler/silencer that had corroded badly around it's rear mount and had come loose - rattling on the exhaust.
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1979 UK 932

[Aussie931]

Just wanted to let you all know that I finally got to the bottom of the rattle.
It ended up being the result of a worn guide spring ( the one that wraps around the caliper cylinder body that Smoothie actually suggested checking).

Although the initial visual inspection I did on the brakes suggested that the spring was OK, I ended up getting desparate when nothing seemed to work and pulled the brake caliper apart. When I removed the spring, although it was intact, I discovered that it wasn't placing the caliper frame under enough tension to stop it rattling around over bumps.

I fixed this by bending the ends of the spring out slightly so that when it was refitted, it held the frame in place more securely.

Thanks everyone for the great tips and assistance. I'll keep the other ideas in mind when the next rattle starts.
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1979 Series 1 924 turbo

[20v924]

20 pts for smoothie!
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A person is smart. People are stupid

[Smoothie]

Yay me!

..almost. (I did think they'd have to be broken to cause the trouble.)
I'll settle for 2pts. and give the rest to Aussie931 for crawling under and doing the actual work.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[82turbo924]

Check for dead hookers