996 EXHAUST BOX BRACKET FIXINGS

[Johnpor996]

Just wondered if anybody had comment to this – I have been removing my 996 exhaust boxes and the three most difficult fixings each side are the nuts that bolt the box itself to the retention bracket, almost impossible to get to.

As it turns out one of retained bolts on the bracket snapped and at over £300 a piece I'm not keen to replace them so have drilled out the retained bolts (or what's left of them) and will simply use a nut and bolt replacement.

My question is does anybody know why the two long bolts that go through the fixing bracket and attached the whole assembly to the retention frame on the car are fixed with the head of the bolt at the top of the bracket and the nut at bottom? Doing it this way means you can't undo the nut and push the bolt upwards to release the whole thing as the bodywork obstructs it, you have two release the retention bracket from the frame which means removing the three almost impossible to get at nuts.

Logically the head of the bolt would go to the bottom, nuts at the top, and if you need to remove it take the nuts off pull the bolt out and a whole thing comes away, but is not fixed like that. I suppose the only logic I can think of is that head at the top means if the nut should vibrate loose the bolt can't get away and mean that the exhaust boxes shaking loose – anybody got ideas?

 

[Space Cadet]

Good observation, would be interested to hear the response...

 

[Marmoset]

It's probably easier in the factory to slip the bolt in from the top so it doesn't fall out. I'd imagine the whole engine and exhaust assembly is married to the chassis in one go, so access after the fact is not a concern.

I ended up shearing a head or two off mine and then had to hacksaw the things to get the box off.

 

[ian_alex]

I'm sure Marmoset is correct, Porsche are very good at efficient assembly and not too worried about us poor blokes who have to dismantle them later when rust has also taken hold!
I reversed mine first time I had the boxes off and its a lot easier next time.

 

[Rich_r]

As above the bolt goes from the top means that if the nut comes off, the bolt still remains in place. If the nut was at the top, the bolt could most likely vibrate and fall out and thus the silencers could drop.

have you removed the wheel to access the 3 bolts that attach to the frame?

 

[martin t]

Very timely thread.

I have just removed and replaced the engine on my 996. One of the biggest problems was, as you have discovered, removing the silencer.

This caused me a few problems, and bothe engines concerned were out of the car on my garage floor.

I could not remove those 3 nuts as they had rotted leaving nothing for the spanner to grab onto.

Those 2 bolts, 1 x long and 1 x short run in tubes inside the mounting and they rust themselves solid so cannot be removed.

The reason the bolts are in that orientation is because if the nut falls off the bolt still holds the silencer on.

So you can see the problem is er 'problematic.

I had to grind off the top and bottom of the 2 bolts to get the silencer of the mounting bracket. I then had to remove the mounting bracket from the engine after first removing the manifolds!!!!

Reassembly was as follows. I bought a length od 10mm x 8mm ID Stainless tube and cut 2 appropriate lengths. Using plenty of copperslip i replaced the bolts upside down, so that in future it will be easy to remove the silencer, and for added security fitted a 2nd nut to eact bolt to lock it into place.

For the mounting bracket and the 3 rotted siezed nuts i used oxy acetalyne to remove them. I cleaned up the threads (not good but good enough) and using more copperslip and new copper dipped flange nuts reassembled the whole lot so in future everything will come apart.

As for those 3 captive bolts: If they are bad cut the off, drill them out and get someone to weld in new ones then gring the back surface flush.

Believe me it is not a job for the faint hearted!

Best of luck.

 

[Johnpor996]

Good advice Martin T, like you one of the long box on mine was totally fused to the sleeve by corrosion so both ends of the bolt had to be cut off to release it. I have to get the car back together tomorrow so went to a Porsche parts place today to get a sleeve, £25 for a bit of tube 5 inches long!

I'm going to do as you have done by reversing the long bolts, head at bottom, nuts at top and a second locknut to prevent anything vibrating loose.

I don't want to think about removing the manifolds if I ever have to – I hear it's a nightmare with bolts snapping requiring drilling out what's left in the cylinder head – nasty!

 

[martin t]

Ah yes the manifolds: £384 for the jig, just for 5 bolts!!!!!

Mind you with the engine on a pallett and tipped on its back it was an easy job to do.......not.

I bought my tube from ebay £6 delivered (3 days) and long enough for all 4 bits.

I have been re attaching the RH mounting this afternoon. Easy when the silencer is not attached.

 

[Robertb]

A friend reversed the bolts when he changed the silencers, worked fine.