The Exhaust took such a long time to line up, that maybe I shouldn't be surprised to have a few teething problems.

But I keep on hearing this thumping noise which is coming from underneath the car!

Its ok on a Two lane black top but when you go over a rut in the road even a very small one, that is when you hear the banging sound.

If the straight pipes had another support, apart from the Two at the back, then I think that it might solve the problem, though obviously it wasn't meant to have one.

Any Ideas?

 

When I lined mine up, I had to adjust several times at the "olive" joints to get the recommended clearance. Get under and shake the pipes. You want at least 1 inch "25.4 mm" clearance everywhere.

 

That sounds like a great idea! but as the ground is much too wet for me to lay on to-day, if I want to get any pipes shaken, I'll ask 'Shakira' to do it!

 

It may not be the exhaust; it could also be worn radius arm bushes or the central gearbox mount.
Both can sound like the exhaust banging when you go over a bump.

 

this is what I was going to ask. Mine only does it on large bumps and sharp turns, so yours could be the same on rough roads

 

100% on the MOT, great job. Exhaust/gearbox mount:

If it is the GB mount the thump should be sound right by your left hip, but coming from lower than the floor. My money is on the exhaust.

I seem to recall you mentioned a ramp? If you have one, the best way is to put the car on it, and as 1800Dougie said, loosen all the joints a touch, downpipes forward, and line it all up ensuring the pipes are at least an inch from everything. Ensure the famous pins are engaged and have their insulators, and that the through-axle pipe is not close to the rear calipers and the cage (ie an inch away from!). This is very hard to do and as the entire exhaust effectively floats a bit, ANY slight closeness to a hard bit causes a bang. Funnily enough, the long run under the car is not usually the cause, far more likely to be the cage or the boxes before the cage, or the boxes in the tunnels each side of the boot.

I suggest that once the pre-cage boxes are OK, and the cage pipes are OK, then chock the pipes that enter the tunnels with wood etc to hold them firmly (ask GF to hold the pipe even better) then (assuming the box to pipe clamp is already loosened), rotate the back box either way a few degrees to give an even gap along the length of the tunnel. Also you can move the box forward and aft to ensure no fouling at the tunnel rear end.

I mean , now the MOT is in the bag, you cabn get down to the serious XJS addict stuff!

Congrats again, and aren't they wonderful to drive!
Greg

 

OMG I hope not! I just want to put the spanners away and enjoy myself for a bit!

 

Hi Greg

You are 'Bang On' Pardon the Pun! but taking into account I've got a 'right hooker' (apart from the GF that is!) I seem to be getting a bit of both of the noises that you describe.

On one hand I'm getting a very loud thump, which does sound like the Silencer in the middle or at the rear but I'm also getting a different noise that seems to be coming from under the passenger seat.

It actually does have a 'ching' 'ching' sound which sounds like breaking China!

Any idea what that is?

Getting back to driving the XJS V12 my 6 pot drives like a Tractor while the V12 pulls like a Train.

I had loads of fun in that underpass, including the Journey back because everyone inside it seemed to be going absolutely mental!

Obviously I had to drive it with a lot of restraint (ish!) but there were times when it looked like, some of those 'Hot Hatches' were driving in reverse, which must have been an optical illusion!

As for getting the GF to hold the Exhaust Pipe!

The girls a 'Grade 'A' Bimbo' so that's never going to happen, although I might suggest it, just to watch the look on her face!

Look out for my Post on Electric Door Mirrors not Working!

'Emu Girl' might give me a hand with those!