Technical Exhaust banging

[stocky]

After advise please.
When cars been standing a while so needs a good turn over to start it the engine can move a bit and exhaust pipe can bang on bottom of body which dosent sound great.
It's a 650 unit, it has a red spring in rear mount and uprated rear springs if that could make any difference.
Doesn't do it often but sounds horrible, anyone any ideas?
Tried to bend tail pipe down slightly but wasn't having it and I didn't want to split it with too much force.
Some photos of setup attached.

 

[Flo500]

Do you know what section of the exhaust is contacting what section of the body? I would expect some level of witness marks.

Depending on what you find, it may be worth checking the gearbox rubber mounts, they tend to control rocking movement of the powertrain.

 

[stocky]

Do you know what section of the exhaust is contacting what section of the body? I would expect some level of witness marks.

Depending on what you find, it may be worth checking the gearbox rubber mounts, they tend to control rocking movement of the powertrain.

Hard to know exactly as its only when I do a long burst on the starting lever but I think its exhaust tail on back under edge of boot, you can see in photo it's quite close.
I'll check those mounts, thanks.

 

[stocky]

Ok had it up on jack and by holding the exhaust pipe and rocking the engine i can see it hits on two places on the exhaust, arrowed.
The video shows me rocking the engine by hand and amount of movement on the mounts, is this excessive?
Dont want to change them if dont need to.
Only knocks maybe once every long turnover but sounds awfull when it does..
Thanks

 

[stocky]

Trouble uploading

 

[stocky]

Answered my own question, looked at a new mount, mine obviously split, two ordered

 

[Mike1alike]

It's like the song. "Bang bang..."

 

[stocky]

Wonder why it was moving so much?

 

[stocky]

Well new mounts fitted, started her up and as she turned over a few timed and sped up bang, exhaust hit body again.
So ive replaced the faulty mounts but its not solved problem.
Not had this on any of my others.
Going to loosen exhaust bracket and see if it can be twisted away from body a bit more.
Other than that think im going to grind tha body away where it hits as per photo.
Perhaps its just an exhaust that wasn't fabricated correctly?

 

[Mike1alike]

Isn't the end part hitting it too? Is there any movement?

Going to loosen exhaust bracket and see if it can be twisted away from body a bit more.

That should work.

 

[stocky]

Loosened bracket but no play in exhaust. Put a long screwdriver in tailpipe and tried to push it down but quite a solid made exhaust.
Measured nearest poin to body before and after, 11.8mm to 14.5mm so a small change.
Will try again and if still knocks grinder coming out.

 

[stocky]

Cut the low part of body, see if it works tomorrow. Before and after photos.

 

[Mike1alike]

Looks very well. Hope it's the fix!

 

[stocky]

Well hasn't fixed it, its hitting on the underneath so I'm not sure what to try next.
Any suggestions?

 

[Mike1alike]

Any chance to rotate it a little but still stay in support?

 

[stocky]

No unfortunately no slack in exhaust, only thing i can think is to put a rubber pad on underside so if it hits it dosent sound so loud.

 

[Mike1alike]

Yes, you could try that.

 

[MalcolmfromMoffat]

I think by now I’d be sparking up the blow lamp!

 

[stocky]

Think you might be right

 

[stocky]

Had a good look this morning and dont think even with heating and a crow bar it'll move enough and I'm worried the pressure needed might snap the weld at the tailpipe and box.
Put some draft exluder tape on bottom where it sometimes hits to dull the noise and going to live with that unless someone has a better idea.