8 replies to this topic

[iandhd]

Ever since the stresses on the car on my visit to 1stLotus my Regal backbox has been vibrating really badly and making a tinny vibration when backing off the throttle. In the service Vauxhall told me it was the downpipe touching the backbox (which I didn't believe because it sounds like a heatsheild or the floor pan), but then again they didn't even spot it was an aftermarket exhaust Minime had a look for me at Hethel and it appears the problem is that the main backbox section is resting on the floor pan at the back. The problem is that now it's getting worse and the heat from the backbox has actually melted the floorpan and part of the exhaust is actually protruding through the floorpan So I'm going to have a closer inspection over Christmas before it gets any worse. Has anyone else had this?

[PaulCP]

Ian I had the downpipe vibrating against the back box fairly early after fitting but no more problems since further adjusting it's position. Are all of the heatshields in place? (mine are). I'll take a look at mine to see how close it comes to the floorpan Paul

[iandhd]

I had the downpipe vibrating against the back box fairly early after fitting but no more problems since further adjusting it's position.

Are all of the heatshields in place? (mine are). I'll take a look at mine to see how close it comes to the floorpan

Yep I had a slight resonating after the initial fitting but it went away too. The heatshield at the top is in place, I don't remember ever seeing any other shields. I'm pretty convinced it's the floor plan making the noise, especially since it's now made a small hole in the floor.

When I look through the rear wheel arch you can clearly see the exhaust box touching the floor plan.

[Thorney]

I'd get it looked at Ian, the exhaust shouldn't touch the understray at all, its made of aluminium and woundn't take much to melt. I may be wrong on this but I seem to remember one of the reasons your car could fail scrutineering on a track day (thats when they bother do do it ) was any fouling of the exhaust on the chassis/body.

[PaulCP]

Ian Just checked mine and there is approx 1 inch of clearance between the back box and the undertray. Also, as i suspected, there is also a piece of heat shield between the box and the undertray. 1st thoughts are whether yours has slipped somhow but i suppose that it would be more noisy if it had but can't understand what's happened to yourheat shield. Paul

[iandhd]

I'm going to get under it today and I'll take a look. I'll try and put a photo up too. Thanks Paul.

[TonyIles]

If I was you, I would check to make sure the hangers are in place, if the back box has slipped, then check to see if there is a connector between the back box and the cat, if that has worked loose and the back box is not a cylinder (i.e oblong) then the box may have dropped on to the undertray, I fitted a sports exhaust (Vauxhall) yesterday, and it was quite fiddly getting the tips central and level, my VX had a heat shroud on the undertary. The Vauxhall sports exhaust is really tiny, more so than the Piper that came off, but certainly sounds good!!

[iandhd]

Well I took the rear floor pan section out and drove the car after securing the flappy bit. It didn't seem to vibrate much if at all, any sounds that were evident I put down to the fact that there were lose sections of floor pan from the removal. I managed to reasemble the rear floor pan with a bit of packing out of the two cross head screws that sit in the middle of the rear floor pan. There is no no contact between the cat and the floor pan but the vibration has returned It's definitely the cat that was touching and not the back box (this is like Paul says... about an inch away and seperated by the heat sheild) The sound is like it's coming from under the seats???? Oh well back under the car I guess

[iandhd]

I got more and more convinced the sound was coming from directly under the car and the metallic vibration continued. I don't know if it's connected but when I was on the M4 yesterday there was a thump in the rear of the car. My immediate reaction was to look in the rearview mirror to see what I'd hit on the road.... I could see nothing. Since then the metallic sound has gone completely ??????? I REALLY need to take a look under this car.