Question about Chimaera Fuel Tank Baffles

[NJ94Chim]

Greetings all.

I have a 94 Chimaera 400. When I'm driving at lowish speeds (15 mph or so) and turn the car tightly enough, I prettty consistently hear a "clonking" type sound from the trunk area. Happens on both left and right hand turns. Gas tank is maybe 2/3 full (which is about as low as I will let it get to). Car has no fuel leaks.

I've seen a couple of posts that mention that the Chimaera fuel tank has internal baffles....is it possible for the baffle(s) to come loose and move around with the sloshing gas - ie be the source of the clonking sound?

If loose baffle(s) is/are the source, can the tank be removed and repaired?

Or maybe its simpler to buy a salvage tank and refurbish it?

Or maybe just buy a new aftermarket tank?

What are the group's thoughts?

Thanks in advance,
Guy

[PabloGee]

Sounds like you need to identify the cause of the sound definitively.

If it is related to the tank, it's not difficult to take it out/replace it.
I wonder (thinking aloud) whether the internal filter might have come loose, though it's lightweight plastic and probably wouldn't clonk.

This article is useful info either way - and it has a photo of the outlet fitting.
https://www.bertram-hill.com/replacing-the-fuel-li...

If you haven't done it already, it might be worth loosening the straps that secure the tank, pulling it forward an inch or two to peer down the back of it - there might be something down there. It would ring like a bell if something is knocking against it.

Are you sure it's not something to do with the anti-roll bar, suspension, wishbones, or as others have encountered - the hubs when worn can make a sound (though it's more of a graunching noise).

[never_thought_id_buy]

Are you sure that it's not the differential making that noise? The LSD in my Chimaera is quite clunky at low speed on lock, especially in reverse.

[PabloGee]

My diff also clonks on takeup when it has either been parked, or if I've let off the gas more abruptly in gear at low speeds.
In my mind it's like the backlash in the diff is producing an audible (and physical) clonk.

But it's not triggered by turning at all - as per the OP's situation.

[Chim72]

I had a similar noise when turning earlier in the year albeit only to the left and at higher speeds. Replaced the diff oil and the noise went away.

Does sound like it’s more mechanical, could be bushes too, particularly the diff mounts, had those replaced a few years ago.

[Russ_Chim]

Hi,

My guess would be the baffles as I had exactly the same problem and replacing the fuel tank solved the problem. I don't think its that common as TVR101 said he has only had to replace fuel tanks a few times on all the TVRs he has worked on, cost was best part of £1k from memory for a new tank. Not sure of the cost of refurbs. I was tempted to leave it, but the garage said that if the baffles are loose then having all of the fuel sloshing around would not be good for handling, particularly on corners, which made sense.

I think he said part of the cause could have been that I had been tightening the fuel cap too much preventing air escape.

Suggesting of the diff is a good one as I also had to have the diff rebuilt as part of a body off rebuild as I was getting a separate noise, although since having it fixed I now getting a rotational noise around 50mph which I haven't been able to solve, so suggestions welcome on that one! I did have the bearings done which were in a poor state and was not helping.