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MG Midget and Sprite Technical - Semi Elliptic Issues with rattles

I have an annoying very heavy rattle which typically occurs on the "drop off" from a speed bump. Everything underneath seems tight and I have emptied the boot!
I am wondering whether it could be something associated with the springs and mounting. No obvious play in the bushes at the back end. Anyone any thoughts?

(lever arm shockers tight; drop links tight; no movement on exhaust system; too heavy to be something in the fuel tank; no movement on prop shaft attachment or joint; springs LOOK ok although the flat rubber packing pieces look a bit stretched; u-bolts tight.fuel pump tight. Shockers not bottoming)
Graeme Williams

Rods for the rear brakes? I think they originally had leather washers inserted where the rods attatch to the cylinder leveres but these are often missing or have dried up and disintegrated. They can make quite a heavy rattle.

Or, if yours is a 1500, does it still have the rubber strap that supports the brake rods near to the middle of the axle?
GuyW

Guy: it's much heavier than that. I did have that issue a while back and have fitted short tension springs to take up the play from the rod down to a cable tie on the spring.
Graeme Williams

Oh, OK.
Not the rear axle bump stops bottoming then?
Does your fuel gauge record correctly?
GuyW

Graeme
Is the noise as the suspension is extended coming off the humps or when it lands
Speed hump speed or faster---
William Revit

Axle housing hitting exhaust pipe?
Stan Kowznofski

Might be silly, but what about exhaust mounts and handbrake rods ?

Good luck !
CH Hamon

Fuel gauge and tank gubbins all ok Guy. Just replaced the float and the noise is much heavier than the float mechanism.
I had shock absorbers bottoming out before so fitted lever arms. This noise has been there all along but now the shock absorber noise has been removed, it's noticeable. I sounds like a hefty lump of steel rattling about in a substantial steel box.
I'll check out the exhause issue, Stan.
It's happening a slow speeds over speed bumps so not pushing the suspensions to extremes. Small pot holes cause it too.
It sounds like something is loose, which would be worrying if it stopped!
I know a man who I am sure would be willing to lend his experience with a run round the block.



Graeme Williams

Good idea to take someone with you, noises travel and sound like they originate from different places by different people and swapping seats for drives. Something hitting the body or underside or exhaust can sound a lot louder or heavier than you would expect from it. External ones you might see marks or clean patches.

Are you sure it's not your wallet hitting the floor?
Nigel Atkins

My thought is that the exhaust might appear in the mix somewhere, or what about bumpers bars or number plate/backing amplified rattling through the boot.
Nigel Atkins

Have you looked inside the transmission tunnel? It isn't easy to get a proper good view and I think you would need a torch and probably a mirror. But maybe there is something just lying loose in there?I

Why I asked if the fuel gauge was working properly is because it is very easy to fit the float sender unit 180 degrees out, in which case the cranked arm of the float causes it to bang quite loudly against the inside of the tank. Despite the lightness of the float, the banging resonates inside the steel box of the tank and can sound quite loud.
GuyW

Yes I had a float banging the top of the tank. Took ages to track it down, but I could simulate the noise by pushing and pulling the car forwards and backwards,and with a sufficient wave building up the clanking started.


f pollock

I'll check the fuel sensor. It's a plastic float.
I'll check the tunnel more thoroughly and also the apertures in the kick panel behind the seats.

No one suggesting about a possible issue with springs and mounting rubbers?
Graeme Williams

Rear wheel bearings ok and the nut tight--? correct thickness gasket-- as in no endplay in the wheel/axle
William Revit

How about something come adrift INSIDE the silencer? Or is the boot catch tight? That caused a rattle on my BGT. While in the boot, is the prop the cause? Tricky to diagnose over the internet!
Mike Howlett

Mike: yes I totally agree. I was just hoping on the offchance that someone would say that they had that too and it turned out to be xyz.
It is far heavier than the potential outcome from a lot of the suggestions - the term rattle needs to be replaced with something which suggests heavier but I can't think of a suitable word.
Graeme Williams

clunk--------
William Revit

clang?
Martin

Does it sound expensive?
Greybeard

A clatter ??

I had something similar on my 1500 and like you changed lots of bits, in the end I discovered that the brake shoe return spring was not fitted correctly, the double coil spring with the extended hook was under the hand brake lever and not around it, changed that and it stopped the noise.

Alan




A Pritchett

A certain ex-BBS contributor (A Law unto himself!) contacted me to suggest he had had similar problems on two midgets due to the metal outers of the front end of the springs being a loose fit. I can imagine this would dreated a heavy enough noise as the weight of the car is behind it. Will check it out and report back.
Graeme Williams

Ahh yes,could be
had that on a B once---it lets the springeye move sideways and clunk against the body bracket
William Revit

I think I have found the problem!

One bolt on the lever arm on one side was slightly loose, allowing the shocker body to slightly rotate on the tight bolt.

THe annoying thing was I couldn't detect any movement when I pushed and pulled. I only found it when I dropped the link off the spring. Up until that point the link locks the free end of the lever arm and since the lever arm is very reluctant to rotate relative to the shocker body, it all felt firm, preventing any feeling of rotational slack. Had both bolts been loose it would have been moving about and detectable. The solution is to tighten both bolts or leave both loose, not just one.

Graeme Williams

Graeme
That's a real issue with new cars that don't get their first service done properly--
All the new parts(like shockabsorbers)are painted when the cars are built and the first few drives wears the paint off and things come loose, shocks, suspension arms etc
If your new shockers were painted when you fitted them then that is probably what happened to them as well, it doesn't take much
William Revit

Much like freshly painted wheels, DAMHIK .
David Billington

Graeme I had the same problem. One of my rear damper bolts wasnt done up tight enough. I could hear a heavy sounding clunk over bumps yet all the suspension components seemed secure. Wriggling the shock by hand didnt show it was lose. Only whne I went to nip up the nuts and bolts I noticed one wasnt tight.


Sorry if I had remembered this sooner I might have saved you some time !
Chris Madge

Graeme,
not enough Weetabix for breakfast, your muscles obviously are not equal to the weight of the car, if you only have two Weetabix then you'll also need a prybar.

Being serious, well done on finding it and reporting back.

Nigel Atkins

We've had terrible clonking on my sons' Nissan Micra. The rear dampers were floppy in the middle so I assumed it was those. Replaced them and....clonk. It turned out to be the arb drop links which looked perfect and were tight. All this on a 20'000 mile car, althlough 22 years old. I suppose the runbber nits are giving up.
Clive Berry

I am forming a new group "Shockabsorbers Annonymous".

You just need to join and introduce yourself "My name is xxxx and I had a loose shockabsorber". Well done Chris and Clive for admiting it.

(In all seriousness it was very tempting not to report back because out of context it seems amateur not to have found this in the first place. However, because the constraints placed by the mounting hiding the issue I decided that others may experience the same problem -I can imagine they have a tendency to work loose. Reassuring that Chris had exactly the same problem and experience).
Graeme Williams

I seem to recall the handbook certainly for the Frogeye says that the security of the suspension bolts should be periodically checked. Nothing in the later midget manual as far as I can see.
Bob Beaumont

it's exactly the type of application where I routinely use nyloc nuts when refitting....
David Smith

Me too! I wonder if I actually nipped it up tight during the fitting in the summer.
Graeme Williams

Graeme ---Would you sign me up please, I would be honoured to be a founding member of your new group
My name is Willy and I have a loose shockabsorber


lol
William Revit

Yep, I too must confess I have suffered the same ailment with slack nuts on my rear dampers.
GuyW

Hi I'm Colin and I might have had loose shock absorbers!

Engine currently on the bench so not able to check if my mystery front end clunk on full lock has gone. There are no signs to suggest there has been any movement but the shock absorber bolts were 1/2 a turn below recommended torque.

Thanks for this thread for making me check.
C Mee

Hello, I'm Martian and I too may have a loose shock.

Reading this thread has gotten me thinking about a clunk/clang/bang I get at the rear when I cross railroad tracks or some such. I'll have to crawl under and take a look.

Funny how these threads get you thinking about a problem that you didn't think you had.
Martin

My shockies are fine, but my car has a loose nut behind the wheel
Greybeard

Grey,

I think most of us here have one of those ;-D
Martin

Haha enjoyed everyone's humour on this one. Thank you.
Graeme Williams

This thread was discussed between 31/10/2019 and 30/11/2019

MG Midget and Sprite Technical index

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