Find that noise

An occasional noise seems now to have become permanent.

It’s a chatter/squeak that is related to road speed (gearbox and engine have no effect). Definitely rythmical according to wheel rotation speed. Difficult to tell on the road whether it’s coming from front or rear, or which side.

I cannot duplicate the noise if I jack and spin the wheels (presumably that’s because I can’t spin them fast enough).

Anyone encountered this, or any ideas, please ?

Regards,
Stuart.

Difficult to diagnose without knowing what sort of noise it is.
Does it alter as you go round corners and load the wheels laterally? If so, it could be a wheel bearing. It could also be a rubbing brake pad, does it alter as you gently apply the brakes? Don’t forget to try the handbrake as well.
Is is a squealling noise, it could be a stone between the disc and brake backplate.
Have you recently fitted new tyres? Road noise can change significantly with different tyres.
Have a good look around, is anything obviously loose and/or rubbing on a wheel or tyre?
Mike

Hi Stuart

Wouldn’t mind betting its the speedo cable !! I have had this before and swore that it was not changed wheel bearings, brake pads, anti squeal plates and various other bits , then disconnected the speedo cable at the box end and bingo silence :blush:

Worth a try and fairly easy to do / prove

Hi Mike/Peter,

Thanks for the ideas. I will have another thorough look around and if no joy try Peter’s suggestion (not my favourite job - removing the right angle speedo drive, although refixing it was worse).

There’s a chance Peter has found the culprit.

I had this noise problem around Christmas time, and then found the speedo was dead (cannot remember if the noise had disappeared at this point though).

I had the drive unit repaired/replaced. Now, less than 3 months later, the speedo needle has started ‘swinging’ again. If it develops as before, then the speedo will eventually fail again.

So there’s obviously a different problem here, but maybe the drive unit is also causing the noise.

We’ll see.

Regards,
Stuart.

All of the Smith’s Speedometers I’ve disassembled (MG, Europa, Spitfire) have basically the same design. A swinging speedo needle is unlikely to be caused by the angle drive. However, a bad speedo cable can easily cause an angle drive to fail.

I have seen three causes of swinging speedo disease:

  1. A crimped speedo cable. This is bad for more than just the cable, because it adds stress to all parts going back to the tranny. In Europas, the result is often the destruction of an unobtainium nylon gear.

  2. Physical contact between the magnetic drive inside the speedo and the needle pickup. The speedo works by the drive plate spinning and magnetically dragging the driven plate along with it in relation to the speed of the drive plate. If the thing gets dropped, mechanical contact can result. Makes a mess of the reading but is usually easily corrected via judicious application of force.

  3. Dissimilar metal bonding at the joint between the speedo cable and the drive plate. There is a brass bushing here that, when the grease dries out (somewhere around 30 years after manufacture) will bind in its steel receptacle. Lubrication and careful working of the joint usually corrects this.

I liberally lubricate all speedo-related components with white lithium spray. I’m hoping that’s good for another decade or so, and it’s very easy to accomplish.

Hi Deni…

Cannot comment on your technical observations, but can only add a practical one:

When this first occurred at Christmas, I secured a new speedo drive cable from Susan Miller, just in case. Tested the old one and found it was fine.
Returned the new to Susan, without any charge.

Whilst my diagnosis may prove to be wrong, yet another example of an excellent supplier’s quality of service.

It could be however, that I’m going to have to re-order that cable after all… DOH !

Regards,
Stuart.

Hi Deni…

Cannot comment on your technical observations, but can only add a practical one:

When this first occurred at Christmas, I secured a new speedo drive cable from Susan Miller, just in case. Tested the old one and found it was fine.
Returned the new to Susan, without any charge.

Whilst my diagnosis may prove to be wrong, yet another example of an excellent supplier’s quality of service.

It could be however, that I’m going to have to re-order that cable after all… DOH !

Regards,
Stuart.

just turn up the radio and wait a while -you will find the problem – :laughing: --ed

Stuart - I agree with a possible speedo cable diagnosis - especially given your recent speedo history. I had a baffling squeek - high pitched - coming from the rear of the car, even at very low speeds (<5 mph). I also could not duplicate it when jacking up the rear wheel. To make a long story short - the nut that holds the rear hub to the tapered shaft was beginning to come loose. Jacking it up just took the stress off of it. Re-bedding, cleaning, and all the normal things to ensure good contact between hub and the shaft fixed it for good.
Good luck
Paul Zimmerman
26/4600

Have checked the speedo cable and right angle drive unit. The cable connection onto the drive was a little loose. Tightened it.

A visual inspection has not revealed the reason for this noise. Tried freewheeling past my neighbour, and even though he could hear it, he couldn’t pinpoint it to the front or rear axle.

Think I’m going to dream up some contraption that will spin a wheel at some speed while the car is stationary, and see if I can find the problem.

Regards,
Stuart.

I would have bet the ranch it was the speedo cable… but… now I’d recommend getting the same neighbor to go for a ride and at some safe point in some open lot, open both doors while the noise occurs at speed to determine right or left. I’ll guess brake pad, rotor rub. They may not drag until there’s some heat build up.
Or how about one rotoflex bolt coming loose, or “dry rotting squeak”, I’ve experienced both on my +2.

If you’ve got a mechanical squeak that you can’t trace and you suspect particular areas (e.g. rubber bushes), try spraying them with WD40. If the problem goes away, you’ve traced the source although the fix may only be temporary.
Of course the trick isn’t recommended for brake squeal…

Mike

Hi and thanks all for the suggestions.

It may be something to worry about, or it may be nothing. Until I find it and then evaluate, I can’t say. Whatever, seems to me it shouldn’t be happening.

At great cost (bar-b-q and beers) have enlisted pairs of ears for help this weekend. No solution = No beer. Might as well give them the scortched food anyway! Any awkward cusses will receive extra sennapods
No beer until solution found.

Will report.

Regards,
Stuart.

Making progress.

During yesterday’s outing to Sue Miller, did a little experimenting. Seems that a dab on the brakes will stop the noise (rhythmical squeaking type noise, with speed related to how fast the road wheels are spinning).

Noise returns after a few seconds, though. Probably from the front, since I changed to +2 calipers earlier this year.

Time to investigate more closely.

Regards,
Stuart.

Sounds like a sticking brake pad. Have you got shims behind the pads or tried a little brake grease on the BACK of the pad?
Mike

Hi Mike,

Yes, anti-squeal shims are fitted (with Copperslip), but I will check your thoughts out.

Regards,
Stuart.

You could try running without the shims, that sometimes works. The shims put a slight side load onto the pads so they are slightly out of line with the pistons and that slight difference usually stops squeal. Sometime taking then off does the job, there is no downside and you can always put them back.
Do the pistons move freely? Sticking pistons is often a cause of squeal.

Mike

Almost definitely the offside front (RHS) causing the problem. Managed to just about duplicate the noise when spinning the wheel by hand.

It seems it may well be the caliper/pads assembly, since forcing off the pads and then spinning the wheel will alter the noise characteristics.

Pistons are both free, so will try removing the shims.

One thing I did notice … the brake disk does not sit centrally within the caliper. One side of the disk is extremely close to the caliper housing. Normal … ?

Regards and thanks,
Stuart.

Stuart

The stack up of tolerances on the various front hub components means that the disk can vary a little in relation to the caliper and not be precisely central. However if the disk is close to hitting the caliper it is normally due to the front upright or spindle being bent due to hitting a curb at some time.

regards
Rohan

Thanks Rohan,

I don’t remember the disk being so close when the baby caliper was fitted (might have been, though), and it is the offside caliper (furthest from the kerb).

I used the +2 caliper mounting plate, and I don’t think I could have fitted that incorrectly.

I better check out the nearside too.

Regards,
Stuart.