tapping noise consistent with roadspeed

lonesailor · Postby **lonesailor** » Fri Nov 17, 2017 2:25 pm

I have a tapping noise consistent with roadspeed in my NA8. It's most noticeable on smooth tarmac at low speeds. I initially diagnosed a problem with the speedo cable binding and tapping against the scuttle but it was still there with the cable disconnected at the transmission, I do have a bit of a flat spot on the front LH tyre caused by a big lockup at Lakeside last week, could this be causing it? I have had a fairly good look at the underside of the car and can see nothing amiss. Has anyone any other suggestions?

manga_blue · Postby **manga_blue** » Fri Nov 17, 2017 3:01 pm

Screws or nails in the tyres?

and, yes, sometimes a flat spot can sound like that too.

bruce · Postby **bruce** » Fri Nov 17, 2017 5:20 pm

Yup, something stuck in tyre.
Or just move the spotted tyre to the back (or fit the spare) and see what happens to the noise.

lonesailor · Postby **lonesailor** » Sun Nov 19, 2017 1:02 pm

Looks like it was just the flat spot. It's going away now, but I can still feel a bit of a bump through the wheel . Thanks for the replies

lonesailor · Postby **lonesailor** » Sun Dec 03, 2017 2:41 pm

That noise has persisted, so I had another go at tracking it down. First I calculated the RPM of the road wheels and am now confident that the noise is one tap per wheel rev. Next , because I suspected a problem with the half shaft universals, I jacked up the back wheels but kept the springs compressed. I started the car, put it into gear and listened for the noise. No tapping , tried it in fifth still no noise ,then the aircon cut in suddenly there it was, ac on, noise ac off no noise ???. The noise appeared to come from under the passengers seat, and it couldn't be replicated with the AC off and more throttle. rechecked all the wheels for stones,nails etc. all OK. could find nothing amiss from around the site of the noise. Then I put the car down and took a test drive. Noise still there with or without AC???. The noise is not loud, but it is there and seems to be getting a bit worse. Anybody got any ideas?

manga_blue · Postby **manga_blue** » Sun Dec 03, 2017 10:53 pm

The AC bit is just bizarre. I have no explanation there.

Otherwise, did the noise move when you rotated the wheels? If yes then look again for tyre bulges, flat spots or a cracked wheel spoke. If not then maybe a cracked brake rotor.

Try weaving on a smooth road, both on throttle and off throttle if you can. Noise increasing when you turn right and disappearing when you turn left indicates a stuffed left side wheel bearing. On/off throttle differences might help you work out if it's front or rear. A crack in the ball race would make one click per rev.

Wheel bearing noises travel all through MX5s and appear to come from strange places. My failed front left bearing noise came from the middle of the boot. I thought it was a stuffed diff for a long time.

SLO_NA · Postby **SLO_NA** » Wed Dec 06, 2017 5:38 pm

If the noise is coming from the interior check the interior blower fan as sometimes they make odd noises from being filled with debris over the years. Also check the engine pulley bearings (Water pump pulley, Non-Power Steering Pulley, Power steering pulley, A/C compressor bearing). Maybe it could also be the half-shafts, driveshaft joints, worn out diff, damaged brake rotors or wheel bearings there are so many other things that could be wrong so i suggest taking your time to look through the components of the car to see if you can find the problem. Good Luck

lonesailor · Postby **lonesailor** » Fri Dec 08, 2017 11:21 am

Had a drive down to the coast yesterday, tapping noise appeared louder, I did however notice that the noise disapeared with a very gentle touch of the brakes, it was still there with a light pull on the handbrake. My conclusion was that it must be in the front brakes. This morning I pulled the driver's side caliper and disk apart without touching the piston and could see nothing amiss, except the shim next to the piston fell out when I swung up the caliper. Cleaned everything up ,wear on the pads a bit less than I expected and short of a small crater on one looked very good. The rotor had a couple of chill spots visible but couldn't be felt ,generally all appeared OK except for a bit of brake dust. I cleaned everything up ,lubricated the slider pins with some lanolin grease and reassembled, took her for a short trip around the block and the noise is gone. Time will tell if this has solved it for good, Perhaps the inner shim was displaced. I will update this if I have any recurrence, in case it helps someone else, otherwise I'll keep my fingers crossed.

lonesailor · Postby **lonesailor** » Sun Dec 10, 2017 5:24 pm

Had a couple of good runs yesterday and today and the noise has gone.

I assume the shim between the piston and the pad was misaligned or there was foreign material stuck in there somewhere. I wish I had a more definitive answer but OK is OK. Thanks for all the input.

93_Clubman · Postby **93_Clubman** » Mon Dec 11, 2017 10:53 am

Well done on your persistence & find the cause.

lonesailor · Postby **lonesailor** » Tue Feb 28, 2023 8:00 am

Here I am again 5 and a bit years later, and the problem has reemerged. I have gone through all the same things as last time with the same(NO clear) result.
I am expecting a new front hub today which I plan to fit to the drivers side (where the noise seems from) to see if that helps. Strange thing is that it comes and goes. It's usually worst on nice smooth tarmac, which is to be expected, but it goes away for a time , then reappears regardles of the surface. My daily drive, an old Hilux, is hors de combat at present waiting on a new alternator which will be 2 weeks. The Mazda is having to do a lot of kilometers at present (My lady is in hospital on the Sunshine Coast and I need to go there a couple of times a week) which is a worry. Any suggestions from someone who has encountered a similar problem would be very welcome.

ManiacLachy · Postby **ManiacLachy** » Tue Feb 28, 2023 10:44 am

I have a similar noise. It's hard to hear unless I'm driving next to a wall at low speed for the sound to bounce back at me, and be audible. I've had the car up on jack stands and ran the engine, put it in gear so the wheels will move, but there is no noise in this situation, nor if I spin the front wheels by hand, it seems to need to be under load.

Your brake diagnosis the first time was very interesting. I wonder if mine might be something similar. It seems to be coming from the rear for me. My hubs feel OK.

I'll be interested to hear how your diagnosis goes this time!

93_Clubman · Postby **93_Clubman** » Tue Feb 28, 2023 11:46 am

lonesailor wrote:tapping noise appeared louder, did notice that the noise disapeared with a very gentle touch of the brakes, it was still there with a light pull on the handbrake. Conclusion was that it must be in the front brakes. Pulled the driver's side caliper and disk apart without touching the piston and could see nothing amiss, except the shim next to the piston fell out when I swung up the caliper. Cleaned everything up, lubricated the slider pins with some lanolin grease and reassembled, took for a short trip around the block and the noise is gone.

Could have been pad rattle - you mention a shim, but were all the parts present, ie clips, springs & shims?
https://mx5mania.com.au/products/copy-o ... ar-na-nb-1

lonesailor · Postby **lonesailor** » Thu Mar 02, 2023 4:15 am

I have just checked all 4 wheel brakes and ensured all shims and the springs are OK and new ( after much hassle and expense to find them) have replaced both front hubs and the problem persists. I still suspect the speedo cable but I am not able to take it out to check and lubricate it without a hoist. I did have a big loose a couple of weeks ago at Lakeside with great clouds of white smoke but can't see or feel any noticable flat spots on any of the tyres. The noise restarted after that I am thinking that I might refit my old 14" wheels and old and rubbish tyres and see if that changes anything. I need to do a few trips up the highway in the next few weeks and am worried about getting stranded. I will, wlile the car is up changing the back wheels, run it in gear to see if the noise is coming from the rear halfshaft universals, although I have spun them by hand and couldn't hear anything amiss. Has anyone an idea where I could get a new speedo cable?

lonesailor · Postby **lonesailor** » Thu Mar 02, 2023 8:43 am

I woke up early this morning after worrying about this half the night. Decided to try swopping my 15" front wheels for the old 14" with the el cheapo tyres which were on the car when I bought it, did a run around the block - no noise! Put the 15 with Hankook RS5 back, and noise came back, obviously the problem is the flat spots, that is unlikely to cause any serious problems so I will put up with it for the estimated 4.5 K left on them, that will be around the same time as it turns over to 300K . I'll do a major service then , fit some new Hankooks or whatever is considered best at that time, and generally tidy her up. I should have seen this for the problem straight away, because it was the same thing that happened the first time. Thanks to everyone who offered suggestions.