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Hey wondering if anyone can help. Ive got a vibration which happens between 105 and 110 kph and only at this speed and is set off more if there is a bumpy section of road. You can feel it thru the steering wheel and its strong enough to make the passenger seat shake when empty of course. I had the wheels balanced recently which helped a bit but its still there and makes driving on the freeway a hassle. My tyres and wheels are non standard 205 x 15 with even tread pattern .

I guess it might be solved with a wheel alignment just wondering if anyone has had the same kind of thing and what they did to fix it

Thanks

Have a hunt for 65mph shimmy on miata.net

I would check for wear/play in the steering rack ends and the tie rod ends.

The best way i have found to check is to jack the car up via the front cross member and then put stands under the lower control arms near the ball joints.
Slowly lower the car so on to the stands until the wheels are in about the same position in the guards as when it is sitting on the ground.
Do not let the stands take all of the weight, just enought to drop the body down so the wheels are at driving position. Leave the jack inplace and put another set of stands under the sil jacking points as a precaution.

If you were to try this with the suspension at full droop the angle the joints will move in is different to when it is driving so the wear might not be noticed.
If you have access to a wheel allignment maching you can do this test on that with the front wheels on the turning plates.

Then with the wheels pointing strait ahead grab the tyre and gently try to steer the wheel about 10mm in and out. If you feel any light knocking or take up when switching directions you have a worn joint. Depending how flexible you are you might be able to grab the tie rod/ rack end and wiggle the wheels again to work out which joint has the play. (its easier if you have a mate to help with this though). Repeat for the other side.

Good Luck,

Rolley.

Ok might be able to manage that. What if I just go for a wheel alignment can they check tie rod ends for play then

The vibrations dissapear over 110kph if that means anything re tie rod ends

I have had it before where a car with a vibration problem has had a wheel allignment and that changed the speed that a vibration came in and out.. depending on the toe and castor it can all change.

The only thing i will ever recommend Pedders for is their safty check. never get the work done there but their reports on joint and bushing conditions are pretty good.

yes Ive been there for a knock in the front end before.....they did all their tests and changed bushes all over the place but didnt pick up the ball joint which was the actual problem....But point taken for a small fee they do a thorough front end test usually, then go somewhere else to get the work done!!

Just checked out that 65mph shimmy issue on miata.net and apparently it seems it could be a tire balance problem. they said that when the balancing was done on a hunter voila machine it was corrected and even sometimes it might be necessay to have them balanced then go for a test drive and go back if there not right

Wonder if we have anything like those machines here on the central coast. When I had them balanced it was done at Jax so I guess I got what I paid for!!

Iv got this too with my NB8B, had it almost 1 year and its done it since I bought it.

I found my stock wheels were very slightly warped which was some of the cause, when I got my new Enkei's on the problem was lessened but still at highway speeds there is a very annoying vibration through the car. Iv had several wheel alignments and balances but nothing has helped so far. Increasing the tyre pressures makes it worse. I run tyres at around 30-32 psi cold but if I were to try 36-38 psi (which isnt really necessary in a mx5 for the road) it makes it almost un-driveable.

Had the entire car checked over on a few occassions now but nothing has been brought to my attention.

Out of curiosity what brand/type of tyres are you running and still the stock 205/45/16?

When I first got my mx5 I got some Bridgestone RE002 tyres fitted then got the same tyres fitted to my new wheels so Im wondering if these tyres have some effect on the mx5 chassis. Not saying Bridgestone is a bad tyre, I really like them but wanting to try something else next time.

Iv tried a mates set of 15" wheels with RSR's fitted, no vibration was felt at all... go figure.

I found "upgrading" from 16" wheels to 15" wheels on my '98 NB8A sorted all my vibration issues. Prior to that, it would feel like a wheel was coming loose at around 60kph!

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Ive got 205/15 firenzas on king rims dont know much about the tires they seem alright.

They say on miata.net that even using lock nuts can cause the problem

Are your wheels second hand Peterd? If so, I would jack the car up and spin them. Using a piece of chalk check if they're buckled (should have been picked up with wheel balance if they are). The wheel balance needs to be balanced to 1/10 of a gram. The which I doubt Jax would do unless you asked them!
The sweet spot for NA's is 28 psi but on your NB which has more bracing you can go higher. Fiddle with it.
These specs dont apply to all cars and its recognised that some are more sensitive than others. In any case, because its only at a certain speed I think you're right in chasing balance.
I've got 002's on both my Mx5's (15" Volks and Speedie wheels on they dont vibrate) so I doubt its the tyres. A great street tyre.

Just take it to another tyre/ wheel specialist and have it rechecked. These things are nearly always related to the latter 2 items. Most problems are the most obvious things- Ockham's razor. You might even be able to do a swap wheels front to back- i.e. the wheel specialist- or even do a swap with someone as a trial. You cannot check wheels out of round or balancing at home - it has to be taken to people with the right equipment and some may have a little better equipment than others. Vibration of steering wheels etc occurs on all cars and the problem solving probably works the same way.

Thanks guys. Yes I've got it booked in for another balance and I'll ask them about the 1/10 of a gram. The wheels were bought new by the previous owner. I'll ask to see if they can check if the wheels run true, but there in pretty good nick so I think there ok. Thanks for the tips

Back to square 1 with the vibration issues

Put new tires on kumho ku 31's had the wheel alignment done suspension tie rod ends checked etc....still got the vibration issue

Everyone seems to have a different opinion of what it might be....and I dont want to be chucking dollars at it to try and find what it is

It could be anything it seems....My next cheapest option would be to try a standard set of wheels on if anyone has a spare set in the Newcastle or Central Coast area and see what happens......Ive got a set of king rims on which look nice but they are probably el cheapos as they have 8 stud holes in them which I guess means that there general purpose fit any car whereas a specialized rim to suit an mx5 could be better???

If anyone can help out Im clutching at straws here....Otherwise I guess I will just have to put up with it its not too bad just a bit annoying