My 2007 mx5 NC sport is handling very poorly on bumpy roads as can be seen in the video below. It brakes straight most of the time on normal roads, but on bad roads the steering swerves. It is always on the same section of road that this happens.
The video below shows me driving along the same piece of road in both directions, outgoing it swerves to right and on return it swerves left.
I’ve tried getting the steering realigned with no success. Also tried running it on both 29psi and 32psi with no difference, I have bridgestones RE050 at front and bridgestone RE002 on the rears.
It’s been happening for the last 6 months and it has passed the MOT since then with no problems. I presume this isnt normal?
I can handle it obviously with both hands on the wheel, but I does require quite abit of work which does make driving trickier on bad single lane back roads when a oncoming car approaches.
Hmm, you might think this is a strange question, but please humour me: how old are the tyres?
Soon after I bought it, mine did this quite alarmingly on one particular piece of road leaving the motorway, a local slip road approaching some traffic lights; it would pull very hard to the right as it hit the tram-lined wear-grooves just when I needed to brake, or even if I did not brake! It wore six year-old Bridgestone Potenzas, the OEM tyres as fitted in the factory, and these had become hard and inflexible with old age even though only half worn. Changing the tyres to supple new Dunlops completely eliminated the problem, and now the car is so very much more stable and sure footed on all surfaces - good or bad.
I had an issue myself when I got it 18 months back as it swerved on braking, turns out fronts were different brands plus different treads so a week after buying I changed the Fronts and that fixed the issue. Rears I replaced 10 months ago. The issue did seem to reappear at the start of this year a while after I changed the rears, I don’t remember exactly when the problem occurred, I also had a puncture fixed on the front left at the start of the year.
Wouldnt have thought the rear tyres would have any affect on the steering, but maybe that is the issue?
I would suggest your alignment is very much the issue.
It is recording zero toe on the front, which will make the car quite pointy and pretty much none existent camber as well. Caster is not recorded. To be honest it doesn’t look like they did anything other than adjust tracking slightly.
I would take the car somewhere that understands what alignment does and ideally experience of these cars, but more importantly understands alignment. Also don’t get hung up on type of machine, Hunter is just a manufacture, like saying I use Facom or Snap-On spanners.
I looked at that I thought all they’ve done is change the tracking, the download section contains settings for non lowered cars of various ride heights, camber and castor (which they’ve not measured) will change according to ride height.
Here’s mine from my previous 5 (340mm front 330mm rear) as an example of what an alignment should look like, the front toe in I find ok for road use as continual steering corrections are not required when driving in a straight line.
I’m based in Belfast, heard charles hurst being recommended on another forum but I guess theyre not as great as I heard. I told them the issues and they said they’d check it and see if theres any issues and came back after adjusting with the above measurements.
You have Bilstein Shock absorbers as standard on your mx5 sport, they are a fab bit of kit on nice smooth roads, but when the car hits anything other than smooth roads they are not easy to control! do a bit of research.
Tyre pressures are key on this car (especially if mx5 is booted with bridgestons or aged tyres) I found that if you inflate tyres to 29psi, first thing, then drive for approx two miles. the pressure increases by at least 1 psi9. So you need to be at 28 from cold.
Lowering a mk3 sport gets rid of the constant fight with the steering wheel because there is less shock travel. the only drawback with lowering is speed bumps.
To eradicate all issues you will need to budget for a set of coilovers. This would allow the cars suspension to be softened to your liking.
Once all the above are fulfilled, then get a precision alignment AND ENJOY
When I first bought my mk3 2.0i 2008 a few years ago,the handling was not good, tended to wander and very twitchy. The tyres were Bridgestones as you have, they were not too old but appeared hard. I changed them to 205/45/17 84V Continental Conti Sport Contact 3 for summer use, the car completely changed and now a pleasure to drive. Later I had a four wheel alignment but did not need much adjustment so made no noticeable difference.
I now have my winter wheels on - 205/55/16 94H Extra Load Dunlop SP Winter Sport 3D. these are great and I hope to have some snow this year to see the cars ability for traction with the LSD!
I spent a lot of time researching and now have the right tyre selection for me, I have the standard 2.0 sport Blitsen shocks and the car is used all year as my only car.
When I got the car they had cheap and awful Mohawks on the rears, no grip at all in the wet. I got a puncture in them one saturday and instead of getting it fixed I decided just to get a proper set of rear tyres on as I needed them for the winter. Unfortunately none of the locals had the same as the front bridgestone RE050 but one of the guys offered me the RE020 which are assymetric. So I currently have directionals on the front and assymetrics on the rear, both sides matching. Chances are the issues are with the rears asymmetrics, I did ask the staff 2 or 3 times if it’d be ok mixing them and he was confident that they wouldn’t cause any issues. Probably scrapping them and repalcing them will fix the issue as the problem only appeared a while after buying them. I may try doing a 4 wheel alignment first as thats the cheaper option but the purchase of new rubber may be inevitable
I would not have thought that dodgy rear tyres should exhibit the symptoms you have described. They may course the DSC to activate more often though. Maybe there is someone on this forum that could enlighten!
How are you adjusting your tyre pressures? My Bridgestone’s are new ,but still quite hard, and may users, I have found, inflate to 28 psi to compensate for this. Plus as the tyre warms up the pressure increases so you need to compensate.
