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MX5 NC Sporadic Heavy Steering


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I've been having an issue for some while now where the effort to move the steering has become sporadic.

For example.

I can set of from work for a 35 mile drive with the steering feeling light and agile. Then after a 20 minute 25 mile drive down the motorway on exiting the steering has become heavier and the handling feeling almost cumbersome. Then left the car overnight in the morning the steering still felt heavy. 10 mile drive to the petrol station for a fill up, set off and the steering has become light and agile again?

 

I beginning to think the issue is suspension or geometry related, maybe a failing ball joint somewhere, although saying that when the steering is light it's a dream to drive on the meisterR r's. I'll try to keep this short, here is a list of things I've done to rectify the problem, but with no joy.

- Replace power steering fluid and bleed.

- Replace drive belt, tensioner and idle pulley.

- Replace power steering pump.

- Over past 18 months have replaced all calipers for reconded.

- Regularly grease calliper sliders.

 

I've brought brake calipers into the equation as the only time I've felt the heavy steering and poor handling and knew the cause was when I had the O/S/F caliper seize, replaced all was good.

 

If anyway has had similar issues in the past and may be able to help, please do so.

Luckily I've got my car book in at WIM for alignment bolt replacement and geometry in a few weeks so this issue may have some more light on it.

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As they've changed the power steering fluid I would assume it doesn't have EPS.

 

Strange problem. I was going to suggest maybe it's something to do with heat but as it happens the next morning when it would be cold it can't be something that needs greasing on the steering column.

 

Has the steering rack been checked at all?

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Hi

 

No my car has normal belt driven power steering

 

I was also thinking heating of the power steering fluid could be causing the problem. As the steering gradually gets heavier over longer journeys. But as stated this can continue when the car is sat over night or even a couple of days. The steering can then become instantly light again without a trigger I've yet to spot.

 

I've erecently replaced all 4 tyres and regularly keep the pressures at the desired 29psi, so I don't think tyres will be having any impact.

 

There maybe an issue within the rack, but I've performed some tests shown to me from other forums and all appears well, especially as the cars steering performs well during occasions.

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Thanks for getting in touch Tony.

 

Odd to say the least. I'm tending towards mechanical myself but I'm running out of ideas to what it could be.

 

Over on Miata.net a few where mentioning that air maybe getting into the steering system somehow, but not loosing any fluid.

If this was the case the power steering fluid would appear with bubbles in the reservoir but this has never been the case as I check regularly.

 

Also why would it all of a sudden change immediately without any steering input. I'm still thinking mechanical as when I get in the car in a morning to go to work, on starting the car you can feel wether the steering is heavy or light without even moving the car.

 

I'm booked in next Thursday 10th @ WIM and after a 100 mile drive I'm 95% certain the steering will be @ its heaviest.

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I'm sure the NC steering has centre weighting which makes the centre point stiffer...The ND is the complete opposite with the steering way to light. In the US their talking about bridging some fuses which i absolutely refuse to do here in the UK.

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I'm not sure if the NC has centre weighing. But the steering does require more force to perform manouvers when the wheel is near centre. But even this weight is noticeably lighter or heavier depending what mood the car is feeling in.

 

Another thing is I've also had vibrations when driving between 80/90 mph. I though it was probably due to poor wheel balancing but having just replaced all 4 tyres along with balancing the vibration is still there. Particularly along a certain section of poorly surfaced motorway. Come to think of it that is usually just before the steering becomes heavy. Or maybe I'm just imagining things.

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Yeah I can drive through the vibration so I don't think it's play within the rack. Just strange how it's at the same speed before and after the new tyres. Will get WIM to check balancing on wheels maybe, probably the fronts more so as the vibration is felt through the steering wheel.

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  • 3 weeks later...

I have similarly varying steering on my Forester, though the problem is t'other way round - when it's heavy there is great steering feedback and you can push the limits knowing exactly what you're doing, safely. When it goes light it's too light and it's difficult to tell which way the front wheels are pointing and easy to over-compensate. 

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When the steering feels normal (lighter) it feels the same no matter what speed I'm traveling. Then it becomes increasing heavier over time and the further I travel.

 

I've recently had the geometry set @ WIM. Has improved handling under normal start up driving but the steering does become heavier.

 

I've recently also replaced the main suction hose to the pump and this has changed nothing.

 

I'm starting to think after much research the problem may be with the seals within the rack between the low and high pressure sides.

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I have no visual sign of any seals leaking and I'm not loosing any fluid. It may be a possibility that the seals inside the rack are leaking from the high pressure side to the low pressure side, causing a reduction in power assistance particularly when the fluid has reached a certain temperature.

 

Not really sure how the rack and pinion works on the NC. Although the heavy steering can occur when the system hasn't run for a number of days and can revert to normal steering assistance just after a quick stop e.g petrol station.

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Have you tried jacking the front, engine running and feeling the resistance of the steering left and right?... Also holding the steering on full lock the valves should scream ( for the want for a better word ) the noise is the pressure being released.... I sometimes test the steering weight lock-on-lock with my finger turning the steering....It's a better way to feel the steering weight. 

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The last time I bleed the system after replacing the suction hose. With the wheels in the air engine not running there was little resistance felt when turning the steering wheel lock to lock. Then with the engine running and turning the steering wheel lock to lock there was a noticeable increase in the force required to turn the steering wheel.

 

I didn't hold the wheel at full lock for to long so didn't notice the valve noise of the pressure being released.

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The next time I get the chance Tony I'll have to give it a go.

 

I did notice the last time I bleed the system it did seem to take longer than usual to remove the air, level dropping in the reservoir.

 

Also I gave it a go by manually moving the front road wheels to see if I could hear anything. All I could hear was a definite whooshing noise and also a metallic scrapping noise on every turn in both directions.

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