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MG MGF Technical - Vibration @ 100KM/H + Strange handling @ speed
|Whilst I was driving on the motorway I noticed some slight vibrations in the steering wheel @ 100KM/H. Also I find the handling pretty strange when driving over 150KM/H. The car goes in a perfect straight line if hands are off the weel. I am a new owner so I have little knowlege about MGF - PLZ post opinions!|
|Wheel balance causing the vibration?|
Can't help on the vibration but the F handling becomes a bit vague and "detached" over about 110 mph (160kph?). This may be the cause of the high speed problem. A lot of people have fitted the Krafthaus splitter under the nose to solve this problem. Rover have addressed it in the new Trophy 160 by adding an additional lip onto the front nose to reduce high speed lift.
Over here the law takes your license away if you are caught speeding over 100mph. I therefore do not do it very often and normally only when driving in Europe.
Hope this helps.
|Basically I can't understand why a car is given a top speed of 210KM/H and cannot reach it because rover forgot to add bits on the car ! My Audi A3 goes up to 207KM/H and handles just SOOOO fine. Sorry for that but I really find it unbelievable. Moreover my old MX-5 could drive up to 190Km/h without feeling like its gonna take off ... Where is the beautifull handling of the F?????|
|The F is going to be more lively than a saloon, its a sports car, but I had mine up to 240 on the clock in France last week and it was fine, vibrations could be caused buy wheel balencing, I had a tape on weight come off last year, it caused the car to vibrate over 100 kph, tracking can make heaps of difrence to handling get it checked, mine has 5 min toe in, much better than the standard.|
I would suggest (if not done yet) that you:
* inspect tyres for any scratches/flat on the tyre tread (I had some once, after a spin and the wheels balance was changed because some rubber had gone)
* have the wheels balanced anyway (when I asked for it, the tech found out on the rear wheels that each time the balance had been done on my car, all the previous used masses had been kept on the wheel)
* check for uneven front tyre wear
What I personnaly reproach to the F at high speed is:
* exhausting noises (well it's a soft-top, but ...)
* lateral wind sensitivity
Hope this helps
|Thanks... I will have all that checked!|
I have had my F to clock up to 140 Mph without problems. Adding a a KH splitter has not as yet made much change. Will try again soon.
|This sounds like a wheel out of balance to me, sometimes alloys throw weights because they are stuck on. Get your wheels balanced at a decent tyre place. This should only cost a few quid.|
Two things usually cause vibration, the tracking being out is one reason, but this usually manifests it's self as wheel wobble throughout the speed range. Wheel balance is another cause which usually has similar symptoms to those you describe, vibration at fixed speeds.
At 150 KM/H you can get an instability, this is quite often down to the front of the car being lifted as air passes under the car. This can be cured with an air dam on the front, several are available, the KH splitter is commonly used and available from B&G or direct from KH I believe. I found just changing to a toe in setting at the front improved things no end here.
|"To complement the MGF", I have a diesel Peugeot 306 that does the hard yards. Recently, I took it in to the tyre fitters and had two new tyres put on to the front. While driving home, I noticed quite a severe vibration when travelling between 80mph and 90mph. So, I took the car back to the garage and got them to balance the wheels again. Fair play to them, they checked all four wheels this time (for free) and said they were fine! Would it be worth me getting the tracking looked at? How would changing the two front tyres affect this? The car was fine before I took it in!|
Note: They balanced the wheels on the car as the alloys fitted by Peugeot didn't have a removable centre piece.
|>> Note: They balanced the wheels on the car as the alloys fitted by Peugeot didn't have a removable centre piece.<<|
I wonder how they can fit the tyre and balance the wheel then?
Common causes have been identified but there are many more...
First though, what is your cars age and mileage? Which wheels and tyres have you got fitted?
Has the car been subject to any known body/suspension repairs and if so when?
Tyres, if original Goodyear NCT3, and parhaps aged now depending on youyr cars age, have a known tendency to 'go off' in both their shape and compound make up. Jérôme's points here are well made.
The answers to my questions can possibly open up the possibility of a number of other mechanical problems that would cause the conditions you have. Certainly the problem is not something that is a characteristic of the car and should not be present. This means there is a defect, be it very minor or not, it needs idnetifying and eliminating.
|Thanks all for your replies. Car is 'only' 4000kms|
I had the geometry checked as well as balance - now its fine :)))))))
|I am getting to the point where I am almost scared to take my 96 F out on the road come wet or dry weather. It used to feel so positive, sticking to the road like glue, but now it kind of floats along, the steering is twitchy and not very positive and the back end kind of waves about. It is really unnerving. I don't like to brake hard so I am stuck at low speeds, although at 70+ it is no better. Going down the M6 the other night, a calm dry (for once) night, I am sure it must have looked from behind like I had taken one over the 8, as it was a constant battle to keep the darn thing in a straight line. |
Had the tyres checked - fine
Had the tracking checked - fine
not run over any kerbs, bumps etc
Rover dealer can't fing anything wrong - but it just is not the same car anymore. I feel like hiring one to make sure I am not going mad.
What now ?
any suggestions please.
|Go and take a test drive. It'd be cheaper than renting one.|
1/ Have it all checked over by a different dealer - bit like a second opinion at the doctors.
2/ Have you/they checked the bushes - I know some of the 'performance' boys have had these changed.
|Matt, look at the shocker bushes, if these are worn the floating at high speeds will be experienced , the rear tie bar bushes also contribute to the 'back end waving' about, easily cured with either spacers or poly bushes(preffered) as are the shockers with poly bushes.Reset the rear tracking after fitting.|
|Matthew, if all the normal problems are checking out okay- as they seem to be here, then there is a clear need to get some more in depth checks performed. I think that the suggestions made by both Ted and Mike are well made- as clearly abnormal wear or damage of a suspension component can result in severely way ward handling. In fact, it is not unheard of for the rear dampers to become detached- you may not necessarily notice this immediately as the hydragas performs the majority of the damping funcion anyway, but reduced control over low frequency undulations on motorways would not be kept under check. Nasty.|
Also look to check wear in the suspension ball joints- these were initial engineered for the Metro. In a more powerful car with larger wheels, these components have been known to wear out prematurely.
I hope this provides some pointers for you.
>Had the tracking checked - fine
How was it done ? By computer controlled 4-wheel alignment ?
Or only with a simple two axle stand ?
What about the ride hight, is it 368mm at the front (+-10mm)
|Many thanks for the suggestions, I will take the car to another dealer and see if the bushes on the tie bar and / or shockers cure it.|
|In addition to that already mentioned re the original post, front end lift is something that is significantly affected by the cars ride height. Knowing the height of some cars this will simply add to a number of other minor issues and create a more obvious negaitive condition.|
The tyres may have been cheched, but what for? Looking for uneven wear and tread depth perhaps. One significant area that affectes far too many cars with the OE fit of Goodyear NCT3 is one where slight carcase distortion and variation in the tread compound characteristics causes just the sort of problems you have. I have seen this on quite a number of cars and only last Thursday found the same condition starting with an S registered car.
On one '95 N car I simply swapped the front wheels for a pair of old MG Maestro 15" with well used Goodyesr NCT2 tyres. The transformation was huge and led to the whole set being replaced by Bridgestone SO2's. The ride and handling have never been so good.
I suggest that the tyres are looked at much closer and if need be contact off line as your in the same County.
This thread was discussed between 19/03/2001 and 01/04/2001
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