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MG MGF Technical - Understeer

I've had the car for 2 months and I'm probably driving faster all the time but what realy bothers me is going around a round about quickly(not fast) and when powering out the front wheels virtualy seem to leave the ground until I back off the gas. I don't really feel good about grinding $350 low profile tyres accross rough bitumen, and I don't think the the car is powerfull enough to pop mono's like a motorbike with not much less torque and about 1/3 the weight. I'm not even going to bother with trying to talk to service due to the reason I got such a good deal in the first place." The car would not perform, it would not rev and was completely stripped of all it's breathing apperatice and every electrical device in the engine bay, and they service guys still could'nt solve the problem. Well I bought it for $10,000 less than the original
$60,000 with $6,000 sterio and a radical exhaust and chip, not too mention it's a targa trophy.
When I heard of the problem I thought about previous experiance with other cars and had a pretty good idea it had to be obvious because computers don't have eyes and mechanics don't have brains. So I sat in it looked around and said "I'll take it." for the said price. He was glad to get rid of it. As I organised my self in my new bargain I pulled out the floor mat that was jammed under the accelerator pedal drove off and laughed my head off. on the first service I told the guy and I think he almost died on the inside."Life is tuff".
Any way back to my original question Does any body have a good understanding of the front suspension and possible reasons for understeer or is it just me thinking on the same wave length as the poor guy who gave me the car?
SimonB


First reaction is that that's the way the car was designed. :o)
If it were otherwise, I think more people would get caught by the back
end stepping out without warning. Call the understeer a warning device. :o)

I don't like it.

One solution is to put the 16" rims on with 215 tyres all round.
That (over here in the UK) is a fairly expensive option.
Alternatively, you could put decent 205 rubber at the front as
well as at the back. That's what I have done and it helps loads.

To state the blindingly obvious, check the tracking of the car too.
Often set badly on Fs. Makes (unsurprisingly) a huge difference. :-)

Let us know how you get on.

Cheers,
Paul.
Paul

I think that I have almost erradicated understeer on my 'F... It is very difficult to get the car understeering on circuits anyway! ;o)

Two solutions:

1. Aerodynamics.

The front of the car suffers from some front end lift- a problem that has been present from the car's inception. Only partially rectified by the small spoiler under the front bumper (it is a black plastic lip seen if you kneel down on the floor and look under the car). The solution to remedy fast road speed understeer is an additional spoiler. I have a KH industries spoiler on my car- and this bolt on goody (about 58 GBP) does a good job. Mike Satur also does a 'bib' spoiler- see his web site on the link from this page.
For descriptions of the spoiler, see http://go.to/mgfgallery

2. Tracking.

Paul as mentioned tracking already. And he is absolutely right- getting this spot on really does alot to improve the handling. As does the ride height.

Make sure that the ride height is at the low end of the standard range (358-378mm; I have my car @ 360mm). Alternatively lower the car a little more- @325mm the handling is something else. But you will need lowering knucles and uprated dampers to achieve the best results.

Alternative tracking settings: This is what has altered my car's handling the most. From the standard 10 Minutes toe out, I have had the front wheels re-set to 10 Minutes toe IN. Bingo- more responsive turn-in, better steering feed back and very little understeer.

Ofcourse this means that the rear end is more likely to step out on the limit (speed no longer scrubbed off in understeering)- but many prefer this trait... except that it is rather difficult to catch successfully in a mid-engined car.

Make these couple of changes, and I think that your questions will be answered!

Cheers

Rob
Robert Bell

Hi Simon,

Is this one of the Targa Tasmania Club Cars (with roll cage etc fitted) ?

What is the configuration of the car.. You say that you are scrubbing $350 tires accross the road. What Tyres and wheels do you have fitted ? What Pressures do you run ?

I have a Standard VVC with the exception on the K&N filter and Lowered Suspension. My car's height is set to about 350mm and I felt that the car understeered too much as well.. although it was much better than the standard car set to the factory heights.

I fitted a set of Bridgstone S02 tyres with 195 on the fron instead of the standard 185s. Now I am please with whow neutral the car drives. I only get understeer when I push the car quite hard, or press right foot hard going through round-a-bouts etc..

I would have liked to have put 205s all round but I was worried about the front tryes rubbing on the inside of the guards when approaching full lock due to the ride height being set so low.

I'm sure the 205 all round would make the car even better but I am still V E R Y happy with the setup that I have now. I think it is a safe way to have the car set up.. Very Neutral with a progression to Slight Oversteer or Slight Understeer depending on how you are using your right foot.

The S02s that I have on the car cost me $1060 OZ dollars to put on the car, and are as good as the origional Goodyears were in the Dry in the wet.. They are quite soft, but judging by the way they are wearing I would expect to get 20,000km to 23,000 km out of the rears, and slightly more from the front.

Two things to remember..
1. The MG F seems VERY sensitive to tyre pressures.. (If mine are even a PSI out you can feel the difference when driving hard.)
2. The Wheel alignment is critical.. I get mine checked every 5,000 km to 7,000 km. And I check my tire wear every time I wash the car (once a week). (I would average around 600~650km per week.)

Hope this helps.

Scott

Scott Martin

If you have the std 15" rims and don't want to shell out for new wheels you can always put some decent 205x50x15 tyres all round, it improved my handling a great deal.

Check the ride height is not over 368mm as the car tends to be a bit unstable at speed if the suspension is high.

Anothe thing that will help is a front splitter (spoiler) for the front, I have got one of these but others have said it makes the car more stable.

Some have said that setting the front wheels to toe in at the front (instead of Rovers suggested toe out)will work wonders too, I think my dealer has done this to my car but I have been unable to get hold of the guy that did it to confirm this.

If you want to go further you can get the car lowered, but that's another story which is filling up much the archive no doubt at this very moment :-)
Tony Smith

>>
I would have liked to have put 205s all round but I was worried about the front tryes rubbing on the inside of the guards when approaching full lock due to the ride height being set so low.
<<

Not a problem.

I have 215's on 16 inch wheels and my ride height is around 320mm and I don't have a problem with the wheels touching the wheel arch liner. I also know several people who have put 205's on the front and not reported any problems.

I endorse everything above, perhaps the order in which to tackle the problem is:

1) Get the tracking and ride height set - as Rob has suggested, toe in at the front is better than toe out and the lower you can go WHILE STILL KEEPING CAMBER IN SPEC the better - for most this will be about 350mm (measured centre of wheel to underside of wheel arch) although some lucky owners seem to be able to go as low as 330mm.

2) Fit bigger rubber on the front - 205's on standard wheels or better still 215's on 16 inch wheels if you want to spend some cash. Bidgestones and Yokohamas seem to be preferable to the Goodyear rubber fitted by Rover.

3) Some sort of front splitter - the KH Assemblies product works very well and they should be able to ship one out to Australia for you.

4) Still not happy? OK its time to lower the suspension by fitting lowering knuckles and replacing the dampers with something better - AVU or Eibach are favourites at the moment. If you go for something adjustable - set them at the softer end of the scale as there have been cases of the mountings cracking when dampers have been set at the stiff end. Remember to check the suspension and wheel alignment after lowering.

5) Still not happy? Get a Lotus Elise I think...

Good luck

Paul
P9 VLS
Paul Sharpe


>Still not happy? Get a Lotus Elise I think...
Thank you, I am!
Love the MG despite the problems, but....

Paul - you are you anywhere near Hereford?
Didn't realise you were from around there before - I was in Hereford for Xmas!

Hope you had a great Xmas & New Year!

Hazel

Simon, as mentioned above the tracking/ 4 wheel alignment is essential to good handling, the NEW track settings for the MGF is 4-12mins toe IN at the front and 4-12 mins toe OUT at the rear, ALL cars should be set at these revised specs. Ride height and shocks to taste but the most impressive mod you can make are the polyurethane bushes , there are 16 in total , these prevent the suspension from squirming about under cornering /accelerating/braking making the car far more responsive. We have tested these and are very satisfied with the results, costs are 224 pounds for the full kit, plus s&h. (reset tracking after fitting )
Hpoe this helps Mike.
mikesatur

This thread was discussed between 26/12/1999 and 08/01/2000

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