understeer - oversteer

[billgatese30]

Handbook doesn't mention the sport, it lists everything else though.

poo

never mind, i could possibly call in a favour and get the use of a wieghbridge.

[6potWil6pot]

Ive shoved my own car on the weightbridge at work and it says 1120kg with no fuel or driver, arent the kerb weights taken with a full tank+driver sat inside? Works weightbridge isnt 100% accurate mind you

[Andy335Touring]

Sorry i messed up the M3 wieghts

[billgatese30]

the weigh bridge that i could poss use is 99% accurate, but it is a bit dodgy as i have to wait till its quiet, my mate is owed a favour and the right guard is on duty on the gate, plus Ԛ£5 for the guard, but i know its accurate. plus i could try it with and without driver and get a printout.

[Simon]

Andrew that owners handbook is different to mine, mine's the late 1989-90 edition..maybe they changed something!

I've also got the original M3 owners handbook and that shows the M3 weight as 1200kg, or 1360kg for the M3 convertible.

[Andy335Touring]

How do you tell the year of the hand book mate ?

It came with my 89' touring(which doesn't prove its original to the car) and its got an 88' copy right ?

The road test figures might be out as it was a US road test or if it was fitted with air con ???

[6potWil6pot]

Your "accurate" weightbridge does sound dodgy, i operate the one where i work myself as its a small yard.
Would be nice to get some "real world" weights of E30s are manufacturer claims arent always that accurate, i think some car mags weight test cars themselves on road tests too.

[Simon]

How do you tell the year of the hand book mate ?

It came with my 89' touring(which doesn't prove its original to the car) and its got an 88' copy right ?

The road test figures might be out as it was a US road test or if it was fitted with air con ???

On the 2nd/3rd page, looks like you've spotted it anyway, mine's 89. Strange why they've changed?!

[billgatese30]

it's where my mate works, the trucks must be wieghed and have a print out so that if they get stopped in britain or europe they can prove the load is legal so it must be regularly calibrated. the only prob is the comapny doesn't like it being used for personal reasons so i have to wait till my mate and the security guard on the gate(my mates friend) is also on the same shift and that i can get there and the bridge not beijng used, it's only at the entrance/exit, but it's not that easy to get the times right if you know what i mean.

[Simon]

Thinking about it the exact weight should be on the type plate anyway, so shouldn't be to hard to find out!

[billgatese30]

good thinking batman, never thought of that

[TVRTASMIN]

Wider tires dont give more grip!

Andrew

? So why do 300+ BHP sportscars have wide tyres. Not to mention F1.

thats down to a combination of excess of power therefore requiring a greater surface area. also they tend to benefit from smooth surfaces to drive on therefore the wider tyres are gripping all the time rather than on the road where they tend to get bumped around in turn decreasing the contact patch.

the best way to increase grip is to maximise useable contact patch

this is a combo of suspension set up
centre of gravity
and tyre choice.

why else would you use thinner tyres in the winter

I've never heard anybody having excess power, as the old adage goes; "some is good more is better".

Wider tyres give more grip. Try fitting your car with a set of those skinny space saver spare wheels and see what happens.
Going to excess on width will be counterproductive and stiffer suspension will offer less grip also. On the road that is.

[billgatese30]

no telling what your other car is then mate

[Simon]

Thinner tyres in the winter is more for snow use, as they cut through the snow better...

I still can't see how wider tyres don't give the benefit of more grip either mind.

[billgatese30]

tire pressure is very important for grip. you want to get it so that the tire is flat on the raod at all times to ensure maximum footprint area. this is also afftected by suspension geometry such as camber etc.

[martin318is]

Grip (To simplify) is down to one thing: Friction.

Friction in the case we are discussing, comes down to a couple of factors:

Material of the wheel rubber
Material of the road surface (Ignoring water on road etc)
Contact Area
Pressure being applied per sq inch of contact area (weight of vehicle on each corner)


Wider wheels will impact the contact area positively, but it will impact the Pressure negatively.

Assuming then, that the tyre width is perfect for a given car, an increase in width will result in a reduction of grip, just as a reduction in width will result in a reduction of grip. For a small car like an E30, there will be an upper limit to the useful wheel width for the vehicle on public roads or on the track without serious modifications.


There are 2 main reasons that race cars have such wide wheels.

1) They are travelling at HUGE speeds and generally their slowest corners are over the normal road speed limit. The high cornering forces will apply more pressure to the load bearing tyres.
2) Areodynamics. Because the cars had generally got effective (not tupperware) wings on and are travelling fast enough to generate real downforce, the pressure on the load bearing tyres is increased.

[Andrew]

Grip (To simplify) is down to one thing: Friction.

Friction in the case we are discussing, comes down to a couple of factors:

Material of the wheel rubber
Material of the road surface (Ignoring water on road etc)
Contact Area
Pressure being applied per sq inch of contact area (weight of vehicle on each corner)


Wider wheels will impact the contact area positively, but it will impact the Pressure negatively.

Assuming then, that the tyre width is perfect for a given car, an increase in width will result in a reduction of grip, just as a reduction in width will result in a reduction of grip. For a small car like an E30, there will be an upper limit to the useful wheel width for the vehicle on public roads or on the track without serious modifications.


There are 2 main reasons that race cars have such wide wheels.

1) They are travelling at HUGE speeds and generally their slowest corners are over the normal road speed limit. The high cornering forces will apply more pressure to the load bearing tyres.
2) Areodynamics. Because the cars had generally got effective (not tupperware) wings on and are travelling fast enough to generate real downforce, the pressure on the load bearing tyres is increased.

this is why F1 cars have such wide tires, and thats why lorries had three axles on the rear to create less damage to the roads, and thats why snow cats have large paws.

Andrew

[TVRTASMIN]

no telling what your other car is then mate

One of my other cars, not a standard road going version.
It will shortly have a 24V Cosworth motor running in it replacing the sedentary TVR tuned Capri engine.

[Simon13]

Just to throw a spanner into the works, by fitting a stiffer rear anti roll bar you can reduce understeer, this to me seems to be a good idea for the 325i boys who need all the help we can get! Or is it more worth while uprating front and rear.

Also me reading again, generally lowereing your car from 15-25 mm will have no real knock on effects for the rest of your suspension. So would a decent Bilstein shock and spring set do wonders for me!

[nwmlarge]

Grip (To simplify) is down to one thing: Friction.

Friction in the case we are discussing, comes down to a couple of factors:

Material of the wheel rubber
Material of the road surface (Ignoring water on road etc)
Contact Area
Pressure being applied per sq inch of contact area (weight of vehicle on each corner)


Wider wheels will impact the contact area positively, but it will impact the Pressure negatively.

Assuming then, that the tyre width is perfect for a given car, an increase in width will result in a reduction of grip, just as a reduction in width will result in a reduction of grip. For a small car like an E30, there will be an upper limit to the useful wheel width for the vehicle on public roads or on the track without serious modifications.


There are 2 main reasons that race cars have such wide wheels.

1) They are travelling at HUGE speeds and generally their slowest corners are over the normal road speed limit. The high cornering forces will apply more pressure to the load bearing tyres.
2) Areodynamics. Because the cars had generally got effective (not tupperware) wings on and are travelling fast enough to generate real downforce, the pressure on the load bearing tyres is increased.

thats an excllent way of putting what i was trying to say lol

[Karan]

Sorry i messed up the M3 wieghts

can i put a 325ix rack on my car as its 3.8 turns, or is it lhd only

just a thought

Karan

[Nick]

Get some good front tires ( i used uniroyal last saturday ) en get some crappy back tires.. make the rear tires 4 bar, and the front 2 bar.. get a 100% diff.. get a rollcage, some good lowering and good suspension ( koni!? ) get a little camber on the front wheels, and now try to get it in oversteer

sorry for crappy english, im 16 and dutch