BMW M1 Physics

I Hope you dont mind but i would like to start a thread here about the Physics update that im working on with Hitman_M3 the
Guy who did the original Physics for the M1 Mod ...

As you know we raced on HSO this year with a newer version of the mod than is available to the General Public .
But several people where not 100% convinced about the M1 Physics .....

I Have been approached by Rfc who are interested in running an M1 series for online racing ,they have showed
a big interest in me releasing V.2 the Newer Version has many improvements with the Model and as you know a full season of 1980 cars and i would really like to release this shortly with the Updated Physics .....

I Really value your Help and will mention HSO and Testers in the V.2 Release ....

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Hitman_M3 (aka Alberto)
Has found a few problems with the M1 Suspension
using New Programs available for rfactor he has found the Suspension detached
similar to the problem Steve found with the F5000 Mod we are working on .......

He has created a New suspension file for us to try ..

I Have added the M1 Physics Susp_pm file to the ftp

Steve and Tiago have tested it for me so far
and this is what we have ...

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Just finished testing the M1 and the first impression is good. The car feels more natural, more intuitive and doesn't behave erractically as before. You can push without having an egg in your gas pedal. The steering feels much better too.

On the down side I think it is very easy to drive, too easy in fact, the car doesn't slide a little bit when on full throttle and I think it jumps a bit, but maybe that's because of the circuit I chose for testing.

I'm going to make a vid for you so that you can see also what I'm trying to say

Tiago
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Just had quick go round donington in the procar,the car drifts superbly through the corners,only fault i can say so far is(huge pause)

The car seems very sensitive on steering,i lowered stering lock to 10 and still too sensitive,which causes huge snap oversteer(when the car wants to swap ends)i tried high and low steering lock and no change,also tried messing with setup but could not cure it,so im not sure if there is a setting for steering sensitivity in the suspension or hdv file....

Steve
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I don't have the steering problem that Steve has, maybe he has the steering sensitivity to high in the game options, but I also don't know what wheel does he use.

I tested the car at osterreichring and as I said before I found very difficult for me to slide it.

Just a note: the oversteer problem Steve reports is exactly the symptome that the orginal car had in our championship, you could never guess when it would snap-oversteer...

The vid is almost uploaded, I'll share it with you in a bit

Tiago
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Some very helpful info here Guys ... Many Thanks

I Sent your info to Alberto and this is his Reply ....

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From what I read in the feedback you received, one of the testers seems to confirm entirely my impressions, while the other has the steering problems. Probably this last one is the result of a weird speed sensitivity, force feedback or whatever hardware setting. The car is, as Tiago points out, now very easy to drive and harder to make slip, but I feel that is how the real M1 was. From action videos I have seen, the M1 didn't actually drift a lot, not even in the slippery urban circuit of Monaco. In PROCAR trim it was clearly over-wheeled with the huge donuts on the rear, and being a mid-engined car, that would make it understeer heavily (Thinner wheels at the front add to that) and have lots of grip under acceleration over track tarmac. On the other hand, the short wheeldistance should guarantee a more difficult behaviour if the car loses grip and starts oversteering heavily -not just a normal slight drift-, and that is more or less what I have experienced when driving it. Easy to keep under control, but if the slide out gets too far, you can't recover it at all, AND you need to push it nearly that far if you really want to make good times. This car is easy to drive until 99% of its potential, but the last 1% is very risky.

Anyway, to make the car more sensitive and with less grip, we could raise the stiffness of the suspension values overall, not allowing soft adjustments. Another area that would make the car much different to drive are tyres. I intentionally made them more abrupt and less forgiving in the initial mod, but there is some room for playing there (A simple modification of one value can make them even spin like crazy under acceleration in any gear). I would suggest that your testers give a try to tyre files (Make a direct swap by backing up the current M1 tyre file and renaming the one you want to use) from the power and glory mod, or any other mod that recreates tyres from the late 60s and 70s.

In any case, if the target is online racing I feel that the current physics are better, because you lose concentration more easily, and a difficult car to drive can be more frustrating. But of course that is just my personal opinion.

Alberto

Sorry if this drags on a bit but i thought it may help us understand the F5000 problem

Unlike Tiago i could drift the car round corners quite easily,tested on hso donington,steering sensitivity ingame on 50%,i never had that problem with the orignal M1 Mod,maybe the weight balance in the car needs looking at ?

i pushed the car hard round circuit testing,tires seemed fine to me,as i had no trouble taking corners sideways
my steering settings have never altered,same with FFB,so that cant be reason the steering feels so sensitive,i have speed sensitivty set at 0 ingame,also the car powerslides nicely
alot could also be down to too much downforce on front end causing the snap oversteer

Steve, maybe your problem is connected to the setup; if I remember correctly, if you adjusted the rear wing lower than 6 and keep the front at 2, the car would slide a lot; what i mean is if you turn to a corner slightly, the car will keep going that direction because the rear end is giving way due to the big difference in downforce between the rear and the front, just like if you try a 79 F1 with 5 at the front and 2 or something at the back.

I tested the M1 with exactly the same setup I used in the championship race and guys here who knows me well know that my setups are always a kind of loose, but still during my testing I always slammed the accelerator out of the corners and the car just kept going.

I forgot to mention one detail that I remember it was the first one I noticed the moment I tried the mod for the first time: the lack of weight, I mean I drive the car but I never feel it has weight. This part isn't easy to explain but, for instance, If I take a Capri in HGT and then the Vette, it's immediate the perception of the weight differences between both. The M1, despite being better still feels a bit "artificial". Sorry but I don't know how to explain this a little better

I'll give it a go this weekend.

THX Steve ,Tiago and Gui
i will pass on all your suggestions to Alberto
THX very much for all the Help ....

Will do some testing too , as i have still a 3 week gap before uni starts

THX Carlo that would be great ,
Can you first try the mod with the old file and then the new one please ...

Carl Larrad wrote:

THX Carlo that would be great , im not sure how you send a link to it but
you can find the new susp.pm file on the ftp ....In Our Private Section ...

Already found it

Tested both susp configurations at Bathurst 2005 (used the same setup for both, 10 consecutive laps)

With the first config (the one used in this year's champ) i had a lot of oversteer and the same unpredictable behaviour of the car, especially exiting the corner, had to be very gentle on throttle.
Also the car wasn't stable on braking zones.

With the 2nd one the car was easier, i could push more, laptimes were average 1s faster than with the previous one,
Found it more stable, even on very late brakings.

THX Carlo

It seems that everyone prefers the 2nd Susp.pm file and this is
confirmed with faster laptimes .......

When we used the old .pm file looking at the laptimes we where doing in the 1980 M1 Series
the laptimes where very close to the times we where doing in the F179 Mod
So the laptimes are probably even closer know....This is surely wrong

I Think we maybe need to look at slowing the cars down a little with this next version of the mod ...

Carlo did you have the same problem as Steve with steering sensitivity ,changing the adjustment on the steering lock
not making any difference to your car or set up ....

Any Suggestions ...

Carl Larrad wrote:

Carlo did you have the same problem as Steve with steering sensitivity ,changing the adjustment on the steering lock
not making any difference to your car or set up ....
Any Suggestions ...

Still need to test a bit later, so far i used only the default steering lock (15.0 i think)

Carl Larrad wrote:

When we used the old .pm file looking at the laptimes we where doing in the 1980 M1 Series
the laptimes where very close to the times we where doing in the F179 Mod
So the laptimes are probably even closer know....This is surely wrong

I think the major problem here and correct me if I'm wrong is with the engine..... I think the car wasn't this fast, but I don't really know the specs of the engine

Oh, and I think it brakes too well too

OK Here is the spec for a M1 Procar

It looks like it would have been a very fast car in a straight line
as it is a light car so it has plenty pf torque
does anyone no how this compares to an F1 79 Car ...

Looking at the spec it was definatly a fast car but Tiago is
right the M1 would have lost a lot of time against the F1 with grip and under braking .....

1980 BMW M1 Procar Specifications

engine Inline-6
position Mid Longitudinal
valvetrain DOHC, 4 Valves per Cyl
displacement 3498 cc / 213.5 cu in
power 350.5 kw / 470.0 bhp @ 9000 rpm
hp per litre 134.36 bhp per litre
bhp/weight
torque 382.34 nm / 282.0 ft lbs @ 7000 rpm
drive wheels RWD
body / frame Fibre-Glass Boady over Box-Section Steel Frame
front wheels F 40.6 x 17.8 cm / 16.0 x 7.0 in
rear wheels R 40.6 x 20.3 cm / 16.0 x 8.0 in
steering Rack & PInion
weight 1020 kg / 2249 lbs
wheelbase 2560 mm / 100.8 in
front track 1550 mm / 61.0 in
rear track 1576 mm / 62.0 in
length 4360 mm / 171.7 in
width 1824 mm / 71.8 in
transmission 5-Speed Manual
gear ratios 2.42:1, 1.61:1, 1.14:1, 0.846:1, 0.704:1
final drive 4.22:1
top speed 309.0 kph / 192.0 mph
0 - 60 mph 4.4 seconds

Looking at Real race stats of the 1980 Hockenhiem F1 race

Fastest lap in F1 was 1:45
Fastest lap in M1 was 2:09
Fastest lap on HSO M1 Procar Q was 1:54 (by are very own Gui )

I know Gui is fast but this is way too fast

I Just worry if we slow the cars down too much
will this spoil the enjoyment of the mod ...

I can't answer that really.... I just know that the DTM cars are slower and still very funny to drive

Slow cars can be fun to drive too, but anyway the M1 is not what I would call a slow car.

Of course the car is way too fast, I think its a combination of everything, it has too much downforce (reducing it would reduce cornering speed and increase braking distance), not enough drag and too good tyres.

Maybe smoothing out the Torque,compression,power curves will help,this is how the engine looks in the mod now.

Based on figures you posted carl it should look like this one i did

Wow well done Steve im going to pass that onto Alberto
would that be the same tool that he used for the susp physics...

I Know when i had my car remapped and it went on a rolling road the
guy was not happy to let it go until he got a continues power band with no dips in it ....

This is a good find ..

No m8 not same tool as suspension,i have had this for about 2 years lol


http://rs159.rapidshare.com/files/116796100/PhysicsEditor1_88A.zip

Ive sent all your comments and suggestions to Alberto and this is his reply ...Interesting reading...
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THX Guys

that was a very interesting feedback, and keeping it in mind, I would like to point out the following:

1.- The car's power and torque figures are accurate. It has 470 HP, as the real one. I'm not sure if smoothing the torque curve would be a good idea. The M1 engine was reportedly peaky, and making it smoother will make it easier to drive and actually improve lap times, since you can exit corners faster at lower rpms. Note that the locked transmission ratios play a key role here, as they do not fit all tracks perfectly -but such was the real car.

2.- Weight: I found when revising the car file that it has been reduced from what I originally set for F1Challenge. It is now a good 100 kilos lighter, so Tiago was absolutely right on that. Giving the car those kgs back should make braking distances longer and a more sluggish behaviour. I must have a look and see if the inertia values were also modified, but I don't think so.

3.- Aero: There's two things we need to consider here:

A) Overall drag: The car has the correct one, since in Hockenheim it barely reaches the correct top speed of 310 km/h.

B) Aero-Grip: Since I had no other references, I used the Ferrari 360 from GTR as a guide for the front splitter and rear wing. The dimensions of those both in the M1 and the 360 seems more or less similar, and they are also made for a mid-engined car. May be, just may be, there is too much aero grip, and while the M1 had no adjustable wings and splitter, I left the adjustments open for the players to be able to set up the car more to their liking. Otherwise they would have been constraited to what my preferences where, but it could be worth at least to fix the front splitter in lowest position and halve the adjustment range in the rear wing.

5.- Suspension: Again taken from the Ferrari 360 when it comes to spring, damper and sway bars values (Not in the geometry or travel), but I feel it is right. The M1 was very, very lowered and must have had a short suspension travel (Just see the wheels in the wheelarchs in any picture), and hence a stiff suspension. This area I'd leave as it is.

On a side note, the three position sway bars seem now to have a much better effect with the new suspension. Nobody else noticed that?

4.- Wheels: In my opinion, here is one of the keys of the actual performance of the car. The wheels were taken again from the 360 Modena, albeit with a more radical grip curve. Probably they give too much grip to the car, but it's difficult to say because the M1 had really huge donuts. Using the 360 wheels "as they are", the original M1 felt simply like glued to the tarmac. I will give a try to a tyre file from a classic sportscar mod. But to use it later we will need permissions from the author.

6.- Weight distribution: We could play a bit here to make the car more uncontrollable when it starts to slide, or more prone to understeer.

/////////////////////////////IMPORTANT CONSIDERATION/////////////////////////////

The PROCARs had very few suspension adjustments available (mainly sway bars and brake bias, from inside the cockpit). The reason is that F1 drivers were not expected to spend some hours setting up their car correctly for each track in all different adjustments possible, but instead to more or less jump into the cockpit and dirve "as it is" with only minor adjustments. Also, if the rest of the grid -non F1 drivers- was allowed to make that testing and adjustments, they would have had an advantage over the F1 drivers, and the objective was instead to have an as much even grid as possible. So I would suggest further locking suspension values, leaving only minor adjustments available to the player (Sway bars, brake bias, tyre pressure). That would guarantee good online racing because grids would be more even, and also players with less talent in setups but who are good drivers would enjoy the experience. And it would also be more realistic!

Once we have fine tuned the mod a bit more, I'm sure we can agree in a set of values that everyone feels right for the M1. I suggest that testers search for M1 videos in Youtube, there are now quite a few of them, and they can feel if the car is behaving correctly.

////////////////////////////// SUM-UP///////////////////////////////////

I'll prepare a set of files with following changes:

- Raise 100 kgs of weigth and revise inertias

- Fix the front splitter in lowest position and halve the adjustment range in the rear wing, or even lock it, then increase the body drag to re-adjust top speed (Will raise).

- Lower the overall wheel grip

-Temporarily, leave the weigth distribution adjustable. That way, testers can have a play with it and make suggestions about which one gives better car behaviour

////////////////Two VERY IMPORTANT notes when testing ////////////////

1.- Not all tracks have the same layout as they ad in 1979. The tracks done for the F1 1979 mod should be the yardstick here, and specially those where the lap times of F1 cars do actually ressemble what they did in real life.

2.- Not all M1s use the same vehicle file. IIRC, there are actually two of them, one for Dunlop and one for the other tyres. If you pick the M1 without Dunlops, the suspension fiule will still be the old one! I'll provide in the next revision full new vehicle files, so as to prevent testers from inadvertedly using the old car.

Cheers Alberto ....
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Wow, now that's a very detailed report. Can't wait to see the car with the added 100 Kgs

I didn't noticed the sway bars because I didn't change anything in the setup. I still remembered something from the championship race and I would have a better FB if I didn't change anything, but I'll try that