Autocrossing the 280e euro - PeachParts Mercedes-Benz Forum

t walgamuth · #1 08-04-2008, 06:58 AM

I decided to start a new thread to talk about my adventures.

Yesterday I went to Fort Wayne Indiana for an autocross. I got up at 530 to make the 9 am sign in and made it with two minutes to spare.

On the way I did not have a clue as to what to expect. The last event I went to in South Bend only had 22 entrys so it was a bit sparse. I thought maybe the Fort Wayne event might be similar.

WRONG DOGGIEBREATH!

There was a massive turnout of 114 entrys. I was working the gate and ran out of release forms required for spectators after signing in probably nearly a hundred. Biggest event by far that I have attended.

there were five other ESP entrys, and I never figured out what three of them were but there were two very fast mustangs that were running close to me.

It was a very long course that took me over 76 seconds to run. The good guys were under 70.....depressing. I had trouble again shifting to second and finally figured out the reason....wear in the shifter (hey it only has 300K some miles on it in a 240d!) made it easy to hit the reverse gate unless you exert absolutely no side pressure on it.

I also was running 30 mm spacers (front only) for the first time and it rubbed on the LF, slicing off narrow ribbons right down by the last portion of wearing surface on the sidewall top, so I loaded up after only four runs, not wanting to ruin a substantially expensiver slick and having no chance for any trophies with the serious competition in attendance.

In checking out what they have that I don't I found some things...more horsepower, more suspension parts available, and very very big tires. The fellow behind me was running 275/45 r 17s. My 225/50r 14s looked pretty puny by comparison. Of course he has a bit more weight too.

I am going to move my slicks over to my 6.5 inch rims from the 5.5s they are currently on. That won't make too much difference I don't imagine but for lack of other possibilities that will be done.

There is a meet at Grissom next saturday (my favorite venue) so I'll get it done before then.

My limited slip seems to be working pretty well. Under some circumstances I can get the inside tire spinning but mostly it hooks pretty well. It is enough to push the front end under some circumstances too.

I am pretty close to 50 50 weight dist, front to rear now, and I could help that a bit by running a bigger battery in the rear. The car with me in it is heavy by 100 to 150# on the left side. If I could just lose 150# it would be about perfect!

Tom W

POS · #2 08-04-2008, 09:00 AM

Autocross on 14's, Tom? Nice little write-up. I've often thought of autocrossing, but ultimately it sounds like a lot of prep for a little action. You learn by doing, however, and it sounds like you're well past step one now. Keep at it - at least it sounds fun!

Whiskeydan · #3 08-04-2008, 10:26 AM

I musta missed the post about the limited slip. What's the ratio and where did you find it?

t walgamuth · #4 08-04-2008, 12:46 PM

Its a 369. We built it up using a 190e 16v inside. The 369 ring needed a shim to mesh properly. Actually my favorite macinist did the work and I watched!

14" wheels are all that are available without using adaptors. They give a nice boost to the gear ratio and lower the car too.

But in the search for more rubber I'm thinking of 15 or 16" wheels with spacers as necessary for next year unless I get a completely different car like a mr2, fiero or lotus seven clone.

Making five runs in an afternoon will seem like enough action if you try it. A one minute run is pretty intense and takes a load of concentration.

Tom W

tankdriver · #5 08-04-2008, 05:20 PM

Quote:

Originally Posted by t walgamuth

I am going to move my slicks over to my 6.5 inch rims from the 5.5s they are currently on. That won't make too much difference I don't imagine but for lack of other possibilities that will be done.

It should make a big difference.
Why are you running front spacers?

In the DC SCCA events, there were typically between 250-300 entrants. The smaller clubs ran 4 heats of 30 or so cars. Few chances at 70 second courses, you're lucky.

Quote:

Originally Posted by POS

Autocross on 14's, Tom? Nice little write-up. I've often thought of autocrossing, but ultimately it sounds like a lot of prep for a little action. You learn by doing, however, and it sounds like you're well past step one now. Keep at it - at least it sounds fun!

There is little prep needed for autocross. Just make sure your tires are in decent shape, your throttle doesn't stick, and your brakes are good. That's all you need. You could run a whole season on all season tires and knock off several seconds from your time each event. A portable air tank and white crayon is helpful so you can adjust tire pressures.

t walgamuth · #6 08-04-2008, 06:04 PM

Just trying for a wider stance and more negative camber.

Do you think its a mistake?

Tom W

tankdriver · #7 08-04-2008, 07:12 PM

Quote:

Originally Posted by t walgamuth

Just trying for a wider stance and more negative camber.

Do you think its a mistake?

Tom W

Can't really say without watching or driving the car. A wider stance up front is going to adjust your weight transfer, sending more rearward. Were you having an understeer problem? (We are talking about wheel spacers, right?)
What camber were you running before? Were you rolling over? Pressures?
As for switching wheel size, I wouldn't just yet. 15s may be a possibility as there's more available for that size, but don't rush put to copy the Stangs. Taller wheel/tire is going to hurt your acceleration big time. Giant tires is how American car companies keep their cars on the road in turns. You're going to need a lot more power to pull out of turns if you went to 16s. What's the stock size, 14?

t walgamuth · #8 08-04-2008, 07:45 PM

I don't understand how the spacers will send more weight to the rear, but if thats true I think it would help. I felt that the wider front track would give less leverage to the rear tires and help with the tendency to push, and make the tires want to roll over less.

I have the 6.5" wide wheels from my old sec and I am planning to put them on with the idea of putting more rubber on the track by allowing the sidewalls to flatten out more.

I have a feeling my biggest drawback is the kumhos instead of the hoosiers I ran last two years. They are less sticky.

Tom

tankdriver · #9 08-04-2008, 08:33 PM

Quote:

Originally Posted by t walgamuth

I don't understand how the spacers will send more weight to the rear, but if thats true I think it would help.

I misspoke. The spacers reduce the amount of weight transferred up front by increasing track width. I can't find my Fred Puhn book for the actual equation (if you don't have it, I highly recommend picking it up http://www.amazon.com/How-Make-Your-Car-Handle/dp/0912656468/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1217896189&sr=1-1 ) but the result is that with a wider track width up front, you'll get less understeer. The front tires will roll over less because they have less weight on them.
You probably need to play with your tire pressures if you changed tires.

Johnhef · #10 08-04-2008, 09:03 PM

Tom you may want to look for the 16" CLK wheels I use on my 124/123 for autocross (look at some of the ax pics i posted in other threads), unfortunatly theyre too small for my current car, the SEC so I'm going to be going to a set of 245/17's in front and 275/17 in rear.

You should come to tri-o-rama in NJ this year for the autocross, I'll be there and we can run against each other

t walgamuth · #11 08-04-2008, 09:54 PM

I would love to but its so far. How 'bout we meet in Ohio and run at the same event?

Tom W

Johnhef · #12 08-04-2008, 11:13 PM

haha ill keep that in mind

tankdriver · #13 08-06-2008, 06:47 PM

If you meet in Ohio, I'm in. If you don't mind a Japanese car.

t walgamuth · #14 08-06-2008, 10:26 PM

I don't mind!

Tom W

t walgamuth · #15 08-06-2008, 10:34 PM

I found that Hoosier offers 275/35 r 15 tires. Installed on my car it will actually be .4" shorter than the 225/50 r 14s I am running. So the gear ration will effectively be shortened a bit and I'll have nearly 2" more rubber on the road on each tire. about 10.8" wide versus 8.9".

Unfortunately the new tires are over $200 ea. and I'll need to buy wheels to mount them to.

Tom W