Locked rear end on dedicated Autocrosser? - Page 3 - PeachParts Mercedes-Benz Forum

tankdriver · #31 07-23-2007, 07:20 PM

Quote:

Originally Posted by t walgamuth

I have not noticed much difference. The traction out of the turns is awesome now compared to before.

Tom W

You didn't change the tire pressures from before? I would've thought there'd be a major change.

t walgamuth · #32 07-23-2007, 07:34 PM

Maybe I don't know enough to know what is appropriate. Do you have thoughts? Should it be lower or higher than before?

Tom W

tankdriver · #33 07-23-2007, 09:47 PM

How did you arrive at the pressures you are running now? Do you mark the tires for rollover? How does it drive - understeer/neutral/over?
It's hard to say what the changes would be without driving it. I don't have any experience with a welded diff, I just figured such a major change would effect pressures.

I autocross my prelude, which is not only open diff'ed but a FWD. I run in STS, though the only modification I've done at this point is wheels.

t walgamuth · #34 07-23-2007, 10:05 PM

It seems pretty neutral to me. The fronts seem to roll over a bit. It wears down the the raised bar on the sidewall. The rears don't wear down as far, but I am thinking of lowering the rear suspension a bit more in the effort to increase grip. I also plan to move the battery to the back so the balance will not require the spare and a full tank of gas to balance it out. I also plan to remove the aux fan and the ac dryer which I am not utilizing anyway. Also the rear and middle muffler will be gone soon. And I am looking for some lightweight racing seats.

That is about it iirc.

Tom W

PaulC · #35 07-23-2007, 10:26 PM

Lightweight hood?

tankdriver · #36 07-23-2007, 10:34 PM

Quote:

Originally Posted by t walgamuth

It seems pretty neutral to me. The fronts seem to roll over a bit. It wears down the the raised bar on the sidewall. The rears don't wear down as far

Neutral before the diff or after? Sounds like you need to bump the fronts up a little. Mark the tires with lumber crayon.

Quote:

but I am thinking of lowering the rear suspension a bit more in the effort to increase grip.

Lowering the rear is not necessarily going to increase grip. If you do it indpendent of the front, you are going to change front to rear weight transfer. A better idea would be to stiffen roll resistance. Have you read Fred Puhn's How to Make Your Car Handle? If not, it's a must read.

Quote:

I also plan to move the battery to the back so the balance will not require the spare and a full tank of gas to balance it out. I also plan to remove the aux fan and the ac dryer which I am not utilizing anyway. Also the rear and middle muffler will be gone soon. And I am looking for some lightweight racing seats.

Why do you need the spare in there? What does it do without it?

t walgamuth · #37 07-23-2007, 10:48 PM

It seems pretty neutral before locking it and after.

The front sits a lot lower than the rear....it appears.

I am running a spare because without it and a full tank the rear seems too light at present. If I move the battery to the rear I can achieve pretty good balance I think and lower weight.

I would like to stiffen roll resistance but finding a stiffer anti sway bar is not possible... i have thought of adding one but so far have had no luck finding one that will work for that. I have some bump stops from my old bmw that I might put inside the shocks on front to reduce roll too. I am aware the station wagon sway bars are thicker but I suspect that they aren't enough different to warrent the cost.

The hood has no sound insulation. but otherwise is normal weight.

Tom W

PaulC · #38 07-23-2007, 11:26 PM

No, what I meant was, is a lightweight hood available for the car?

t walgamuth · #39 07-24-2007, 06:06 AM

I don't think so.

Tom W

Ara T. · #40 07-24-2007, 06:34 AM

I believe you can have someone custom make a sway bar for you... I read about that somewhere.

t walgamuth · #41 07-24-2007, 07:27 AM

I am pretty sure that is true, but it sounds expensive.

Any body ever had a custom bar made for the 123?

Tom W

tankdriver · #42 07-24-2007, 09:05 AM

Quote:

Originally Posted by t walgamuth

I am pretty sure that is true, but it sounds expensive.

Any body ever had a custom bar made for the 123?

Tom W

You can try these guys:
http://www.smallfortuneracing.com/

Also, there are directions on how to make one yourself in the Puhn book. If you look at the S2K bar from the link, you can see it's a 3 piece bar, not a solid one - those parts can be bought. I forgot where I saw them, but it's another way to make your own.

How long have you been autocrossing?

John Doe · #43 07-24-2007, 11:23 AM

In the late '80s I got anti-sway bars, ect... from a company called Nuspeed, iirc. Don't remember it being that expensive, either.

t walgamuth · #44 07-24-2007, 12:32 PM

Thanks, guys. I will check those two sources out.

Tom W

Orkrist2 · #45 07-24-2007, 09:32 PM

Autocross is great but I try to just have fun and avoid spending too much money on things to improve my time. Then again my car is too old to be a serious contender anyway so I don't feel the pressure!