"Open" Rear?

[Cashburn]

Someone was saying something about an "open" rear on these?



Nice one Sid!

[trularin]

Smokem'

Where is Milford?

[JayBar]

WoW,
And it looks like you have 17 inch tires.

[Cashburn]

The smoke show is by Sid at London I assume (snagged it from his gallery). He does have the 17" Polished.

Oh, Milford is in CT ...

[jeffko]

That's Sid alright. 1 week after taking delivery of a roller he is in London doing burnouts. I think you can see him smiling even from this angle.

[JayBar]

Just what is Sid using to light up those tires, and what rear does he have.

[uncltodd]

Note that Sid's right front is almost off the ground.

Friends have mentioned that to me about Gunrack, but it's hard to do a burnout with sticky Nitto's. She just grabs asphalt and goes.

Sid, you need a second rollbar.

I noticed that your license plate is all bent up.

So is mine.

I keep a carefully sealed gallon of fuel in the boot because #139's fuel gauge is a cruel joke.

Have fun, 'Mano.

UT

[JayBar]

Just what is Sid using to light up those tires, and what rear does he have.

[madmaxx]

I smoked my tires the other day and left a rubber road to freedom as Sid did with both wheels burning and leaving rubber. Did some cars not come with "positraction". I thought these had a clutch mechanism that locked up above a certain rpm.

[JayBar]

Madmaxx,
The tread started to show that the BMW open differential could "lay rubber" with both tires. The standard BDR comes with an open differential the M3 option has a lockup rear.
Those kits using a Ford differential will have "positraction".

[madmaxx]

Thanks JayBar,
So does Sid have the M3 rearend? I am pretty sure I do not have the M3 option and I roasted both of them!!!

[JayBar]

Originally posted by JayBar

Madmaxx,
Please read again.
Madmaxx,
The tread started to show that the BMW open differential could "lay rubber" with both tires. The standard BDR comes with an open differential the M3 option has a lockup rear.

I also have an open rear axle and can spin both rear tires even with the drag radials, but only if I try.

[pitstop]

i'm missing something. is cashburn's car laying the dual patches with posi or is it showing that a cobra can do that with an open rear end?

[JayBar]

I give up!

[Excaliber]

Any open rear is capable of turning both tires when traction is identical. The short wheel base and and excellent "straight back, both sides equal" weight transfer of the BDR suspension is what's making this "one legger" work so well here. Assuming it IS a "one legger". There is no discernible body roll to one side or the other based on the picture. Well done! I wonder what, if anything, BDR has done to make the suspension work better as far as "weight transfer" goes? Like put the battery on the side of the car that "lifts" under accelleration (as an example). Or different shock valveing, spring rates per side. Perhaps the BMW suspension itself has incorporated desiqn features to compensate for the weight transfer?

Longer wheel base and softer suspension travel (a typical "car")will exagerate the car body lift to one side. Shifting weight to one tire while "unloading" the other. In that case the unloaded tire breaks loose well before the loaded tire does (IF it does).

On a road course in a turn where one tire is under greater load than the other it is much more difficult to get the unloaded tire to hook up (if not impossible). In a low speed sweeper turn the inside tire WILL go up in smoke. This was quite common "back in the day" and was the main reason various forms of "posi traction", "lockers" etc. became popular.

Look at the "body roll" of the old 289 Cobras in a corner on a road course. It was extreme to say the least. One way to overcome the unloaded tire traction problem is to "drift" the car. Throttle over steer just as you enter the corner. That helps keep the car "flatter" through the turn, but VERY tricky and NOT the "fast way" around a corner.

Detroit offered "posi" like units on passenger cars mainly to deal with snow and mud related traction problems. A one legger with a tire in the mud and one on the pavement aint going nowhere!

I understand there were a number of law suits against GM "back in the day" when posi units were first introduced. With both back tires spinning the rear end wants to come around one side or the other. Particularly troublesome in the snow, people would loose control to easily. THAT led to "softer" semi posi units, there are a great variety of them on the market today.

It appears from the picture here the driver (Sid?) is correcting by turning the front wheels slightly to the right to compensate for the rear end trying to come around. THAT to is a sign that indeed BOTH rear tires have equal traction (for some reason)!

[madmaxx]

Thanks Excaliber. Your explanation was confirmed yesterday. After roasting them again (both tires) I went home and jacked up the car. I can spin one tire while holding the other one still. So I do not have positraction, but I can still lay down rail road tracks

[Excaliber]

Impressive!

[pitstop]

thanks. now i get it.

[got snake?]

The Windy City Cobra Club recommends Corbelt champagne for the first burnout. We had a little celebration when we got to Columbus. The cobra just got done 2 days before we left on Thursday. I was told do a burn out or else. So I popped the bottle took a few swigs...then they poured some on my rear tires and told me to hit it! Thats the story and I'm sticking to it!!!

I have the standard BDR suspension. whatever that is. That was done in first gear.

"It appears from the picture here the driver (Sid?) is correcting by turning the front wheels slightly to the right to compensate for the rear end trying to come around. THAT to is a sign that indeed BOTH rear tires have equal traction (for some reason)! "

If you look in my gallery there should be a pic with the finished burn out. you will see the tire marks start going to the left. When the weight transfered the the rear the front was really light. I tired to keep it straight but the front did not have enough tire on the ground to stay in control. it started to get away from me a little so I lifted.

THE SID

[tony martin]

SOCK IT TO THEM SID,ONE LEG OR TWO!!! YOUR BRD IS REALLY HAULING ASS!!

CONGRATULATIONS ON GETTING IT TO GETHER FOR LONDON.

DRIVE SAFELY,

REGARDS