I think I'm going to go 3.91 when I get paid. I emailed diffs online and I'm waiting on their reply. I will not drive this car this summer without LS

BDR DRIVE TRAIN
 

MORNING GUYS,

I THINK ALL OF U DISCUSSING THIS DIFF. ISSUE SHOULD DRIVE A CAR WITH AND WITHOUT THE LS UNIT.
UNDER NORMAL TO SPORTY DRIVING U WILL FIND IT HARD TO TELL THE DIFFERENCE.
I MIGHT ADD THAT A DRIVER NEW TO THE WEIGHT AND POWER OF THE ROADSTERS WILL FIND THE VEHICLE FAR EISIER AND SAFER TO DRIVE WITHOUT THE LS.
IF U NEED TO DRIVE ONE OF THE CARS GIVE REG A CALL IN FLORIDA AND I AM SURE THAT HE WILL BEABLE TO ARRANGE A DRIVE WHEREVER U MAY BE. BDR HAS ENTHUSIASTIC DEALERS AND FRIENDS ALL OVER THE USA WHO HE WOULD PUT U IN TOUCH WITH THAT U COULD GET TO DRIVE A CAR.
SHOULD U NEED TO KNOW ANYTHING REGARDING THE TECHNICAL ASPECTS OF THE BDR PLEASE DO NOT HESITATE TO WRITE ME. I AM ABLE, AND WILL GIVE U, THE STRAIGHT ANSWERS, AS HONESTLY AS I KNOW, TO ALL YOUR QUESTIONS.
AS "SUPER DOC" SAYS WE ARE JUST TRYING TO HAVE FUN WITH OUR TOYS.
WE ARE ALL IN THE WORDLWIDE WONDERFUL FAMILY OF COBRA.

MAY U ALL HAVE MANY MANY MILES OF SAFE FUN.

REGARDS

Opps. Sorry, I forgot to mention the M3's diff. You are correct, it will help lap times as well as the brakes.

I have to disagree here. The differential supplied with the car is the standard differential that comes standard in the suspension package used in the car. It's not "A Problem" that needs fixing. It's one of the items that allows the car to be priced as it is. I've driven or raced at least 2 dozen BDR cars and I personally believe that the 80/20 stock diff is very addiquate for putting power down. Both tires pull.

Hope this helps.

Boudy

GUYS

I will have to agree with Tony on this matter, most people drive the standard BDR will immediately notice the smoothness of the cars drive, LS units will make the beast fill more beastier or robust when driving, it has a tendency to tighten the feel of the car. The standard rear will be fine for most enthusiast who drive their cars with more finess and an occasional smoking of the expensive tires. My car is a beast, it drives like a beast sometimes, sometimes it impresses(SCARES) the h--ll out of me. That is what I wanted when I ordered my car, that is why she has over 600 horsepower on tap. I have done alot of racing over the years and I still believe you can never have to much horsepower. Though I have considered buying another BDR with a very mild 302 standard issue to be able drive everyday and also the wife could drive. Bottom line is that for most daily cobra driver enthusiast the standard issue rear is adequate.

DON

Hello from Guadalajara, Mexico. You'll have to excuse my ignorance on this issue (to make it worse I had a few Margaritas this evening).

So what I'm hearing is that with the standard rear suspension - I'll be able to spin both rear tires during WOT acceleration. Maybe I'm having trouble with this because I've never had a car that only spun one wheel during a burnouot (that would be awkward and seriously suck). Also, when I was given a test ride in a BDR while visiting the facility in Boynton Beach, I was a passenger and Frank Dodd was driving. Then again, I wouldn't have pushed the BDR even if I had been driving because it had a new engine in it (maybe they should have a demo that's been broken in for clients to try out).

When you refer to the 80/20 stock differential, does that mean that 80% of the power is transferred to one wheel and 20% to the other?

Ok, I have followed this thread with interest. First I had an FFR with LS and a stock 302 engine with 17 inch Kuno tires. If I wanted to I could have worn the tires (both) to cord. Lot of noise and smoke but no go.
Now with the stock BDR suspension 3.10 and a 351(321hp at rear wheels), it has 17 inch wheels and Nitto DR's. I hardly get any wheel spin. The car just squats and moves out. I have only made three full power runs , I have not gotten used to the car yet. But my best time was 12.33 at 111mph, and a 60foot time of 1.86.
Now I have not been on a drag strip in 45 years prior to my recent run, so these times don't mean a lot to me. I had never done a burn out, it was kind of exciting, but I found it dificult to spin the wheels or wheel in the burn out area. I don't think it mattered much the car still went like hell. By way of compairson I saw a write up in CAr and Driver ,while waiting for a flu shot, of the new hot corvette. It did the 1/4 in 12.8sec and if I am not mistaken it has a LS rear.
So bottom line if the car hooks up and moves out and you don't break parts, who cares if it only leaves behind one black stripe. Well the guy whose A$$ you are kicking will have something to look at as he watches you pull ahead.
Then again if you have 15 inch wheels (with the lack of good available tires), maybe you should look for a LS.

To re-inforce what JayBar said...

Back in August, I had #139 for a weekend with 15" BFG's.

In a controlled situation, 65' LR, 25' RR, measured by my loyal fans.

Now, with 17" sticky Nittos, a chirp, she squats down, and grabs asphalt.

Two people I trust swear that the LF came off the ground at launch.

Blue smoke don't win races.

But sticky Nittos will throw little rocks into your paint job like you wouldn't believe!

I call it "battle damage" and live with it.

UT

Some of the comments in this thread remind me of a conversation I had in the barracks at Fort Benning, GA in 1966. Teen-agers from all over the country talking cars and girls.
I will never forget two statements I thought bizarre even at that tender age.
One was a Southern boy who said the only test of a “hot” car where he came from, was the amount of, or length of the “rubber stripe” a car could lay. The other comment was in a discussion as to which car we dreamed of buying. Another guy stated that he would never buy a car that could not spin the wheels shifting into third gear.

I just assumed that as we grew up and technology improved and tires got so much better that now the idea is not to spin the wheels but to dig in and go.

That said, I can only state that the stock Backdraft suspension 3.10, 17” Nitto DR tires, digs in a moves out. I have a 351 not stroked and after my third full power run (ever) turned 12.3 at 111mph, with 60’ time of 1.86.
I think if you give the stock non-LS rear (with decent tires) a chance will you will be quite happy with its performance. Unless you come from the same town my old army buddy did, and judge a car by the stripe it leaves behind.

If you are running 15” wheels your choice of tires is so limited maybe you should just be content with the authentic look and forget performance, because even LS will not make your car equal to one with 17” Nitto DR’s.

Sorry for the double post I lost my power while sending my first post, thought it was lost. Hence the re-write. Same thought just embelished by morning.

I must agree with what's been said . I ordered my BDR with the standard rear end pkg and the 17" Nitto DR. Under full power she just squats and goes. No tire smoke,squeals or fish tails. With a full power shift it barely barks the tires in 3rd gear.
David:D

For TICO

Ok friend, I've read all the posts and comments and here's the bottom line from a Backdraft owner that runs a 392 stroker 430 horse motor in my car.

You said you want a BIG BLOCK but you didn't say how you polan to use the car. What's your pleasure? Road racing, drag racing or just cruising and showing it off to friends?

I just raced mine on a road course in Las Vegas with 17" wheels and very sticky HOOSIERS on it and in the corners it lifts the front wheels off the ground about 2" in each corner and had NO traction issues what-so-ever. I love the Indep Front and Rear suspension and the car outhandles anything on the track in my opinion. It does everything right that you would want a car to do.

I am running a USED 3:93 diferential I purchased from Beemer World that is a USED 80/20 LS and have no complaints about traction at all! All I did was take out the stock 3:10 and replaced it with the 3:93, put the 17" tires and wheels on it and went racing.

Do NOT under-estimate the BMW rear end, it will handle about anything you can throw at it in my opinion.

By the way, the BIG block cars being heavier in the front end may NOT handle on a road course as well as a good stroked 351 block.

If your looking to go drag racing and want to WIN, then maybe you need to rethink your overall plans. Every second off your E.T on a drag strip will cost you about $10,000 in equipment upgrades.


Doc

Doc, I never said I wanted a big block engine. I said I would like a Roush 427R or Keith Craft Racing 427W (both are stroked 351W engines). My inquiry was because of a comment I read on another thread that questioned the BDR drivetrain.

By the way Doc, keep up the good work at racetracks and shows. Sounds like you're having a blast. I hope to be doing the same sometime next year.

Thanks to all for your replies. When I order my Backdraft it will be with the standard drivetrain and 17" rims & tires.

For Tico

Thanks for clarifying things and your reply.

Comment regarding 17" wheels. They are pretty and I love the ones I have that I use for racing BUT they ride a LOT harder than the 15" tires and wheels. I have both sets! One for street (15's) and one for racing (17's).

If you don't plan to road race the car I recommend the 15" over the 17" just for the ride factor alone.

My 2 cents!
Doc

added to wrong post

I wonder.......
 

I suppose by now, 6 years later, Tico has made up his mind about getting a Backdraft. But, let him reply, if he is still around.

SkipB

Bmw rear
 

Well, for those interested. .....here's my (old) BMW rear end.:mad: 391 ration with 25% LSD.

Broke it after driving 1500km to the Australian Cobra Nats. Turned 8 laps before crunck! Turned a tooth. Make sure when you do your diffs that you DON'T re-use torque bolts and make sure you set the diff lap low on the teeth. :CRY:

http://www.clubcobra.com/photopost/d...rown_wheel.jpg

Car is now running BMW Motorsport shot/peened crown wheel and pinion :3DSMILE:with 25%LSD.

305 slicks, 351w hi HP and Jerrico 4 speed box.

Spookypt

Spooky you ar ethe only failure I have heard of in many years. I have heard of drive shafts, suspension, ...

Seems to me that it is a pretty stout diff.

Not a happy camper at the moment!
 

Sadly, the diff is only a small portion of the overall issues I've had with my car. And in fairness on this issue it's not a BDR fault. (Although who re-uses torque Bolts????) Lets just call it wear and tear.
On the balance at this point I'm staying tight lipped about the other "issues" as I am hopeful REG and TONY and the THE BACKDRAFT CUSTOMER SERVICE EXPERIENCE will play apart in keeping me on the + side of the BDR experience.

Stay tuned I guess.

Goodluck.....

Thanks, if the current response (or lack thereof) is anythig to go by I'm not hopeful!:CRY: