BDR rear end opinions please (BDR owners)

[pjmoore2003]

I like my open diff: Roush 402. I barely break the tires loose anyway -- 315s! I'm babying anyway right now with the engine being low mileage.

I like sliding around corners too, and you should be able to do it with the BMW open diff. LSDs are great, but this is a road car and you're only going to spin the tires if you really try hard.

My .02, and that's all its worth since I'm a new owner...

Rick, do you miss it? Such a fun ride...


PJ

[Cashburn]

Rubbing it in! Easy on a rainy day like today. Wait until this weekend... Sorry Rick.

[Excaliber]

I haven't had an open diff for so long I'm pretty sure I wouldn't like it. I was out driving just the other day and with gentle but increasing throttle was able to induce a nice drift around a corner and control it well using the throttle. Throttle over steer wouldn't be nearly as easy with an open diff, it would be more like grab a handfull of e-brake or jerk the wheel or possibly a clutch dump. Some other technique than I've gotten used to.

In Hawaii we had "drift sessions", organized events specifically FOR drifting at the road race track there. There is no question what I learned from drifting has made me a better, SAFER driver on a regular road race track and on the street. The SCCA guys hated the drifters by the way, hated them with a passion! If you got sideways during an SCCA solo event you could be accused of "drifting" and disqualified. Shesssh, gimme a break!

[Gatorac]

To answer the original posters question.....I have a BDR. I have owned and driven it for 6 years. I have a 408 from Southern Automotive with 460 horsepower (absolutely perfect engine combo for this car BTW). The open diff never been an issue. The independent rear of the BDR is not the same as the old straight axle cars. Get on the gas and she squats down in back and just goes. She goes fast. I have less wheel spin then my FFR with the traction lok 8.8 and a 302 under the hood. Less wheel spin then my 03 Cobra with independent 8.8 traction lok rear. Less wheel spin then my 08 Corvette with an LSD and 436 Horsepower AND FREAKIN' TRACTION CONTROL.... It probably has something to do with the 315 Nitto drag radials on the back. You ask if I would do it again? No question I would pick the same diff and tire combo again. The standard diff is a NON-ISSUE.

Of course you'll find some very valuable information here from someone who doesn't have a BDR. You decide....

BTW if you want to add a particular poster to your "ignore" list, click on that particular posters name and select "View Public Profile". You'll see an arrow next to "User Lists". Click on that and a drop down will appear for you to select "Add User To Ignore List". Like magic you'll no longer be forced to see that particular users useless information they feel they must post on every thread. Happy surfing and good luck on your Cobra search.

[Excaliber]

Hey GATOR, does it drift? Of course not, it's an open diff. Throttle over steer? Aint gonna happen. Your "racing" experience seems to be limited to a straight line and drag radials.

So much for your sage advice.

[Gatorac]

You sir are clueless. First off drifting is not the fastest way around a road course. Second, you don't need an LSD for trailing throttle or throttle on over-steer. My track experience is limited to an SCCA comp license and I instruct for Chin Motorsports at tracks all over the Southeast, so I may be wrong. I live an hour from Sebring and spend quite a bit of time there. While it does have 2 very long straights, it has 17 corners. If you think throttle on over steer is the best way for a fast lap time, uhh, well I guess that figures. Now if the OP wants to drift, maybe he should just weld the gears in the rear together. Although that was not the question he asked.

I suggest you put me on your ignore list and we can both not be bothered by each others posts. Instructions are above. Don't you have another thread to pad your post count by adding nothing of value to? You have 6 fricken posts on this thread alone of which you've made it obvious you know nothing about.

[Excaliber]

I've found that kind of response typical of SCCA folks, they don't understand the basics of drift or why it's relevant. The only understand it's not the fast way around a track, of course it's not. It's the fast way to learn how to deal with getting in trouble on the track without actually getting in trouble on the track!

We drive 90" wheel base high horse power cars that will swap ends real fast. Practicing a controlled slide, hanging the rear end out and learning to deal with it could mean the difference between saving the car when it gets crossed up or a crash. This controlled slide technique is called "drifting", it takes considerably more skill than going around a race track "fast". Such knowledge could well make the difference between a crash or not.

You can learn it on a snow covered parking lot, a dirt field or road or by low speed throttle oversteer on pavement or at a local "drift session". With an open diff, it will be much harder to induce under any of the above mentioned conditions.

I find it amusing that an SCCA comp licensed person would actually suggest an open diff is superior in RACE TRACK conditions? Puhlease, your pulling my leg right?

[pjmoore2003]

Drift this... Seriously? You'll have so much fun with the open diff on the road and you won't ever worry about it catching abruptly... have to share the great photos my buddy took...

[Excaliber]

Good grief you guys! You are drunk on the BDR open diff thing, this is incredible. Yes it is "safe", no question there, but seriously, you want 500 horse, a 90" wheel base AND "safe"????

How many replica's besides a BDR have you ever seen with an open diff? It's virtually zero, there's a reason for that.

[pjmoore2003]

I regularly drive a 99 Mustang Cobra with about 345hp. It has an IRS and an limited slip. Tires are only 275s in the rear. It spins the tires a lot easier than my BDR.

Something with there being very little weight to push down the road, these tires just grab and go.

Food for thought on Limited Slip, which typically I do favor and recommend, I just haven't seen the need in the BDR: http://www.youtube.com/watch?v=AHmSDXrVG84

With that, I'll shut up now. Good luck Kevin, will be interested in hearing your view whichever choice you make once you have keys in your hand.

[LMH]

We drive 90" wheel base high horse power cars

Not for those who drive BDR's. 92"
Larry

[Cashburn]

Ernie,
92" wheelbase on a BDR. Come and drive one sometime, until then you cannot assume too much. I have not driven your ERA so I cannot judge or compare. I think we need you and TB to go for a drive so we can atleast let you understand.

You have a guy here (Gatorac) that has been flogging his BDR for years, just as you have your car. I think that carries as much weight as your experience, not post count. And I type this with respect...

BDRs just dig, that's how Tony Martin (sure look him up sometime) has developed them...

[Excaliber]

Never said they were a bad car. I doubt there are any BDR's competitively running a road course with an open diff, Gator included. I seriously doubt there are any BDR's running under 12 seconds in the 1/4 with an open diff and street tires (personally I run in the 11's, with street tires). Traction, across the board, for ALL Cobras is the number one limiting factor when it comes to performance, accelleration or cornering.

For the best performance it's just a no brainer, you need an LSD of some kind. If your mostly street driving, going in a straight line, not seriously running SCCA events, are happy with a mid 12 or low 13 second quarter mile time on street tires or willing to run slicks (I wouldn't on the street) then an open diff may work well for you.

While it may be safer in the short term, I question how safe it might be in the long term? When you get used to the car and start to push the envelope and the rear end steps out, will you know how to handle it? How will you learn? I think a good drifting session is a great way to figure that out. Do it on wet pavement, low speed, in a big parking lot, but do it BEFORE it happens on the street, with other cars all around you.

[pjmoore2003]

http://www.youtube.com/watch?v=LqjMcKW0FTE

Anyone know if this car had an LSD?

Since it looks like RT3B and is spinning both tires, I would say yes, but hard to be sure in a straight line...

Anyway, this car is obviously capable of 12s.

One member's take on the LSD he put in his car: Backdraft IRS Update

[spookypt]

http://www.youtube.com/watch?v=pUIa0RRsbj0

What is/did Reg D run in this?????????????????

[conan]

I have had my BDR for 6 years also and have thrashed it around quite a bit. I have no issues with the "open diff". Believe me the car will get sideways with both tires spinning. I'm running a Ford racing 351W, 385horse with 315 drag radials. I had the same concern about going with a LSD. When I met with Reg he pretty much talked me out of the LSD. He told me to take the car and drive it and if I was not happy with the open diff he would put in an LSD diff at no charge. Well 6 years later I still have my "open diff".
Nuff said.

[Cashburn]

The 0-60 video was quite sometime ago, I know it was on the standard BDR tires and it may have been the standard rear. When they sent the car "the rules" were to send your most popular selling combo...

The Sebring video is a TD car that is not sold for street use, yes it has the LSD and a lot of other things for the track. Video also shows a French driver (note flag on helmet) and not Reg.

The LSD vs. non-LSD question is a $400 question. By this I mean you can have it swapped in later for less than a $400 delta vs. getting it when your first purchase the car.

Is it worth $400 to the customer to get comfortable with the car first AND determine through a year or two of use if they NEED it and what GEARS they should choose?

That's my theory...

[Mark Brye]

My BDR had an open diff with 3:46 gears. I put about 3000 miles on it with the non LSD. It layed rubber with both tires every time. No traction problems at all. I now have about 1000 miles on a Matrix Motorsports 3:73 LSD. Still lays rubber with both tires My 1/4 mile times may be better with the LSD and 3:73 gears but I am sure it would be the steeper gearing and not the LSD as I never had one wheel peel with the open diff.

[RMHINC]

Jay,
That is a good theory ! Here is another one "life is to short". All I know is that every one of my cars can make me smile on the worst day when I push that start button All my cars do have start buttons except my wife's Lexus GX 470 .
PJ those are great pictures & I do miss the car but I'm glad you are getting a chance to enjoy it . Here is another theory about life "enjoy the process " So while I miss my car PJ I'm enjoying the process of the new Cobra build . Charlandk enjoy your new car process ! There is a lot of good information here so you can figure it out . Some of you guys should spend a hundred bucks & go lay on a couch & talk to someone

BDR 902, BDR GT40,65 Vette Coupe,67 GT500R,06 BMW M5,05 SL55 AMG

[charlandk]

Once again, thank you all for your input (especially those of you BDR owners who responded). I truely appreciate it!

I think I have my mind made up.
I am still going to do a little researching but I believe I will go with the LSD for a few reasons:

I like the rear gear options that are available with the LSD vs the standard rear end.
I am going with the T56 Tranny and with the standard rear and 3.46 gear, that tranny's 6th gear is really not needed. I will go with a 3.91 rear. This will give me better acceleration and then the 6th gear will come in handy.

The traction and overall performance of the car has to be better with the LSD. (may just have to be a little more careful getting aquainted with it.)

I believe that this is an option that I will ultimately decide to get down the road if I were to go with the standard rear end so to me, it makes sense to just order it the way I want it up front.

While I have no intentions of ever selling this car, I believe that I will have more luck with resale if I were to have the LSD.