PDA

View Full Version : Now I know why 540I is slow of the line.


Darkness95m3
04-15-2005, 08:52 PM
Now I know why my 540I is slow of the line. I donít have a Limited Slip Differential.
Does anyone know where I can purchase a LSD unit? I believe just getting the LSD unit and leave the stock gearing I would improve the ľ by at least 3 or 4 tenths. Ad MarkDís software and another 2 tenths quicker maybe more. This would make the 13.5 sec ľ within my goal. Or am I just dreaming.

AMG_POWER
04-15-2005, 08:54 PM
13.5? I dont think so 13.9 maybe...

M50E30
04-15-2005, 09:06 PM
Sell the M3 and save your pennies and just do this........ http://www.jimmy540i.com/sc540i.htm

Darkness95m3
04-15-2005, 09:15 PM
Sell the M3 and save your pennies and just do this........ http://www.jimmy540i.com/sc540i.htm


Eventually I will supercharge my 540i. However with no LSD my first acceleration would suck. LSD + Supercharger would be a lot better.

M50E30
04-15-2005, 09:20 PM
Eventually I will supercharge my 540i. However with no LSD my first acceleration would suck. LSD + Supercharger would be a lot better.

Definatly LSD! I did it when I put in the M50. *th-up*

GEEE$
04-19-2005, 04:30 PM
Now I know why my 540I is slow of the line. I donít have a Limited Slip Differential.
Does anyone know where I can purchase a LSD unit? I believe just getting the LSD unit and leave the stock gearing I would improve the ľ by at least 3 or 4 tenths. Ad MarkDís software and another 2 tenths quicker maybe more. This would make the 13.5 sec ľ within my goal. Or am I just dreaming.

If you're a good driver(say with a 60 of around 1.8)...you should be able to run consistently high 13's all day long with that setup.





G$

Darkness95m3
04-19-2005, 05:35 PM
If you're a good driver(say with a 60 of around 1.8)...you should be able to run consistently high 13's all day long with that setup.





G$

Cayuga will tell.

RevShoT
04-19-2005, 05:38 PM
i have a 3.15 LSD out of an M3, 600 bucks, perhaps someone could tell us if it will work in his car? and if the gears will be enough?

Darkness95m3
04-19-2005, 05:44 PM
i have a 3.15 LSD out of an M3, 600 bucks, perhaps someone could tell us if it will work in his car? and if the gears will be enough?

If anyone knows please let us know.

RevShot it's sold if it will work.
I will call my buddy at Performance Cars, he will let me know.

RevShoT
04-19-2005, 05:47 PM
If anyone knows please let us know.

RevShot it's sold if it will work.
I will call my buddy at Performance Cars, he will let me know.

sounds good PM when u get a hold of him and ill take it out of my car i live 20 min from you too

i work in vineland so we could meet up there too

rear end has 80 K on them

Darkness95m3
04-19-2005, 05:59 PM
sounds good PM when u get a hold of him and ill take it out of my car i live 20 min from you too

i work in vineland so we could meet up there too

rear end has 80 K on them

Will do.

330DTM
04-19-2005, 06:14 PM
Darkness95m3,

If you're still out of luck looking for a LSD for your 540i, check out http://www.diffsonline.com/pricing/pricing5.htm

They can rebuild your diff or you can even change your ratio as well.

Darkness95m3
04-19-2005, 06:41 PM
Darkness95m3,

If you're still out of luck looking for a LSD for your 540i, check out http://www.diffsonline.com/pricing/pricing5.htm

They can rebuild your diff or you can even change your ratio as well.


Kewl! Thanks.

Mystikal
04-19-2005, 07:01 PM
An LSD has nothing to do with acceleration.

A shorter final drive ratio is what you're looking for.

Darkness95m3
04-19-2005, 07:21 PM
An LSD has nothing to do with acceleration.

A shorter final drive ratio is what you're looking for.

I think you might be wrong. With LSD the car would hook up a lot better, giving me better 60' times. This would also give me a shorter ET and higher MPH. Now the driver being on LSD that might slow me down by a few minutes. LOL j/k

330DTM
04-19-2005, 07:23 PM
An LSD has nothing to do with acceleration.

A shorter final drive ratio is what you're looking for.

I think his original post also mentioned accelerating off the line; in otherwords, perhaps he isn't getting the traction off the line?

Darkness95m3
04-19-2005, 07:28 PM
I think his original post also mentioned accelerating off the line; in otherwords, perhaps he isn't getting the traction off the line?

Dude, this sucker has no traction off the line. The rear tire just lights up.
Either you bog the car of the line or you melt the tire. I havenít found anything in between.

Mystikal
04-19-2005, 07:38 PM
If both drive wheels are on ground with equal grip, an LSD would not improve your times by any measureable (and repeatable) amount.

Darkness95m3
04-19-2005, 07:43 PM
If both drive wheels are on ground with equal grip, an LSD would not improve your times by any measureable (and repeatable) amount.

Correct me if I'm wrong but on the 540i only one wheel is the drive wheel.
With LSD in place would make both wheels the driving wheels, hence more off line acceleration.

Shuller1458
04-19-2005, 08:38 PM
If both drive wheels are on ground with equal grip, an LSD would not improve your times by any measureable (and repeatable) amount.

You little bit off here. LSD will defenatly improve noticeble acceleration. When you lunch a car with open diff, eather left or right wheel will have better traction. and that's where most of the power will flow resulting in more spin, and less traction, and slower times.

Go for LSD! Good luck, time your car (0-100km/h, 1/4 mile...) before and after LSD. so we can compare. ;) good luck.

:)

Mystikal
04-19-2005, 10:59 PM
Correct me if I'm wrong but on the 540i only one wheel is the drive wheel.
With LSD in place would make both wheels the driving wheels, hence more off line acceleration.

No, you would not be any quicker off the line, given both wheels have equal traction. An open diff will be slower in turns or if the tires are on two different surfaces, but otherwise, the grip level is the same. I know it's hard to believe, but it is true. The power will channel to the wheel with less grip, but if both have the same, the force accelerating the car is the same as with an LSD.

When you lunch a car with open diff, eather left or right wheel will have better traction. and that's where most of the power will flow resulting in more spin, and less traction, and slower times.

You just proved my theory right without noticing. You stated that either the left or right wheel will have better traction, which is a compromised situation. On smooth pavement with both tires on the road, the LSD really wouldn't do anything.

Another key point to remember is that if you are breaking traction beyond a very slight level, you are running slower than if you eased off a little bit. Because of this simple concept, an LSD wouldn't do much in a drag race.

Axxe
04-19-2005, 11:19 PM
I can relate, here's my story:

When I got my E30, I thought the car had an open diff. Any sort of slide would suck a lot, and off the line I would leave on black strip. All in all, it sucked. Then I wanted to swap in the LSD out of my iS, but first I checked the tag on the diff in my 4-door. Sure enough, factory installed LSD, but why wasn't it locking? No friction modifier. Just changed the oil, and now the car hooks up much better off the line (on the street, never been to a track), and slides can be held for a long time :). Back-to-back comparision, and it was night and day for hard driving.

Shuller1458
04-20-2005, 12:17 AM
Mystikal, so you say LSD cars lanch as fast as regular open diff, on normal smooth road? So what about dragsters (since we are talking about straight accel.) who have almost perfect asfalt with very good griptires have LOCKED diff (left and right axel shafts are acutally connected to each other, making it one big long axel.). Why do they have it, since you saying that it should not affect acceleraction times. ?

tlaselva
04-20-2005, 12:29 AM
I think you might be wrong. With LSD the car would hook up a lot better, giving me better 60' times. This would also give me a shorter ET and higher MPH. Now the driver being on LSD that might slow me down by a few minutes. LOL j/k

Your partially right.

It may decrease your ET, as this is all dependant on traction and driver skill.

MPH is heavily basted on HP. Unless you increase that, better traction will not show an increase in your traps.
Actually, with really good traction, like a D/R on a grippy track, you may even loose a few MPH on your run.....

IMO, S/C the sucker! Only way your going to see some real performance improvement! *th-up*

Darkness95m3
04-20-2005, 09:10 AM
Your partially right.

IMO, S/C the sucker! Only way your going to see some real performance improvement! *th-up*

That's what I wanted to do. Until the wife heard our conversation, to leave the daily driver stock. Which was your suggestion. Why couldn't you say SC the sucker in front of the wife? J/k
How's the Vette doing?

RevShoT
04-20-2005, 09:20 AM
pay not attention to mystikal, hes a numb nut and knows nothing about drag racing


a LSD will improve your time because traction= lower 1/4 times

with a LSD the power will be divided to the 2 wheels instead of an open set up delivering power to 1 wheel

in truth yes, you will loose a bit of time because the power is now being shared by 2 wheels but you will never notice this because your 60 foot times will improve drastically due to traction off the line!

keeping it simple if you have bad traction issues you loose time off the line, the use of a LSD will allow the use of 2 wheels to provide traction and a better launch and better 60' times, which results in less wheel spin and less time on the 1/4 mile ticket.

in theory you will loose a few MPH because the power is now being shared by 2 wheels instead of 1 but the traction improvements are outweight the loss of power once in motion

tlaselva
04-20-2005, 09:21 AM
That's what I wanted to do. Until the wife heard our conversation, to leave the daily driver stock. Which was your suggestion. Why couldn't you say SC the sucker in front of the wife? J/k
How's the Vette doing?

Well, if it's your daily beater, S/C it isn't the best of idea's to be honest.
There's a bunch of small things that can be done for a few extra ponies, but once you look at the cost, IMO, the extra 1 or 2% more HP isn't worth it.
(Was looking into goodies for my Wife's X5).

Vette's going in next week for the new motor, but not before a few runs at Cayuga this Sunday. :)

RevShoT
04-20-2005, 09:24 AM
Because of this simple concept, an LSD wouldn't do much in a drag race.

wow your such a fool!! i cant belive u said that!!


1/4 mile racing is all won off the line!!! you either hook up or loose plain and simple!

a LSD takes advantage of both wheels vs an open just carrying a dead wheel off the line

jmalixi
04-20-2005, 10:05 AM
LSD will definitely improve drag times if you have too much power getting wasted due to lack of traction. Not sure how many of you remember Posi-Trac (GM's brand name of LSD) but it was a "must-have" for muscle cars. Without it, you'd just be spinning your wheels and not making any progress off the line.

A 540i definitely has enough power that when mated with a limited slip diff, it will be awesome off the line.

Darkness95m3
04-20-2005, 10:08 AM
Well, if it's your daily beater, S/C it isn't the best of idea's to be honest.
There's a bunch of small things that can be done for a few extra ponies, but once you look at the cost, IMO, the extra 1 or 2% more HP isn't worth it.
(Was looking into goodies for my Wife's X5).

Vette's going in next week for the new motor, but not before a few runs at Cayuga this Sunday. :)

Oh. There you go again and the wife is right behind me reading.
I know. I agree with you.

Edit

The wife has left the Bedroom. So what I plan to do is turbo charge the M3 and place the existing blower on the 5 series. That's after the house is completely finished. So hopefully by Spring 2007 it will be done.

Mystikal
04-20-2005, 12:53 PM
You guys are all still missing an important point: the wheels are not spinning. There is no need to divert power from one wheel to the next, because the amount of traction available to each is essentially equal. If you like wasting time with wheelspin, sure an LSD will benefit you. But if you're actually hooking up (with the 235's or 255's stock on the back of the 540i, you should be able to connect perfectly, 310lb-ft or not), the open differential is NOT a hindrance. And don't bring up built drag cars, they have enough power available that wheelspin all too easily comes into play. Stock RWD sports sedans do not apply to the same rules of physics.

Revshot, I'm not going to bother addressing you anymore. I feel like I'm too old for this, despite the fact that I think we're the same age. Cut it out already.

jmalixi
04-20-2005, 01:14 PM
Dude, this sucker has no traction off the line. The rear tire just lights up.
Either you bog the car of the line or you melt the tire. I havenít found anything in between.

I thought the issue was highlighted above. If not, what is the issue then?

RevShoT
04-20-2005, 04:31 PM
I thought the issue was highlighted above. If not, what is the issue then?

FINALLY someone making sense here!!!!


guess jay seems to miss the repeated point that he has NO traction off the line and an LSD would bennifit his cause greatly

jmalixi
04-20-2005, 04:43 PM
FINALLY someone making sense here!!!!


guess jay seems to miss the repeated point that he has NO traction off the line and an LSD would bennifit his cause greatly
However, Jay is correct in saying that with the right tire, it is possible to fix the traction issue.

RevShoT
04-20-2005, 04:45 PM
However, Jay is correct in saying that with the right tire, it is possible to fix the traction issue.

tires only take you so far if his car dosent hook up off the line chances are a drag slick or R compound on 1 single wheel working will not be effective

trust me this is what i do, if its one thing i know its drag racing

Mystikal
04-20-2005, 05:06 PM
Adding an LSD to make better use of wheelspin off the line is just patching up a bigger problem.

If he is either bogging or spinning, then correct clutch slippage on the launch needs to be used. AWD cars typically get stuck with this issue and in some no amount of slipping can avoid the bogging, but for a RWD car (especially one with such a broad powerband, cars with sudden turbo surges may have a problem) the bog/spin issue can be avoided with proper technique.

If wheelspin is seriously too hard to avoid, better/wider tires should be able to solve it. Once again, although powerful, the 540i is still equipped with "only" 310lb-ft and is very heavy, plus RWD. The weight transfer plus relatively wide stock tires should yield very good traction, with the right driving technique.

Darkness95m3
04-20-2005, 05:16 PM
Adding an LSD to make better use of wheelspin off the line is just patching up a bigger problem.

If he is either bogging or spinning, then correct clutch slippage on the launch needs to be used. AWD cars typically get stuck with this issue and in some no amount of slipping can avoid the bogging, but for a RWD car (especially one with such a broad powerband, cars with sudden turbo surges may have a problem) the bog/spin issue can be avoided with proper technique.

If wheelspin is seriously too hard to avoid, better/wider tires should be able to solve it. Once again, although powerful, the 540i is still equipped with "only" 310lb-ft and is very heavy, plus RWD. The weight transfer plus relatively wide stock tires should yield very good traction, with the right driving technique.

But it's so hard! :( My M3 is so easy to get going without spinning. I spent about 60min in a parking lot trying to implement this perfect clutch throttle technique. Either the car bogs and comes to life and then proceeds to melt the rear tire, or it just melts the rear tire. :confused:
Darn I might as well just leave the BMW TCS system ďONĒ. *th-up*

Mystikal
04-20-2005, 05:22 PM
It could take a while to learn, especially with the E39's vague factory clutch. 60 min trying in a parking lot could get rid of that problem rather quickly though. :D

Paul540/m3
04-20-2005, 05:46 PM
It could take a while to learn, especially with the E39's vague factory clutch.

Maybe do the CDV delete and that might help things out a bit, it'll be more like the M3 as it doesn't have a CDV.

BMetal
04-20-2005, 05:51 PM
An LSD has nothing to do with acceleration.

A shorter final drive ratio is what you're looking for.

If you're sitting there smoking one tire when you could be putting the power down with two and less slip, why wouldn't you accelerate faster off the line??

Mystikal
04-20-2005, 08:10 PM
Maybe do the CDV delete and that might help things out a bit, it'll be more like the M3 as it doesn't have a CDV.

Good idea, I know of a few 325Xi owners who really liked the results from removing the delay valve.

If you're sitting there smoking one tire when you could be putting the power down with two and less slip, why wouldn't you accelerate faster off the line??

Read the thread.

Darkness95m3
04-20-2005, 08:39 PM
Maybe do the CDV delete and that might help things out a bit, it'll be more like the M3 as it doesn't have a CDV.


Tel me more Paul please.

SickFinga
04-20-2005, 08:50 PM
I'll agree with Jay on this one. Stock 540i will not benefit from LSD in a 1/4mile race. It just doesnt have enough HP to make wheels spin too much.

A car with a better power to weight ratio will definitly benefit from LSD

RevShoT
04-20-2005, 08:56 PM
I'll agree with Jay on this one. Stock 540i will not benefit from LSD in a 1/4mile race. It just doesnt have enough HP to make wheels spin too much.

A car with a better power to weight ratio will definitly benefit from LSD

how so? with an LSD your wheel breaking point( the point where the wheels break loose) is increased which means you can launch harder and at higher RPM's preferably above the peak torque line (4000rpmish? for a 540?)

2 wheels provide better traction then 1, thus higher launches can be acchived

SickFinga
04-20-2005, 09:03 PM
how so? with an LSD your wheel breaking point( the point where the wheels break loose) is increased which means you can launch harder and at higher RPM's preferably above the peak torque line (4000rpmish? for a 540?)

2 wheels provide better traction then 1, thus higher launches can be acchived


sure 2 wheels are better than 1.
But, every car has an optimal launching RPMs, I believe it is when it makes the most torque. Not sure about 540, but on m3 it is somehwhere around 3500 rpms. You wont get much wheelspin launching at that RPMs on 540 or M3. Even if you do, I also believe that you have to ride your clutch a bit in the first gear for a perfect lauch.

Also, what most of you missing, from what Jay was saying, that even open diff will spin BOTH wheels IF load is the same on both wheels.
Check Vlad's burnouts in his E55, boths wheels are spinning and he has an open diff.

RevShoT
04-20-2005, 09:10 PM
sure 2 wheels are better than 1.
But, every car has an optimal launching RPMs, I believe it is when it makes the most torque. Not sure about 540, but on m3 it is somehwhere around 3500 rpms. You wont get much wheelspin launching at that RPMs on 540 or M3. Even if you do, I also believe that you have to ride your clutch a bit in the first gear for a perfect lauch.

Also, what most of you missing, from what Jay was saying, that even open diff will spin BOTH wheels IF load is the same on both wheels.
Check Vlad's burnouts in his E55, boths wheels are spinning and he has an open diff.

to a point ur right, in an open diff if the load is equal both wheels will lock up, but on the drag strip can you really depend on this being a reiable form of traction? deffinitally not

your right when you say it is best to launch just about your max torque output (im guessing 540 is around 4K not sure) if your getting mass wheel spin then a LSD will reduce the spin and allow you to hook up off the line and your 60' times will go down drastically

however if you have an open diff and lauch just above your peak torque and spin like crazy your then just wasting time makeing smoke. bring your launch down to where the tires breaking point is optimal, you should hear a chrip from the tires and then launch, this however is a bad method cause your now limiting your car by the traction you can recieve which results in slower E/T.

the best launch is no smoke a quick chirp and all acceleration, launching about your torque peak is the only way to reach your cars optimum performace in the 1/4

i work at a drag shop on weekends i know my shit if its one thing i know good

btw: when launching is not always best to jump pop the clutch and hammer it, best methods are to ease the clutch and gas, sometimes when im at cayuga my foot is still on the clutch as im shifting into 2nd, its all about getting the launch down perfect= races are won in the 60' time zone

Mystikal
04-20-2005, 10:51 PM
to a point ur right, in an open diff if the load is equal both wheels will lock up, but on the drag strip can you really depend on this being a reiable form of traction? deffinitally not

I think you can rely on that. Otherwise, that really wouldn't be a good drag strip. What's the point of testing cars if the surface varies like that?

your right when you say it is best to launch just about your max torque output (im guessing 540 is around 4K not sure) if your getting mass wheel spin then a LSD will reduce the spin and allow you to hook up off the line and your 60' times will go down drastically

See that's my point, which it seems everyone but Vlad missed. You should not be getting any wheelspin in a stock 540i, to avoid it you should be slipping the clutch more to maintain the optimum RPM to stay at the torque peak; if you're spinning the wheels, you're letting out the clutch too quickly, and wasting energy.

however if you have an open diff and lauch just above your peak torque and spin like crazy your then just wasting time makeing smoke. bring your launch down to where the tires breaking point is optimal, you should hear a chrip from the tires and then launch, this however is a bad method cause your now limiting your car by the traction you can recieve which results in slower E/T.

You're absolutely right, spinning is wasting time. What you're missing is that if you are NOT spinning the tires in the first place, an LSD doesn't do anything. The open diff is just as good as transferring the proper amount of power, the amount that does not lead to wheelspin.

the best launch is no smoke a quick chirp and all acceleration, launching about your torque peak is the only way to reach your cars optimum performace in the 1/4

Exactly. Which, in conclusion, is why an LSD would not benefit in this case, nor any other car with similar characteristics. All you want is a quick chirp, with which an open diff would not uselessly spin one wheel, especially good 235+ section width tires on a 3900lb car.

RevShoT
04-20-2005, 11:30 PM
your still missing his problem, he IS getting massive wheel spin and cannot hook up, normally if he didnt get it it would be pointless but he is getting bad wheel spin on all his launches, therfor an LSD would be highly reccomended

M50E30
04-21-2005, 12:01 AM
LSD = Better grip.

Better grip = Ablity to launch at a higher RPM range.

End of story!

Darkness95m3
04-21-2005, 10:09 AM
LSD = Better grip.

Better grip = Ablity to launch at a higher RPM range.

End of story!

Party Crasher!

Paul540/m3
04-21-2005, 10:11 AM
Tel me more Paul please.
Here's some websites you can check out that explain the whole procedure. I just ordered my modified CDV a week ago and have yet to install it.

http://www.uucmotorwerks.com/html_techtip/techtips/check_valve.htm

http://www.zeckhausen.com/CDV.htm

*wiggle*

Darkness95m3
04-21-2005, 10:43 AM
Here's some websites you can check out that explain the whole procedure. I just ordered my modified CDV a week ago and have yet to install it.

http://www.uucmotorwerks.com/html_techtip/techtips/check_valve.htm

http://www.zeckhausen.com/CDV.htm

*wiggle*

Thanks Paul.