Putting my 3.15 diff into my 540i6, quick question ..

[loborph]

Hi everyone!

I received my 3.15 diff this week, hope to put it in this weekend.

My question: when I rotate the input (drive shaft) the outputs spin as expected - very smooth.
when I rotate the output, the resistance varies - a little jerky. Is that normal? The other side spins in the opposite direction as I turn it (which is normal, I think)

I thought about putting a quart of 30w oil in it to wash it out and check for shavings.

All input is appreciated - thanks.

Bob

[bE34ST]

Flushing the diff and putting new fluid in it might be a good thing to do regardless, for a little peace of mind at least.

[ninetyseven1]

Hi everyone!

I received my 3.15 diff this week, hope to put it in this weekend.

My question: when I rotate the input (drive shaft) the outputs spin as expected - very smooth.
when I rotate the output, the resistance varies - a little jerky. Is that normal? The other side spins in the opposite direction as I turn it (which is normal, I think)

I thought about putting a quart of 30w oil in it to wash it out and check for shavings.

All input is appreciated - thanks.

Bob
I think thats normal. Mine did that IIRC. Just make sure you fill it correctly. Should take close to 2 quarts of 75w90 synthetic gear oil and it needs to be filled in the PROPER fill hole until it leaks out a light stream of oil. Best to fill it or top it off after its installed on the car. The fill hole is the one on the back.

[angeleye540i]

I've never put my hands on one in that way but knowing what I know schematically about this device it would make sense to me... I played with Capsella as a kid I don't know if anybody remembers that but it was the start of a lot of future engineering

[NordmanMg]

I thought all 540i/6 was with 3.15 by default

[sooch]

I believe it is 2.86 in manuals and 3.15 for autos. I'm sure someone more versed in e39 will correct me..

[NordmanMg]

I feel like I have 3.15 in my '03 540i/6, but might be it there was a difference between regular 540i/6 and m-sport 540i/6

[gmak]

3.15 is the m-sport offering.

[Flounderasu]

I believe it is 2.86 in manuals and 3.15 for autos. I'm sure someone more versed in e39 will correct me..
2.81

[AngelEye5]

Every E39 540i has a 2.81 rear only the 99-03 540i auto sports have a 3.15 gearing. No E39 has LSD except for M5.

[NordmanMg]

Every E39 540i has a 2.81 rear only the 99-03 540i auto sports have a 3.15 gearing. No E39 has LSD except for M5.

I think all 2003 m-tech cars (true m-sports) auto's and manual's have 3.15 (?)

[gmak]

Yes. It's one of the definitions of the M-sport, in my experience looking for them - but I think that I agree with AngelEye5 that it's the automatics only. I haven't seen a 6-speed with 3.15 in my limited experience. :dunno:

[NordmanMg]

When I'm driving on highway at 70 on 5th gear my rpm's are right on 2500,
Anyone with automatic transmission can say what they're rpm's at 70mph?

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If I look to the diff, will I be able to recognize a type of it gearing? It have to have label right?

[ninetyseven1]

When I'm driving on highway at 70 on 5th gear my rpm's are right on 2500,
Anyone with automatic transmission can say what they're rpm's at 70mph?

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If I look to the diff, will I be able to recognize a type of it gearing? It have to have label right?

IMO, all manuals should have come with a 3.15 and all automatics should have come with a 3.38. and they should of given the auto trans the ability to shift into 5th at like 60 mph instead of like 110. That would have been nice! lol

[angeleye540i]

So my 2001 540 Sport6 has its stock differential which I've been told is a 3.15 so my question is which one can I or should I get? I have a stage 4 Dinan setup so my revs are increased, I hit 70 with ease in 2nd gear last night

[angeleye540i]

So my 2001 540 Sport6 has its stock differential which I've been told is a 3.15 so my question is which one can I or should I get? I have a stage 4 Dinan setup so my revs are increased, I hit 70 in 2nd gear last night

[ninetyseven1]

No 6 speed cars came with a 3.15 and software has nothing to do with the gear ratios. If your hitting 70 in second gear then you have a 2.81. with the 3.15 you will barely hit 60 in second but you will be faster overall. Go with Stage 1 or 2 software.

[angeleye540i]

No 6 speed cars came with a 3.15 and software has nothing to do with the gear ratios. If your hitting 70 in second gear then you have a 2.81. with the 3.15 you will barely hit 60 in second but you will be faster overall. Go with Stage 1 or 2 software. well yes it does because it allows me to have higher road speed in each gear if I were to have a different gear ratio in my differential that would add torque and reduce road speed in each gear then the software definitely affects it because if my redline is higher my gear speed is going to be higher than a stock engine with a different differential if I didn't have a higher redline I probably wouldn't even be considering this

[angeleye540i]

I know it doesn't have to do with the gear ratios but it is incentive to change my differential ratio because I can essentially have the same road speed I had when I was running stock but more power and torque with a high revving engine so on you get my point

[angeleye540i]

The only reason I said that is because somebody on another thread told me that I already had the 3.15 differential and I wanted to just make it clear that I didn't because I was pretty sure I had the 2.8

[angeleye540i]

Well that settles it I'm ordering the 3.15... Obviously the software doesn't directly affect the gear ratios in that it doesn't change any gear ratios but it is definitely a reason to consider changing the diff which I am doing unless somebody tells me not to in the next few hours... Some people of said it's like a whole new car I would like to know for myself

[angeleye540i]

No 6 speed cars came with a 3.15 and software has nothing to do with the gear ratios. If your hitting 70 in second gear then you have a 2.81. with the 3.15 you will barely hit 60 in second but you will be faster overall. Go with Stage 1 or 2 software. what I was saying is that I already have the stage 4 software to go with my stage 4 set up which includes the throttlebody cold air intake high flow air mass meter and of course stage 4 software

[ninetyseven1]

well yes it does because it allows me to have higher road speed in each gear if I were to have a different gear ratio in my differential that would add torque and reduce road speed in each gear then the software definitely affects it because if my redline is higher my gear speed is going to be higher than a stock engine with a different differential if I didn't have a higher redline I probably wouldn't even be considering this

One has nothing to do with the other. You should do the 3.15 swap regardless.

[angeleye540i]

OK one last question before I order this thing how many labor hours can I expect if I have a really honest mechanic which I do and he hooks me up on top of his usual honesty and reasonable deals but in general average how many labor hours are we looking at to put this differential in? I don't have the time to do it myself nor do I probably have the tools no I definitely don't have the tools wish I did someday I will I'm going to be buying a whole bunch of tools and a lift to soon and turning my carport into a full function garage anyway the question was how many labor hours to swap out a differential? And that's my last question or post on this thread

[angeleye540i]

And by the way I perfectly understand the relationship between the engine RPMs and the gearbox gear ratios and the differential gear ratios to say the engine revs are not related to the gear ratios and road speed is just not true

[ninetyseven1]

And by the way I perfectly understand the relationship between the engine RPMs and the gearbox gear ratios and the differential gear ratios to say the engine revs are not related to the gear ratios and road speed is just not true

Your car is set up from the factory with a 2.81 ratio in the rear, putting in a 3.15 will make it accelerate faster. You dont need any software to compensate for anything. Its not connected at all.

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OK one last question before I order this thing how many labor hours can I expect if I have a really honest mechanic which I do and he hooks me up on top of his usual honesty and reasonable deals but in general average how many labor hours are we looking at to put this differential in? I don't have the time to do it myself nor do I probably have the tools no I definitely don't have the tools wish I did someday I will I'm going to be buying a whole bunch of tools and a lift to soon and turning my carport into a full function garage anyway the question was how many labor hours to swap out a differential? And that's my last question or post on this thread

It took me 3-4 hours my first time. The second time I took it out and put it back in in under an hour. I suggest you tell your mechanic to re-use your stock out put shafts from your differential. Because depending on what used diff you buy ,the output shafts may not fit. This happened to me when I purchased my 3.15 diff. The output shafts that came with it were too big. This diff supposedly came out of a 2001 740i sport and I put it in my 97' 540i with just a swap of the output shafts.

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I would say count on 4 hours for the average mechanic. Maybe longer to be honest with you. Depends on his skill and if he does his homework first. This is a BMW and requires a lot of attention to detail.

[angeleye540i]

He's a 5 star BMW specialist... He knows his stuff and my other guy altho 120 instead of 100 per hour is A BMW and Dinan specialist been working for or with BMW of North America for 30 plus years... One of those two will be doing the work second is also five star rated (or 4.9)... "Auto Europe" is the mom and pops place and "Performing Imports" is the Dinan place both are in ATL area and very good if anyone in the area needs work done the right way by someone besides themselves.

[angeleye540i]

Your car is set up from the factory with a 2.81 ratio in the rear, putting in a 3.15 will make it accelerate faster. You dont need any software to compensate for anything. Its not connected at all. - - - Updated - - - It took me 3-4 hours my first time. The second time I took it out and put it back in in under an hour. I suggest you tell your mechanic to re-use your stock out put shafts from your differential. Because depending on what used diff you buy ,the output shafts may not fit. This happened to me when I purchased my 3.15 diff. The output shafts that came with it were too big. This diff supposedly came out of a 2001 740i sport and I put it in my 97' 540i with just a swap of the output shafts. - - - Updated - - - I would say count on 4 hours for the average mechanic. Maybe longer to be honest with you. Depends on his skill and if he does his homework first. This is a BMW and requires a lot of attention to detail. I only mentioned the software because I ALREADY HAVE it therefore mentioned it so u can understand my specific motors powerband that's all I just wanted to keep in mind my rev is not limited that's all... And by the way I would NEVER just leave my baby with just anyone I've been driving an 01 540 sport since 04 between two different models and have replaced and done just about any work there is possible to be done to these cars I have learned something the hard way but if there's one thing I know for sure it is who to take my car to but I really do appreciate all the info I'm probably going to order the new diff tonight... I have 60,000 miles on my current clutch which I put in 120,000 miles where my factory original clutch failed but on my first 540 factory original clutch failed at 67,000 The day I bought the damn thing so that tells you something right there I made my second 540s clutch last twice as long as my first one between the wear I put on it and the first owner... Anyway I mention that because This clutch will probably keep going for a good amount of time I don't see it going anytime soon it's definitely not slipping or anything but I'm wondering how much money I could save doing the diff and the clutch at the same time probably not enough but I'll feel really stupid if this clutch goes out a week or even month after I put the new diff on... You know you never can tell with these hydraulic clutches

[angeleye540i]

i'm sorry I wasn't clear with my word choice... I already have the stage four setup and therefore A higher differential gear will be a nice complement to what I already have going... That's all I was ever trying to say

[ninetyseven1]

i'm sorry I wasn't clear with my word choice... I already have the stage four setup and therefore A higher differential gear will be a nice complement to what I already have going... That's all I was ever trying to say

Yes it would be a nice addition I agree

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I want to put in a 3.38 or 3.46 eventually

[mcgnms]

1) All manual transmissions came with a 2.81:1 differential. The manual and automatic transmissions have different ratio's themselves also.
2) A higher Redline in your case is not really that great of a reason to get a 3.15:1. Unless you have some good breathing modifications you're likely to lose average power by shifting past redline and this effect will increase with higher gears.

[angeleye540i]

1) All manual transmissions came with a 2.81:1 differential. The manual and automatic transmissions have different ratio's themselves also. 2) A higher Redline in your case is not really that great of a reason to get a 3.15:1. Unless you have some good breathing modifications you're likely to lose average power by shifting past redline and this effect will increase with higher gears. I have every breathing modification possible made by Dinan on the intake side, hi flow HJS cats and free flow resonator back Magnaflow exhaust... So no headers but pretty much everything else including the high flow throttle body...

[angeleye540i]

Yeah I mean they totally put these gear ratios married to this motor for a reason but I would normally not even think about changing anything if I didn't have the modifications I already have... The stock 540 factory six speed is a total work of art... I've been driving one for the past almost 12 years and just recently got into modifying it... Now that I have all the breathing modifications I wanted along with some software to run them I think the differential is a perfect little icing on the Dinan 5 cake

[loborph]

SO I got the diff in. On my test run I noticed some slop in the drive line. I'm guessing I either damaged the CV joint or my new diff is less than perfect. This slop is a "thump" that I can hear and feel.
It happens when I apply throttle while coasting in gear, and releasing the clutch - most noticeable when starting from a stopped position, and first to second gear. Its seems to run fine, but the thump makes me nervous.

I'm gonna crawl under the car later today to check all my nuts & bolts <script id="gpt-impl-0.4217925881914071" src="http://partner.googleadservices.com/gpt/pubads_impl_75.js"></script>and hopefully diagnose.

Any thoughts?

Is there

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Found it.

Its the new (rebuilt) axles. With the rear end lifted, car in neutral, parking brake off - I can rotate the tires (both sides) just a bit (1/2inch of tire travel) before the axle shaft begins to turn.

I guess I'll run em until they fail.

For reference, the new axles (larger & quite a bit heavier) need M12 x 50mm bolts at the diff. (vs M10 x 43mm)

(I suppose that I could swap out the output flanges with the old diff and re-use my old, smaller axles.)

[philly98540]

The 540 output flanges will not work with the M5 Diff, but there is an output flange from another car that is a direct swap (someone help me here, I forget) that will enable 540 axles to connect to the M5 diff.

What kind of axles did you get?

[JimLev]

E34, E28, and a few other work. I posted info on this same thing a few times.

[TerraPhantm]

Your car is set up from the factory with a 2.81 ratio in the rear, putting in a 3.15 will make it accelerate faster. You dont need any software to compensate for anything. Its not connected at all.


Well, you do need to tweak the software if you want cruise to work. DME determines what gear its in by calculating RPM/kmh

[loborph]

The 540 output flanges will not work with the M5 Diff, but there is an output flange from another car that is a direct swap (someone help me here, I forget) that will enable 540 axles to connect to the M5 diff.

What kind of axles did you get?

the diff is from a regular 540i with automatic. its an open diff with 3.15s - not a LSD. shafts and flanges are larger/heavier.

its possible that the shafts are as they are supposed to be. Since an auto will always provide some forward pressure, the slop would not be noticeable. Only when power is taken off the drivetrain do i feel the thud of power being returned to the wheels.

[RocketSurgeon]

I wanted to mention that my 540I also has the 3.15 differential swap, and I too have the thump. The axles have zero play, but the input shaft has perhaps 20 degrees of play in it. I can only surmise that the used diff is worn out. When the car is held in place with the brakes, and cycled between reverse and drive, the input shaft will click back and forth, but the output shafts don't move at all. Perhaps the sport differential was built with slightly greater tolerance, or more likely, my diff is just shot. I'll probably just swap my original diff back in and check the 3.15.

[angeleye540i]

I had the same thump when my driveshaft needed replacing... It was the worst when launching in first or starting in second from slow speed...I have a retro fitted M5 LSD