BMW E30 Differentials Guides

[Zoggee]

In response to a thread http://www.bmwclubmalaysia.com/forums/showthread.php?t=27899&page=2maybe this would help.

 

[B33mEr]

.............

 

[kissmatt]

I start with question..
My 320 using 4.10 LSD..
Started to use last year..
But now I face a problem!!
The diff made loud noise..
I did replaced diff oil last month..
Found out lots of metal chipping..
Any clue what went wrong inside the diff?

 

[Zoggee]

I start with question..
My 320 using 4.10 LSD..
Started to use last year..
But now I face a problem!!
The diff made loud noise..
I did replaced diff oil last month..
Found out lots of metal chipping..
Any clue what went wrong inside the diff?

wrong diff. oil? but most LSD makes noises due to wear and tear. using the wrong flange,wrong shims,wrong torque tightening pressures..wrong driving style? better get a spare.

 

[AAM]

just want to know - what is the most suitable rear differential ratio for E30 M20 mod to 3.5L ( M ) engine ?

mine have an issue - can only speed up to 160km/h when the tachometer reading touches the redline !!!


is it a rear dif. issue or something else ?


thanks.

 

[fabianyee]

I start with question..
My 320 using 4.10 LSD..
Started to use last year..
But now I face a problem!!
The diff made loud noise..
I did replaced diff oil last month..
Found out lots of metal chipping..
Any clue what went wrong inside the diff?

Loud noise? lots of metal chippings??? can be worn crown and pinion gears... it will whine like a pig... Can also be worn bearings... better to open it and see what's the condition of the gears.

just want to know - what is the most suitable rear differential ratio for E30 M20 mod to 3.5L ( M ) engine ?

mine have an issue - can only speed up to 160km/h when the tachometer reading touches the redline !!!


is it a rear dif. issue or something else ?


thanks.

M20 mod to 3.5??? U mean you're using the M30 3.5 engine???
What rear diff ratio are u using? auto or manual gearbox??
ur issue is definitely incompatible final drive ratio for the engine and gearbox.

 

[AAM]

Loud noise? lots of metal chippings??? can be worn crown and pinion gears... it will whine like a pig... Can also be worn bearings... better to open it and see what's the condition of the gears.


M20 mod to 3.5??? U mean you're using the M30 3.5 engine???
What rear diff ratio are u using? auto or manual gearbox??
ur issue is definitely incompatible final drive ratio for the engine and gearbox.

fabian, thanks for your comment/inputs.

yes , mod to 3.5 L ( Manual ) - M30 3.5 engine, manual gearbox.

Rear diff ratio - dont know - will check it afterward.

Need help to address this issue n to optimise its performance:

1. What should be the ideal rear diff ratio/final drive ratio

2.Any advice on the size of the exhaust piping/silencer boxes

3.Any advice on the fuel pump change


P/s: Bought the ride, 2 doors wide body 2yrs ago on " as is where is basis " - no details on the mods done and have not done any major repairs/parts replacement, other than normal servicings. Suspension, i think was upgraded to stiffer sets.

thanks.

 

[r37720]

is it true difference ratio gives different acceleration performance?

 

[Jules]

is it true difference ratio gives different acceleration performance?

think of your bicycle which can change gears........

 

[r37720]

think of your bicycle which can change gears........

for my current rides 2.5L - 6 cylinders motronics manual transmission, I am currentl using 3.73. Is this the best or can I optimised it further. Someone told me should go for 4.1

 

[fabianyee]

fabian, thanks for your comment/inputs.
yes , mod to 3.5 L ( Manual ) - M30 3.5 engine, manual gearbox.
Rear diff ratio - dont know - will check it afterward.
Need help to address this issue n to optimise its performance:
1. What should be the ideal rear diff ratio/final drive ratio
2.Any advice on the size of the exhaust piping/silencer boxes
3.Any advice on the fuel pump change


P/s: Bought the ride, 2 doors wide body 2yrs ago on " as is where is basis " - no details on the mods done and have not done any major repairs/parts replacement, other than normal servicings. Suspension, i think was upgraded to stiffer sets.

thanks.

stock M20 2.5 manual comes with 3.73 final drive... for your manual 3.5, u can probably use that or a lower ratio like a 3.45 or 3.25..

for my current rides 2.5L - 6 cylinders motronics manual transmission, I am currentl using 3.73. Is this the best or can I optimised it further. Someone told me should go for 4.1

4.10 on your M20 2.5 would enhance the acceleration... but engine RPM would be higher at the same speed once you swap from 3.73 to 4.10...
IIRC, for 3.73, your RPM should be about 2500rpm at 100kph. for 4.10, RPM would be 3,000rpm at 100kph...

 

[AAM]

stock M20 2.5 manual comes with 3.73 final drive... for your manual 3.5, u can probably use that or a lower ratio like a 3.45 or 3.25..





fabian, thanks a lot. will be posting on the progress of this issue. :top:

 

[Zoggee]

AAM if you got time,search google for BMW ETK. Lots of stuff to see from there.

 

[r37720]

4.10 on your M20 2.5 would enhance the acceleration... but engine RPM would be higher at the same speed once you swap from 3.73 to 4.10...
IIRC, for 3.73, your RPM should be about 2500rpm at 100kph. for 4.10, RPM would be 3,000rpm at 100kph...

This also means the fuel consumption will be high right?

 

[kissmatt]

Loud noise? lots of metal chippings??? can be worn crown and pinion gears... it will whine like a pig... Can also be worn bearings... better to open it and see what's the condition of the gears.

TQVM fabianyee..
I should open up the diff sooner..
Hopefully my worn crown and pinion gears still OK..
If bearings, then straightaway i will replace them..

BTW, sometimes my diff feels disengage..
Even though i'm throttling, but i feel my tires has no force acts on it..
Like you push clutch while car is running..
Emm.. Hard to explain..
Any ideas, what went wrong?

 

[AAM]

AAM if you got time,search google for BMW ETK. Lots of stuff to see from there.

Zoggee, thanks.:top:

 

[Jules]

for my current rides 2.5L - 6 cylinders motronics manual transmission, I am currentl using 3.73. Is this the best or can I optimised it further. Someone told me should go for 4.1

I am no guru but for a large capacity - u dun want ur engine to be revving faster than necessary....so AFAIK, the 4.10 were for the punny 1.8! My 323 uses a 3.25 and i think the E30 M3 as well.

Mind you, it also depends if auto or manual so a search on ETK to confirm is best.

 

[fabianyee]

I am no guru but for a large capacity - u dun want ur engine to be revving faster than necessary....so AFAIK, the 4.10 were for the punny 1.8! My 323 uses a 3.25 and i think the E30 M3 as well.

Mind you, it also depends if auto or manual so a search on ETK to confirm is best.

your 323 running dogleg gearbox with different ratios... 5th gear is 1:1 vs the usual 1:0.8...

 

[AAM]

stock M20 2.5 manual comes with 3.73 final drive... for your manual 3.5, u can probably use that or a lower ratio like a 3.45 or 3.25..





fabian, thanks a lot. will be posting on the progress of this issue. :top:

update on the issue : guess what......the metal tag ( screwed to rear diff. ) indicated the final drive ratio is 3.45! ........... so how come my ride cant run ?

so my conclusion........my answer is as good as anybody......... the tag was switch........but the rear diff.......

hopefully ,to get the guinine one soon......3.45 ratio.

 

[fabianyee]

update on the issue : guess what......the metal tag ( screwed to rear diff. ) indicated the final drive ratio is 3.45! ........... so how come my ride cant run ?

so my conclusion........my answer is as good as anybody......... the tag was switch........but the rear diff.......

hopefully ,to get the guinine one soon......3.45 ratio.

before u do anything... What the RPM in 5th gear when the speedo is showing 100kph???