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View Full Version : Just install my new 4.10 Diff


MatyBMW
04-29-2004, 01:28 PM
Well, BMW Mississauga just installed my 4.10:1 differential. Going from a 3.73 to a 4.10 is a great upgrade and I suggest it to any E30 325 owner. Excellent value.

Since my older diff was wining a bit I decided to replace it. Now I notice significantly better acceleration, especially in 3rd, 4th and 5th.

The car is now even more of a joy to drive :)

Mystikal
04-29-2004, 03:32 PM
An internally stock M20B25 is actually slower with a 4.10. Not in higher gears as you mentioned, but then again you're burning plenty more gas.

MatyBMW
04-29-2004, 03:58 PM
I'm only burning 'plenty' more gas if i utilize my vehicle in a higher RPM range. If I keep the RPM's at the same limit as I normally drive plus accelerate at the same pace, theoretically I should consume the same amount of gas.

The only problem you run into is when you drive in 5th on the highway. Your RPM's will be higher at fast highway speeds.

Slowered318
04-29-2004, 04:42 PM
Originally posted by Mystikal
An internally stock M20B25 is actually slower with a 4.10. Not in higher gears as you mentioned, but then again you're burning plenty more gas.

what do you mean by slower? top speed or 1/4 mile?

the taller gear in the back increses torque to the wheels therefor using more of the engines power to exherate :)

It's like using a longer lever to pry up a rock :confused:

Mystikal
04-30-2004, 02:17 AM
Nah, it's just way too short for the engine's power curve. With a 4.10 you actually get through the meaty part of an M20's powerband too quicky, and the 0-60 and 1/4 both suffer. It "feels" faster, but it's really not.

And you're burning more gas ALL the time. No matter what speed you're travelling at, the RPMs are higher and therefore there is more fuel in the mixture.

bmwm5lover
04-30-2004, 02:33 AM
im happy with my 3.73, maybe a 3.9 sumtin later on :D

The Sly
04-30-2004, 02:44 AM
A 4.10 in a E30 325 i or IS is faster than the E30 M3..That is why they put the 3.73 in the 325i back in those days ..
If the 325i would of been faster with the 4.10, it would not justify paying more for a slower E30 M3....

Slowered318
04-30-2004, 04:28 AM
Originally posted by The Sly
A 4.10 in a E30 325 i or IS is faster than the E30 M3..That is why they put the 3.73 in the 325i back in those days ..
If the 325i would of been faster with the 4.10, it would not justify paying more for a slower E30 M3....

there could be some truth in that.. but i think it's mostly to give the 325 slightly better fuel economy.. but other 5spd. E30's are 3.96 or higher (m3, 318is,325ix)

my 318is is a 4.10 and i get 500 km's to a tank.. so go figure... it would be so slow with a 3.73 diff! and i bet you any money that i would go faster in the 1/4 mile if i droped in a 4.4... cause at the end of the 1/4 mile i just top 3rd.. so if i could get more into 4th id benifit cause 3rd gear takes way too long in the E30's

Jordan
04-30-2004, 05:00 AM
Selected Cars: 1. BMW 325IS 1987 STOCK
2. BMW 1987 325IS 4.10
3. BMW M3 1989

Car Number 1 2 3
--------- --------- ---------
Time to Speed
0-30 mph.... 2.3 - 2.3 - 2.4
0-40 mph.... 4.1 - 4.0 - 3.3
0-50 mph.... 5.4 - 5.3 - 5.4
0-60 mph.... 7.8 - 7.7 - 6.9
0-70 mph.... 9.9 - 9.6 - 8.8
0-80 mph.... 12.2 - 12.1 - 12.1
0-90 mph.... 16.1 - 15.9 - 15.0
0-100 mph.... 20.1 - 19.6 - 18.4

Time to Distance
0-100 ft..... 3.3 - 3.3 - 3.2
0-500 ft..... 8.6 - 8.6 - 8.4
0-1320ft..... 15.7 - 15.8 - 15.5
@ mph .... 89.0 - 89.5 - 91.5

Top Speed.... 138 - 134 - 141

5-60 mph, 1st
Gear Start... 7.4 - 7.2 - 6.9

30-50 mph
2nd Gear..... 2.4 - 2.3 - 2.9
3rd Gear..... 4.1 - 3.7 - 5.2
4th Gear..... 6.7 - 5.8 - 8.8
5th Gear..... 9.5 - 8.0 - 12.9

50-70 mph
2nd Gear..... 3.3
3rd Gear..... 4.1 - 3.7 - 5.1
4th Gear..... 6.4 - 5.6 - 8.3
5th Gear..... 8.9 - 7.6 - 12.0

Mystikal
04-30-2004, 01:43 PM
So the 0-60 and 1/4 times are a dead heat, but the passing times show a good improvement. Fair enough. This is if you can live with the sky-high revs at 140km/h and resultant decrease in mileage though.

Bob Loblaw
04-30-2004, 02:45 PM
You shouldn't be driving 140 km/h anyways. ;)

Eurostyle
04-30-2004, 05:10 PM
Originally posted by Mystikal
So the 0-60 and 1/4 times are a dead heat, but the passing times show a good improvement. Fair enough. This is if you can live with the sky-high revs at 140km/h and resultant decrease in mileage though.

I still dont know why you think the revs would be sky-high!? I went from 2.73 to 3.91 and it was just noticable, even highway speeds, gas did not suffer; went to Quebec city with the same $$$ as usual...

elraton16
05-14-2004, 03:34 AM
i know this is kind of an old thread but heck...

i have a 4.10 diff in my car but it isnt stock. It hauls ass and i suggest it........if your okay with really really burning gas. i mean really.

objec
05-14-2004, 11:49 PM
Mystikal is right

the ratio goes with the tranny, the power you feel is just torque, it will slow you down top speed ,

i went from a stock 325e diff to a 4.1 and it was 100mph at 3500 rpms. mpg will suffer, i did not relize until i had it on the highway.

snd84318i
05-15-2004, 12:43 AM
ok so whats the difference here . the higher the number the faster your take off? but the lower the number the faster your top end? is there a way to tell from your vin # wha tsize diff your car came with ? how about tranny gears couldnt you get those changed to help in the top gears with the higher diff? thanks

felixthecat
05-15-2004, 01:18 AM
you can tell what diif is in your car(if its stock)just by the model...
and a higher gear (4:11)will give you more torque whereas a lower number(2:90) will give you better fuel economy and top end..
the 325is is perfect with a 3:73....
and slowered,318's have a 3:46.....

_dk_
05-16-2004, 01:00 AM
perfect? i beg to differ- going from 3.73 to 3.91 in my car helped acceleration a LOT- and i turn 3200rpm crusing at indicated 70mph(~115kph?) on the freeway. works very well for me...

felixthecat
05-16-2004, 01:06 AM
where did you get a 3:91???

_dk_
05-16-2004, 01:16 AM
mine's from an e28 M5. i hear you can also get one out of a manual e30 325ix.

felixthecat
05-16-2004, 02:13 AM
huh...thats good to know,thanx for the info*th-up*

_dk_
05-16-2004, 02:37 AM
np :)