Author Topic: Is a 3.25 LSD too tall for the m42? (Read 6540 times)

KyleTaylor · « **on:** August 13, 2008, 10:22:14 PM »

I drive the interstate most of my miles, and would like to have a quiter ride. the four banger is nice and calm below 3000, and 75 mph is more like 4000...

I have a 3.25 LSD that I have been trying to sell with no sucess that I would like to put to use... can anyone comment with experience in using a 3.25 in place of the 4.10? I have read that the 3.73 is perfect, but I have what I have.

KenC · « **Reply #1 on:** August 14, 2008, 09:13:12 AM »

I think your acceleration would be greatly diminished.

Why not just pop it in and give it a try?

tjts1 · « **Reply #2 on:** August 14, 2008, 12:23:06 PM »

Give it a try. I think you'll be happy with it. The poor acceleration argument is greatly exaggerated. I've been using a 3.64 differential for over a year and I would never go back. I would like to go a bit taller still. Maybe a 3.44 out of a 318ti.

Frankie · « **Reply #3 on:** August 14, 2008, 01:44:28 PM »

I just bought a 3.73. Is there a big difference between that and 4.10?

EN318isPDX · « **Reply #4 on:** August 14, 2008, 01:54:43 PM »

I could have sworn i saw a thread where someone link to a web site that will tell you where you rev will be with different gearing.

nuvolarossa · « **Reply #5 on:** August 14, 2008, 03:20:50 PM »

http://diffsonline.com/techinfo/GearingCalculator.xls

put e30 gearing ratios in it and enjoy

gjuuu · « **Reply #6 on:** August 14, 2008, 03:45:15 PM »

one with the e30 gear ratios already in it
http://members.dodo.com.au/~wawawa/

tjts1 · « **Reply #7 on:** August 14, 2008, 04:04:29 PM »

Quote from: Frankie;54873

I just bought a 3.73. Is there a big difference between that and 4.10?

http://www.m42club.com/forums/showpost.php?p=26477&postcount=28

Boyracer · « **Reply #8 on:** August 15, 2008, 10:09:13 AM »

Quote from: Frankie;54873

I just bought a 3.73. Is there a big difference between that and 4.10?

If you do not need that 4.1 anymore I could accept it as part exhange for camshafts

Open 4.1's go for 50-75� in ebay but shipping to finland is biatch... I would prefer 4.27 or even shorter but they seem rare.

Did few simulations on Cartest software:

E30 318is 4.1:

0-40 kmh 1.9 s
0-60 kmh 4.2 s
0-60 kmh 6.1 s
0-100 kmh 9.8 s
0-120 kmh 13.2 s
0-140 kmh 18.8 s
0-160 kmh 25.4 s
0-180 kmh 38.6 s
top speed 200 kmh

E30 318is 3.73:

0-40 kmh 2.1 s
0-60 kmh 4.4 s
0-60 kmh 6.5 s
0-100 kmh 10.1 s
0-120 kmh 13.7 s
0-140 kmh 19.2 s
0-160 kmh 26.3 s
0-180 kmh 37.6 s
top speed 201 kmh

3.73 diff gives slightly better combined fuel consumption but I suspect this is not what you are after

Frankie · « **Reply #9 on:** August 15, 2008, 03:46:26 PM »

Well, that is not bad...we will soon see the difference

I lose so much time on track without LSD.

My friend bought a 4.27 LSD from BTCF forum few days ago...dammit. Price was 300 euros.

Boyracer · « **Reply #10 on:** August 15, 2008, 04:07:51 PM »

Quote from: Frankie;54949

My friend bought a 4.27 LSD from BTCF forum few days ago...dammit. Price was 300 euros.

Lucky motherfecker! Price seems low for any LSD, let alone short geared one!

I need to buy new set of cogs for my current 3.45 LSD to make it shorter and it needs to be done by expert = expensive. Might as well modify 25% lockup to 40% or even stiffer at the same time...

kiulu · « **Reply #11 on:** August 16, 2008, 01:31:09 AM »

Quote from: Frankie;54949

Well, that is not bad...we will soon see the difference I lose so much time on track without LSD.

My friend bought a 4.27 LSD from BTCF forum few days ago...dammit. Price was 300 euros.

I'll bet that he bought it from me..

Boyracer · « **Reply #12 on:** August 16, 2008, 04:19:14 AM »

Well, do you have another to sell?

kiulu · « **Reply #13 on:** August 16, 2008, 04:39:33 AM »

Quote from: Boyracer;54972

Well, do you have another to sell?

Unfortunately no..

Boyracer · « **Reply #14 on:** August 16, 2008, 08:16:01 AM »

Quote from: kiulu;54973

With: m47n crank, holset hx40 super, tial 60mm wg, tilton 3-plate cluth, itb's, eagle, wiseco, etc...

That parts list looks promising. Could you start new thread on buildup section about your project?

ITB's (S50B30 or some other?), Tilton multiplate clutch + flywheel and M47 crank are something that I'm ptaricularly interested