97 m3 4/5.....rear diff ratio info

[jrkoupe]

greetings my pals


...97 m3 4/5...its had 4 owners, all well versed in mods and mature choices. Im wondering if the diff is still stock ratio?...seems torquey and strong



I know tire size/ wheel size matters .......BUT!



pls share what your rpms are in 5 th, and what your diff ratio is.....

at 70 mph....

at 80 mph?.....


thnx!!!


PS:
only 17 inchers w/ 235 to 255 need reply....wink wink

[marcva]

I'll let you know when I get out on the highway, but these cars rev a little high in the highway.

Marc
1997 m345, 193k

[marcva]

Also, I went to 7.5s ask the way around and run the stock 235s. My next tires will likely be 225/45s. Plenty for how I use the car these days.

[pbonsalb]

Look at diffsonline under the technical tab. Use the spreadsheet and plug in your rear tires and 3.23 and 3.38 and 3.46 and 3.64 to see where your car matches up in 5th, which is 1.00 ratio, for a given speed.

[jrkoupe]

Look at diffsonline under the technical tab. Use the spreadsheet and plug in your rear tires and 3.23 and 3.38 and 3.46 and 3.64 to see where your car matches up in 5th, which is 1.00 ratio, for a given speed.

where is the spread sheet option ?...I do not see it

thnx

[blckstrm]

It's at the top of the technical page:

https://diffsonline.com/bmw-differen...formation.html

You could also have a 3.15 - we just found one in a 97 sedan with a manual swap. Super disappointing for my friend who just bought it, but they must have had to replace the original at some point and just bought what was available.

[jrkoupe]

I found another site.

3.38 rear 245/40 70 mph 3218 rpm
3.23 " " 3076

etc etc

[scoobiedoo2029]

I found another site.

3.38 rear 245/40 70 mph 3218 rpm
3.23 " " 3076

etc etc

there is a tag on the rear passenger side of the diff cover stamped with the ratio unless someone removed it.


prety sure all manual 1995 m3's are 3.15 all manual 96+ are 3.23 and the automatics are a 3.38. all are lsd. i think all the later non M cars have open diffs because of the asc-t and the early 325is's got a lsd. I dont recall ratios.they are all 188mm diffs like an e30. the 210mm diffs are a euro m3 part and i think some crap box e36's got a small case diff. 168mm? i saw a 2.93 at carisle this weekend no idea what it came out of.


the stock 3.23 setup is rather mean for an oem. the trans ratios are the same as a e46 m3 without a 6th gear and that has a 3.73 diff. but that is around 4000 rpm in 5th at 75mph. but 3rd would feel so much better...

[blckstrm]

the stock 3.23 setup is rather mean for an oem. the trans ratios are the same as a e46 m3 without a 6th gear and that has a 3.73 diff. but that is around 4000 rpm in 5th at 75mph. but 3rd would feel so much better...

It's all about 0-60 times for the oems. It's also about making your new car faster than the old one. The heavier E46 needed the higher redline and shorter diff to be faster to 60 than the E36 Evo.

In a similar vein, this is how we got the 3.23 in the US car. A 3.38 swap is faster, but you have to shift right before 60 given the stock car's redline, which makes it too slow to 60. It all makes sense when you play with the gearing calculator.

[GG///M3]

It's at the top of the technical page:

https://diffsonline.com/bmw-differen...formation.html

You could also have a 3.15 - we just found one in a 97 sedan with a manual swap. Super disappointing for my friend who just bought it, but they must have had to replace the original at some point and just bought what was available.

I love 3.15 gears


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[pbonsalb]

With more torque.

[scoobiedoo2029]

I love 3.15 gears


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whats your thought on the "feel" of that gearing going into 3rd from 2nd at normal driving?

my stock s52 driveline makes me want a 3.36/3.46 to quicken up 3rd in normal DD shift from 2nd.. but i wonder if carrying 1st and 2nd out longer with a 3.15/2.93 might be a better feeling setup.

dont really want to increase the highway rpm. theise cars are like a 4 speed on the highway, and traffics moving at 80 nowadays or im getting run over.

[blckstrm]

whats your thought on the "feel" of that gearing going into 3rd from 2nd at normal driving?

my stock s52 driveline makes me want a 3.36/3.46 to quicken up 3rd in normal DD shift from 2nd.. but i wonder if carrying 1st and 2nd out longer with a 3.15/2.93 might be a better feeling setup.

dont really want to increase the highway rpm. theise cars are like a 4 speed on the highway, and traffics moving at 80 nowadays or im getting run over.

I'll grant it might be more revs than you want, but these things are more than capable of 80 mph.

A 3.38 is like most mods for these cars - noticeable, but not jaw dropping.

[GG///M3]

whats your thought on the "feel" of that gearing going into 3rd from 2nd at normal driving?

my stock s52 driveline makes me want a 3.36/3.46 to quicken up 3rd in normal DD shift from 2nd.. but i wonder if carrying 1st and 2nd out longer with a 3.15/2.93 might be a better feeling setup.

dont really want to increase the highway rpm. theise cars are like a 4 speed on the highway, and traffics moving at 80 nowadays or im getting run over.

Like like the 3.15 on turbo setup cars. Also 2.93 with a turbo setups as well


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[pbonsalb]

Hard to have your cake and eat it, too. I have run 3.15, 3.23, 3.38 and 3.64. I really enjoyed the 3.64 around town and it was tolerable for a short highway drive but no fun if you like to cruise at 80-85. Buzzing along at 4000 was not much fun in the E36. I did not mind so much in the E90M3 but that is a different kind of engine.

The 3.38 is probably as far as I would go in a daily driver E36 that does roadtrips unless I was a 65-70 mph driver. The 3.15 seems so relaxed in comparison. If you can get the performance you want with one, or, even better, a 2.93, think about it. I used to drive my 99 528i that had a 2.93 and think about how civilized it was and what a great highway cruiser it was compared to my E36 with 3.23 or 3.38 or 3.64.

With the shorter diff, it helps to mod to continue to make power to higher rpm so you can shift later. M50 intake, cams, headers, midpipe, etc., and a 7000-7200 rpm limiter.

With the 3.64, I was seriously thinking about a 6 speed swap. Instead, I changed from a centrifugal supercharger to a turbo and had so much torque that I went back to a 3.15 and it was so fast that I thought about a 2.93. It was also really pleasant to have relaxed cruising again.

A 2.93 would be great but they are custom since the 188 E36 case did not come with one in LSD form in the US and you can’t swap the gear into the E36 LSD. You have to use the old E30 188 LSD.

I changed to a 6 speed for transmission durability purposes a couple of years ago and really like the 6th gear. Still on a 3.15, but it is a 210 so I could swap in 2.93 gears if I wanted (it’s not that simple, but I have a friend who could help). Anyway, the overdrive gear is really nice on the highway. Think about one at some point if it is a mod you can afford and it fits your needs. Download the spreadsheet under the technical section at diffsonline and plug in various diff ratios, your tire sizes, and look at the 1.00 5th and the 6th gear rpm for Getrag 0.80 — ? and 0.88 for ZF.

[scoobiedoo2029]

A 2.93 would be great but they are custom since the 188 E36 case did not come with one in LSD form in the US and you can’t swap the gear into the E36 LSD. You have to use the old E30 188 LSD.

really? . i was under the assumption that all these diffs where the same 188mm deal but in a different housing and one could swap parts around with normal diff building

i still have several e30/e28 lsd diffs i kept for this reason. the 3.23 in my m3 is lowest i have but there is a 3.46 a 3.73 an a 4.10 in my shed. so i cant diversify my semi useless part pile with non M e36 parts?


ive been thinking of modifying a e36 rear subframe to accept the 4 point mounting of the older diffs. only because i have 3 of them and they have 4 bolt input flanges that might bolt up maybe. really i think im just keeping parts to make sure my shed dosnt blow away,

[pbonsalb]

E36 188 LSD can go longer to only 3.15 but can go shorter without issue — like 3.91 or shorter. I forget the details. The fix is the LSD guts from a 6 cylinder E30 but I also forget the details. 2.93 LSD is possible that way.

Don’t know about fitting the entire diff from an older car but it can probably be done. I run an E32 750il 3.15 LSD in my E36 subframe with some modifications.

[RRSperry]

I've had a 3.38 40% lsd in my car with both the stock 5 speed and the E46 M3 6 speed. IIRC, with the 5 speed it was about 3,700 rpm at 80ish.. With the 6 speed is like 3,100.. My 6 speed is noisier than the 5 speed was.

[bimma360]

I stumbled onto this really good calculator during my own research.

https://www.endtuning.com/gearratios/