Installed a S3.73 in the ol' 535

[Stir Fry A Lot]

I'm very happy with it. It's a bit more high strung than I'd prefer but it is always on cam and the exhaust note is beastly at all speeds. I noticed the difference coming from the 3.64 much more so than when I bumped it from 3.46. Overall I'm very pleased. Just from my initial impressions I think I may actually start minding my gas milage a bit more now though. But then again the constant fun factor of it more than outweighs the drawbacks. I'd say its the ideal ratio for driver's that are a bit younger. I'll be fine with it for a few more years though :D

[5senses]

I'm very happy with it. It's a bit more high strung than I'd prefer but it is always on cam and the exhaust note is beastly at all speeds. I noticed the difference coming from the 3.64 much more so than when I bumped it from 3.46. Overall I'm very pleased. Just from my initial impressions I think I may actually start minding my gas milage a bit more now though. But then again the constant fun factor of it more than outweighs the drawbacks. I'd say its the ideal ratio for driver's that are a bit younger. I'll be fine with it for a few more years though :D
Did u do a dyno with the previous differential as well as plan on doing 1 with the current differential?

[jfj707]

Did u do a dyno with the previous differential as well as plan on doing 1 with the current differential?

?

[MarchelloBB]

?

Dyno test. Due the the question mark, i'm guessing you didn't though, it doesn't really matter.

[makaveli2k]

Changing the Differential isn't going to change HP numbers.

[5senses]

well whats the butt dyno telling you?... realistically gimme a ballpark #

[jfj707]

Dyno test. Due the the question mark, i'm guessing you didn't though, it doesn't really matter.

Below is what I was referring to. Gearing doesn't change HP....


Changing the Differential isn't going to change HP numbers.

[Stir Fry A Lot]

Butt dyno says that it woke my ass up by quite a bit over not just the 3.46 but also the 3.64 as well. I had no idea that I would feel it that much since the difference was even less than the first lowering I did. Its still limited by the motor but there is a much greater amount of push going through the gears.

[kipwinger]

So, you found one. I was just getting ready to PM you since I just pulled a S3.64 out of my e32. Let me know if you want to trade....


BTW I love my S3.73 mated up to the M30.

[Stir Fry A Lot]

So, you found one. I was just getting ready to PM you since I just pulled a S3.64 out of my e32. Let me know if you want to trade....

No way Jose :stickoutt although I do miss the civilness of the 3.64.


So, you found one. I was just getting ready to PM you since I just pulled a S3.64 out of my e32. Let me know if you want to trade....


BTW I love my S3.73 mated up to the M30.

It is a great ratio for it. Very glad I didn't go 3.91. First is just where I want it.

[kipwinger]

Well fine. I'll just have to live with option to change from 3.46 to 3.64 to 3.73.

[5senses]

So, you found one. I was just getting ready to PM you since I just pulled a S3.64 out of my e32. Let me know if you want to trade....


BTW I love my S3.73 mated up to the M30.
Do tell.. whats the difference even with the S? gears? ratios?

[thesixerkid]

+1

I put my 3.73 about a month ago and I love it. I have the same set-up: b35 w/ a 260/6.

FWIW, I used to have a 3.46 (still for sale btw) in this car.

I also used to have a 3.91 in my m30b35 powered '89 635csi before I turbo'd the car. 1st was too short as was 5th.

The 3.73 is the perfect match for this engine and transmission.


Do tell.. whats the difference even with the S? gears? ratios?

The "s" means a limited slip.

[Stir Fry A Lot]

S means one tire don't spin, both of 'em do. Posi traction if you will.

[535ipower]

Do tell.. whats the difference even with the S? gears? ratios?
I believe the S stands for having a LSD..

[5senses]

so my 25%lsd could possibly be the 3.91

[thesixerkid]

so my 25%lsd could possibly be the 3.91
Look on the back tag.

[Stir Fry A Lot]

Your's a stick or automatic? They have different gearing ratios. The lower it is the faster off the line it goes. Most came with 3.46's and some came with S3.46's. You can look under the back of the car and look for the tag hanging off the back to see what you have. I think with autos you can go down to a S4.27. Its more wear on your engine and tranny though.

[m60b30530i]

try a 4.10lsd , i like it around town but the high way is a killer.

[Stir Fry A Lot]

F-that, I can and will only imagine.

[m60b30530i]

F-that, I can and will only imagine.

along with a stage 3 clutch, its insane in traffic lol. but its also a diff destroyer no popping of the clutch for me. it will chirp up to 4th but i don't drive like that anymore after the first diff went :stickoutt. plus when i do go FI i will want a 3.15lsd or something a little higher but for now i like them.

[KyleCleveland]

How long did it take for you to swap? Maybe next summer we hit up infineon and run a few 1/4s.

I bet your 535 is on par with my 540 on the strip now.

[kipwinger]

That's straight up ridiculous.

[screwbiedoo15]

Very cool, Max. After tuning and this your car must be pretty damn quick...

[Stir Fry A Lot]

I can honestly say that it is now. We should meet up sometime so you can try the 3.73. 2nd, 3rd and fourth are bananas. The acceleration has quite a bit of punch to it now. I originally thought this ratio would only make the car a little more anxious without much benefit but this .09 really turns it into a whole 'nother car.

The 3.64 would still require a fair amount of throttle just to get my 245s to dig even just a little but the new ratio has it springing from every stoplight now.

[ILoveMPower]

Just the reaction I wanted to see. It seems like myself and you StirFry has similar taste in mods and I was questioning if it would be worth it to go with the 3.73. Thanks for making the answer obvious

- JK

[Stir Fry A Lot]

This is definitely the diff to have no doubt. I edited my previous post with a little more info in case you missed it. Both Screw and I did our 3.64s around the same time and neither of us wanted to change the dynamics of our cars too drastically. The 3.73 changes it drastically but for the better. We both agreed that while we felt the '64 it was really quite a mild upgrade. There was still a small dead zone before it started to breath just like the stock 3.46. With the 3.73 everything moves very seamlessly in perfect visceral harmony now. Viva la B35!

[bigsixe34]

hey max where did you find your diff? i've wanted for some time to shorten the gearing on mine as well, preferably to 3.73. i kinda predicted something along the lines of what you said in the 3.64 not making much difference. since i got my car i haven't come across a 3.73 for sale either... :(

[Stir Fry A Lot]

a friend of the shop gave his m20/5 e34 to us to salvage. My 3.64 had just pooped out so I threw it in.

[kipwinger]

You can find a 3.73 in the early M5 and the m20 525i. At least this is what I have come to understand.

[bigsixe34]

You can find a 3.73 in the early M5 and the m20 525i. At least this is what I have come to understand.
sweet. i thought it was exclusive to the M5. should make the hunt a little easier :stickoutt although i would imagine an LSD in a stock m20 car would be a bit hard to come by?

[kipwinger]

I'm not sure but, If it has the cold weather package then it should have a LSD.

[Stir Fry A Lot]

they seem pretty abundant in California. I imagine even more on the eastcoast. From what i've read the internals from e30 small case diffs are interchangable if you get too hard pressed to find an oem one.

[bigsixe34]

they seem pretty abundant in California. I imagine even more on the eastcoast. From what i've read the internals from e30 small case diffs are interchangable if you get too hard pressed to find an oem one.

i guess so maybe, just gotta keep my eye out more. you know, there's never been much desire in me to be hitting all the m20 e34s in the lot when i go...:stickoutt

[Stir Fry A Lot]

Its definitely worth a look for the diff. I finally feel like I'm getting the most out of my car and all the goodies I've added to it. Its even lowered my desire to turbo it by a smidge. I don't know what was in that .09 but it sure has given me a new appreciation for my frankenjalopy. I had actually recently began to become a bit disenchanted with it but after the first mile I immediately regained my faith. /rave

[screwbiedoo15]

You can find a 3.73 in the early M5 and the m20 525i. At least this is what I have come to understand.

Isn't the 3.73 out of an m5 a large case diff?

[kipwinger]

I believe so. I want one bad.

[5senses]

So look for an early M20? If so there's 1 @ pull apart and i'll get it this week!!!!
If need b i'll send u a pm or email while im there stirfryalot.. thanks

[Stir Fry A Lot]

yeah, look for the tag and make sure it says s3.73. So your car is a 5 speed? I'll pm you my number. Just text me if you have any questions.

[PorscheH6]

Wanna race? :D

I'm still pissed I lost you and Eric after the meet last year...stupid San Francisco..

[Stir Fry A Lot]

That's your side moreso than ours. lol. And coming from one asian to another its the driver not the car :stickoutt

[merikgvr4]

Stir, what rpms are you running at say 75mph? I got a tranny and driveshaft for my swap and researching which rearend I will use for my touring. TIA.

Erick

[Stir Fry A Lot]

Less than 3k but you'll want a lower ratio for a touring I believe. You also have a different engine so my car would not be the best example.

[thesixerkid]

I'm around 3K rpms at 75mph with a 235/40/17 tire.

Depends on the tranny thats attached to the motor

[merikgvr4]

ok, thanks to you both for the replies.