kolosy build / track journal-ish

as far as NA-based diff providers, I'm a bit interested in OS Giken Spec-S. I think driftflo's dislike for them stems from them only doing tuning on their own, and their OTS setup not being great. since iirc they are based in SoCal, I was particularly interested due to likely easier accessibility to support. I've looked into the SunBeam OS Giken as well but as much of a fan as I am of them, correspondence with them is... difficult (when they do respond).

dogbone went into a fair bit of detail on his OS Giken setup: https://www.m3post.com/forums/showthread.php?t=1158445&page=8
(post 173, then part 2/3 later a few posts down, imo one of the best diff posts on this forum)

M3SQRD - how do you feel about a 3.62 for the DCT? any issues with street driving (i.e., sitting at 4000rpm going 80)? considering a move to 3.45 down the line to mitigate this, but wondering if I would see any benefits from getting a clutch-type LSD with the same FD. tangentially, I think it's objective that a clutch-type LSD would be an improvement over the OEM unit, but I would have to get a datalogger and identify the actual benefit of a higher FD to quantify that aspect.

edit: I wonder if the F87 CSR diff would be a good fit for E92 M3 - 3.46 ratio

bipp wrote

how do you feel about a 3.62 for the DCT?

forget the 3.45 and get the 3.62

3.45 is a GOOD medium for street and track driving, but after running 3.45 for a while, i would rather get the 3.62 back in the car.

I don't lose much top speed, not like i need to do 200mph anyways. and you'll feel a more notable torque gain/difference with the 3.62 over the 3.45

Although a 3.45 w/ ESS G1 is absolutely perfect. my friends Time Attack M3 has this set up

he has the Drexler 6 clutch w/ 3.45 (i don't remember what ramp he went with)

omgzirra_exe wrote

forget the 3.45 and get the 3.62

3.45 is a GOOD medium for street and track driving, but after running 3.45 for a while, i would rather get the 3.62 back in the car.

I don't lose much top speed, not like i need to do 200mph anyways. and you'll feel a more notable torque gain/difference with the 3.62 over the 3.45

Although a 3.45 w/ ESS G1 is absolutely perfect. my friends Time Attack M3 has this set up

he has the Drexler 6 clutch w/ 3.45 (i don't remember what ramp he went with)

man that sounds great but i just don't wanna sit at 4000+ rpms going reasonably quick on the highway LOL

i am very tempted to try a clutch type LSD with the 3.15 FD but maybe a 3.45 would be a best of both worlds - maybe I can just move to 295/30 tires or something down the line for a bit shorter gearing there as well

i do like the idea of a 3.62 though - def seems fun

bipp wrote

man that sounds great but i just don't wanna sit at 4000+ rpms going reasonably quick on the highway LOL

i am very tempted to try a clutch type LSD with the 3.15 FD but maybe a 3.45 would be a best of both worlds - maybe I can just move to 295/30 tires or something down the line for a bit shorter gearing there as well

i do like the idea of a 3.62 though - def seems fun

nah no point in staying with 3.15s if you're doing a diff, just get 3.45 at that point and be happy. its enough to wake the car up more. but like i mentioned 3.62 does that just a bit more and it's overall better imo.

So here's where I think I'm landing for this phase:

- full interior strip out (started that this past weekend), including speakers, and radio
- full cage
- single hump dash conversion
- quick disconnect wheel
- halo driver seat + non-halo for passenger. I'm having a hard time finding a Sparco showroom nearby, would be good to try those before paying double for a Recaro. BK mounts, i think. not even sure i need the passenger one tbh, but i think some events around here consider your a race car without one and don't let you enter.
- HVAC delete
- AC compressor+condenser delete (+old ps pump conversion)
- Do the carbon roof before sending it to the cage shop
- Lexan rear glass since I have to pull the glass anyway to do the roof
- Diff is on the table, but depends on where the budget lands. i think i can do everything else for 10-12K, diff would be another 5. seems like a lot at this stage.

that should keep me busy for the winter!

kolosy wrote

So here's where I think I'm landing for this phase:

- quick disconnect wheel

Depending on how big of a hurry you're in I may have a way, way cooler option than KMP on the horizon for this.

amg6975 wrote

Depending on how big of a hurry you're in I may have a way, way cooler option than KMP on the horizon for this.

i'm listening...

cage build scheduled for January, track season doesn't start until late april around here.

kolosy wrote

- halo driver seat + non-halo for passenger. I'm having a hard time finding a Sparco showroom nearby, would be good to try those before paying double for a Recaro. BK mounts, i think. not even sure i need the passenger one tbh, but i think some events around here consider your a race car without one and don't let you enter.

my preferred halo seat GREAT side support!

https://racetech-usa.com/shop/RT4200HR-racing-seat?srsltid=AfmBOooXzG5WC0dRpBUWy8cZE4Ses_yFo8lMr15wOXrxeeBkt2sgd286

omgzirra_exe wrote

my preferred halo seat GREAT side support!

https://racetech-usa.com/shop/RT4200HR-racing-seat?srsltid=AfmBOooXzG5WC0dRpBUWy8cZE4Ses_yFo8lMr15wOXrxeeBkt2sgd286

Great. one more seat I have to chase down somewhere to sit in.

bipp wrote

as far as NA-based diff providers, I'm a bit interested in OS Giken Spec-S. I think driftflo's dislike for them stems from them only doing tuning on their own, and their OTS setup not being great. since iirc they are based in SoCal, I was particularly interested due to likely easier accessibility to support. I've looked into the SunBeam OS Giken as well but as much of a fan as I am of them, correspondence with them is... difficult (when they do respond).

dogbone went into a fair bit of detail on his OS Giken setup: https://www.m3post.com/forums/showthread.php?t=1158445&page=8
(post 173, then part 2/3 later a few posts down, imo one of the best diff posts on this forum)

M3SQRD - how do you feel about a 3.62 for the DCT? any issues with street driving (i.e., sitting at 4000rpm going 80)? considering a move to 3.45 down the line to mitigate this, but wondering if I would see any benefits from getting a clutch-type LSD with the same FD. tangentially, I think it's objective that a clutch-type LSD would be an improvement over the OEM unit, but I would have to get a datalogger and identify the actual benefit of a higher FD to quantify that aspect.

edit: I wonder if the F87 CSR diff would be a good fit for E92 M3 - 3.46 ratio

Sorry for the slow response. I didn’t receive a notification.

I absolutely love my 3.62 FD LSD DCT. I’ve been driving clutch-type diffs since 2004 (diffsonline 4.10 FD LSD with lightweight flywheel with CSL trans software on my SMG e46 M3 - actually feels just as good as an e92M3 DCT) and I find they lock faster than the stock viscous M variable diff which loses most of its locking ability by 50k miles, less if heavily used on track. The difference in performance of the clutch LSD and stock is night and day. Getting back to throttle sooner, better control off corners, awesome stability under braking, and the ability to lay down awesome pairs of stripes when you feel like it. The 3.62 FD pulls almost three full car lengths through the 1/4 on my e92 M3 with stock 3.15 FD (same stage 2 tune and raised 8600 rpm redline). Cruising at 60 and 80 mph, the engine rpm’s are ~2.8k and ~3.8k rpm, respectively. With an 8.6k redline you hit 60 mph at the top of 2nd gear. On Summit Point Main, the 3.62 FD is roughly 1.00-1.25 sec quicker than the 3.15 FD. However, the 3.62 FD has a MCS 2WR suspension and the 3.15 FD has a JRZ RS1 suspension. There’s roughly a 0.5 sec advantage with the 2WR (also different spring rates 700/1100 lbf/in vs. 600/900 lbf/in). So the 3.62 FD is roughly 0.50-0.75 sec quicker per lap than the 3.15 FD. What the times don’t show is the better overall accel, decel, corner exit, off throttle driving experience with the 3.62 FD.

FYI, Track/S recently installed a 3.85 FD LSD DCT on an e92 M3. That thing must be an absolute blast to drive!!

M3SQRD wrote

FYI, Track/S recently installed a 3.85 FD LSD DCT on an e92 M3. That thing must be an absolute blast to drive!!

Every time I use it I like it more

I remember you asked me for a pic at 3000rpm in 7th:

Track/S wrote

Every time I use it I like it more

I remember you asked me for a pic at 3000rpm in 7th:

I bet it’s an absolute monster to drive!! I know what the difference between stock and 362 (13% shorter gearing) feels like but I can’t imagine what the difference between 3.62 and 3.85 (5.5% even shorter gearing) must feel like! You’ll have such a grin on your face while on track or mountain trips with the 3.85 FD that your face will be stuck with that grin for hours after the drive I love how you can use 7th gear when just cruising around town. Only downside is you can’t go over ~60 mph (< ~3k rpm is my limit) when warming up the engine.

Thanks. The difference at 60 mph is ~150 rpm and at 80 mph it’s ~200 rpm, respectively, for the 3.62 and 3.85. If I was doing this all over again, I’d seriously consider switching to a 3.85 FD.

Thanks for the donation 🙏

Making some progress since taking it down for the season. Most of the interior is out, and the HGK roof came in. Having a mobile glass guy come by tomorrow to take out the front and rear. Going to try to reinstall the front when I'm done, but go plexiglass for the rear.

kolosy wrote

Making some progress since taking it down for the season. Most of the interior is out, and the HGK roof came in. Having a mobile glass guy come by tomorrow to take out the front and rear. Going to try to reinstall the front when I'm done, but go plexiglass for the rear.

Are you installing the roof cross support, the one that comes with slick tops? How are you anchoring it in place? When I was penciling this project it looks like the piece is surprisingly available, I figured it was something I would have to source from a junk yard or eBay used.

I was thinking about welding versus jb weld versus bolts. I’m sure welding is preferred but not a skill for me…..yet.

Mad respect taking this on yourself!

CamasM3e93 wrote

Are you installing the roof cross support, the one that comes with slick tops? How are you anchoring it in place? When I was penciling this project it looks like the piece is surprisingly available, I figured it was something I would have to source from a junk yard or eBay used.

I was thinking about welding versus jb weld versus bolts. I’m sure welding is preferred but not a skill for me…..yet.

Mad respect taking this on yourself!

I’m starting to think the availability is a mirage, first place I tried to order it from listed 1-3 day availability and then cancelled as nla next day. Will try a few others, but also not super worried since I’ll be putting a cage in and DRLane makes the point that the main hoop serves the same purpose. I think rivnuts are the way to go there, unless you have a spot welder.

yeah, just had another site cancel. i'm pretty sure it's NLA.

more gunk working its way out. have the sides of the roof drilled out too, and ground down the front and rear edges to expose the spot welds. hoping to drill those off this eve and maybe pop the roof off.

i will say, i don't know how people pull that sun roof out with the seats still in place (or the windshield for that matter, that's the route i ended up taking)

it's out! spent almost as much time fighting with the secret adhesive as i did the actual spot welds, but it's out.

now i've gotta decide how and if to fill in the handful of spot welds where i went too far through. looks like most that went through are harmless, but there's one or two where it's a triple stack and there's something underneath that's also welded on.

Track/S wrote

Every time I use it I like it more

I remember you asked me for a pic at 3000rpm in 7th:

I have a spare 3.85 fd from when I did a diff on my manual car. I was worried the 3.85 would be too short for the DCT, but that doesn't seem too bad... Good to know!

spent the last couple of weeks waiting for the roof bow to show up (actually two, the one i found as available first still hasn't arrived, but then a rando ebay seller got one to me in under a week).



but now that it's here (and after talking with DRLane ), i'm having second thoughts about it. i think i'm going to with his suggestion and drill the 4 holes for the roof and secure it that way for the time being (no glue yet), then ship it off to the cage builder that way so he can do his measurements and take the roof off. he can also then decide if he wants to install the roof bow (and ostensibly he could just spot weld it in then instead of me messing around with rivnuts), or have the main hoop perform the same function.

i used the wait time to press on stripping the interior. the dash came out today!





i'm going to ship the car off without a dash, and then stick a single hump one in when it comes back. wouldn't have messed with it but the cage guy wanted it out so i might as well use this opportunity to do the conversion and also yank the heater core.

lastly, i've been fortunate enough to help amg6975 do some beta testing on his GWS replacement and so wired that up and dropped it in just before yanking the dash



it fits very solidly, was straightforward to wire up (i've always been impressed with how easy BMW connectors are to depin) and worked on the first try. since the dash came out, I took that opportunity to take out the AiM ECU connector that I had wired in at the fusebox connector and will now be able to move it over here as well.

I've got about a month left before it needs to ship out, and while the interior work is about done for now, I still want to delete the heater core, AC and SAP in that time. Feels like it *should* be enough, but who knows.

My buddy and I are trying to get out to COTA for the Chin day in April, we'll see if that can happen.

continuing to take advantage of some work downtime, i've started on the engine bay side of things. yanked the SAP pump, and confirmed that i'll need to get the engine harness out of the way to get to the valves and the rest of the plumbing (not that there was any real doubt, but you never know).

the heater core is disconnected, and i've got VicS5 's suggested U pipe in place to loop the coolant pipe back to the aux pump bypassing the heater core. one nice benefit of doing this together with the SAP delete is that I think i'll have an easier time getting at the right EGR valve with the extra coolant hoses out of the way, and with the steering shaft disconnected. we'll see though. i've been waiting for over a month on the OE blockoff plates, but the vendor claims to have shipped it this week so hopefully that's the case.



definitely running out of garage space lol. surrounded by a mix of things that need to go back in and things that i can't bring myself to toss (iDrive, etc.).

If you encounter further delays on the OE EGR block off plates, I used these from NRW Design. They included the gaskets.
NRW Design S65 cover plates