"Spring 2022 Update"
I mentioned I collected a few parts in my previous update post and in no particular order: SPL Parts toe links with lockouts, Bimmerworld Solid subframe bushings, SLON VANOS covers, and Dinan under-drive pulley. When I stared at the pile of parts, I realized I may have strayed off the original path I wanted to take with this car.
TL;DR
- Going back to the original plan
- Installed Dinan Pulley
- Laguna Seca 5/29 recap.
"Car Philosophy"
In my introductory post, I wanted to build a street car that can track 1-2 days a year without fuss. During COVID Shutdown, my inner racer steered that direction towards track use. I think perhaps a little too much. I think it was time for a re-evaluation of the direction of the car.
The tuning philosophy is "This is a street car first, track use second." type of ordeal. Even with the M CS models and GT3 Touring as models, that still means there will be compromises to track use.
"Slight adjustment of plans"
So what does that actually correlate to? Well, for starters, my current suspension spring rates will be reduced. I enjoyed the street comfort of the original 400/700 lb/in springs I had but it was soft for some corners at the local tracks. I ended up going to 600/900 to test out what most folks on this forums say is the limit for street comfort tolerance. While the car feels great on track, the street use part is having some odd pitching issues on larger bumps. I was able to dial the pitching this past weekend but if there are certain bumps that still feel odd, I will move towards a middle ground.
As a reference, 3DM Motorsports sells a "Track Day" package that utilizes 450/800 with Ohlin R&T coilovers and I aim to use that as a starting point. Similarly, the Bilstein B16, M3GTS all have rates around 515/800. My gut is telling me to run the softer 450/800 rates and keeping it at this level. It may squat more in steady state in corners but it might be the compromise to keep the car more compliant on the street.
Solid subframes are still on the table but only with refreshed OE diffs instead of poly. I do not want the whine. I also decided against adjustable arms for the sake of simplicity and longevity. I ended up selling my SPL rear toe links with lockouts for this very reason. A 4.10 final drive is up in the air but I might just do it to give that lower end pep the car somewhat suffers from on the street. The local tracks seem to work okay with the 4.10 gearing (at least in sim racing testing) so that shouldn't be an issue.
"It's maintenance when you replace stuff that is old right? :)"
On a maintenance note, the car has basically original accessory parts. With my Dinan pulley purchase, this worked out for an upgrade embedded into a maintenance routine. I opt to replace the water pump pulley, idler pulley, and belt tensioner pulley. I went with the cheaper route which involved replacing the pulley instead of the full pulley assembly BMW sells. In hindsight, I should've done the PS Pulley too. Oh well!
Parts Courtesy of Chris!
https://www.m3post.com/forums/showpo...8;postcount=47
- Idler pulley - BMW OE - 11287841531
- Dust cap - BMW OE - 11287535867
- A/C || PS tensioner pulley - INA - 5320557100
- Alternator || Water pump tensioner pulley - INA - 5320342100
- Dust cap x2 - BMW OE - 11287835996
- Water pump pulley - BMW OE - 11517838676
- Dinan Pulley
- Napa 6PK1421 belt
- Bremmem 6DPK1070 belt
The install was insanely easy with the help of
Johal E32 . One of us help the belt tensioner and the other slipped on the belt in seconds. Couldn't have been easier.
wyatth was also there with Don for support.
As far as power, I don't feel anything lol. I'm sure its better and smoother but yeah butt dyno has no idea even though Dinan said 11hp lol.
"Laguna Seca; We meet again"
On Sunday May 29th, My wife and I went to a private track day and it was an eventful one. I finally mounted my old RE71R 275/35/18 stock from last year to give it a go at Laguna for a PB.
Long story short, only had first session with the M3 that day and the day was pretty much over. I'll gloss over the details but hopefully next time I can run sessions and gain some time!
I was able to find some betting damper setup with 10R/8C, 9R/8C damper settings and I actually enjoyed this with the 600/900 springs. Maybe that might stop me from moving to 450/800 for a little bit.
## AIM Solo
With only 1 session done for the day, it was already apparent there is a lot more room. Bummer I wasn't able to get more sessions in but it is what it is and I'm happy that is the only thing I'm bummed about.
#Green = 1:46.154 RE71R 1st session on 600/900
#Red = 1:45.681 old time on PS4S on 400/700 before the spin.
Since this was the first session on sticker RE71R, I was taking it easy. G-Sum (the sum of both Lat and Log G forces) was showing 1.76 max vs the older 1.54 from the PS4S/RS4 tires. I didn't even reach the limit of the tire yet! I think there was definitely a 1:43/1:44 for sure in there, maybe more but that was all I was aiming for.
-I shorted shifted a few places since it was the 1st session so I could see some time there.
-Didn't even reach ABS limits so clearly I wasn't braking hard enough yet!
"What's next?"
As a recap, Solid subframe bushings, OE Diff bushings, possibly 4.10 final drive, maybe new 450/800 springs. Slon covers, Valve covers, fuel injectors for maintenance. That's probably all she wrote for this build and just enjoying laps and backroads!
Cooling upgrades will follow depending on need but for now, it seems fine for now.