DocWalt's 2022 WRB BRZ

[DocWalt]

This weekend was Philadelphia SCCA region's Al Holbert Memorial autocross weekend. I've been the winner of the two day event the last two years, but this year with my class having a harder PAX handicap and having the "wrong car" for my class I knew it would be tough. I was able to just pull off the win last year even with the "wrong car" but competition has been really stiff this year! Lots of really fast drivers in the Philly region and we had drivers visiting from all around!

Day one was great, Amy and I were getting used to the new OS Giken diff, more on that later. Amy was super happy with the car and I felt like it was easier too. We did pretty darn well, I won STR and was sitting fourth for the Holbert trophy. Amy was really competitive in STR as well!

Amy's fastest run:

My fastest run:

I went a little faster on my 5th run when I really learned the diff, but I tagged a stupid cone in the process.

Amy was very happy on day 1!




Day two was even more fun, but other folks got faster! I ended up finishing fourth for the Holbert, less than a half second back over two days. Not at all unhappy considering the limitations of my car in STR. Amy had a weird issue on one run, the car popped out of first gear for no apparent reason about 25 feet off the line.

Amy's fastest on day 2:

My fastest run on day 2:

For feedback on the differential, Jon at Shaftworks USA *killed it* on the diff! It's a pretty decent difference in driving style, but it's really rewarding and fun to get it right... and more importantly I think it's made the car faster. The car is more stable on entry and really really forgiving of chucking the car around. When you're mid corner in a sweeper and you feel like the front end isn't going to hold on anymore, you can start to roll on the gas and it just tucks the nose wherever you have the steering wheel pointed. SOOOO nice to be able to get on the gas earlier and power out of the corner sooner. On top of the behavior change, the new differential puts down power over bumps so much better than the stock Torsen limited slip, it just accelerates forwards all the time instead of chattering and hopping.

[LRNAD90]

Originally Posted by DocWalt

For feedback on the differential, Jon at Shaftworks USA *killed it* on the diff! It's a pretty decent difference in driving style, but it's really rewarding and fun to get it right... and more importantly I think it's made the car faster. The car is more stable on entry and really really forgiving of chucking the car around. When you're mid corner in a sweeper and you feel like the front end isn't going to hold on anymore, you can start to roll on the gas and it just tucks the nose wherever you have the steering wheel pointed. SOOOO nice to be able to get on the gas earlier and power out of the corner sooner. On top of the behavior change, the new differential puts down power over bumps so much better than the stock Torsen limited slip, it just accelerates forwards all the time instead of chattering and hopping.

So the OS Girken is a clutch pack style limited diff, right? I always thought Torsen style diffs were supposed to be smoother and more predictable, while having the benefit of not loose performance over time due to wear of the friction plates/clutch packs.

So just curious, what makes it so much better, and does this apply for first gen car's as well? Is it just that the set-up of the differential, and it's resulting characteristics is better suited to the car, or?

Genuinely curious, as (from an OEM standpoint anyway), I've always found Torsen diffs to react more predictably than clutch plate styles..

[RedReplicant]

Jon also did the OSGiken in my S2000 and he nailed that thing too. Car was much more happy to dive for the apex on entry and perfect for throttle steering mid corner to exit.

Also got rid of that kind of annoying skip-hop that torsens will do on the street in slower 90 right corners.

Excellent work on your wins, the car looks great

[DocWalt]

Originally Posted by LRNAD90

So the OS Girken is a clutch pack style limited diff, right? I always thought Torsen style diffs were supposed to be smoother and more predictable, while having the benefit of not loose performance over time due to wear of the friction plates/clutch packs.

So just curious, what makes it so much better, and does this apply for first gen car's as well? Is it just that the set-up of the differential, and it's resulting characteristics is better suited to the car, or?

Genuinely curious, as (from an OEM standpoint anyway), I've always found Torsen diffs to react more predictably than clutch plate styles..

The OS Giken diff is indeed a clutch type diff. It uses finely ground steel plates that aren't coated in friction material so the wear is nearly non-existent and it will last a lot longer than a traditional clutch type diff tat does use friction material.



The diff setup would be the same (or nearly identical anyway) for a first gen car. Same benefits for both, Jon developed the diff tuning on a first gen.



The issue with a Torsen is that it has a set TBR on power, isn't tunable, and when you spin a wheel on power the diff just "gives up" since the Torsen is a torque multiplier. When one wheel is spinning you're multiplying by almost zero and the wheel with grip gets almost no torque. All of the torque just goes to the freely spinning wheel. This is an issue on bumpy surfaces, curbs on track, loose surfaces like ice and snow, etc. where one wheel will have way less grip than the other wheel.



OEMs use Torsen diffs because they're effectively no maintenance and no OEM is going to spring for the cost of an OS Giken diff over a more basic clutch type that uses fewer disks and friction materials that wear out. Nobody wants to buy a car that needs expensive maintenance regularly and almost nobody is going to pay the extra cost for an OS Giken.

[e1_griego]

+1 on Jon's OSG setup. He's set up 3 of 4 of my OSGs (the other is just off the shelf and 'good enough') and they're always fantastic.

[DocWalt]

I will say, as I mentioned in an earlier post, I wasn't even that sold on a new diff... I only did it because I know I'm adding power down the line and I know the deficiencies of the Torsen.

I'm impressed even just driving around, maybe more than I am at autocross. The driving style change at autocross was pretty big but also not sure it would necessarily be "faster" on a smoother site. Definitely easier to drive though and that's worth a lot in a 3 run scenario

[autoracer86]

Originally Posted by DocWalt

The OS Giken diff is indeed a clutch type diff. It uses finely ground steel plates that aren't coated in friction material so the wear is nearly non-existent and it will last a lot longer than a traditional clutch type diff tat does use friction material.

Go on.... is that true ?? I know the Giken is the go to diff but I didn't know it was supposed to last long. Do they have a published service interval ? Yearly rebuilds have always turned me off switching to a clutch pack diff

[DocWalt]

Originally Posted by autoracer86

Go on.... is that true ?? I know the Giken is the go to diff but I didn't know it was supposed to last long. Do they have a published service interval ? Yearly rebuilds have always turned me off switching to a clutch pack diff

Yeah, I bought the OS Giken for my ND used from Noel, sent it off to Jon for inspection and to tweak the setup. Everything looked great, then I ran it and the new owner of the car hasn't done anything besides change fluid either.


OS Giken talks a bit about it here: https://osgikenusa.com/pages/the-os-...-lsd-explained


Someone uploaded a more in depth document here but I hate direct linking PDFs haha: https://www.ft86club.com/forums/show...27&postcount=1


Added a pic of the disks inside my ND's diff after a couple of years of Noel's usage:

[autoracer86]

Now I just need more money ! Thanks Ken

[DocWalt]

Originally Posted by autoracer86

Now I just need more money ! Thanks Ken

Sorry.

[DocWalt]

Installed the SYMS Racing Team oil pan, install went smoothly and I didn't really have any RTV in the pickup after cleaning it out a year ago or so.






Their instructions were pretty good, once translated to English:

[nissanfanatic]

Originally Posted by DocWalt

I installed Eibach's 10mm extended stud/spacer kit using the balljoint spreader tool method on my 2022 BRZ today. Pretty simple as it is on the first gen or most other cars. Warning though, the 2022+ BRZ with aluminum knuckles uses different torque specs than first gens (now 88.5 ft-lbs for the two caliper bracket/knuckle bolts and 70.1 ft-lbs for the four hub/knuckle bolts) but more annoyingly, the knuckle is in the way and there's no way to install extended studs without pulling the hub. Not a huge deal and overall pretty simple!

Thanks so much for posting these torque specs! Did you happen to do the rears? I've been trying to track down the spec on the hub bolts for the rears but only seeing 1st gen specs...

Also, ThinkPad in your second post <3

[DocWalt]

Originally Posted by nissanfanatic

Thanks so much for posting these torque specs! Did you happen to do the rears? I've been trying to track down the spec on the hub bolts for the rears but only seeing 1st gen specs...

Also, ThinkPad in your second post <3

They're identical to first gen, same parts in the rear

Love my thinkpad! Easy as all heck to work on and/or upgrade too. Due for an upgrade in a year or two but whatever. Certainly not a gaming machine but plenty for what I use it for (tuning and remote log in for work)

[Petah78]

Originally Posted by DocWalt

Installed the SYMS Racing Team oil pan, install went smoothly and I didn't really have any RTV in the pickup after cleaning it out a year ago or so.

I have seen a few people installing the SYMS baffle indicating that it will resolve the right hand turn oiling issues and it's widely used in the JDM racing series/track goers. However, i have not found much info online. Have you heard the same and is this the reason why you choose this specific baffle?