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Lof8 - Andy
Lof8 - Andy GRM+ Memberand SuperDork
10/22/20 7:26 a.m.
bluej (Forum Supporter) said:

In reply to Lof8 - Andy :

You might be able to arrange a co-drive. I'd potentially be down.

I do appreciate the offer and I'll keep that in my memory bank!  However, I've never been a big fan of ripping on someone else's equipment.  I've done it a few times in the past, but I know the time, effort, and money that goes into most people's toys and I dread being the one behind the wheel if/when something goes wrong.  It causes me to drive more cautiously.  If I make the journey, it's a ways in the future and I'll see what makes the most sense at that time.  Again, thank you for the offer!

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
10/23/20 4:15 p.m.

While everyone is at the challenge, I'm here messing with this diff.  Finally got the right shims, which got the backlash into the exact middle of the tolerance and moved the drive pattern fully onto the gear teeth.

Here are the specs so I don't forget:

So I pulled it all apart again to clean everything:

Installed the pinion seal and crush sleeve and fought with that for a good while to get it to 140ft-lbs of torque and get the preload set properly:

Then stuck the carrier back in, torqued it all down, double checked the backlash again, and sealed it up:

Yoinked the stock diff out:

Did some measuring and decided that the axles were too close to call- the snout thing on the very end may or may not hit the Supra LSD guts and prevent the snap ring from engaging:

So I did some precision deathwheel work and cut it off both axles:

Aaaaand installed:

Then, since the exhaust was off already and the center joint has gotten annoyingly leaky:

Lighter, simpler, louder:

Then I drove it for the recommended initial 15 miles before letting the new gearset cool down- the tires scrub a little at low speed, and there's a little understeer when coasting through paved corners, but the one tire fire is completely gone and it's WAY more predictable when sliding on any surface, especially over bumps.  The 4.88 ratio is totally streetable, 70mph cruising is right around 4k rpm so a little high but not crazy, and it feels good when accelerating and shifting and all that.  The lower gearing might be detrimental for rallycross since 2nd only goes to 50mph or so, but we'll find out in a few weeks.  I've got right around $700 into this diff compared to the $2500+ an aftermarket clutch pack LSD would cost so I'm quite happy with it.

TurnerX19
TurnerX19 SuperDork
10/23/20 7:10 p.m.

Are you aware that Drifting drive was a PHA competition venue in the middle 1960s? Until somebody had a really bad one going over the yump....

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
10/23/20 7:28 p.m.

In reply to TurnerX19 :

That's amazing, I had no idea!

95maxrider
95maxrider Reader
10/27/20 10:42 a.m.

Props on getting that diff working, very impressive!

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
10/27/20 11:28 a.m.

In reply to 95maxrider :

Thanks!  Really, other than the axles, it all fits together like it's meant to be there- if I wanted to buy $100+ worth of shims right off the bat I could have done it very quickly, but it took a while because I was trying to cheap out and use math to figure out what to order instead.

I've been driving it to work to get the 500 mile break-in cycle on the new gears done so that I can change the diff oil again and move on to worrying about other things, so far so good.

kodachrome
kodachrome New Reader
10/27/20 12:24 p.m.

Posting some of my favorite BRZ pictures from the DC Rallycross here since the thread needs more dirt and color in it. 

 

solfly
solfly Dork
10/27/20 12:40 p.m.

great pictures!!

MrChaos
MrChaos GRM+ Memberand SuperDork
10/27/20 1:27 p.m.

i keep coming back to toyobarus since they are decently cheaper than ND's. Especially for a rallycross platform

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
10/31/20 3:14 p.m.

The new differential has a slow leak from one of the axle seals- in retrospect it would have been worth the $20 to put fresh ones in there while it was apart.  It's easy enough to do with it mounted, but annoying and the part is going to arrive a day or two before the next rallycross.

To make myself feel better about that, I checked the breakaway torque now that it's broken in:

155lbft, not bad for some old salvage Supra parts and Tractor Supply shims!

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
10/31/20 3:48 p.m.

Well, at least it's not leaking from a seal you DID replace :)

 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/2/20 6:58 a.m.

Ordered some snow tires because they're cheap and available and I might as well before it gets colder- 4x General Altimax Arctic 12 and 2x Firestone Winterforce (original, older production).  The Altimax Arctics are a really good all around snow/ice tire for winter events, and the original Winterforces make really good mud/slush tires and are $50/ea so I figured having a pair would be good since they can either be spares or be swapped onto the rear if things get melty.  I don't even know if there will be any winter rallies I can attend next year, but being able to go out and play in the snow is never a bad thing.

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/2/20 11:04 a.m.

Going to make myself a little shopping list post here so I can remember all of the crap that I need to be on the lookout for as various sales appear.

For the car:

  • Seats [ebay, 425]
  • Seat side mounts [425]
  • Harnesses [Rallynuts]
  • Harness anchors [Rallynuts]
  • Intercom, Stilo WRC if possible [Murray]
  • Roll cage padding [425]
  • Fire extinguisher mounts [Amazon]
  • Roof scoop [Murray]
  • Dash flocking kit [Flock-it]
  • First aid kit [rally.build]
  • Spill kit [rally.build]
  • Triangles [Amazon]
  • Lexan for back windows
  • Battery mount/box [Speedway]
  • Battery cables [Speedway]
  • Killswitch [Speedway]

 

For myself:

  • New helmet to replace my expired one [purchased via Rallynuts]
  • New Hans device to replace my horrible Zamp one that disconnects itself [purchased via Rallynuts]
  • New firesuit wouldn't hurt since my old Sparco is disgusting and doesn't breathe well

 

Hoping to have the car logbooked some time early next year, Adam Brock will be out in January to cage it so I need to gut the interior before then and establish whether I need any electrical workarounds once airbags are disconnected.

Nesegleh
Nesegleh Reader
11/2/20 12:00 p.m.

In reply to ¯\_(ツ)_/¯ :

Ahh this just reminded me of like 10 things I forgot I need to buy. 

fun times...

Robbie (Forum Supporter)
Robbie (Forum Supporter) MegaDork
11/2/20 12:03 p.m.

by harness anchors do you mean the triangle shaped metal pieces that the harness goes through and you bolt to the car? Or something else?

My challenge car harness came with 6? those and I didn't use all because my straps could wrap around a bar. I'm also relatively sure I've got a battery box or two laying around the garage unused. 

If you can actually use em I can get photos. 

AWSX1686 (Forum Supporter)
AWSX1686 (Forum Supporter) GRM+ Memberand UltraDork
11/2/20 12:11 p.m.

In reply to Robbie (Forum Supporter) :

That reminds me, I believe I also have a batch of harness anchors. Can bring them to Rallycross Saturday if you'll be there. 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/2/20 12:29 p.m.

In reply to Robbie and AWSX :

Like these, for the eye bolts on the lap and antisubmarine belts:

AWSX1686 (Forum Supporter)
AWSX1686 (Forum Supporter) GRM+ Memberand UltraDork
11/2/20 12:48 p.m.

Ok, not what I have. I have these or similar: https://www.jegs.com/i/JEGS/555/70040/10002/-1

Ian F (Forum Supporter)
Ian F (Forum Supporter) MegaDork
11/2/20 12:51 p.m.

In reply to ¯\_(ツ)_/¯ :

After that rally crash story Sara posted, I think halo seats are in your future.

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/2/20 1:00 p.m.

In reply to Ian F (Forum Supporter) :

Yeah.  I don't like that there doesn't seem to be a testing standard for the halo, or that it makes it harder to escape through the window, but it's hard to deny the number of more experienced people who claim that they have been saved by them.

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
11/2/20 3:41 p.m.
¯\_(ツ)_/¯ said:

Going to make myself a little shopping list post here so I can remember all of the crap that I need to be on the lookout for as various sales appear.

For the car:

  • Seats (have a pair of Sparco Sprints sitting here but wouldn't mind some halo seats, most likely Momo Daytona based on size/measurements/price)
  • Seat side mounts
  • Harnesses
  • Harness anchors (x6 or x8 depending on 5 vs 6 point)
  • Intercom
  • Roll cage padding
  • Fire extinguisher mounts
  • Roof scoop
  • Dash flocking kit
  • First aid kit
  • Spill kit
  • Triangles
  • Lexan for back windows
  • Battery mount/box
  • Battery cables
  • Killswitch

 

For myself:

  • New helmet to replace my expired one
  • New Hans device to replace my horrible Zamp one that disconnects itself
  • New firesuit wouldn't hurt since my old Sparco is disgusting and doesn't breathe well

 

Hoping to have the car logbooked some time early next year, Adam Brock will be out in January to cage it so I need to gut the interior before then and establish whether I need any electrical workarounds once airbags are disconnected.

So I guess Sara talked you into the halo seat huh :D

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/4/20 8:55 p.m.

Signed up for this weekend's rallycross and replaced the axle seal after work today:

I was going to take a picture of the old one, but when I pulled it out of the housing it went flying away at something approaching the speed of sound and I have no idea where it went, so here's the new one installed:

Drove it, seems fine- I'll put a few more miles on it tomorrow before changing the gear oil, then pack up for another trip to Summit Point.

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/9/20 8:02 a.m.

DC Rallycross 7 and 8 Season Finale, Summit Point WV

This has been the first full season of rallycross I've run in years, and I really had one goal in mind at the beginning- get this car developed, shaken down, and reliable by the last event.  It's fitting, then, that this weekend it finally had the new clutch pack diff and shorter gearing, and on top of that, I had bluej codriving with me on Saturday to really make sure the car could hold up to back to back runs.

The drive down was uneventful but I definitely don't recommend the 4.88 gears for anybody who does a ton of highway driving- it still works fine, but buzzing along at 4k+ rpm for hours on end isn't super relaxing.

The weather was unseasonably warm, sunny, and generally awesome, and the usual crew was in attendance plus Ozgur and Ricardo shaking down a new stage rally car as well as a number of first time rallycrossers including AWSX in his lowered Miata.

Saturday we ran on Barn Course, which is fast and hard packed- my immediate impression of the new diff was super favorable.  Where the car used to wiggle around and change direction under power, it's now super consistent, but bluej noted some understeer on turn-in so I dialed a little more rear bias into the brakes.  Thinking about it, that makes sense since the rear wheels are coupled together a bit more now, so where it might have locked one rear brake or the other with the Torsen it now needs enough braking back there to slow them both down at the same time.  An extra quarter turn on the bias knob had things feeling great, but I had already collected a ton of cones on my first two runs so I was effectively out of the running.

The gearing, as predicted, is actually not awesome for rallycross.  I still believe it's the right choice for stage rally, but on DC's long courses it frequently leaves you with the choice of riding the limiter in second gear or shifting to third before downshifting again a second or two later, with both options probably eating a bit of time when compared to having a slightly taller second gear.  Feels awesome exiting corners though, and I really never felt like the car was hurting for power or traction.

Bluej had me a little worried on his early runs- he didn't seem to mesh with the car immediately and I was concerned that I had accidentally built something that required a lot of practice to manage.  By the middle of the session, though, he was running pretty much on pace (which again, in MR in DC region is FAST) with cones here and there.  I think by the end he wanted a BRZ so I'll call that a win, and the car didn't have any issues with two drivers back to back.

Everybody hung out for a while afterwards, it got way colder but the clear skies meant we spotted a few satellites and shooting stars overhead.  Eventually the crowd thinned out as people went home, and those of us who were camping enjoyed a bit of fried chicken reheated on a Tundra's exhaust manifold before turning in.

I've camped at all of the doubleheaders this year, but this time I berkeleyed up- I basically packed the same gear that we brought to Panthera, but had my crappy one-person sleeping bag instead of the good double bag, and with no dog and no Sara to add heat I was freezing even with all of my layers on.  It was not a particularly restful night.

The next day, we were over on the choppier, shorter Tree Course and I wanted to try and drive clean since I had been hitting cones all season.  That worked great on my first run, but on the second I came through the finish WAY too sideways and picked up four cones after crossing the line, leaving me in position to duke it out with Mike Golden for seventh place in the season championship.

The rest of the day was pretty uneventful, the diff still felt great although it was hard to work out where to use third vs. second gear just like it had been on Saturday.  Irish44j and I switched cars for one run, his car felt great and easy to drive as always although my head was pinballing off the narrow halo seat constantly, and he said the BRZ was "a big Miata with more power" which sounds like a compliment to me.  Yet again, no issues and I never so much as opened the hood.  When the day was done, I went straight home and was asleep by 9pm- would have loved to stay and celebrate with everybody a bit, but I was running out of steam and just wanted to make the drive while I was still somewhat awake.

Overall, this car has seen 9 days of rallycross and about 3k miles total since I purchased it earlier this year- it has had effectively no failures, handles the way I'd like it to, puts down power like it should, and is super predictable.  Cage time is in January, which will kick off a whole series of interior, exterior, and safety related projects, then it'll be ready to get out there and go fast in the woods.  I can't wait!

AWSX1686 (Forum Supporter)
AWSX1686 (Forum Supporter) GRM+ Memberand UltraDork
11/9/20 3:49 p.m.

In reply to ¯\_(ツ)_/¯ :

Nice seeing you! The car looked like it did great. I've mentioned it before, but it makes it hard to resist finding a BRZ of my own. laugh

In other news, I am definitely keeping an eye out for at least stock height suspension to do more next year, Longer travel suspension may have to happen eventually which of course I'll be in touch for pointers, but for now going to try and stick with dirt cheap. Also while the Miata made the hour drive home perfectly fine, Sunday it decided to start a cylinder 4 misfire. Haven't gotten it figured out yet, but hopefully it's fairly simple. Hard to say if it was Rallycross related ot not. Fun times

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
11/9/20 4:34 p.m.

In reply to AWSX1686 (Forum Supporter) :

The only reason I could see rallycross doing that in would be vibration/bumps causing a loose connection somewhere.  If you want stockish suspension pointers, Shawn (moxnix) and Katie own the NB with unicorns all over it that you saw out there, I'm sure they'd be happy to tell you what exactly they've done to it other than the amazing paint scheme.

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