BRZ Rally Car

In reply to TXratti :

Thanks again for sending it to me!  I saw the box and had to get it open and try to fit things together immediately.

The factory 4.88s have a unique 3rd member that precludes ever changing the gears again. The pinion is slightly offset so the ring gear is thinner than normal. Meaning the carrier you have won't work.

In reply to thatsnowinnebago (Forum Supporter) :

Well, that's the final nail in the coffin for finding a used set then- aftermarket it is, thanks!  And lookie here, Nitro even says they fit the Frisbee carrier.

¯\_(ツ)_/¯ said:

In reply to TXratti :

Thanks again for sending it to me!  I saw the box and had to get it open and try to fit things together immediately.

You're very welcome! Sorry for the delay, and glad that it arrived decently quickly and intact.

Some disassembling and a lot of cleaning:

I'm waiting for various parts and tools to show up but I can rebuild the LSD if I pick up some shims from tractor supply so I'll probably do that tomorrow.

What is the axle spline diameter and count? I may have the tools made up to torque check the clutch pack preload. If what I have is the correct size they are yours, I'll drop them off next time by.

In reply to TurnerX19 :

30 spline, somewhere in the low 30mm diameter range off the top of my head- should be the same as most Toyota 8" stuff.

This thread has me both excited and disappointed...

Excited because this is bonkers and I love it,

Disappointed because I have been seriously slacking on any REAL progress on my cars or updating my threads here and your moving at a lightning pace!!

Keep up the fantastic work!

In reply to DjGreggieP :

Thanks!  But sorry.  But Thanks!  This is the only pace I know how to work at.  

Not so close, no cigar.....My tool is 24 spline X 25mm....

In reply to TurnerX19 :

Maybe it's for the smaller Toyota stuff found in the late 70s/early 80s cars?

Apologies to anyone who was on the edge of their seat waiting for exciting LSD shimming action, some parts for the trailer arrived so I'm going to knock that out tonight:

In reply to ¯\_(ツ)_/¯ :

Tool was originally made to do Datsun live axles. I had a customer who habitually left the drain plug loose. I built a bunch of them before he realized he shouldn't work on the car, just drive it!

Took the Supra LSD apart for some work- below image is the parts in order:

So, let's go over what's happening here- the spring in the middle sits in a pocket and pushes out on the clutch packs to create some initial lockup force.  On a mk3 Supra diff with the plates alternating as shown, that's roughly 75ftlbs of initial breakaway torque to get the wheels to come uncoupled, and when there's additional wheelspin the spider gears push out on the clutch packs too giving some additional locking force.  To figure out how much I want to shim for more lockup, I measured the spring pocket:

and the spring itself:

So that means the spring is compressed about .273" for the stock 75ftlbs of breakaway.  I want to increase that, and these Tractor Supply shims come in a 6 pack for 99 cents:

They're exactly the right inner and outer diameter to sit under the spring nicely.  So, to guesstimate how much breakaway torque each of these will add I can divide 75ftlbs/.273 for a ratio of about 275... something units.  Multiplying that by the shim thickness of .078" says that each one adds somewhere around 21.5ftlbs of lockup.  When I did this on the Merkur I aimed for 250ftlbs because that car really needed help rotating, but since the BRZ is pretty naturally tail happy I think I'm going to aim for closer to 150ftlbs instead and see how that feels- using three of these shims will get me around 140ftlbs so I'm going to start there.  I reassembled it, and will have to wait a while to check it on the car since I don't have all my gear bits yet.

In other news, I am signed up for a Susquehanna region rallyX tomorrow and today I managed to fail to find the pinion flange I need for the truck gears in a junkyard, so I had to order one instead.  The junkyard trip was still worth it because I got to see this:

Which yard?

In reply to TurnerX19 :

Harry's in Pennsburg.

In reply to ¯\_(ツ)_/¯ :

Thanks.

¯\_(ツ)_/¯ said:

In other news, I am signed up for a Susquehanna region rallyX tomorrow and today I managed to fail to find the pinion flange I need for the truck gears in a junkyard, so I had to order one instead.  The junkyard trip was still worth it because I got to see this:

Danger Ranger!

Oh, and good work on the rally car too. 

Rallycross!  This venue, the Farm Show lot in Harrisburg, is apparently cursed for me because it always rains when I'm there.  Got to grid behind a sweet 200sx though!

Also visible in that photo are lxnm and the Buckler/Royer shark e30.  I'm going to let the hood mascot from that car demonstrate the conditions for you:

As you can see by the front of the duck, there was powdery dust, and as you can see by the droplets aft of the duck, there was also moisture.  This somehow didn't result in mud, but instead distinct sections of wet grass, moon dust, and packed clay.

It was actually surprisingly grippy, although ruts formed pretty quickly in some places and it was easy to lose a lot of time if you got off the line.  The car had no issues and my driving was the usual fast but sloppy sideways cone party that I have trouble getting away from.  At lunch time I was sitting in second in MR.

Afternoon, same deal but slightly dried out, and I battled with the e30 the whole time.  The results page says I won, but barely- even when I'm not running in DC region I'm always one cone away from an e30 I guess!

I'm still super happy with the car, and this weirdo surface did a great job reminding me to keep working on putting a real diff in it- lots of "oops, that wheel is in the dust/mud/grass" incidents.  Overall this was a really well run event with plenty of seat time and it was good catching up with some of the guys who don't make it down to DC events.

Back to the diff- got out one of my least favorite tools:

I like the theory behind bearing pullers, but they're easy to accidentally damage things with and no matter how many components the kit has I always wind up with some bullE36 M3 like this:

The good news is that, with everything apart, the bearings, the surfaces they ride on, and the distances to the gear mounting faces from those surfaces are all as close to identical as my calipers can measure.  In theory, if the new gears and bearings are all dead on I should be able to use the shims that came in the IS300 case and be in spec for everything, but we'll see.

I wanted to reuse the bearings because I'm cheap and the Lexus they came out of looks to have been going very fast before colliding with something, but I'm not convinced that they survived the removal process so I'm going to order pinion and carrier bearings.

In reply to ¯\_(ツ)_/¯ :

I usually add a bit of heat, especially when using clamshell pullers. Makes a world of difference, and you don't need a whole lot- heat gun will do the trick. 

In reply to Recon1342 :

I'll try that next time, thanks!  I'm planning on using temperature to my advantage when installing the bearings, the pinion gear and diff are in the freezer right now.

In reply to ¯\_(ツ)_/¯ :

I don't remember how many bearings I removed from axles and hubs back in my days at the auto parts house, but it was quite a few.  Maybe it's possible to remove a bearing using a press or puller without damaging them, but more often than not they were trashed.  Of course, since my task was to install new bearings saving them wasn't a concern.  Sometimes I couldn't get a solid grip on the inner race (we only had a few splitters to work with), so I would cut off the outer race and the bearing carrier.  Especially after one bearing I was removing exploded all over the shop. 

¯\_(ツ)_/¯ said:

In reply to Recon1342 :

I'll try that next time, thanks!  I'm planning on using temperature to my advantage when installing the bearings, the pinion gear and diff are in the freezer right now.

2-300 degrees is usually plenty for installation. Basically watch for lightly smoking oil and you're there. If the bearing discolors, you went too far.
 

For removal, I just add a bunch of heat until I get it to move. I've had a few old ones that required a torch to remove, but they didn't spend life in an oil bath either.