BRZ Rally Car

Sunflowerbw said:

In reply to ¯\_(ツ)_/¯ :

Ferrari-powered Subaru?

I don't see any footage from Big White yet but yes, Ferrari powered Subaru.  Sam built it for a displacement loophole which has since been closed, but even with the added restrictions it's an amazing vehicle.

since you seem to like the snow, time to bring your car north and give it a try.........Rallye Perce-Neige (rallyeperceneige.com)

In reply to DeadSkunk (Warren) :

We may try Tall Pines next year if things work out, we'll see!  One of us is going to need to learn some French if we want to attend the Quebec events.

¯\_(ツ)_/¯ said:

In reply to DeadSkunk (Warren) :

We may try Tall Pines next year if things work out, we'll see!  One of us is going to need to learn some French if we want to attend the Quebec events.

Just come up and compete!  Most of the officials and volunteers speak both languages anyways

Lousy photo, but I did some crappy welding, replaced the secondary catalyst next to the transmission with a resonator, and rebuilt the section of the exhaust that goes under the subframe since it was getting pinched shut after lots of hits.  Not my finest work but the existing tubing has a lot of clay and mud seemingly permabaked into it so, good enough:

Test fit exhaust, looks like it hopefully won't heat the transmission much, assuming that was the problem:

Removed some stuff:

The skidplates in particular do a whole lot of work:

Zapping new weld nuts in various spots and re-reinforcing the subframe braces that I mount the front skidplate to are just part of regular maintenance:

Pulled the diff and replaced the plates- I think the original mk3 Supra plates probably earned their retirement, although they still looked ok if slightly worn.  I also removed about 30% of my preload shim thickness, since the new plates are thicker:

Pulled the 50mm struts for cleaning and regreasing:

Internal cleanliness good, grease level acceptable, straightness of passenger side ok, driver side...

It's not a ton of bend, but it's definitely not straight. I'm going to run this and if it folds any time soon I'm going back to 40mm stuff, the added effort and expense of the larger struts buys a LOT of $150 40mm inserts.

I kind of think nobody checks these and they just might run for a long time with a slight bend- they don't bind in the housings so for now I can pretend I don't know. 

*note to self* - be ready to change left front strut at first service this spring..

In reply to ralleah :

Since we have full spares now, just a 10mm socket, 19mm wrench, 19mm socket, and something to snip a couple zipties.

In reply to ¯\_(ツ)_/¯ :

I was talking to the apprentice tech at work the day I yeeted in to work on a flat tire and told him about how rally service crews might swap a whole subframe/suspension/etc in 40 minutes. 

It's only a couple bolts on top and a couple on the bottom, and you keep your spares as whole assemblies not bits and pieces.

¯\_(ツ)_/¯ said:

Test fit exhaust, looks like it hopefully won't heat the transmission much, assuming that was the problem:

Removed some stuff:

The skidplates in particular do a whole lot of work:

Zapping new weld nuts in various spots and re-reinforcing the subframe braces that I mount the front skidplate to are just part of regular maintenance:

Pulled the diff and replaced the plates- I think the original mk3 Supra plates probably earned their retirement, although they still looked ok if slightly worn.  I also removed about 30% of my preload shim thickness, since the new plates are thicker:

Pulled the 50mm struts for cleaning and regreasing:

Internal cleanliness good, grease level acceptable, straightness of passenger side ok, driver side...

It's not a ton of bend, but it's definitely not straight. I'm going to run this and if it folds any time soon I'm going back to 40mm stuff, the added effort and expense of the larger struts buys a LOT of $150 40mm inserts.

I kind of think nobody checks these and they just might run for a long time with a slight bend- they don't bind in the housings so for now I can pretend I don't know. 

I ran some seriously bent struts on my roadrace fc and didn't notice any difference.  I ended up changing them "just bcause".  

In reply to wvumtnbkr :

I've conducted this experiment on the rally car too- slightly bent struts work fine, it's that pesky part where they bend more and eventually snap that really presents a problem. 

There was one more annoying maintenance item in the suspension- the front control arm bushings.  With the extra travel they eventually do this:

Pop them out (with a hammer and socket) and make sure the holes look ok:

And clonk some new ones in the same way:

A view of these installed at full droop shows why 9" of travel is the absolute limit of the stock front control arms:

A bunch of reassembly later and the underside is back together:

Always good to get the car back on its' wheels again:

The new LSD plates have been broken in by doing gentle figure 8s in a parking lot for 15min and it feels great- a much more progressive slip limiting action, as opposed to the windup and clunk that was happening previously. 

Breakaway torque is now a nice even 100ftlbs, down from 140 previously. If it exhibits any one-tire-fire I can add the shim back in, but it actually feels like it locks slightly sooner with the fresh plates so hopefully it's happy. 

Pete. (l33t FS) said:

In reply to ¯\_(ツ)_/¯ :

I was talking to the apprentice tech at work the day I yeeted in to work on a flat tire and told him about how rally service crews might swap a whole subframe/suspension/etc in 40 minutes. 

It's only a couple bolts on top and a couple on the bottom, and you keep your spares as whole assemblies not bits and pieces.

unless you have an e30, in which case you're replacing the whole assembly, including the hub/spindle smh......which means the spare assemblies are bigger and heavier.....

¯\_(ツ)_/¯ said:

 

 

A view of these installed at full droop shows why 9" of travel is the absolute limit of the stock front control arms:

A bunch of reassembly later and the underside is back together:

Any way you could switch those to a balljoint setup? Man, that's strange to have them flex that direction, as opposed to having the vertical "lollipops" the way the e30 has, which basically last forever

In reply to irish44j (Forum Supporter) :

I actually bought a spherical bearing setup for the stock arms... which didn't have nearly enough angle so I couldn't use it.  The correct answer would definitely be a pivot with the axis going the correct direction- this is one of my least favorite design choices on the entire chassis. 

So, could you orient that slightly bent strut 180 degrees from where it was so hopefully the next big hit straightens it out? Probably wishful thinking and maybe they spin over time as they're cycled.

In reply to adam525i :

They definitely spin freely in the housings, although once they're bent they tend to sit with the bend straight in towards the strut tower.

It is very hard to get a spherical bearing to have very much articulation and keep strength.

The real "fix" would be making all new arms and mounting points to put the bushings both axial... if you wanted to make getting spares in a hurry difficult.

One might try twisting the ends of the arms, cut and weld back on style, but then you are trusting your welds when you hit stuff at speed...

Changed the transmission oil (watery) and cleaned things. Car seems mostly ready for whatever comes next:

Transmission assessment time- original 2013 on left (grindy/difficult 3rd & 4th) and 2015 on right (shifter jammed past 3rd, box stuck in neutral):

When I removed the tail housing on the newer transmission, the shift rod came with it and some of the shifter mechanism fell out.  A little examination revealed the culprit. 

Despite being a 2015 transmission, I installed my 2013 tail housing onto it when I put it in because the original was damaged. This turned out to be my main mistake. Examining the two, I found this:

2015 housing:

2013 housing:

At some point, Aisin moved the stop for the shift mechanism from somewhere else inside the case to this spot on the tail housing. By swapping it over, I inadvertently created an arrangement where the only stop for 1/3/5 was the spindly little forks and snap rings of the back end of the shifter mechanism- eventually things all flexed and moved just the right way, and the whole shift rod escaped, lodged itself behind the neutral safety switch, and various other pieces of internal shift mechanism exercised their newfound freedom. 

I haven't found an obvious failure mode on the original 2013 box so unless I figure how to disassemble that one further, I assume it's just normal damage from running too hot and abuse.

Lesson learned, no mixing and matching parts, even seemingly identical aluminum castings. 

Subaru transmission design engineer be like...

In reply to irish44j (Forum Supporter) :

IIRC it's an Aisin design, so Toyota?

Pretty sure it was also used in the S15, IS200, and RX-8s, possibly Miatas.  It has a horrible reputation in RX-8s so Mazda stopped using them and went in-house, or I may have the order backwards

Snow! We only had about a 3hr window of reasonable coverage before it became rain and therefore slush, but I made use of the whole thing:

First up were the trusty Blizzaks- they behaved like I remembered, wanting to just be on the verge of slipping but not past.  In a rear wheel drive car, this generally means on straights you're feathering the gas a lot, then trying to threshold brake, then sliding the back end to rotate the car (careful the grip falls off drastically), and then managing the exit to try and keep the car pointing the right way as you hunt for the magic wheel speed that makes it go.

Made puddles in the shop and switched to some Alpha Verity retread things I couldn't resist a sale on- Santiago was running these last year and said he had grip everywhere. Compared to a Blizzak the tread is more open, there's a huge groove down the middle, and the compound is noticeably softer:

Got back out there and yes, they're definitely different. The grip feels similar to a tractionized Blizzak until you slide or get wheelspin- then the magic happens. The sliding grip level of these is WAY better than the Blizzaks, as is the steering response on anything slushy or deep, so you can drive them more aggressively without it biting you- the key is going to be learning to dial it back enough anyway, since they don't punish you for overdoing it nearly as much. 

Semi related, a demonstration of why we tape the roof scoop off in the snow:

Those Veritys look like the $60 winter tires that I bought as dirt fronts a while back.