Alternative rear disc conversion?

[Neinris]

Alright, here we go...

I've known about this for quite a while, almost 2 years now. Not sure if this is more cost effective than swapping the rear axle with the 2012+ SE.

I've found this thread from another Toyota forum, and it's not even about the Yaris, it's a 10th GEN Corolla.

https://www.toyotanation.com/threads...e-swap.390125/

BLUF:
This involves installing bracket plates for the calipers to mount on. Part numbers of said plates/splash shields are 47803-02020 (right) and 47804-02020 (left).
IF these plates in fact fits on the Yaris, it could be a game changer. You wouldn't need to swap out the whole axle, and your wheels will stick out 10mm farther, which would then make the rear wheels stick out more than the front, which I don't mind.
I kind of wanted to be the first to do it, but I'm sharing it now to see if anyone dares to try it out, and I don't really have the funds right now.

I know most would argue that these light cars don't really need disc brakes in the back, blah, blah, blah... If you're not interested, you can stop reading. But for those who are curious, this might be worth your while.

Here are most of the parts that the other poster used for his rear disc brake conversion (my apologies, I can't seem to copy the table but I hope you can still figure out what category falls where):

P/N Quantity Price EA Description
0446602310 1 $ 40.88 Disc Brake Pad Set (Rear)
4780402020 1 $ 122.13 Brake Dust Shield (Left, Rear)
4780302020 1 $ 122.13 Brake Dust Shield (Right, Rear)
90947A2023 2 $ 46.13 Brake Hydraulic Hose (Right, Rear)
4782102160 2 $ 96.43 Disc Brake Caliper Bracket (Left, Right, Rear) Mounting, Disc Brake Cylinder. A bracket for a disc brake caliper.
4785002180 1 $ 150.51 Disc Brake Caliper (Left, Rear)
4783002180 1 $ 150.51 Disc Brake Caliper (Right, Rear)
4243102200 2 $ 53.31 Disc Brake Rotor (Rear) A single disc brake rotor
4642002151 1 $60.27 E-Brake R
4643002151 1 $60.27 E-Brake L

The big thing that I want to point out, P/N 42431-02200, has the same dimension as P/N 42431-52080, which is the part number for the 2012 Yaris SE rear rotor. Do I have your attention now?
So, first things first to get this to work, the splash guard would have to fit on the Yaris, if not, we're dead on the water. Next, need to sort out what else from that list can be used on the Yaris, well some are straightforward, the calipers can be used, and the pads, since the rotors are the same dimension. And finally, is this more cost effective than the axle swap? Probably easier to tackle than the axle swap, especially if you're by yourself.

There you have it Ladies, another stupid idea from me. I hope someone is crazy enough to test it out before me.

[remcafee]

well it certainly is an alternative i personally do not like the fact of have a whole different rear suspension geometry not designed for our cars but for a corolla, having the rear wheel stance out would not make sense as our front end needs major help already, if its for a look thing i guess, but the yaris se rear disc swap is perfect as their is no change in rear suspension gemoetry and everything still lines up as the factory would want, the corolla brackets and mounting holes physically look larger than ours, once i see an old corolla roll through our dealer ill take a peek and let you guys know though. edit: just realized youre not doing anything to disturbe rear axle positioning but just hub length and flange thickness, i think it would work just waiting to find an old corolla come in so i can measure the length and height of the flange thickness on the corolla axle

[Neinris]

Originally Posted by remcafee

well it certainly is an alternative i personally do not like the fact of have a whole different rear suspension geometry not designed for our cars but for a corolla, having the rear wheel stance out would not make sense as our front end needs major help already, if its for a look thing i guess, but the yaris se rear disc swap is perfect as their is no change in rear suspension gemoetry and everything still lines up as the factory would want, the corolla brackets and mounting holes physically look larger than ours, once i see an old corolla roll through our dealer ill take a peek and let you guys know though. edit: just realized youre not doing anything to disturbe rear axle positioning but just hub length and flange thickness, i think it would work just waiting to find an old corolla come in so i can measure the length and height of the flange thickness on the corolla axle

Remcafee, thank you! I appreciate you taking the measurements. I hope this takes off.

[06YarisRS]

Sub'd. This is something I've thought would be a great upgrade. Would there be any issues with fluid metering and balancing of brake forces front to rear? The Yaris brakes must be designed to distribute a specific force per axle. The caliper pistons are surely much larger in surface area than the tiny wheel cylinder pistons. I'm no fluid dynamics engineer, but I do wonder about this. Do the rear disk and rear drum cars use the same master cylinder?

EDIT: Not positive, but the 2008 Vitz RS uses master cylinder (47201-52280) and 2008 Yaris uses (47201-52320). May not make any difference.

[Neinris]

Originally Posted by 06YarisRS

Sub'd. This is something I've thought would be a great upgrade. Would there be any issues with fluid metering and balancing of brake forces front to rear? The Yaris brakes must be designed to distribute a specific force per axle. The caliper pistons are surely much larger in surface area than the tiny wheel cylinder pistons. I'm no fluid dynamics engineer, but I do wonder about this. Do the rear disk and rear drum cars use the same master cylinder?

Adam, at another thread it's mentioned that if you have ABS you're fine without having to install a proportioning valve. If you don't have ABS, it's is highly recommended that you install one. It's not really that hard to install one, I was trying to argue if having braided lines on the front, and regular lines on the rear would suffice, but that's not advisable neither.
Obviously if or WHEN I do this, I'll be installing the bigger rotors in front. The stock front rotors are 255mm in diameter, the SE rear rotors are 259mm, and the SE front rotors are 275mm. Most of you already knew that.

[06YarisRS]

Originally Posted by Neinris

Adam, at another thread it's mentioned that if you have ABS you're fine without having to install a proportioning valve. If you don't have ABS, it's is highly recommended that you install one. It's not really that hard to install one, I was trying to argue if having braided lines on the front, and regular lines on the rear would suffice, but that's not advisable neither.
Obviously if or WHEN I do this, I'll be installing the bigger rotors in front. The stock front rotors are 255mm in diameter, the SE rear rotors are 259mm, and the SE front rotors are 275mm. Most of you already knew that.

Haha, not 5 minutes after posting, I scrolled down and saw the other thread. This may sound completely silly, but I'm not sure if I have ABS or not on my 2006. Haha. Pretty sure my old '08 did. Going to go look at my wiring diagrams.

EDIT: Guess this answers my own question:

[remcafee]

yeah the abs is actually wonderful in our cars it has electronic brake force distribution and meters brake proportioning electronically not just front and rear both EACH individual wheel separately from one another, so if you dont have abs youre actually gonna have to do more work lol

[enviri]

its been talked to death. no one has done it. do it, make it happen. people will credit you.
I've used XRS pads before the '12 SE was out so yeah its pretty good on dimensions.

just hope the hub bolts line up :P

[Neinris]

Originally Posted by enviri

its been talked to death. no one has done it. do it, make it happen. people will credit you.
I've used XRS pads before the '12 SE was out so yeah its pretty good on dimensions.

just hope the hub bolts line up :P

WOW! I even got Enviri’s attention! What an honor!
Not sure what you’re referring to when you said “talked to death”.
All I’m doing is bring the idea to give others a possible other option. If I do this it’d be in a distant future, I’d rather spent my money on the engine swap. And besides, my other dumb idea is to try and see if the 2nd GEN Scion xB’s rear axle frame fits the Yaris. Can you say 5X114.3?

[remcafee]

i found a rear axle beam from a yaris se with the calipers and everything they left on it for about $240 its not as pricey as you think assuming you get junkyard parts and its perfect fitment for our cars, if its cost youre worried about, have a fabrication shop weld on some rear caliper brackets to your rear axle beam and youre good to go, just source the calipers and lines and such afterwards

[Neinris]

Originally Posted by remcafee

i found a rear axle beam from a yaris se with the calipers and everything they left on it for about $240 its not as pricey as you think assuming you get junkyard parts and its perfect fitment for our cars, if its cost youre worried about, have a fabrication shop weld on some rear caliper brackets to your rear axle beam and youre good to go, just source the calipers and lines and such afterwards

It really all comes down to cost, and availability. Who would want to pay more for something if they can get it for less? The other poster bought everything brand new, of course it'd be more expensive. They can also be found from the the junk yard. Are the Yaris SE more abundant than the Corolla and I think Matrix that the splash guards/back plate came from?

Getting it welded crossed my mind, but my aim is a DIY for the mass. Also it could be slightly off and make the pads wear irregularly. Another thing that crossed my mind was tracing the back plate from the SE and getting one made and slapping it on top. But since I came across the other thread I thought it'd be cheaper to get the splash guards than getting one manufactured.

I need to get my vapor canister and pump replaced. I was going to scower the junk yard for one, maybe I'll scower for a splash guard as well and see how it fits.

[enviri]

yaris se and corolla XRS...the numbers may be similarly small!! the biggest thing is if that caliper mount matches with our hubs, everything else is trivial. if that caliper mount fits a yaris rear caliper also, then holy crap. My original idea is to make a hubspacer with caliper mounts, and did consider the xb2 rear shield but it wont fit.

since when did i become famous?

[Neinris]

Originally Posted by enviri

yaris se and corolla XRS...the numbers may be similarly small!! the biggest thing is if that caliper mount matches with our hubs, everything else is trivial. if that caliper mount fits a yaris rear caliper also, then holy crap. My original idea is to make a hubspacer with caliper mounts, and did consider the xb2 rear shield but it wont fit.

since when did i become famous?

LOL! Always been famous to me, I’ve seen your name around. Almost up there with CTScott in my book.
The thought I have with xB2 is a complete axle frame swap to try switching to 5x114.3. The axle has the same spline count as the Yaris, so swapping the steering knuckle might be an option. That’s for another story.
Like I said, I too thought about tracing the SE hub mount and getting a plate made, but it might be more expensive to get manufactured.
Well I hope me sharing this inspires others to try it out. Gonna go to the junkyard this weekend. Crossing my fingers...

[CrankyOldMan]

I have an SE rear axle in the garage and there's a 10th gen Corolla in the local junk yard but it only has drum brakes. If I could pull the rear hub I could at least compare bolt patterns and bore diameter since the hub is common to all variants of that gen Corolla.

[Neinris]

Originally Posted by CrankyOldMan

I have an SE rear axle in the garage and there's a 10th gen Corolla in the local junk yard but it only has drum brakes. If I could pull the rear hub I could at least compare bolt patterns and bore diameter since the hub is common to all variants of that gen Corolla.

OH MAN! Now we Cranky involved!!!

Please do! I may or may not find a XRS in the junk yard, I'm sure I'm not the only one who would appreciate it.

[enviri]

apparently the rear dust shield extends to 2019....maybe other parts. trying to find them used :P

[Neinris]

Originally Posted by enviri

apparently the rear dust shield extends to 2019....maybe other parts. trying to find them used :P

Cool! Cool! I guess I’ll just start looking for Corollas with rear disc brakes in the junk yard. The evap canister are also similar if not the same. So might be two birds with one stone.

[Neinris]

Went to the pick and pull today, couldn’t find a Corolla with rear disc brakes. I tried pulling out a hub from one of the, but it was really on there. The other ones were sitting on mud, so I didn’t bother. I’ll try another pick and pull this weekend.