Ok.. Makes since. Which caliper uses the 231mm?? As I thought it was the 13WL?


So the OP should be fine with the calipers being 13WL provided everything else is in good working order and no air in the system. Since the movement of fluid is the same and all the pistons are the same size using the surface area of fluid to push. So all these spongy pedals are just air in the system? Interesting learn something new everyday. :-)

When I did the upgrade on the 97 Limited Puppy Hauler I left the old calipers hang and connected until I had the upgrade connected.

When it was time to connect the new calipers I made sure the MC was full and the bleeder was open before hooking up the new brake hose to give the air a place to go.


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The 13WL caliper is the 231mm. BigFishAllDay explained the difference between the two really good in his write-up:
"The mechanical difference boils down to the updated caliper being much larger to hold a larger pad....The early style pad (in the 13WE caliper) will be less than 5” (4-11/16” or 199.5 mm) in width; the (pads in the) later update (13WL caliper) is more than 5” (5-5/16” or 231 mm)."
This is referencing the brake pad backing plate, but the brake pad material is very close between the two as seen in this post: https://www.toyota-4runner.org/3378920-post1.html

I think what people are saying is a "spongy feeling brake pedal" is really just the nature of the brake system due to an increased piston size in the front calipers. Some cases could be air still in the system or old fluid that has absorbed too much moisture. When the caliper piston size increases then the master cylinder has to move further in order to make up for the added piston volume. This means the brake pedal is easier to push and must be pushed further. Some people will notice it and some people won't. It definitely depends on the driver. I borrowed my dad's car the other day and it shakes horribly, but my dad didn't notice it at all.

I know my 1998 with the 13WE calipers work great for me. My rims fit without grinding things and the only reason i changed them was to get rid of the warping rotor. :-D

OP out of curiosity, do you find that when you press the pedal when moving - take your foot off the pedal and then quickly press it again that it firms up?

If so, I have a nearly identical scenario going on with mine post TBU.

Just for documentation purposes, I went with the PowerStop KC2324 Z23 daily driver set up with Rotors, pads and calipers and StopTech 95044007 lines.

FWIW With this set up, the rotors were thicker (but same diameter as OE), the calipers larger (had to trim dust shield) and in turn the pads were larger as well. (I am not sure if this set up was 13WE or WL if I am being honest)

It stops. It will stop short. The shudder from the original warped rotors is now gone. But the OCD in me knows the pedal was firmer on the OG set up then it currently is, aside from quickly pressing the pedal the 2nd time when braking. That seems to have a more original feel for me.

That said, I am going to anxiously follow this.

I chalked it up to mine being an 01 with ABS and some people just seemed to have a different pedal after the TBU and dealt with it. I'd love to get to the bottom of it myself.