Poor Brake Performance After TBU

[mesooohoppy]

It makes sense that the 231's will not feel right in our trucks, that's a lot more fluid to push with a master cylinder not designed/sized for that. So I think [MENTION=28464]eimkeith[/MENTION] is on the right path with the bigger master cylinder :thumb:

please elaborate. the calipers between the tundra and 3rd gen t4r look the same in size. its also not like your jumping up in piston size either. im under the impression most of the issues come from improper bleed proceedures (see post 20).

picture for reference:
https://www.yotatech.com/forums/att...installed-98-gen-3-4runner-tundrabrake022.jpg
t4r caliper on the left.

 

[absalom]

This is why I don't recommend the TBU. I had the same issue on one of our 3rd gens, and could never get the pedal close to stock feel. Braking never gave me the confidence that I had prior to the TBU.

Good luck, OP!

 

[Bad Luck]

please elaborate. the calipers between the tundra and 3rd gen t4r look the same in size. its also not like your jumping up in piston size either. im under the impression most of the issues come from improper bleed proceedures (see post 20).

picture for reference:
https://www.yotatech.com/forums/att...installed-98-gen-3-4runner-tundrabrake022.jpg
t4r caliper on the left.

Read this for a very thorough comparison between stock and tundra brakes: Hard to find Specs, Info & Measurements on 231mm 13WL Tundra Calipers & Rotors

Edit: If you haven't already try using this 3rd Gen specific google search: https://www.google.com/search?q=site%3Atoyota-4Runner.org%2F3rd-gen-t4rs%2F&rlz=1C1QJDB_enUS784US793&oq=site%3Atoyota-4Runner.org%2F3rd-gen-t4rs%2F&aqs=chrome..69i57j69i58j69i59l3&sourceid=chrome&ie=UTF-8
Type what you're looking for after all the info that's already in the search bar.

 

[spartacus]

Alright, here's where I landed.

Since the truck was with them already, I went ahead and let them bleed the ABS system. Between the additional bleeds and adjusting the rears and the push rod, the brakes are golden! I know there's speculation that the stock master cylinder doesn't have what it takes to drive the larger calipers--from what I can tell right now, that's not the case. My brakes are nice and stiff now, and engage right where I'd expect them. Could a bigger master cylinder further improve the brakes? Maybe. But I'd say the TBU with 231mm calipers is just fine with the stock one.

Thanks everyone for the suggestions and the sanity check!

Glad they sorted it out for you.

 

[mesooohoppy]

This is why I don't recommend the TBU. I had the same issue on one of our 3rd gens, and could never get the pedal close to stock feel. Braking never gave me the confidence that I had prior to the TBU.

Good luck, OP!

so did you try to fix the issue, or did you just go back to stock?

 

[mesooohoppy]

Read this for a very thorough comparison between stock and tundra brakes:

i have been doing some research and i still need to do more. but from what i have been reading, my take away is that the bleed procedure has a lot of do with the success of your tbu swap. if you stave the MC, it eventually ends up starving the abs unit, which can be a pain to bleed (from what ive read, also common on other toyotas).

a fair amount of the people who arent satisfied with the swap claim they werent happy with the pedal feel and went back to stock; most of these i come across on this forum do not further elaborate.

the measurements on the first link you showed me do in fact confirm the tundra caliper is bigger overall (but not by much). which would likely mean that there is slightly more passage length for the fluid to reach the piston; although i wouldn't think this would require a larger MC. these calipers really arent that much larger and you arent jumping up in pistons either.

sorry for not multi quoting. it doesnt seem to work on this forum.

 

[TonyB66]

I'm putting a larger master cylinder in. :/

Decided upon which one yet?

 

[jkeith.w]

Decided upon which one yet?

Yeah I bought it about a year ago or so - let me check my records and see what the part number was. I got the corresponding booster as well.

 

[Bad Luck]

[MENTION=402644]mesooohoppy[/MENTION] When I did mine I purchased an assortment of silicone caps to cap off the brake lines to keep from losing too much brake fluid. Worked like a charm

 

[T4R2014]

I hate my tundra brakes so much. Like Jeremy Clarkson hitting a laptop with a hammer level of hate.

 

[mesooohoppy]

ooooh, thank you for that! i saw that on one write up but totally forgot about it. will for sure purchase those.

 

[absalom]

so did you try to fix the issue, or did you just go back to stock?

I used the following to attempt a fix:

- pressure bleeder
- TechStream cycling the ABS solenoids
- Gravity bleeding
- Traditional 2 person brake bleeding, with engine on and off

I saw some improvement, but never to where I was happy with the feel.

 

[jeech]

i have been doing some research and i still need to do more. but from what i have been reading, my take away is that the bleed procedure has a lot of do with the success of your tbu swap. if you stave the MC, it eventually ends up starving the abs unit, which can be a pain to bleed (from what ive read, also common on other toyotas).

a fair amount of the people who arent satisfied with the swap claim they werent happy with the pedal feel and went back to stock; most of these i come across on this forum do not further elaborate.

the measurements on the first link you showed me do in fact confirm the tundra caliper is bigger overall (but not by much). which would likely mean that there is slightly more passage length for the fluid to reach the piston; although i wouldn't think this would require a larger MC. these calipers really arent that much larger and you arent jumping up in pistons either.

sorry for not multi quoting. it doesnt seem to work on this forum.

This. I believe this was the biggest culprit for the crummy brake feel, as I saw the largest improvement after this was done. I've only done some preliminary research on the process to bleed the ABS, but I'm glad I let the shop do it.

 

[jeech]

I should also note that I started out with terrible brakes. I bought this truck back in January, and the rotors were the most warped of any I've seen. The shudder was unbelievable, especially on a downhill. They were also spongy and slow to engage.

All this to say that the only thing I have to compare their current state against is that, and the 2013 Elantra we have--which if you're familiar with that vehicle, you know that if you just look at the brakes you're in a hard stop. So while I'm pretty dang happy with the upgrade, I can't say if it feels what stock should feel like, as I haven't really experienced well-maintained stock.

 

[Snowden]

This is why I don't recommend the TBU. I had the same issue on one of our 3rd gens, and could never get the pedal close to stock feel. Braking never gave me the confidence that I had prior to the TBU.

Good luck, OP!

Jordan did you end up going back to original calipers ? I feel a bit the same way with the 199mm TBU I did to my '98. I've never been overly impressed with the mod. I'm contemplating going up to the 231mm but frankly I'm always more concerned with the long brake pedal travel and I'm still going to have that with either 199 or 231. Lately my brakes have been feeling quite a bit worse. So I'm pretty on the fence about what to do. Whatever direction I go in I'm going to switch to braded lines which I hadn't done previously. The expansion pov regarding the rubber lines does make sense and maybe that's contributing to the issue.

 

[19963.4lsr5]

Jordan did you end up going back to original calipers ? I feel a bit the same way with the 199mm TBU I did to my '98. I've never been overly impressed with the mod. I'm contemplating going up to the 231mm but frankly I'm always more concerned with the long brake pedal travel and I'm still going to have that with either 199 or 231. Lately my brakes have been feeling quite a bit worse. So I'm pretty on the fence about what to do. Whatever direction I go in I'm going to switch to braded lines which I hadn't done previously. The expansion pov regarding the rubber lines does make sense and maybe that's contributing to the issue.

Recently a member did the TBU and had your issues and he took it to a garage and had them bleed the brakes and ABS unit and it restored his pedal feel. Do not know how to pulse the ABS without braking hard in stones. There might be a way using the test port bolted to the intake.


Sent from my iPhone using Tapatalk

 

[absalom]

Jordan did you end up going back to original calipers ? I feel a bit the same way with the 199mm TBU I did to my '98. I've never been overly impressed with the mod. I'm contemplating going up to the 231mm but frankly I'm always more concerned with the long brake pedal travel and I'm still going to have that with either 199 or 231. Lately my brakes have been feeling quite a bit worse. So I'm pretty on the fence about what to do. Whatever direction I go in I'm going to switch to braded lines which I hadn't done previously. The expansion pov regarding the rubber lines does make sense and maybe that's contributing to the issue.

IMO, I don't see how braided lines could be the answer. The poor pedal feel wasn't there prior to the mod, so why would it fix it now?

I sold the vehicle, and have had several 3rd gens since then. None of which had the TBU mod done. Instead, I've maintained the brakes using strictly OEM gear and have been very satisfied with the bog standard brakes.

The TBU attempts to fix an issue that really doesn't exist. Downshift on steep grades, use quality OEM rotors and pads, and high quality fluid and these brakes are great!

 

[Supracool03]

Just completed TBU with 199 calipers on 1996, it stops good but there is a lot of travel on the pedal. If I replace the master cylinder and brake lines, will it make a difference?