Normal braking is underwhelming at the moment. If I slam them eventually theres a point where the fronts grab in a big way and stop the car with great prejudice, but normal braking is unimpressive and theres that pesky hard brake pedal at the top of the stroke when i slam the brakes.

I just talked to my mechanic and am going to bring it by to have him drive it. He said the brakes were even "super touchy" when the truck left the shop. Will update with results.

My 4runner is doing the same thing. Installed used OEM booster and same issue. When I panick stop I have no assist.

Under normal braking conditions does the pedal function as normal? A brake booster should generally just work or not. There really isn't much too them. A non-properly functioning master cylinder can cause all sorts of issues.

Great video of a breakdown of the inner workings of a master cylinder and brake booster: YouTube

I'm interested to see what the outcome is as well.

This is extremely vague. Did you have the issue before swapping to another OEM booster? I'm under the assumption you did since you swapped parts. Throwing grenades at problems isn't the way to go.

The boosters rarely go bad. Go pull one from a junk yard and put it in with your new vavle.

Well I would not have swapped if I had no brake issues.

New napa calipers
OEM pads and rotors
New SS brakes lines
Multiple bleeds
New OEM check valve
Used OEM brake booster
New rear pads, turned OEM drums and adjusted

Only thing left really is the master. Everything works great other than panick braking. I get no assist for a good 2 to 3 seconds then it will start to assist.

Make sure you properly bench bleed the master cylinder or it just won't ever work right. Having it work right besides when you panic brake makes me believe it isn't the vacuum booster. There isnt anything inside of them that are going to operate differently when panic braking vs regular braking that I'm aware of.

The master never completely lost fluid and so should not need bench bleeding. May try that next when I get her ready to sell.

I took the truck back to my mechanic today and he agrees that I am not getting full boost, but the Booster is functioning. What he said was intriguing and I had not considered it.

I have a generic vacuum leak code and the vacuum lines are old, loose generally in ill repair. He seems very confident that the Booster is not benefitting from full vacuum, and the problem is exacerbated with a pedal stomp due to the high amount of vacuum quickly demanded. He pumped it a few times and concluded that the Booster is most definitely not getting all of the vacuum assist that it should be. Apparently if I fix the vacuum leak, he's pretty confident the brake performance will improve due to the increased vacuum to the Booster.

Additionally I have a really low idle right now which he is saying is worsening the lack of vacuum issue. He said to clean the throttle body and replace the crusty vacuum lines and see what happens.

I'll update back with results but it makes sense to me.

Thanks for update. I kind of thought the same thing was happening to me. So I went through every vacuum line possible and all seems well. I have a cheap ebay intake and went over all that thinking it was issue but cant find any leaks. I ran this intake for literally 8 years without issue but thinking of swapping stocker back in. Let me know what you find!

Not sure if it'll work in this instance but a lot of guys home make (myself included) a pvc pressure cap with a fitting(to hook up to an air compressor). Tape or clamp it on to your intake and now you can easily check for leaks without the car running. Probably only need like 20-30 pounds to test for any leaks. Great for testing leaking intake manifold gaskets (long story)

Basically the same thing as this:
YouTube

just without the cigar portion. You can also do the cigar/smoke testing instead if you like!

Yes that's how do we boost leaks on our turbo cars with a spray bottle and soapy water. But a home smoke machine vacuum tester would work also.

I'm going to sell it so might just let next owner know.

I know it's been a while but I think I got this figured out.

The cheap Chinese "reman" booster that was put on the truck was functioning, but I was suspicious about the check valve. I removed the check valve and blew into it both ways. It allowed backflow unless a lot of pressure was applied, and in the direction of flow there was a lot of resistance. I bought a Toyota original check valve, but the cheapo booster has a hole for the check valve that's not Toyota factory sized, so the Toyota valve was too large.

I went to Advance and bought a cheapo $6 dollar generic check valve, installed it, and voila. WAY better braking. There was so much resistance through that janky check valve that it wasn't allowing all the boost through.

I am wondering if I can find a Toyota vehicle with the smaller check valve so I can install a Toyota brand check valve, but for now the cheap plastic once has helped a lot.

I have never been impressed by 3rd gen 4runner brakes. Ive been driving cars since the 1960's Ive been twisting wrenches with my dad starting in the late 50's. my taco was the same, my 90's Toyota pickup ( before they were called tacos) stopped good, My 95 corolla stopped better. I went through everything after getting my 4runner. then I did the TBU, stainless lines, new cylinders in the back, new check valve, made sure the cams on the parking brake were good, bled, bled bled, before and after the tbu
while it stops good, im not impressed
but a whole lot better than the American drum brakes of the 50's. 60's and late 60's early 70's when discs were up front

[QUOTE=BamaDrewski
Just 16 months later, the POS has failed leaving me in the lurch. So, word of warning for anyone considered this brand (Cardone) of re-manufactured brake booster - DON'T WASTE YOUR MONEY.

Agreed, Cardone sucks, after warrantying the racks in 3 different vehicles a total of 9 times I won't use them anymore. Local parts stores can't even get a Cardone rep to show his face. F them.
Also agree with 3bears that the Toyota 4 piston calipers suck, but the drum brakes last forever. I have also seen a lot of Toyota master cylinders fail suddenly for no reason. Boosters, not so much. Any new aftermarket parts are Chinese, just say no. Go with good aftermarket reman, or new, remanned, or used OEM. I think Napa has the better reman stuff.