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Discussion Starter · #1 ·
So I was checking a few things out before I head out on a trip and I saw a bit of fluid around this boot and hose, there apears to be a bit more fluid in the boot as well brakes feel good but what am I looking at? The hose that comes out of this boot heads to a bracket on the rear axel?
 

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Discussion Starter · #3 ·
Thanks for the info, we did just put on 5100's and AAL in the back I will read up on this and check into the small seal leak! Thanks.
 

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2015 Toyota Tundra DC SR5 5.7L
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Thanks for the info, we did just put on 5100's and AAL in the back I will read up on this and check into the small seal leak! Thanks.
If you lifted the rear, you will probably require a minor adjustment, which is accomplished either with the locknut setting or bracket height to adjust for it. The link shows you the procedure.
 

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So this valve is where I can adjust the sensitivity of my brakes? I ask because mine are so damn sensitive I can never come to a complete stop without giving myself and any passengers whiplash, damn near.
 

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Is that what it's for?
 

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So this valve is where I can adjust the sensitivity of my brakes? I ask because mine are so damn sensitive I can never come to a complete stop without giving myself and any passengers whiplash, damn near.
Read the post linked above. It explains what the LSP&BV does. Note that to properly calibrate it requires very specific weights, brake pressure applications, and line pressure measurements.
 

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So this valve is where I can adjust the sensitivity of my brakes? I ask because mine are so damn sensitive I can never come to a complete stop without giving myself and any passengers whiplash, damn near.
Nope its just your right foot stomping on brakes. There is no such a thing as too sensitive brakes is you drive/ride the thing for more that 3h after getting it. Slow down, dont stomp on it. There is no such a thing as adjusting sensitivity. You can on purpose let some air in the brake system then you'll get softer brake pedal and weaker braking force. Warning - nobody does that and its highly NOT recommended to do so actually its opposite(no air in brake system) but it would work :crazy3d:
 

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If there's no way to adjust sensitivity as you say and no air in the brake lines (as I've bled them 3x now) then my brakes must have some kind of wierd issue. They work great don't get me wrong, it's just I hate barely touching the pedal and it feels like I'm slamming on em. Sorry for hi-jackin the thread a lil.
 

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Let some air back in :D that will help with sensitivity.
Go to Toyota dealership and test drive couple more Tundra's and you'll know if your brakes are any different than other Tundras. I test drove about 10 Tundras before i got mine just to make opinion how the truck should drive, handle, feel. Some had too sensitive brakes in the rear - the rear would lock up before front - not good, probably someone was messing with proportioning valve.
 

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Discussion Starter · #11 ·
So I think I have 2 issues here, first is that after we lifted the truck, my wife said she thinks the brakes dont work as well, so that got me looking at things and that is when I think I found what may be a leak at the valve body see pic at top of post. Now this must have been just a chance thing because I dont think the leak has anything to do with the AAL in the back. So I made a braket and moved the load arm up the amount of the lift and I cant tell but I think I gained a bit of rear brake performance back? Well anyway now onto the leak. I removed the boot that covers the modulation valve and found that this boot is sealed rather well and cant figure out if a small amount of fluid is normal in this boot or not. Would some other owner check theirs out for me. The boot seals with a group of o rings and washers like if there were to be a leak Toyota does not want you to know about it. If it were leaking wouldn't air be getting into my brake system and making it soft on pedal feel. Thanks for any input guys I just ordered the Haynes manual to help with some insite as the local Toyota dealer plays dumb and say bring it in so we can work on it all day.
 

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You should not have any leaks period.
 

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Discussion Starter · #13 ·
You should not have any leaks period.
That is my feeling too, but if fluid is coming out, why isn't air going in, or it such a small amount that I do not feel it in the pedal?
 

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It is probably a very small leak and the quantity of air in the line hasn't affected anything yet. You need to replace the proportioning valve before it worsens.
 

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Discussion Starter · #15 ·
It is probably a very small leak and the quantity of air in the line hasn't affected anything yet. You need to replace the proportioning valve before it worsens.
Do you know if I can rebuild the valve, it looks like it comes apart with a snap ring, after you remove the dust boot, or do I have to buy a whole new cast valve assembly? If that is the case then this sounds like something for more of a mechanic because the valve if new will most likely need adjustments with guages and other tools. Is this a problem you have seen before I can not find much info on it anywhere. Thanks Brian
 

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I just looked it up in the shop manual and you can disassemble the valve however it doesn't show anything about rebuilding it. You might just need to replace the cast part of the valve but you won't know until you take a closer look at it. The manual does state that the wear limit for the piston is .7mm so if its less than that it needs to be replaced.
 

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Discussion Starter · #17 ·
Thanks for the info, the funny thing is that I and others out there would never know if this valve was leaking untill it became a large amount of fluid because of how the boot seals it off, I just found it becasuse I was looking around at my wife's request, and as it turnes out I dont think this is the reason the brakes feel less than normal, it is because of the location change of the load bar on the axel. I have corrected that with a bracket now I am working on this leak and I will check with a toyota parts department to see if there is any rebuild kit or just a new valve. Any more input would be great if other could look at their valve and tell me if they see any fluid or anything.
 

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I can tell you that my valve has no such leaks. I was back there to replace the stock line with a russell ss line and my valve was dry.
 

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Discussion Starter · #19 ·
So I called the local dealer today and got a quote of $177 for the new valve body, there is no parts or rebuild shown for the load valve. The dealer says 1 hour to put it in so $125 in labor, they claim this includes adjustment of the valve and bleading of brakes. They want me to pony up for a $129 brake flush, but my feeling is that most of this will get taken care of by replacing the valve. $177 + $125 labor sounds to good to be true. So what do you guys think. The other side note is that the part is 3 to 4 days out as the dealer has not sean a leak in this area of the valve before. Lucky me, a problem all my own. For $125 in labor I am not going to mess with it.
 

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Have you checked with any of the local shops to get a quote besides the dealer?
 
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