Braking still not easy

I've had poor braking as long as I can remember. Raising the LSPV helped a tiny bit. Now that I replaced the booster it almost feels worse than ever, though more linear.

- Tundra brakes & stainless lines
- 35x12.5 rear, 35x10.5 front
- New brake booster
- Bled master cylinder
- Bled all 4 corners + LSPV
- New fluid
- No ABS

The brake I wouldn't describe as spongy or hard, but I have to press it very hard and practically to the ground to stop... To the point where after a lot of stop and go traffic my foot hurts.
The only thing I haven't done is replace the master cylinder, but it is not leaking. Is it possible it's still an issue? Is there a larger MC I can go to?

 

I know someone who used the tundra's and the extra large front cylinders seem to overtax it..while the rear cylinders made contact first....causing them to wear

After a year he pulled them off......and found unusually high wear on the two leading shoes.

SO if you need that extra breaking ......it may not be a good longevity solution...

I'd forsure watch em close...


Curious to others solutions on this......popular upgrade...
....not many complain...

 

Almost makes me wonder if you have corrosion in a hard-line, but seems a long shot. Could be a bad braided stainless line as well. Not likely but since you seem to have checked everything else I might consider it.

 

hmmm
per your mods, you obviously know how to bleed brakes/LSPV
that would be my 1st guess but not applicable here

maybe this will point you in right direction
i encountered on my 'swapped' car
i just had poor braking from the swapped Brembo calipers(SS lines as well BTW)
i bought 'bigger MC' (stamped on the MC(Subaru))
no real help
then someone advsd tht if you swap the entire brake system, must swap all parts
he said everything even the rear proportion valve(located under hood)
(i didnt)

well i bought the STI booster
fixed the issue

so STI booster/MC/calipers are all from same model
think of anything that sends pressure needs to be the same
GL

 

The only thing you didn't mention in your list was properly adjusting the rears. Those being out of adjustment (even just a bit) can have a bigger affect when you have the larger capacity 13WL calipers up front. And, though the rears are supposed to self-adjust, I find that they often don't. Given your current situation, that's where I'd start.

 

Interesting ^^^^^

guessing here
But that would point to LSVP

delete that sucker
Then control rear brake bias manually

 

Not really. (Edit: but I can see how I wasn't clear in my original reply, so thanks for this)... It's not about the percentage of braking that they provide - the LSVP works fine for that, it's more about them being adjusted "to loose," so that when you press the pedal, you have to move more (a larger volume of) fluid to exercise the drum cylinders.

When the rear isn't properly adjusted on a stock truck, moving that additional volume into the cylinders is "ok" ("not as noticeable") but when you have larger front calipers (with a larger internal volume), it becomes much more noticeable since you're moving even more fluid throughout the system.

Technically you should be able to adjust the rears using the star gears through the backing plate, but sometimes that doesn't work very well, and the only way to really adjust them is to take the drums off and clean the gunk out of the internals, and then adjust the star gears.

Some details that show you the star gear you use for adjustment: Step by Step Tacoma Rear Drum Brake Shoe Replacement – AdventureTaco

 

Honestly deleting the LSPV was one of the better things I've done. It just gets rid of a potential problem and there's no real reason to have it.

 

^^^ this

This is the exact problem I had with my 3/4 ton Dodge Cummins 4x4 and towing. The 5th wheel tongue load would not compress the rear springs enough to sufficiently open the LSPV and the rig would not stop. It is pretty scarry shit to have your truck pushed through stop signs because of insuffient braking. I tried all of the normal "fixes" then I came across a service bulletin from Dodge that said that if you routinly use you truck at 70% or more of GVRW take the LSPV out of the system. Problem solved. The only downside is running around unloaded, the rear tire will lock with a moderate pedal application, tires and brake shoes are cheap, wrecks arnt.

 

Could be OP’s lspv is not functioning properly, that being said I would start by checking rear shoe adjustment. The self adjusting feature on these trucks is not very good.

 

I confirmed that my LSVP was junk bc prior owner just had the ole’ Firestone complete F/R brake job 30k before I got the taco. After my F bearing install, I discovered that front pads had less than 50% material left on the front pads.
Both sides…..even wear

Just for giggles, I inspected the rear drums……zero…I mean zero wear.

Searched TW and confirmed the LSPV failed. Who knows how long the taco was stopping on 100% front brake bias.

“If you can install a SC, you can install a manual rear proportion valve “
I.E. LSPV delete

 

Thanks for hopping on this everyone. It has been a good deal of time since I've inspected the rear drums and for all I know they're not even working. So I'll make that a priority.

I've considered doing the LSPV delete and have the manual one in my Amazon cart, but I've held off because I don't fancy making brake lines. If there's a kit somewhere I'm not aware of, maybe someone can point me to it

 

Can’t vouch for it, but have read it works for the first gen Tacoma as well. Definitely check prior to ordering. It also puts the manual valve under the bed, which may not be ideal.

https://www.firstgentundra.com/firs...te-kit-for-wilwood-manual-proportioning-valve

 

Not exactly sure on your 99 non abs
But my 96

got to find the LSPV return line and block it(no need for it with manual P valve)
It’s a 8ft line…..I just left it hanging, out of the way.
Then a pretty short brake line(2ft-/+) with female ends to go from P valve to line on rear axle that splits to both sides

I had short brake line that I used in past to bench bleed MC’s….i used that
There is a thread of mine w good pix…4-5 months ago
Not perfect/professional install (as one member described as wonky) but works/no leaks / and used/fabbed materials that I had on hand

If u buy a jegs/summit P valve, need metric adapter…..cheap and easy to find at oriellys
NP to pm me anytime treyus

 

Good pt CA

mine is under bed….easy
I figured set it and forget it

Seen under hood setups….much more professional looking. But I don’t race, and don’t need to adjust rear B bias when confronted with different rd race tracks (as far as elevation changes/off camber corners/race car concerns)

 

Here are the adapters needed
And the inexpensive rear P valve I used

 

I had this exact same issue after doing my Tundra swap/new rears... bled the brakes probably 4 times no change thought I adjusted the rears properly. Truck was in the shop doing a rear main asked them to double check my work while it was there. They did a power bleed + properly adjusted the rears and it is amazing. Feels like a whole new truck. I'd double check the rears and if you can pressure bleed, do that. They charged something like $80 for the power bleed + rear adjustment

 

I'll have to find your post, not able to visualize it

Tbh though my truck is so high it's probably more convenient under the bed than under the hood lol

 

Unless you haul freight.....that manual one will work great.

Getting rid of that valve is eliminating a part that is designed to fail one day...


Not only that but that return line just recirculates old burnt fluid back thru the whole system......dumbist thing I've ever seen

 

Is there an easy way to see if it's failed? Can you block off the return line and run w/o a proportioning valve completely?