Hydro boost - rock hard brake pedal (3 Viewers)

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An 80 with a new MC, 4 new calipers, 4 new quality rotors and ceramic pads stops fantastic.

An 80 with corroded, stuck old calipers, organic pads and glazed over rusty rotors sorta stops. Adding hydroboost doesn't fix all the other stuff that's barely working.

Hydroboost does work great. Better than vacuum by a lot.
 
baldilocks said:
I explained this to you yesterday in the Hydro Booster thread. Your MC bore is too big for your calipers. Its large diameter moves much more fluid per every centimeter of brake pedal movement. It’s filling your calipers almost instantly and creating the hard pedal feel. The brakes feel weak because the PSI of brake line pressure is now reduced due to the oversized MC bore. The factory MC has a 1 inch bore. That SD MC probably has 1 1/4” bore or even larger. This is basic hydraulics.

I suspect the hydro booster has an internal defect based on the fact fluid shoots up out of the reservoir from the return circuit. I understand the desire to convert to a hydro booster but not with garbage parts.
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hey sorry bout that. i took what u said and investigated last night. you are correct the bore it significantly bigger. also the return line to power-seeking box was too large so not enough pressure was being kept in the hyrdo unit. i changed the hose and braking force was increased to the point where lock up can occur in an emergency.

braking effort is increased as you mentioned also cause of the hydro unit. and travel is less due to more brakign fluid being pushed.

again i appreciate your input and advise. it was spot on
 
i am also goign larger brakes front and rear so that may help also with pedal feel
 
Maybe I missed it, but what are these bigger brakes you speak of? Are they OEM compatible parts, or the big ticket aftermarket kits for sale?
 
jjdeneen918 said:
Maybe I missed it, but what are these bigger brakes you speak of? Are they OEM compatible parts, or the big ticket aftermarket kits for sale?
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Have you read this informative thread?

forum.ih8mud.com

HOW-TO: 5th Gen 4Runner Brakes on an 80

I'm still finalizing the last few pieces of this upgrade but wanted to share the details with folks. I've seen a few other brake upgrades that involve different rotors and a bit of machining but in my opinion this is the easiest way to get bigger brakes without the extra work. I've seen a few...
forum.ih8mud.com forum.ih8mud.com
 
jjdeneen918 said:
I converted to hydro boost a few years ago after reading this thread & vacuum booster failed.

I do believe the brakes have improved, but at the same time I feel “meh” with the results.

I went with the same booster in the original post, Corvette MC, I believe has a 1 1/8” bore (suggested by Matt Sweeney), & Wilwood proportioning valve.

I have deleted the LVSP & have original OEM calipers.

I’ve never locked up the brakes. While at a stop, the rig starts to creep forward. I have to apply additional pressure to keep stopped.

My ex refused to drive it. She felt she didn’t have the strength to stop it. But she was a tiny human.

Any recommendations?
I’m thinking maybe getting rid of the ABS unit could help? Im also thinking a rebuild of the OEM calipers could help?

Any thing else from the collective resources here?
Click to expand...

1-1/8 is too big for the 80 brakes in my opinion. I would go 1 or 1-1/6.
If your calipers are original they are coming up on 30 years old, so start there.
 
yup 5th gen 4runner brakes are my plan. hoping the MC feels better with that. if not i will downsize the bore and try again
 
jjdeneen918 said:
Not opposed going Wilwood, do they offer both of these sizes?
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Willwood does NOT offer a 1" or 1 1/16" unfortunately. 1 1/8" is 100% without a doubt too big for this setup. The 80 stops amazing here though, it just takes a lot of pressure from my foot to get it to stop(stiff pedal). If the OP brakes don't work in addition to a hard pedal, sounds like an additional issue to me. The 1 1/8 Wilwood works great for me, it's just sized too big resulting in a stiff pedal.
@Madcrix12, the 4R calipers will change nothing on the pedal firmness. I went the narrow superlight 6 piston Wilwood. They spec this for the 4R with a OEM system so they don't upsize piston displacement causing other issues. Best bet, coming from many people here confirming, looks to be the T100 1 1/16 MC. @cruiseroutfit generally seems to have these on hand. I have one I still need to put on, The Wilwood just looks much better and I'm not bothered enough to change it out....
 
on the rocks said:
Willwood does NOT offer a 1" or 1 1/16" unfortunately. 1 1/8" is 100% without a doubt too big for this setup. The 80 stops amazing here though, it just takes a lot of pressure from my foot to get it to stop(stiff pedal). If the OP brakes don't work in addition to a hard pedal, sounds like an additional issue to me. The 1 1/8 Wilwood works great for me, it's just sized too big resulting in a stiff pedal.
@Madcrix12, the 4R calipers will change nothing on the pedal firmness. I went the narrow superlight 6 piston Wilwood. They spec this for the 4R with a OEM system so they don't upsize piston displacement causing other issues. Best bet, coming from many people here confirming, looks to be the T100 1 1/16 MC. @cruiseroutfit generally seems to have these on hand. I have one I still need to put on, The Wilwood just looks much better and I'm not bothered enough to change it out....
Click to expand...
The T100 MC has a two hole mounting flange to fit a Bosch hydro booster?
 
I read the 4Runner caliper/rotor thread. Very interesting. I like that it uses all OEM components, minus that hub spacer.

If I went this direction, seriously considering since I already intended to rebuild/replace calipers anyways. Would you still recommend changing the MC from 1 1/8” currently to a smaller 1 1/16” or 1” setup? If so, which size would be better?

If recommended, I’ll downsize the MC bore size. Currently running the PO’s same GM hydro booster. Off hand, are there GM MC’s compatible in those sizes? If so, anyone know which applications from or part numbers?

Question about lug nuts. I’m currently running the 17” Tundra/Sequoia wheels with a 1” Slee Spidertrax wheel spacer. Would I have fitment issues or lug nut issues?

Thanks in advance.
 
jjdeneen918 said:
I read the 4Runner caliper/rotor thread. Very interesting. I like that it uses all OEM components, minus that hub spacer.

If I went this direction, seriously considering since I already intended to rebuild/replace calipers anyways. Would you still recommend changing the MC from 1 1/8” currently to a smaller 1 1/16” or 1” setup? If so, which size would be better?

If recommended, I’ll downsize the MC bore size. Currently running the PO’s same GM hydro booster. Off hand, are there GM MC’s compatible in those sizes? If so, anyone know which applications from or part numbers?

Question about lug nuts. I’m currently running the 17” Tundra/Sequoia wheels with a 1” Slee Spidertrax wheel spacer. Would I have fitment issues or lug nut issues?

Thanks in advance.
Click to expand...
Since I avoid making too many changes on a system all at once, I’d either install the 5th gen 4R brakes with the current MC and see how it works for YOU, or find out what size MC the 5th Gen came with and do that.

It doesn’t seem like you’d have any lug nut issues to concur as the rotors are bolted to the inside of the hub.
 
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baldilocks said:
Since I avoid making too many changes on a system all at once, I’d either install the 5th gen 4R brakes with the current MC and see how it works for YOU, or I find out what size MC the 5th Gen came with and do that.

It doesn’t seem like you’d have any lug nut issues to concur as the rotors are bolted to the inside of the hub.
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I agree with that sentiment. But at the same time, if the consensus is 1 1/8” is too big, do it all at the same time as it’ll be another job to bleed the system again & again.

I don’t think the T-100 MC is an option for me since I have a GM hydrobooster installed.
Curious if anyone does know what GM MC, with 1 1/16” bore would work for me.
 
on the rocks said:
Willwood does NOT offer a 1" or 1 1/16" unfortunately. 1 1/8" is 100% without a doubt too big for this setup. The 80 stops amazing here though, it just takes a lot of pressure from my foot to get it to stop(stiff pedal). If the OP brakes don't work in addition to a hard pedal, sounds like an additional issue to me. The 1 1/8 Wilwood works great for me, it's just sized too big resulting in a stiff pedal.
@Madcrix12, the 4R calipers will change nothing on the pedal firmness. I went the narrow superlight 6 piston Wilwood. They spec this for the 4R with a OEM system so they don't upsize piston displacement causing other issues. Best bet, coming from many people here confirming, looks to be the T100 1 1/16 MC. @cruiseroutfit generally seems to have these on hand. I have one I still need to put on, The Wilwood just looks much better and I'm not bothered enough to change it out...
Click to expand...

jjdeneen918 said:
I agree with that sentiment. But at the same time, if the consensus is 1 1/8” is too big, do it all at the same time as it’ll be another job to bleed the system again & again.

I don’t think the T-100 MC is an option for me since I have a GM hydrobooster installed.
Curious if anyone does know what GM MC, with 1 1/16” bore would work for me.
Click to expand...
I have not installed but the Sweeting unit uses the 1-1/16" reservoir from a mustang. It was too cheesy for me, I have a 1-1/8" based upon their recommendation. I am getting closer to being able to complete the work and have no idea of how it will perform, can't be worse than my old system was...
 
on the rocks said:
Willwood does NOT offer a 1" or 1 1/16" unfortunately. 1 1/8" is 100% without a doubt too big for this setup. The 80 stops amazing here though, it just takes a lot of pressure from my foot to get it to stop(stiff pedal). If the OP brakes don't work in addition to a hard pedal, sounds like an additional issue to me. The 1 1/8 Wilwood works great for me, it's just sized too big resulting in a stiff pedal.
@Madcrix12, the 4R calipers will change nothing on the pedal firmness. I went the narrow superlight 6 piston Wilwood. They spec this for the 4R with a OEM system so they don't upsize piston displacement causing other issues. Best bet, coming from many people here confirming, looks to be the T100 1 1/16 MC. @cruiseroutfit generally seems to have these on hand. I have one I still need to put on, The Wilwood just looks much better and I'm not bothered enough to change it out....
Click to expand...
glad to report that after bleeding the system i can get the brakes to lock up HOWEVER yup the pedal is hard as hell as a result of the oversized MC. after all the air was removed from the power steering setup it is holding steady at the full mark when hot. no over flowing.

i am currently researching a 1in bore or 1 1/16 bore ford MC. if anyone has a link i would appreciate that
 
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Azca said:
I have not installed but the Sweeting unit uses the 1-1/16" reservoir from a mustang. It was too cheesy for me, I have a 1-1/8" based upon their recommendation. I am getting closer to being able to complete the work and have no idea of how it will perform, can't be worse than my old system was...
Click to expand...
What size tires do you run? Will ABS be retained or removed? Brake pedal feel will feel much better in that you won’t wonder if you are not stopping because pedal travel is at its end and that inclination towards doing a primer pump (which takes up precious time) prior to the stopper pump will be completely gone. You won’t be constantly wondering what’s wrong with your braking system and what can be done to fix it. However, you have to become accustomed to using a bit more of that leg muscle for normal around town stops but when you really put the force down the car will stop shorter and your foot won’t be in the engine compartment. Eliminating ABS, the LSPV and it’s associated mile of plumbing will make bleeding as easy as opening the caliper bleeders and letting gravity do the work.

Start off with new rotors and semi metallic pads so yo can bed those pads into your new rotors properly. I run the Hawk Super Duty pads. I did run ceramic pads before and wasn’t overly impressed. Be sure calipers are in proper condition of course and install steel braided soft lines at all soft line locations.

Installing hydro boost and 1 1/8” MC solved the problem that was driving me up a wall. Is it perfect? No it’s not but my brakes were further from perfect before. For those who run 37” tires, or larger, like myself, the hydro booster and larger MC puts us in a position to run larger hardware at the wheels for improvements in braking over anything a stock set up could do.
 
If you run full ceramic also run slotted rotors. The slots prevent any of the ceramic downsides.

The rotors will be trash in 20k miles, but they will stop great.
 
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