Hydro boost - rock hard brake pedal (2 Viewers)

[Azca]

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.

I am also running 35s, deleted ABS and LSPV, and added a Baer proportioning valve. I am thinking of bumping this up to 37s and doing the 4 runner brake upgrade but want to do it in stages.

I was having god awful time bleeding this and poor braking. Downhill ascents, and not crazy ascents, were scary as I could not get her to stop. I can put up with firm/hard. Not stopping is another matter.

 

[baldilocks]

I am also running 35s, deleted ABS and LSPV, and added a Baer proportioning valve. I am thinking of bumping this up to 37s and doing the 4 runner brake upgrade but want to do it in stages.

I was having god awful time bleeding this and poor braking. Downhill ascents, and not crazy ascents, were scary as I could not get her to stop. I can put up with firm/hard. Not stopping is another matter.

I get under two inches of pedal movement even under harder braking and would not call it “hard” or compare it to a faulty vacuum booster feel at all.

I went through the 5th gen upgrade thread again yesterday. Looks great except that, it appears that running backing plates and also being able to periodically recheck torque of the knuckle stud nuts is not possible.

Who has installed the Landtank 80 series brake upgrade kit? It uses 100 series calipers and Wilwood rotors that are sized in between the 80 series and 5th gen’s. Simpler but probably not quite as effective.

 

[Azca]

I get under two inches of pedal movement even under harder braking and would not call it “hard” or compare it to a faulty vacuum booster feel at all.

I went through the 5th gen upgrade thread again yesterday. Looks great except that, it appears that running backing plates and also being able to periodically recheck torque of the knuckle stud nuts is not possible.

Who has installed the Landtank 80 series brake upgrade kit. It uses 100 series calipers and Wilwood rotors that are sized in between the 80 series and 5th gen’s. Simpler but probably not quite as effective.

As flimsy as the backing plates are, I am wondering if deleting them would be an issue? I have nut-huggers that I will also be installing as well.

 

[baldilocks]

As flimsy as the backing plates are, I am wondering if deleting them would be an issue? I have nut-huggers that I will also be installing as well.

The backing plate keep a lot of crud off the rotors which, IMO, is a good thing. There appears to insufficient clearance mount the backing plates without them mashing into the stud nuts.

How soon will you do the 5th gen brakes? I’m interested in following your process.

 

[Azca]

The backing plate keep a lot of crud off the rotors which, IMO, is a good thing. There appears to insufficient clearance mount the backing plates without them mashing into the stud nuts.

How soon will you do the 5th gen brakes? I’m interested in following your process.

I still have to get it on the road and quite a bit to do. If I have it up and moving by summer, I will be happy.

 

[Spaggyroe]

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.

Here's a Wilwood with 1" bore.

Wilwood Disc Brakes 260-8555-BK Wilwood Aluminum Tandem Master Cylinders | Summit Racing

Free Shipping - Wilwood Aluminum Tandem Master Cylinders with qualifying orders of $109. Shop Master Cylinders at Summit Racing.

www.summitracing.com

 

[on the rocks]

Good find on the Wilwood 1" bore, if the mounting matches up, it would mate up with the Wilwood proportioning valve much better. I would consider that route over the optional kitted 1 1/8" GMC MC just on looks alone if that matters(also don't remember if GMC offers a 1 1/16" bore, I remember last time I was looking they are hard to come by matching the HB mounting). If I get a chance, I may grab one and test it, I need to get on mounting my rear Wilwood calipers some day... All parts are in collecting dust waiting for me including an oversized PSC PS reservoir to replace the crappy OEM hoping for better PS fluid flow.

I decided to go Vanco instead of Sweeting, they insisted on the 1 1/8" bore just like Sweeting, IMO, they are wrong, so there is a chance the 1 1/16 may be ok with the hydro boost conversion, I would ask them if they can match one up(*EDIT- or ask them if the ^^ 1" Wilwood MC would fit and work ok). Other than that they were great to work with. The lady that is a part owner communicated really well. As mentioned the 1 1/8" is amazing if the rest of the system is working well, I just need to remember when I take it out of park, I'm pressing the brake pedal MUCH harder than on other vehicles. When driving, I generally notice the stiff feel much less and it stops amazing.

Sorry about the misinformation on the T100 MC matching up. I was going to go that route and never pulled it out of the box hoping the Wilwood MC worked. Suppose I should offer it up on the classified section now....

I don't want to derail the thread but since some of you are considering a caliper swap, you may check with @cruiseroutfit and see what they found out on the 14" Newer Tundra caliper fitment. I know they were looking into fitment on the 80 around 4/22. Maybe they can provide dimensions or feedback on how that went. The 4R caliper swap only uses a 13.3 rotor. Also, I could be wrong but I believe Wilwood now offers a dust seal on superlight 6 piston calipers spec'd for the 4R and 14" rotors now as well. I have had zero issues with mine hanging up but don't drive it a lot.(edit*- this was brought up by several people here with the non sealed piston setup again, zero issues here, I have been in mud, snow and water crossings, but did trim the rotor dust shield not remove them)

 

[jjdeneen918]

Totally lost looking for a 1 1/16” bore MC that would mate to our GM hydrobooster.

Don’t even know where to start as I don’t know the application for our boosters.

There are more 1” MC’s out there, but again don’t know if compatible.

If I end up with a 1” MC, would my brake pedal feel the same as stock, not this hard pedal that requires Superman strength to stop & remain stopped? But still work better than a vacuum booster? Or is the 1 1/16” the better option given the hydrobooster I now have?

I don’t care to start buying dozens of MC’s to find a potential & possible compatible unit.

 

[Spaggyroe]

Totally lost looking for a 1 1/16” bore MC that would mate to our GM hydrobooster.

Don’t even know where to start as I don’t know the application for our boosters.

There are more 1” MC’s out there, but again don’t know if compatible.

If I end up with a 1” MC, would my brake pedal feel the same as stock, not this hard pedal that requires Superman strength to stop & remain stopped? But still work better than a vacuum booster? Or is the 1 1/16” the better option given the hydrobooster I now have?

I don’t care to start buying dozens of MC’s to find a potential & possible compatible unit.

I'm not sure of what the right answer is for your application, but I can tell you that the difference between 1" vs 1-1/16" is about 12%, meaning that with the 1", your pedal will travel about 12% more and your line pressure will increase about 12% as well.

 

[jjdeneen918]

I just sent an email to Matt Sweeting for advice. I’ll post any info I receive.

 

[jjdeneen918]

I'm not sure of what the right answer is for your application, but I can tell you that the difference between 1" vs 1-1/16" is about 12%, meaning that with the 1", your pedal will travel about 12% more and your line pressure will increase about 12% as well.

So to extrapolate your data percentages, a 1 1/8” bore would be a 6% decrease in travel & 6% decrease in pressure?

If I’m thinking this correctly, why would you ever increase the bore diameter ever? Seems like you’re going in the complete wrong direction.

I also think my understanding/math is wrong on this, because it just doesn’t make sense. There must be something else going on.

Or a 24% pedal increase, but 24% more pressure.
But if I’m experience “creep” at stop, then decreasing bore size would make this problem even worse.

 

[Spaggyroe]

So to extrapolate your data percentages, a 1 1/8” bore would be a 6% decrease in travel & 6% decrease in pressure?

If I’m thinking this correctly, why would you ever increase the bore diameter ever? Seems like you’re going in the complete wrong direction.

I also think my understanding/math is wrong on this, because it just doesn’t make sense. There must be something else going on.

Or a 24% pedal increase, but 24% more pressure.
But if I’m experience “creep” at stop, then decreasing bore size would make this problem even worse.

1" bore vs 1-1/16" bore = ~12% difference (closer to 13 actually)
1-1/16" bore vs 1-1/8" bore is also ~12% difference
1" bore vs 1-1/8" bore = about 26% difference

The reason for a larger bore size is if you need more volume for your calipers. Ford super duty's for example have up to a 1-1/2" master cylinder bore, which is absolutely massive. This is needed to displace more fluid for their massive caliper pistons.

Going down in MC bore size increases line pressure, but eventually you'll reach a point where you aren't moving a high enough volume of fluid to operate the calipers. Essentially, you'd run out of pedal travel before your brakes are fully applied... no bueno...

Here are some comparisons in various M.C. bore sizes to show the corresponding surface area of the piston for each size.

Dia. (Fractional)	Surface Area
1	0.785
1-1/16	0.887
1-1/8	0.994
1-3/16	1.108
1-1/4	1.227
1-5/16	1.353
1-3/8	1.485
1-7/16	1.623
1-1/2	1.767

In a nutshell, brake systems are "matched". The master cylinder bore needs to be sized in such a manner to give the caliper pistons the volume and pressure needed. This is part of the service you get when you buy a package from wilwood, baer, or other brake component company. It's not something that a home gamer can't figure out on their own. If you're running stock 80 series calipers, it's a pretty safe bet to stick with the stock 80 master cylinder bore size, which I believe is 1".

 

[jjdeneen918]

Very well explained, thank you.

Sounds like if we’re keeping 80 series calipers, then keep the 1” MC bore.

The only thing that should change is the booster, vacuum to hydroboost. And hydroboost is just delivering more force than vacuum, more efficient, or something. Correct?

I am curious why these companies keep advising to increase to 1 1/8” bore. Having to Superman the pedal is fatiguing & annoying.

 

[Spaggyroe]

You’re correct. Hydroboost (typically) puts out more force than a vacuum booster.

I’m still puzzled by your problem though. The Hydroboost (even with a 1-1/6 or 1-1/8” mc) likely generates as much line pressure as a vacuum booster with 1” mc. Very strange.

 

[PIP]

Have any of you checked your ps pressure?

Most of my hboost and ps experience is with Saginaw pumps. They run 1400 psi standard. If the 1fz pump is even 100 psi less it can make a substantial difference in how the pedal and steering feels.

 

[jjdeneen918]

A quick search revealed this thread where the OP states it’s 1200 PSI. In the same thread it mentions the 96 LC has 1350 PSI.

I have a 96.

Modifying Stock Power Steering Pump To Increase Pressure (Hydraulic Winch)

The 96 FSM states that the minimum power steering pump pressure is 1350psi. So one could assume that regular pressures are slightly higher, and maybe meet the MileMarker minimum spec of 1500psi. Maybe. No mention of flow rate (GPM)

forum.ih8mud.com

 

[jjdeneen918]

I tracked down my original build page for when I installed my hydroboost. Page 2 has all my pictures & status.

Also the phone number to the company I used & business card images. I emailed them last week, no response yet, so I’ll try calling them today to source a compatible MC with a smaller bore size.

Hydro boost brake conversion

Finally made some progress today. I got the OEM brake booster out of the rig. now to bring it to Power Brake Service. I spoke to the owner last week, he requested I bring in my booster to look at since it’s been a long while since he put together a hydro booster together for an fzj80. one...

forum.ih8mud.com

 

[jjdeneen918]

I attempted to call power brake service, the number on their business card, it states the number is out of service.

That’s a bummer. I was hoping to inquire with them about a new master cylinder, that will mate to our GM hydrobooster’s that has a smaller bore size than 1 1/8”.

Does anyone know what hydrobooster we have? Like a model number or vehicle application?

With that info I could start to search, without that info, I don’t even know where I would start.

 

[jjdeneen918]

I did a google reverse image search with my booster.
First picture (booster sitting on a gray truck seat. You can see a number of 0787 on the booster, but that hasn’t helped with searches for me.
Additional pictures were a possible match.
Pictures state it from a Dodge, but I was told mine a GM booster.
Can anyone confirm this is correct?

 

[Spaggyroe]

@jjdeneen918 , I think that might be hard to track down via images. I believe that Delphi manufactures these for GM, Dodge, Ford, and others. I’m guessing there are minor variations like the spread of the MC mounting studs, fittings, etc.