Brake questions

[aprosise]

I've been going through a bit of troubles with my brakes lately and need to pick some bodies brain.

In the past 10,000 miles (within the year) I've replaced all rear brakes components (drums, wheel cylinders, shoes, spring kits), front calipers, front pads, hoses, body to axle lines, booster with 4 runner master (1" bore).

The only original brake components that are left are the body hard lines, front rotors and proportioning doo-hickey that mounts below the master cylinder.

Background- I blew out both front calipers at the same time (complete brake loss and fluid pouring out of pistons...it was -10 degrees out.) I also have blown both front brake lines at different times, but the rubber was looking pretty dry rotted so I believe that was just age.

I'm not sure exactly when it happened but a couple months ago, my peddle started feeling more firm with less travel that you would expect from power brakes. I also noted much less power in the brakes. Sometime after that the front calipers went. Since then I replaced booster and master thinking that was my problem. Brakes feel exactly the same. I have about a 1/3 travel and power compared to Steve's fj60. Brakes have been bled about a million times. At least a couple quarts through the system. I seem to have good vacuum and the booster seems to be working....pump the peddle then fire it up and the peddle depresses.

When I pulled the master for replacement, I noticed the front port was bone dry and rusty. This is weird because the front brakes worked fine and I got fluid while bleeding.

Brake pad wear is normal all the way around and my rear brakes are properly adjusted.

So how common is it for the proportion in valve to fail? I'm down to the valve in all my troubleshooting and replacement. I can't seem to find a new one available. Does anybody have a good one that they want to sell? Is there a good way to rebuild this? I didn't see anything about it in the factory service manual....May have missed it though.

Anybody have insight?

 

[rckhound]

Have you checked the vaccum going to the booster?

 

[60wag]

Make sure the vacuum fitting that screws into the intake manifold isn't partially clogged with carbon.

 

[Rezarf]

You can replace the proportion img valve with a wildwood aftermarket one, they're the bet in the biz IMHO.

 

[AimCOTaco]

Bad check valve on the booster vac side maybe? (easier than the safety valve thing..)
Does the pedal pump up and go hard with the engine off?

It almost sounds like you had 1 circuit working in the master and the propotioning/safety valve was keeping your other circuit going before the rebuild.... odd for sure and I can see why you want to try another proportioning valve.

 

[aprosise]

Ill check for carbon build up and Ill also order a wilwood proportioning valve to take that out of the equation.

Pedal pumps up hard when the motor is not running, when I start it, the pedal falls about an inch when vacuum builds up. Check valve is brand new, and vacuum feels strong (Using my finger as a gauge) Ill put and actual gauge on it tonight and see where im at.

 

[aprosise]

So if I'm going to add a proportioning valve, will one line go straight to the front brakes, and one through the valve and then on to the rear brakes? I thought the original valve was to direct all pressure to front or rear brakes if one set fails?

http://www.jegs.com/i/Wilwood/950/2...9&cadevice=c&gclid=COrwgrG3vMUCFQwzaQod9kwAMg

 

[YYOODDAA]

So if I'm going to add a proportioning valve, will one line go straight to the front brakes, and one through the valve and then on to the rear brakes? I thought the original valve was to direct all pressure to front or rear brakes if one set fails?

http://www.jegs.com/i/Wilwood/950/2...9&cadevice=c&gclid=COrwgrG3vMUCFQwzaQod9kwAMg

The purpose of the proportioning valve is to bias the braking power from the rear to the front. It does this by limiting the amount of line pressure to the rear brakes. This is all either the original valve or the wilwood valve does. It does not send brake power to one or the other in the event of a front or rear brake failure.
For installation, you are correct the front line is a direct connection and the rear line goes through the new valve. Delete the factory valve! FYI most your aftermarket valves are setup with SAE inverted flare adapters, but Toyota uses metric steel brake lines and nuts. On my mini truck I used the yoda metric steel line with SAE nuts at the valve to avoid a mess of adapter fittings and it all fit together without any leaks or issues.

Honestly I've been in the industry for many years and I've never seen a proportioning valve actually fail. I've seen techs change them only to find out their problem still exists and for this reason I have my doubts that this is your problem, not to say they can never fail, but in my experience it is rare.
I see you have several Yodas but your posting doesn't specify which one is broken, so I'm assuming your working on your FJ?
I have a couple of questions:
1) what kind of flexible brake lines are you using steel braided or rubber and how long are they?
2) Your new master cylinder you say has a 1" bore, is that bigger, smaller or the same as the master that came off your truck?
3) Check the rear of your vehicle for a proportioning valve. It will be mounted to the frame, plumed into the rear brake line and have a rod that connects it to the rear axle. I know the mini trucks have these, but I don't know if Toyota used these on the FJ's. These valves are prone to failure and I would recommend you delete it if it is there. Its purpose is to be an adjustable proportioning valve that changes in accordance with the load you have in the back of the truck.

Some things to think about,
If your new master cylinders bore is larger than the bore of the master you removed and you did not go to a larger caliper piston to match you will have a harder brake pedal.
If you are using longer braided steel lines, these lines flex and expand considerably more than stock rubber and they will cause a weaker feeling brake system if you have excessive lengths.

These are some of the common issues I've found over the years with modified brake systems so I hope this info helps you with yours.

 

[aprosise]

The purpose of the proportioning valve is to bias the braking power from the rear to the front. It does this by limiting the amount of line pressure to the rear brakes. This is all either the original valve or the wilwood valve does. It does not send brake power to one or the other in the event of a front or rear brake failure.
For installation, you are correct the front line is a direct connection and the rear line goes through the new valve. Delete the factory valve! FYI most your aftermarket valves are setup with SAE inverted flare adapters, but Toyota uses metric steel brake lines and nuts. On my mini truck I used the yoda metric steel line with SAE nuts at the valve to avoid a mess of adapter fittings and it all fit together without any leaks or issues.

Honestly I've been in the industry for many years and I've never seen a proportioning valve actually fail. I've seen techs change them only to find out their problem still exists and for this reason I have my doubts that this is your problem, not to say they can never fail, but in my experience it is rare.
I see you have several Yodas but your posting doesn't specify which one is broken, so I'm assuming your working on your FJ?
I have a couple of questions:
1) what kind of flexible brake lines are you using steel braided or rubber and how long are they?
2) Your new master cylinder you say has a 1" bore, is that bigger, smaller or the same as the master that came off your truck?
3) Check the rear of your vehicle for a proportioning valve. It will be mounted to the frame, plumed into the rear brake line and have a rod that connects it to the rear axle. I know the mini trucks have these, but I don't know if Toyota used these on the FJ's. These valves are prone to failure and I would recommend you delete it if it is there. Its purpose is to be an adjustable proportioning valve that changes in accordance with the load you have in the back of the truck.

Some things to think about,
If your new master cylinders bore is larger than the bore of the master you removed and you did not go to a larger caliper piston to match you will have a harder brake pedal.
If you are using longer braided steel lines, these lines flex and expand considerably more than stock rubber and they will cause a weaker feeling brake system if you have excessive lengths.

These are some of the common issues I've found over the years with modified brake systems so I hope this info helps you with yours.

Thanks for the input.

All my Stainless braided lines are from Earl's performance.

Im running a 1" bore master currently with stock calipers, but in the next couple weeks ill be installing 4 runner calipers. There was absolutely no difference in pedal feel after I installed the 4 runner master and booster.

No LSPV's in 60 series cruisers. They only put them on 62's

I beginning to think I just have low vacuum. I still haven't been able to get a gauge on it. I have about a 1/3 of the brake pedal "Squish" that my brother's 60 does. The reason why I think this is weird is all the blown brake parts Ive gone through and the brake pedal felt fine before I started blowing the lines and calipers.... everytime it happened was just driving to and from work, no excessive braking force.

 

[YYOODDAA]

So if I'm going to add a proportioning valve, will one line go straight to the front brakes, and one through the valve and then on to the rear brakes? I thought the original valve was to direct all pressure to front or rear brakes if one set fails?

http://www.jegs.com/i/Wilwood/950/2...9&cadevice=c&gclid=COrwgrG3vMUCFQwzaQod9kwAMg

The purpose of the proportioning valve is to bias the braking power from the rear to the front. It does this by limiting the amount of line pressure to the rear brakes. This is all either the original valve or the wilwood valve does. It does not send brake power to one or the other in the event of a front or rear brake failure.
For installation, you are correct the front line is a direct connection and the rear line goes through the new valve. Delete the factory valve! FYI most your aftermarket valves are setup with SAE inverted flare adapters, but Toyota uses metric steel brake lines and nuts. On my mini truck I used the yoda metric steel line with SAE nuts at the valve to avoid a mess of adapter fittings and it all fit together without any leaks or issues.

Honestly I've been in the industry for many years and I've never seen a proportioning valve actually fail. I've seen techs change them only to find out their problem still exists and for this reason I have my doubts that this is your problem, not to say they can never fail, but in my experience it is rare.
I see you have several Yodas but your posting doesn't specify which one is broken, so I'm assuming your working on your FJ?
I have a couple of questions:
1) what kind of flexible brake lines are you using steel braided or rubber and how long are they?
2) Your new master cylinder you say has a 1" bore, is that bigger, smaller or the same as the master that came off your truck?
3) Check the rear of your vehicle for a proportioning valve. It will be mounted to the frame, plumed into the rear brake line and have a rod that connects it to the rear axle. I know the mini trucks have these, but I don't know if Toyota used these on the FJ's. These valves are prone to failure and I would recommend you delete it if it is there. Its purpose is to be an adjustable proportioning valve that changes in accordance with the load you have in the back of the truck.

Some things to think about,
If your new master cylinders bore is larger than the bore of the master you removed and you did not go to a larger caliper piston to match you will have a harder brake pedal.
If you are using longer braided steel lines, these lines flex and expand considerably more than stock rubber and they will cause a weaker feeling brake system if you have excessive lengths.

These are some of the common issues I've found over the years with modified brake systems so I hope this info helps you with yours.

 

[YYOODDAA]

Thanks for the input.

All my Stainless braided lines are from Earl's performance.

Im running a 1" bore master currently with stock calipers, but in the next couple weeks ill be installing 4 runner calipers. There was absolutely no difference in pedal feel after I installed the 4 runner master and booster.

No LSPV's in 60 series cruisers. They only put them on 62's

I beginning to think I just have low vacuum. I still haven't been able to get a gauge on it. I have about a 1/3 of the brake pedal "Squish" that my brother's 60 does. The reason why I think this is weird is all the blown brake parts Ive gone through and the brake pedal felt fine before I started blowing the lines and calipers.... everytime it happened was just driving to and from work, no excessive braking force.

Here is a thought for you, your brakes felt fine before your brake lines failed. Going back to what I said about steel braided lines expanding; your old lines were close to failure and allowing for a much larger expansion than they normally would. The lines expanding under breaking would make your peddle feel solid but still allow that extra "squish" and pedal travel you think your missing. (Note: keep in mind that we are talking about a very small amount of fluid volume and what seems like a very small amount of fluid loss to us, at that scale is actually a large percentage of the overall fluid transfer in the braking system.) My point being now that you've fixed your squishy broken lines and many other problems, your breaks may not actually be broken in any way, there exactly how they are supposed to be with your current setup.
Now to explain in theory why your pedal is harder than your brothers. I have a felling your new 4 runner master is larger than the stock master you took off and this will without a doubt make your pedal harder and not travel as far, but this condition was masked by the failing brake lines. I know the new master on my mini, that I got off of a 4runner, is larger than my old factory master. This explains the harder pedal than what your brothers has.
You can fix this issue with either a larger brake booster, converting to hydro boost or increasing the size of your caliper pistons.
Again this is all just theory, I cant say anything for sure with the data you've given me so far, but going off of experience and the info we have disused so far I'd say this is close.

 

[aprosise]

Ill try a couple more things tonight and throw a gauge on the vacuum line. That should at least give me one answer.

 

[YYOODDAA]

keep in mind that flow is as important as PSI in this case. A good flow check along with a PSI gauge is while the engine is running\ pull the vacuum line off the booster. The engine should stumble and die or at least come very close to dieing. If it passes those two tests do the following. Hook everything up and run the engine for a few seconds, shut the engine off, do not touch anything especially the brake pedal. Walk away for 3-5 min and then pull the check valve off the brake booster. If the check valve and the booster have no leaks you will hear air rush into the system. If one or the other is bad you will hear nothing when you open that side of the system to atmosphere.

A third test that can sometimes be of use is with the engine running hold your foot on the break pedal and easy on and off pressure. You might be able to hear air leak around the shaft at certain points in the pedals travel. It will make a whistling noise. It can be hard to hear and if you have loud exhaust you'll need to use a stethoscope with the end removed so you just have a open hose you can hold up under the dash and listen. Again this is kind of a rare issue, but I have had it happen in the past so it might be worth the time to try if all else fails.
Good luck

 

[ToyodaTocco]

Your brake pedal travel sounds about right for the upgrades that you did. Your hydraulic ratio has changed now with bigger master cylinder but same size calipers. Check out this write up for more ratio stuff.
http://home.4x4wire.com/erik/4runner/brakes/

You say that both your front calipers failed with total brake fluid loss. Did you get fluid on your brake pads? If so, they may be saturated and should be replaced. Also, if the pads or rotors get a nice glaze on them then this will reduce braking considerably. Check for heat spots on your rotors also. This may seem redundant but some times its the simple stuff that gets you.

 

[Crash]

Jeff, I'm confused by your post.

"Honestly I've been in the industry for many years and I've never seen a proportioning valve actually fail."

"Check the rear of your vehicle for a proportioning valve. It will be mounted to the frame, plumed into the rear brake line and have a rod that connects it to the rear axle. I know the mini trucks have these, but I don't know if Toyota used these on the FJ's. These valves are prone to failure and I would recommend you delete it if it is there."


I've been dealing with under-performing brakes on the FJ62 lately and have wondered about the efficacy of the OEM LSPV. Seems that recently, since CM2015, installing OEM rear drum shoes ((rear brakes) vs. the NAPA sourced shoes that were in the system has greatly ameliorated the problem but always wanting more. Please elaborate on your comments.

 

[OilHammer]

Jeff, I'm confused by your post.

"Honestly I've been in the industry for many years and I've never seen a proportioning valve actually fail."

"Check the rear of your vehicle for a proportioning valve. It will be mounted to the frame, plumed into the rear brake line and have a rod that connects it to the rear axle. I know the mini trucks have these, but I don't know if Toyota used these on the FJ's. These valves are prone to failure and I would recommend you delete it if it is there."

First one he's referring to is the non-adjustable one bolted to the brake booster. I've never seen one fail other than one that was open to atmosphere and rusted.

The one he's saying fails, is the optional one over the rear axle. Since it's mechanical and constantly adjusts, THIS is the part that fails. That, and people monkey with them over the years. I've only ever had one truck that actually had the adjustable one in the rear and I had to bend the rod to deal with the lift. PITA. Cool concept, but meh...not worth it.

 

[YYOODDAA]

Sorry I didn't specify the two different styles of valves very well. The lspv can have many issues (to many moving parts & located in a bad area & corrodes) I'm not a fan. But the standard proportioning valve found on most vehicles and usually mounted under the master cylinder or close to it are bullet proof and very rarely fail.
As for your drum brake question, your getting into a whole new area of discussion. You could have a hydraulic caused balance issue (lspv valve) it could also be caused by improperly adjusted drum brakes (to lose). A shoe material compound issue, hydraulic failure are the cylinders actually moving when you hit the brakes? I used to think glazing was a bigger issue but over the years I've seen so many rotors and drums that where hard as a rock mirrors and still worked fine that I've adjusted my opinion of that to a much lower level of priority when diagnosing brake problems.

 

[YYOODDAA]

Your brake pedal travel sounds about right for the upgrades that you did. Your hydraulic ratio has changed now with bigger master cylinder but same size calipers. Check out this write up for more ratio stuff.
http://home.4x4wire.com/erik/4runner/brakes/

You say that both your front calipers failed with total brake fluid loss. Did you get fluid on your brake pads? If so, they may be saturated and should be replaced. Also, if the pads or rotors get a nice glaze on them then this will reduce braking considerably. Check for heat spots on your rotors also. This may seem redundant but some times its the simple stuff that gets you.

Agreed!!!!

 

[aprosise]

Checked my vacuum... 15 in. hg steady at idle..... Good enough for the booster to work properly

I was starting to think my rear shoes might be glazed... And I replaced the pads when I replaced the front calipers.

While I was Jackson's tonight, he noticed my brake pedal was about an inch lower than his.... When I put the new master and booster in, I kept the same adjustment as the one I pulled out. I'm going to look into that also.

Proportioning valve comes tomorrow and the 4 runner calipers will be in late next week. I'm sure I'll have things figured out then.

 

[rover67]

Did you check to make sure you had good vacuum flow? no carbon on the nipple?