Want Power brake booster swap and keep drum brakes?

[76cj7chick]

As IO alluded to in a Modern correctly spec. Master Cylinder or Brake Proportioning valve......... the Residual valves are internal.

Brake systems are all about moving hydraulic fluid volume and creating pressure to do the work , therefore the correct bore size in the donor Master Cylinder should be matched to whatever brake system your using..........as will as the pedal ratio which will be different for a manual vs a Boosted system.

Wow! Way more complex than I originally hoped.. But looks like I may need to move my PV it may be in the way of the exhaust... But I've also been debating on getting engine block huggers...
Just empty every pocket..

 

[76cj7chick]

I agree with Tarry and IO, as I stated, I do not have external residual valves on my setup, and my brakes work great. Given the fact that you are trying to use a disc/drum master cylinder on a drum/drum set up, you could encounter problems. I ran that risk with my set up, so I proceeded with caution until I had everything balanced out. There was some initial undesirable braking which the adjustable PV took care of. Another reason for residual valves from what I have read about them is, they are necessary if the master cylinder is located below the floor level.

Hmmm.. I may wait on this idea.. unless my exhaust pipes won't fit due to the brake PV location... then I would need to move the pv... Preferably up further on the Mc like the blazer.

 

[tarry99]

Wow! Way more complex than I originally hoped.. But looks like I may need to move my PV it may be in the way of the exhaust... But I've also been debating on getting engine block huggers...
Just empty every pocket..

Not very complex if you stay with a complete donors system, or you verify what Bore sized Master your swapping and what the original use was........or you just do the math.............there is allot of crossover among Brake components in Bore size Etc. The engineers do that to accommodate many factors in the vehicle there building, be it weight, tire size Etc.........That's why when folks start messing around with junk yard swaps , some results are good while others are disastrous........when legitimate companies put together various brake upgrades for the most part they have already worked out the math so the components do work correctly.........you can research your stuff on the internet via part numbers and bore sizes to see how they match up.

A Drum/ Drum MC will be one sized while a Disc / Disc or Disc / Drum will be another......Not to say that what you have in front of you is incorrect either. You just have to check to verify that it will work or be prepared for a surprise.

The pedal ratio has to be correct for a manual vs Boosted system or the pedal will be touchy.

Your stock PV valve is non-adjustable....if it was adjustable there would be a knob on it.

A Vacuum Booster is great to have.......most are universal and only size to fit comes into play or matters........some are single chambered while others are smaller with dual chambers...........your motor has to be able to create about 21 inches of vacuum to operate that system correctly.....for most stock motors in good condition that should not be a problem.........

If you were to add a Booster the brake lines up front would all need to be re-done anyway.........so don't get hung up on your current PV valve location right now as it may all have to be moved as your build progresses. If you just can't live with it right now, un-do it and move it aside.....of course bleed the system prior to driving again........

 

[IOPort51]

Hmmm.. I may wait on this idea.. unless my exhaust pipes won't fit due to the brake PV location... then I would need to move the pv... Preferably up further on the Mc like the blazer.

life is for learning child. Welcome to the path to enlightenment.

You will need an MC with equal sized pistons. the only one I am familiar with is the Corvette.

 

[76cj7chick]

life is for learning child. Welcome to the path to enlightenment.

You will need an MC with equal sized pistons. the only one I am familiar with is the Corvette.

Alrighty then.
Could you recommend the best years and trains? I may need to check out my local junk-yards.

 

[76cj7chick]

Not very complex if you stay with a complete donors system, or you verify what Bore sized Master your swapping and what the original use was........or you just do the math.............there is allot of crossover among Brake components in Bore size Etc. The engineers do that to accommodate many factors in the vehicle there building, be it weight, tire size Etc.........That's why when folks start messing around with junk yard swaps , some results are good while others are disastrous........when legitimate companies put together various brake upgrades for the most part they have already worked out the math so the components do work correctly.........you can research your stuff on the internet via part numbers and bore sizes to see how they match up.

A Drum/ Drum MC will be one sized while a Disc / Disc or Disc / Drum will be another......Not to say that what you have in front of you is incorrect either. You just have to check to verify that it will work or be prepared for a surprise.

The pedal ratio has to be correct for a manual vs Boosted system or the pedal will be touchy.

Your stock PV valve is non-adjustable....if it was adjustable there would be a knob on it.

A Vacuum Booster is great to have.......most are universal and only size to fit comes into play or matters........some are single chambered while others are smaller with dual chambers...........your motor has to be able to create about 21 inches of vacuum to operate that system correctly.....for most stock motors in good condition that should not be a problem.........

If you were to add a Booster the brake lines up front would all need to be re-done anyway.........so don't get hung up on your current PV valve location right now as it may all have to be moved as your build progresses. If you just can't live with it right now, un-do it and move it aside.....of course bleed the system prior to driving again........

The main reason I wanted to upgrade to power brakes is because the v6 blazer engine's exhaust pipe is in the way of the PV. (I do hope to convert to power one day) but would really like to get the jeep back on the road. --As I am still looking for a reputable welder to make a tranny and tcase cross member for me.. :dunno:

 

[mriplaybass]

Might want to check this out.

74 86 Jeep CJ7 CJ5 7" Power Brake Booster Master Cylinder w Mounting Brackets | eBay

Claims it is disc/disc, disc/drum, or drum/drum compatible. Add an adjustable PV, and your on your way. That way you are not messing with trying to make parts from several different doner vehicles work together. $139.95

Messing around trial and error with brakes, scares me. Especially with your level of experience. This is supposed to be a direct bolt in for a CJ which allows you to use the original brake pedal. I think all of us here on the forum would breath a little easier knowing that you have good brakes when you make your maiden voyage with your Jeep! :driving:

 

[IOPort51]

Might want to check this out.

74 86 Jeep CJ7 CJ5 7" Power Brake Booster Master Cylinder w Mounting Brackets | eBay

Claims it is disc/disc, disc/drum, or drum/drum compatible. Add an adjustable PV, and your on your way. That way you are not messing with trying to make parts from several different doner vehicles work together. $139.95

Messing around trial and error with brakes, scares me. Especially with your level of experience. This is supposed to be a direct bolt in for a CJ which allows you to use the original brake pedal. I think all of us here on the forum would breath a little easier knowing that you have good brakes when you make your maiden voyage with your Jeep! :driving:

This is really a pretty good deal. the MC for, I believe, a 79 corvette is about $30 new/rebuilt. I like to stay away from junk yard parts for the brakes. The hardest part to source, for me was the mount/adapter. A friend had one and sent it to me. I used the manual MC on a power booster for it's smaller piston and greater mechanical advantage ratio. the two MCs are identicle except for the piston bore size.

 

[IOPort51]

It just occurred to me that you could use the MC you have and mount it ti a booster and adapter. The PV can be moved up closer to the MC similer to a later model ford. the short tubes in the MC kit will help you do this but you will have to modify the brake lines a bit to make this happen. Did you ever notice that nothing is ever as easy as you first think it will be?

 

[tarry99]

The main reason I wanted to upgrade to power brakes is because the v6 blazer engine's exhaust pipe is in the way of the PV. (I do hope to convert to power one day) but would really like to get the jeep back on the road. --As I am still looking for a reputable welder to make a tranny and tcase cross member for me.. :dunno:

76.......So your willing to upgrade to Power brakes just cause the PV is in your way?..........Again if you were to do the Power Brake upgrade You will be making new Brake Lines to complete the system so the choice is easy as far as I see it........1) move your current PV over a few inches from its current location by cutting into the brake line system and make new lines.....( same as you would be doing up front if you went Power) or 2) do your power conversion now and be done with it........either way your cutting and making new Brake Lines be it to complete the power , move the existing PV and even if you moved everything up front you still have to make lines where you removed the old PV to hook that part of the system back up!.........

One last option may be that there is enough slack in the brake lines at the PV that one might be able to just coax the PV over to clear the exhaust enough while not kinking or damaging the Brake lines.........

As far as the Brake options ( MC, Booster , Adapter ) that others have shown above as an option , keep in mind that if that system requires the adapter shown that will also change the Ratio as the adapter is Offset via the linkage .......... Notwithstanding its doubtful that your non-power system push rod from your Pedals will line up correctly on a Horizontal plain do to that offset.........

Sorry to add confusion to your Brake Upgrade......but brake upgrades can be very confusing unless you know what to look for and pay close attention to all of the Specific Brake System needs for correct operation. Then and only then will you have a system that operates correctly.

 

[76cj7chick]

76.......So your willing to upgrade to Power brakes just cause the PV is in your way?..........Again if you were to do the Power Brake upgrade You will be making new Brake Lines to complete the system so the choice is easy as far as I see it........1) move your current PV over a few inches from its current location by cutting into the brake line system and make new lines.....( same as you would be doing up front if you went Power) or 2) do your power conversion now and be done with it........either way your cutting and making new Brake Lines be it to complete the power , move the existing PV and even if you moved everything up front you still have to make lines where you removed the old PV to hook that part of the system back up!.........

One last option may be that there is enough slack in the brake lines at the PV that one might be able to just coax the PV over to clear the exhaust enough while not kinking or damaging the Brake lines.........

As far as the Brake options ( MC, Booster , Adapter ) that others have shown above as an option , keep in mind that if that system requires the adapter shown that will also change the Ratio as the adapter is Offset via the linkage .......... Notwithstanding its doubtful that your non-power system push rod from your Pedals will line up correctly on a Horizontal plain do to that offset.........

Sorry to add confusion to your Brake Upgrade......but brake upgrades can be very confusing unless you know what to look for and pay close attention to all of the Specific Brake System needs for correct operation. Then and only then will you have a system that operates correctly.

Thanks tarry. Its okay. I may just move the PV for now as funds are tight and I would like to get the engine tranny swap and steering column swap and heater swap done first...Too many projects and they all seem to cost so much time and money.
Thanks again for the advice.

 

[76cj7chick]

Might want to check this out.

74 86 Jeep CJ7 CJ5 7" Power Brake Booster Master Cylinder w Mounting Brackets | eBay

Claims it is disc/disc, disc/drum, or drum/drum compatible. Add an adjustable PV, and your on your way. That way you are not messing with trying to make parts from several different doner vehicles work together. $139.95

Messing around trial and error with brakes, scares me. Especially with your level of experience. This is supposed to be a direct bolt in for a CJ which allows you to use the original brake pedal. I think all of us here on the forum would breath a little easier knowing that you have good brakes when you make your maiden voyage with your Jeep! :driving:

Okay Bass, Thanks for the part number and all.
I will take a picture of it for future projects, like I told tarry99, I have several going on right now and am somewhat stressed about them all. Also, Limited on funds. That is unless I can sell (trade) some of the parts I don't want or need.

Thanks again for the help.

 

[76cj7chick]

This is really a pretty good deal. the MC for, I believe, a 79 corvette is about $30 new/rebuilt. I like to stay away from junk yard parts for the brakes. The hardest part to source, for me was the mount/adapter. A friend had one and sent it to me. I used the manual MC on a power booster for it's smaller piston and greater mechanical advantage ratio. the two MCs are identicle except for the piston bore size.

I agree with you IO. Got too many things that were broken or missing parts from the junk yard.

 

[tarry99]

Thanks tarry. Its okay. I may just move the PV for now as funds are tight and I would like to get the engine tranny swap and steering column swap and heater swap done first...Too many projects and they all seem to cost so much time and money.
Thanks again for the advice.

76...........Before you move the PV I would wait until your project is farther along.......and here is why. Moving things early may not be necessary. You need to first visualize how each move will accommodate the end results....... And then move down the chain visualizing each and every other thing that may need to be corrected or moved..........Point is there could be other things in your way later that may force you to come back and re-engineer what you just did.

Until you have worked out all of the needs for clearance everywhere.....and you feel the move is your only option I would consider just to un-bolt the PV and move it aside for now , unless there is a compelling reason for keeping the brake system intact? Just my Opinion!

 

[76cj7chick]

Hey guys,

Thought I'd give an update on the brake upgrade since it may help someone else thinking about doing the same.

After I got my jeep back from the shop (with police help) Many more issues came up with the jeep.
The biggest one was finding metal shavings in my fuel lines and clogging the throttle body. (And finding slight milky (water contamination) in the engine oil. (that's for another thread.)

But today I wanted to update on my brake upgrade... And since I noticed they drained one of my reservoirs, I decided to go forward with getting rid of the manual brakes and going for power brakes.

I wasn't sure if the new (universal) brake assembly would work so I opted for a used YJ assembly from a seller on eBay for only $30.shipped. (I believe its a single diagram and ultimately want dual but, for now its way better than manual brakes.)

I got the brake assembly yesterday and my brother helped me install the brake booster, master cylinder assembly as four hands is much easier than two. The bracket fit perfectly in the four holes that were already cut out by, the manufacturer? (The manual brakes fit in two different holes)

I had to lower the brake pedal by pushing in the brake switch but the push rod fit perfectly on my brake pedal "loop".

Since the blazer 4.3 engine had power brakes, it has the brake vacuum port so I just need to get a slightly longer 1/2" hose (the original hose is too short by 2 ")

All I have to do now is get the adjustable PV and some brake line.


Thanks again guys for your help!

 

[Lumpy Grits]

Looks OEM-Good job.

LG

 

[76cj7chick]

looks oem-good job.

Lg

thanks lumpy!