Power assist for a 77 cj5??

[IOPort51]

I am looking for a page with some decent insight into putting power assist brakes in a 77 CJ5 . hopefully will work with disk/disk system.

Have found some vague stuff for 80s cjs that I think have different peddle arrangements.


anybody seen anything??

 

[BC CJ]

I recently read about the brake master cylinders for disk vs drums. Drums need a check valve to keep a little residual pressure in the lines while a master cylinder with disks should not have these valves. Also you need proportioning valves to make sure the right flow is going to the front and rear (I think stronger to the front as they do most work-that should avoid locking up the rear brakes).

Thats probably old news to you but I think so long as that stuff is set up right whatever pushes the hydrolic fluid (power assist or not) doesn't really matter. It should be easy to hook up a booster as so many Jeeps were factory equipped with power brakes in 77.

 

[Jimbos76cj]

Any power brake set up from a CJ should mount right into yours. The only difference may be the pedal/rod. my buddy just put a set up on his CJ and the rod was about 2" shorter then the stock one.. nothing a lil jeep ingenuity couldnt fix.

 

[tarry99]

I am looking for a page with some decent insight into putting power assist brakes in a 77 CJ5 . hopefully will work with disk/disk system.

IO ,
I'm a little old school on the disc's all the way around backed up by power especially if your running a more normal sized tire.
I see a lot of guys with that setup but they also have monster tires on the Rig and with that additional rotating weight I can sure understand the need.

Might be a good blog to get some Pro's and Con's on the subject.

 

[IOPort51]

The disk project started out as just something that looked like a challenge to put together and it's a cool thing that doesn't show unless your looking for it. But I will be the first to admit that even with just the 31x10.50s BFGs the stopping is kind of underwhelming.

according to the laws of physics, and my Limited knowledge of them, disks should be about 30% more efficient than drums. The whole thing is turning motion into friction into heat and dissipating the heat. Basically disks cool off better than drums and they are easier to service. So far it's a win/win as far as I can see.

But like everything else, the devil is in the details.

I am looking for a page with some decent insight into putting power assist brakes in a 77 CJ5 . hopefully will work with disk/disk system.

IO ,
I'm a little old school on the disc's all the way around backed up by power especially if your running a more normal sized tire.
I see a lot of guys with that setup but they also have monster tires on the Rig and with that additional rotating weight I can sure understand the need.

Might be a good blog to get some Pro's and Con's on the subject.

 

[tarry99]

The disk project started out as just something that looked like a challenge to put together and it's a cool thing that doesn't show unless your looking for it. But I will be the first to admit that even with just the 31x10.50s BFGs the stopping is kind of underwhelming.

according to the laws of physics, and my Limited knowledge of them, disks should be about 30% more efficient than drums. The whole thing is turning motion into friction into heat and dissipating the heat. Basically disks cool off better than drums and they are easier to service. So far it's a win/win as far as I can see.

But like everything else, the devil is in the details.



IO,

Not sure if you now have drums all the way around or have the factory option Large Disc front version and rear drums that were available for the model years 77-78?
You are right the disc's will outperform the drums in all categories while adding an increased level of braking & cooling.
In either case I have found that it is possible to "overbrake" that lightweight Jeep vehicle while running a more conservative sized 31-33" tire.
I think the first level of going to the Disc's on all 4 corners is a great move, but adding power to that combination might be pretty aggressive especially on the street................Just my Opinion!

Your a smart guy so I'll be watching for feed back.

 

[IOPort51]

thanks for the vote of confidence.

I guess the trick is to not step on the peddle too hard.

 

[Old Dog]

IO
I'm not saying this is right but I just put the 8.8 with disc brakes in mine and they are hooked up to the stock cj power brake m/c and the stock p.v..
The pads do not drag the rotors and it seems to stop like normal. (like yours not very quickly)
I need to find a slick hill I can do some controled stops on to see if I need a adjustable p.v.
As a side note I just took it wheel'n sat. and I really like the rear disc's after running through water/mud.

 

[tarry99]

IO
I'm not saying this is right but I just put the 8.8 with disc brakes in mine and they are hooked up to the stock cj power brake m/c and the stock p.v..
The pads do not drag the rotors and it seems to stop like normal. (like yours not very quickly)
I need to find a slick hill I can do some controled stops on to see if I need a adjustable p.v.
As a side note I just took it wheel'n sat. and I really like the rear disc's after running through water/mud.

Old dog,
that's good feedback so did you have your 35's on? or the 33's?
I'm assuming you were using the PB booster , is the pedal sensitive at all?

 

[Old Dog]

Old dog,
that's good feedback so did you have your 35's on? or the 33's?
I'm assuming you were using the PB booster , is the pedal sensitive at all?

I have the 33x12.5's on, they ride smother, so I could get better feed back from the swap.
Yes I have power brakes but they never have been real good. Right now I'm running the old rotors which have some rust and the old pads that still looked good. I plan on buying new rotors and pads when the money tree starts producing.

 

[IOPort51]

thanks Dog, anyway you look at it 33s are pretty big boots and 35s more so. there is a lot of leverage exerted on those brakes.

I am going to suggest you go ahead and replace the PV, I had very unimpressive boosted brakes on the J-10 until I replaced the PV and it was a marked improvement. that was stock disk/drums and I think it has a single diaphragm booster.

apparently the PV can go bad and restrict with out completely cutting off one end of your brakes.

I have the 33x12.5's on, they ride smother, so I could get better feed back from the swap.
Yes I have power brakes but they never have been real good. Right now I'm running the old rotors which have some rust and the old pads that still looked good. I plan on buying new rotors and pads when the money tree starts producing.

 

[Old Dog]

do you think I should replace it with a dics/disc pv from something else, or just get an adjustable one?

 

[IOPort51]

Disc Disc or Drum Drum Proportioning Valve Kit Left Side Brass MBM-PV4K-2

this is what I have in mind for mine.

I can't make a call on what the right move is but it seems that there should be no bias needed, I don't think there was any with drum/drum brakes just the residual valve in both ends. Some one tell me I don't know what I am talking about, please.

do you think I should replace it with a dics/disc pv from something else, or just get an adjustable one?

 

[Purple77CJ7]

I can't make a call on what the right move is but it seems that there should be no bias needed, I don't think there was any with drum/drum brakes just the residual valve in both ends. Some one tell me I don't know what I am talking about, please.[/QUOTE]

I believe there is bias in the brake system with the factory non-adjustable proportioning valve. The front brakes do about 60 to 70 % of the braking = bias. With all the modification I have done to my Jeep, running 33's, I prefer adjustable proportioning valves. With the added weight of all the mods added to my Jeep, being able to fine tune the system is nice. I have found with my set-up, I am running with as much pressure to the rear disks as I can get. Now stopping is not so scary.
I see from my I-pad it doesn't do quotes to good!

 

[IOPort51]

How much adjusting have you had to do and how did you decide you needed adjustment. What, in your opinion, is right and how did you get there.

I can't make a call on what the right move is but it seems that there should be no bias needed, I don't think there was any with drum/drum brakes just the residual valve in both ends. Some one tell me I don't know what I am talking about, please.

I believe there is bias in the brake system with the factory non-adjustable proportioning valve. The front brakes do about 60 to 70 % of the braking = bias. With all the modification I have done to my Jeep, running 33's, I prefer adjustable proportioning valves. With the added weight of all the mods added to my Jeep, being able to fine tune the system is nice. I have found with my set-up, I am running with as much pressure to the rear disks as I can get. Now stopping is not so scary.
I see from my I-pad it doesn't do quotes to good![/QUOTE]

 

[Old Dog]

I think the most important thing for me would that one end or the other didn't lock up first and make the jeep go out of control going down steep slippery hills.
The trick will be finding a good hill to check it out on that won't kill me if things go bad.

 

[tarry99]

I think the most important thing for me would that one end or the other didn't lock up first and make the jeep go out of control going down steep slippery hills.
The trick will be finding a good hill to check it out on that won't kill me if things go bad.

Old Dog,
You make a good point.......Locked up brakes / tires = No Control.
I've had that brake lock up happen many times before and found myself up shifting or getting on the gas just to keep the wheels rolling, which makes for an exciting down hill ride.
I am more of a fan of compression braking with minimal brake application when possible.

 

[Old Dog]

Old Dog,
You make a good point.......Locked up brakes / tires = No Control.
I've had that brake lock up happen many times before and found myself up shifting or getting on the gas just to keep the wheels rolling, which makes for an exciting down hill ride.
I am more of a fan of compression braking with minimal brake application when possible.

One of the down falls of running an auto. is there is only Limited compression braking. Something you learn to live with.
Theres a lot of times I'm on the brake and the guy in front of me with the manual Transmission is not.

 

[tarry99]

One of the down falls of running an auto. is there is only Limited compression braking. Something you learn to live with.
Theres a lot of times I'm on the brake and the guy in front of me with the manual Transmission is not.

Old Dog,

And that is the point I was making regarding over braking a vehicle. It boils down to skills and the terrain in which the Jeep is being used.
Big tires and large rotational weight versus smaller tires & less weight off road are two different animals , but may be controlled by similar brake packages that will act totally different from each other.

 

[Old Dog]

Thats why I was thinking an adjustable pv might be better.