WJ Booster Incompatible with MJ

[Salvagedcircuit]

My brakes have been exceptionally soft since I purchased my MJ. I bled the brakes several times and nothing improved. I tried bleeding the prop valve as well, and the dash light never engaged. There was a considerable amount of crud in my master cylinder and being this vehicle is 34 years old, I opted to just go with a WJ Booster+Master and a wilwood prop valve. I purchased a Cardone 5C-473163 booster, a Raybestos MC390511 Master Cylinder and a wilwood 260-13190.

 

The removal of the old equipment went smoothly, but the new WJ booster is physically incompatible. The hole for the booster in the firewall is 2.17in. The diameter of the cardone booster is 2.30in.
The booster never sat flush with the firewall. I bent up the firewall seam as well, and nothing I did was able to make the booster sit flush with the firewall. The brake pedal bracket obstructs the booster hole in the firewall, but that is normal with the MJs and I've seen it in other MJ firewall photos. I tried moving that bracket over as far towards the passenger side as possible, but alas, the booster would not fit. I used a large pry bar as well, but it was not enough.

 

For the people who succeeded with this conversion, what method did you guys use to make this work? There are several factors that could be causing my fitment issue:
-Cardone used the wrong OD on the booster diameter
-There is a lot of variance in build of the MJ
-People who did the conversion and documented it forgot to describe the amount of modification needed to make this work (enlarging the firewall hole).

Let me know what you guys think!
Thanks!

 

 

 

[MiNi Beast]

I just had to enlarge main hole a bit and it went in alright. Other then that it was seemingly straight forward. Brake pedal hole fit a little loose but came together alright. Just need to finesse it to fit. Take a break and go back at it. You'll get it. 

[howeitsdone]

Zero modification needed at that hole when using OE. Can't speak for aftermarket, but seems you've found out. Go to Lowes/Home Depot and get composite spacers like below. Add a few on each side. Only modification is slight bend above it. The hose will sit fine behind too. Because the original booster had an angle at the back to help with clearances you either have to take out a lot of material or use some sort of spacer. If worried about water leaking then you can put some tape or whatever else over the gap where the booster meets the firewall and create a little "roof" otherwise there have been threads where people fabricated an actual spacer. I think Cruiser did if I'm not mistaking.

 

Not the perfect solution but worked for me.

 

 

 

 

 

[howeitsdone]

Might be worth it to return the new part and get a used booster of you don't want to enlarge that hole.

[Pete M]

didn't they come with an aluminum spacer?  or am I thinking of the XJ's version?

[howeitsdone]

25 minutes ago, Pete M said:

didn't they come with an aluminum spacer?  or am I thinking of the XJ's version?

 

There was a thread I found where Cruiser mentioned something like that. I think they were trying to figure out the best way to replicate. It's a bit of material, but could be an easy gig for someone with a 3D printer 

[howeitsdone]

[Salvagedcircuit]

Thanks for all of the replies. There was no spacer included in the cardone kit.

At this point I believe my options are either widen the firewall hole or use a longer arm booster and spacer.

I CADed up a spacer myself. I will attach the dxf for others to use. I plan on having spacers waterjet out of 1/8 and 1/4 in aluminum. This way if I need to stack them, I can.

However, If I use a spacer, I need a longer booster arm to the pedal. Which Jeep had a dual diaphragm booster but a longer pedal? I forgot. Was it the ZJ? or a late model 97+ XJ?

I very much prefer buying a new booster and master. I will not be pulling used parts from a junkyard that may have problems that I am unaware of.

 

Thanks for any input guys!

 

 

[fiatslug87]

The 95 (&96???) XJs had an aluminum spacer with the dual diaphragm booster. Also had a foam gasket between the firewall and spacer.

 

 

[Salvagedcircuit]

4 hours ago, fiatslug87 said:

The 95 (&96???) XJs had an aluminum spacer with the dual diaphragm booster. Also had a foam gasket between the firewall and spacer.

 

 

You sir are awesome. Is this the stock XJ 97+ spacer that came with the booster?

Still trying to decide what to do.

Thanks

[fiatslug87]

Stock spacer from a 95 XJ.

[cruiser54]

As soon as I saw "Cardone" I felt uncomfortable. 

I've done about 3 or 4 of these WJ conversions. and a 95 to 96 conversion. 

Junkyard sourced parts, making sure I got the set-up with the flexible lines included. 

Yes, the firewall needs to be massaged with the WJ booster. 

There are other advantages though. Seems more powerful than the 95 to 96.

You don't need to rearrange stuff in the engine bay. Pedal is the correct height.

[boxyjeep]

I did this swap with those specific parts without issue (beyond having to bend up the firewall seam above the booster).  Didn't use a spacer and didn't need to enlarge the hole.  Very weird.

 

[cruiser54]

Think "Cardone"..

[Salvagedcircuit]

Thanks everyone for the responses. So far I've put 4 months of work into this comanche and it seems that I'm building a vehicle from a parts catalog.

I apologize that I've been late to respond here, the drivers CV joint on my folks grand cherokee failed and I've been consumed by that all week. The good news is they now have a new front end suspension with new shocks, stabilizer arms and CVs, but I am left with a golden radioflyer without a handle.

 

I'm leaning toward using the longer arm dual diaphragm booster and bracket. I just have to determine which one and if its worthwhile to spend the premium on finding a new old stock mopar setup.

 

During the failed install, I did notice that the paint around the entire brake booster+master region of the engine bay is bubbling and peeling off. I realize it's 34 years old, but who knows maybe the master or booster has been leaking for a while.

 

Along the way, it turns out my exhaust manifold has a nice crack in it to compliment my repair efforts.

 

My plan was to document the dual-diaphram + wilwood prop valve upgrade in complete and post it to comancheclub. It is something missing from the project guides and would be useful to have. The wilwood prop valve is currently being returned to wilwood for analysis, there were distinct burrs on the brake fitting orifices.

 

I am beginning to think this will be nothing more than a sunday vehicle and not a daily driver at this rate. I just don't see how this is going to be working, reliable and undercoated before winter.

 

 

[cruiser54]

I would love to see someone do a write-up on the WJ booster. I'll help. 

[Salvagedcircuit]

1 hour ago, cruiser54 said:

I would love to see someone do a write-up on the WJ booster. I'll help. 

That means a lot cruiser. Thanks.

I'm thinking that if I remove the brake pedal assembly, mount the booster than mount the pedal assembly, I may have better luck with a successful install.

The WJ Booster is mopar part# 5011261ab.

Cardone and Crown make a clone of it, but of what quality, I don't know.

The cheapest mopar WJ booster is $350 that I can find. My local Mopar parts dealer has one left and wants $536.

The last time mopar produced a WJ booster was close to 20years ago. Who knows what shape the rubber diaphragm is in. A recently manufactured 3rd party booster may be a better option.

[cruiser54]

But no matter what, isn't the firewall hole too small?

Think about brake light switches also. You won't have to grind the booster rod. 

I've always done the install with the pedals installed. 

[Salvagedcircuit]

The starett caliper in the original post showed 2.177in. This was measured from the side of the diaphragm hole in the firewall to the intruding brake pedal bracket. I forgot to measure the actual diameter of the hole in the firewall for the booster. It is possible that my brake pedal bracket was poorly welded or loosely stamped at the factory, but it didn't matter at the time because the diameter of the single diaphragm was smaller than the diameter of the WJ booster.

I tried to line up the WJ diaphragm as best as I could, but it would not fit because the brake pedal bracket always impeded the path of the booster arm.

[cruiser54]

But no matter what, isn't the firewall hole too small?

Think about brake light switches also. You won't have to grind the booster rod. 

I've always done the install with the pedals installed. 

[cruiser54]

That said, the pedal bracket can shift once the booster is out. It needs to be re-centered.

 

what size studs are on the new booster? 

[howeitsdone]

11 hours ago, cruiser54 said:

I would love to see someone do a write-up on the WJ booster.

 

This is the one that I followed during mine. Only wrong info was saying 8mm bolt. It's actually an M8. Everything else was fine. And links to discussion about prop valve upgrade.

 

 

This one helped too when it came to the bubble flare fitting info. Also where I saw the spacer discussion.

 

 

[boxyjeep]

I feel bad after reading this.  I was messaging with @commissioneranthony a few weeks ago and he asked about this upgrade/swap and I outlined how I did it in my '88 in a day with no issues (minus the brake light switch).  I used the following parts:

1. Booster: CARDONE 5C473163 (RockAuto)
2. MC: RAYBESTOS MC390511 (RockAuto)
3. Adapters you may need: AGS BLAB312, AGS BLAO380 (RockAuto), as well as some 3/16" brake line to flare.
4. Proportioning valve: Wilwood 4444/30 260-11179 (Amazon)
5. Standard Motor Products SLS66 Stoplight Switch (Amazon)

I couldn't get the original switch to reliably work (even after filing down the arm), so I installed the SLS66 brake switch in the original cruise control/trans brake switch location (no longer had those) and wired up a relay for the trans brake signal to the TCU.  I also removed the load sensing valve in the process.

 

If there is one thing I've learned with these trucks, there will be some frustrations trying to get them reliable.

[Salvagedcircuit]

9 hours ago, SoCalJeepComanche said:

I feel bad after reading this.  I was messaging with @commissioneranthony a few weeks ago and he asked about this upgrade/swap and I outlined how I did it in my '88 in a day with no issues (minus the brake light switch).  I used the following parts:

1. Booster: CARDONE 5C473163 (RockAuto)
2. MC: RAYBESTOS MC390511 (RockAuto)
3. Adapters you may need: AGS BLAB312, AGS BLAO380 (RockAuto), as well as some 3/16" brake line to flare.
4. Proportioning valve: Wilwood 4444/30 260-11179 (Amazon)
5. Standard Motor Products SLS66 Stoplight Switch (Amazon)

I couldn't get the original switch to reliably work (even after filing down the arm), so I installed the SLS66 brake switch in the original cruise control/trans brake switch location (no longer had those) and wired up a relay for the trans brake signal to the TCU.  I also removed the load sensing valve in the process.

 

If there is one thing I've learned with these trucks, there will be some frustrations trying to get them reliable.

 

No hard feelings at all. @SoCalJeepComanche you have been a great help to me and an inspiration. I have a huge amount to respect to all of you on this forum, that's why I joined.

It takes a true caretaker to keep one of these comanche's alive. I am truly learning that now.

The more frustrating thing is learning to live with the hodgepodge assemblies. Torx, metric and standard at the same time!

Thankfully there's no British standard thread. I'd really lose it :D

I am going to take @MiNiBeast's advice:

 

On 8/17/2022 at 1:53 PM, MiNi Beast said:

...Just need to finesse it to fit. Take a break and go back at it. You'll get it. 

 

I plan on reinstalling the old booster, torquing it back to spec and taking some measurements.

I plan on buying both a booster & master for both an XJ and WJ and making a few spacers. I will make (2) 1/8in spacers, (1) 1/4 spacer and a 5/16 spacer.

I will then remove the booster and brake pedal and then try the install again.

There should be a replacement prop valve in the mail from wilwood this week and I will have to set aside a weekend to do the booster+master+prop valve install.

 

P.S. There's  also a '91 longbed comanche in new jersey that is oh so tempting. No fusible links. Dedicated fuse box. no renix. Less vacuum tubing. Little rust. Hubba Hubba Hubba.

 

Please send help

[Salvagedcircuit]

Here's an update.

I'm on my second cardone booster + raybestos master and everything fit nicely.

However, there were no brakes whatsoever.

 

I bypassed the rear load sensing valve and removed the distribution block from the front and plumbed in a new wilwood prop valve.

I bench bled the master cylinder in a vise and then installed the master to the booster.

I connected everything up and started bleeding the brakes but no fluid would pump. Nothing bled from the passenger rear drum cylinder.

I checked the temporary brass 5/16 union I used to mate the brake lines from the prop valve to the front brake lines.

When I removed the master+booster combo, the lines were completely dry.

 

I am baffled with why this is not working. There was some confusion with the installation. Raybestos does not make it clear why there is a second o-ring for the master cylinder. There is a rectangular profile o-ring that ships on the rear face of the master and there is an additional circular profile o-ring that they include in a separate little baggy with a warning note. The warning says "make sure to replace the seal on the master flange before mounting." I attached an image.

I tried the master+booster with just the rectangular profile o-ring and then both the rectangular profile o-ring and the circular oring stacked.

The same result kept happening. Nothing is being pumped. The master cylinder would push up and down about 10 degrees with every foot pump. I made sure to tighten the master to the booster, it was not loose.

 

After doing some research, I believe I made (2) critical mistakes:

1. We bled the master cylinder by pumping the cylindrical post in the vise and pressed too far (more than an inch) with a flat head screwdriver
2. I did not realize that it was possible to have a master and booster misaligned. I believe I may have damaged the master by not checking alignment. I saw a video of another guy checking alignment with a usb endoscope camera via the vacuum pump port. This is what I plan to do next round.

The master cylinder post apparently is not supposed to be pressed more than 1inch. I talked with a cardone ase technician about this. It seems better to bleed the master when mounted to the booster so there is more consistent travel within the allotted travel requirements.

 

Some questions I still have:

-Do I use both the Square and circular O-ring? I called raybestos and the fellow thinks you use both. He mentions that the rectangular profile o-ring is a "gasket" and the circular profile o-ring just stacks. He was not entirely sure.

 

Lastly, here's how she sits now with factory rims acquired.

 

Thanks for all the help so far guys.