TRUCK MASTER CYLINDER UPGRADE ADVICE

[bkahler]

1 hour ago, Young Ed said:

You need an early 39-45 pushrod that doesn't have the gap between the threads and the yoke

 

I would imagine the odds of finding one of those is probably pretty slim.  I do have a spare pushrod that I plan on modifying and will save the restored one with the rest of the parts that I'm swapping out.  

[bkahler]

43 minutes ago, Tooljunkie said:

Think i cut almost an inch off my push rod. Without adjusting my brake shoes pedal travels1/2 way to floor. 

 

That would imply that there should be no contact from the brake pedal arm to the plastic reservoir.  It will be nice if it works out that way.  

 

Thanks!

 

 

[DJ194950]

Have you thought about changing the plastic reservoir to a plug(s) that convert to a remote reservoir setup?

 

They (the adapters) used to be readily available, but I have not looked for a while myself.

 

Found a video about 1 kit, but many cheap  single plug type used to be out there. These is as far as I looked not knowing if this may be of interest to you.

Hope that what you already have works as in, no changes! ?

 

DJ

 

 

[Young Ed]

7 hours ago, bkahler said:

 

I would imagine the odds of finding one of those is probably pretty slim.  I do have a spare pushrod that I plan on modifying and will save the restored one with the rest of the parts that I'm swapping out.  

I had one in my truck and learned the hard way I needed the longer one.....maybe that short one will finally come in handy

[bkahler]

14 hours ago, DJ194950 said:

Have you thought about changing the plastic reservoir to a plug(s) that convert to a remote reservoir setup?

 

They (the adapters) used to be readily available, but I have not looked for a while myself.

 

Found a video about 1 kit, but many cheap  single plug type used to be out there. These is as far as I looked not knowing if this may be of interest to you.

Hope that what you already have works as in, no changes! ?

 

DJ

 

 

 

DJ, a remote reservoir is certainly a possibility.  I'd prefer not too in that I would then have to find a place to mount it and that wouldn't necessarily play well with my "as stock as possible" goal.  Originally I was trying to build a totally stock truck but as time as gone by mostly due to necessity that goal has changed a little.  For the time being I'm keeping my fingers crossed that everything will play nice together

 

I wouldn't mind having a remove reservoir for my Argosy motorhome and might just look into what options are available for it.

 

Thanks!

 

Brad

[bkahler]

7 hours ago, Young Ed said:

I had one in my truck and learned the hard way I needed the longer one.....maybe that short one will finally come in handy

 

Another good reason why we tend to hang onto left over parts even though we have no use for them

 

 

[Tooljunkie]

Wonder if the original master being tilted have something to do with clearance. 
im curious how close my resevoir is now. I never really paid attention.

[Tooljunkie]

14 minutes ago, bkahler said:

 

Another good reason why we tend to hang onto left over parts even though we have no use for them

 

 

Its not hoarding, its saving for future projects. Stuff i have been saving forever is now getting used. 
 

[bkahler]

3 minutes ago, Tooljunkie said:

Wonder if the original master being tilted have something to do with clearance. 
im curious how close my resevoir is now. I never really paid attention.

 

As near as I can tell it seems the width of the reservoir is the issue, there doesn't seem to be a height issue.  

 

I'll get a measurement of the MC width and post it sometime today.

 

 

[Jim Roach]

Has anyone had this clearance issue that used the Jeep MC?

[bkahler]

34 minutes ago, Jim Roach said:

Has anyone had this clearance issue that used the Jeep MC?

 

I don't recall any response saying they've used the tall reservoir MC. Most seem to have used the one that slopes.  

[bkahler]

I shortened and installed the pushrod this afternoon.  The results aren't promising for the tall reservoir ?

The length of the pushrod allows the pedal to be retracted all the way with minimal play between the pushrod and the MC piston.  

 

 

 

 

This is what it looks like with the pedal depressed 1/2 way to the floorboard.  This equates to about 5" of pedal travel.  

 

 

This is what happens when the pedal depressed full stroke.  At least I think it's full stroke.  It hangs up on the side of the MC so it might actually move a little farther down.

 

 

 

I adjusted the pushrod so there is less than a 1/16" of play before the piston starts to move.  The pedal return spring should keep the pushrod from riding on the piston.  

 

I think it might be time to go back to the salvage yard and find one of the sloped reservoir MCs and see if that makes a difference.   Looking at various pictures online it looks like some reservoirs might be narrower than others.  I can hope!

 

Brad

 

 

 

Edited February 2, 2020 by bkahler

[Tooljunkie]

There is a good chance the other reservoir will fit. With any luck. 
have popped them off before to clean them. 

[bkahler]

Had a few inches of snow last night but I still decided to spend the morning sloshing through a couple of junk yards in the area but had zero luck finding any MC or reservoir that would be reasonably close to fitting.  It didn't help that all the vehicles were covered in snow which made it difficult to find Jeeps.  

 

I'm pretty much convinced this style of MC will interfere with the brake pedal when the pedal is depressed just like the style of reservoir that I have now.  The pedal interferes with the section of reservoir that is closest to the mounting point of the MC and this MC appears to be just as tall in that area.  

 

 

 

This style of MC might have a better chance of clearing due to its oval shape but I don't have any clue what model vehicle this MC came from.  It also appears shorter than the Grand Cherokee MC which is a plus as the complete MC could be moved farther forward which might help with pedal clearance.

 

 

 

I'm also now considering some sort of remote mount arrangement but so far my searches haven't been to productive.  I'll keep looking though.

 

What master cylinders have others used in the B3 series of trucks that actually fit and didn't interfere with the full stroke of the brake pedal?

 

I'm even considering just using my original (brand new) MC.  I've never experienced a MC failure which is one of the reasons I'm considering this approach.

 

Brad

 

[Tooljunkie]

Have you considered popping off the resevoir and flipping it around?

would have to trim off the tabs and come up with a different way to retain it, but it might give you the clearance. Or simply angle it a couple degrees. If you are building another adapter, that may be all you need. 

[bkahler]

9 minutes ago, Tooljunkie said:

Have you considered popping off the resevoir and flipping it around?

 

Just did it and it does lower the top where the pedal travels by about 1/2".  However I will need to do some grinding on my adapter plate to provide some clearance for the reservoir.  I'll do that tomorrow.  If I remember right I needed about 1" or slightly more to provide full pedal travel.

 

 

9 minutes ago, Tooljunkie said:

would have to trim off the tabs and come up with a different way to retain it, but it might give you the clearance. Or simply angle it a couple degrees. If you are building another adapter, that may be all you need. 

 

Surprisingly it was symmetrical

 

About an hour ago I ordered this Dorman M290378 MC from Amazon.  Should be here Sunday.  It appears to be considerably narrower due to its oval shape.  The brake pedal only needed about 1/8" to 3/16" clearance on the one corner for clearance.  I think the mounting holes are slightly different which is no biggy.  This MC is from a 97-06 Jeep Wrangler.  After discussion with Eric he thinks most Wranglers had rear disc brakes so it should be appropriate.

 

 

 

I bought a GM disc/disc proportional valve from Amazon as well.  From what I've read it should do the job of eliminating the separate brake residual valves.  The information came from a company called MDM.

 

 

 

[bkahler]

Actually I misspoke, I do need two 2 lb residual valves installed along with the proportioning/combination valve.

 

Maybe Jeff Balazs will chime in here, I seem to recall reading a post from him about having removed his residual valves after using his truck for a while.  Then again I could be wrong about this!  My memory isn't all that great anymore......

 

Found Jeff's post about the residual valves.  He removed the front one.

 

This post has even more info on the residual valves.

 

Brad

 

Edited February 8, 2020 by bkahler

[bkahler]

Just finished trying TJ's idea of reversing the reservoir.  I did gain about 1/2" of travel at the top of the pedal but still not enough to fully stroke the MC.   This time I took a measurement of actual piston travel in the MC and came up with 15/16" of travel.  I believe the Cherokee MC has about 1-1/2" of piston travel so there is still a fair amount of travel left.  With the pedal depressed and the arm just touching the reservoir there is about 4-1/2" of travel before the pedal hits the floorboard.  It starts at about 10" of travel so 5-1/2" of travel equates to about 15/16" of piston movement.  This means the pedal will be just a little above the floorboard before the piston bottoms out.  I believe the original MC has about 1-1/2" of piston travel as well.

 

I get the Wrangler MC tomorrow and I hope to fabricate an adapter before the end of the day.  Hopefully I'll be able to post more info tomorrow night.

 

 

 

 

 

[Jeff Balazs]

Hey Guy's;

Here is a photo of the M/C in my 52 3/4 ton. It is a stock 2002 Grand Cherokee m/c. I made an adapter plate and added a Wilwood adjustable proportioning valve. I did have residual valves in the initial build but they were causing the fronts to drag. Also I needed to shorten the original adjustable rod a bit. Initially the linkage needed some fiddly little adjustments to prevent brake drag. Once I got that where it should be I was good to go.

 

Btw my axle is a Dana 35 3.55 ratio with 12" discs. There is nothing wrong with these axles as long as the seals are replaced and the gear lash is set correctly. You certainly don't need a beefier axle with our L6 powerplant.

 

These brakes and the higher ratio rear axle are without any doubt the best upgrade I could have done during my build. I drive this truck every day in relatively heavy and fast moving street traffic. The truck itself is no hot rod but when it is up to traffic speed I don't have any worry about it stopping quickly if needed. And believe me I have put them to the test. We have more than our fair share of crap drivers here in Southern California.

 

Hope this helps.

Jeff

 

 

[bkahler]

Jeff,

 

Thanks for the info and picture.   That's the same MC I've been trying to fit.  Do you happen to know how close your brake pedal gets to the top of the plastic reservoir when you have the fully depressed the brake pedal?  

 

Thanks!

 

Brad

[Jeff Balazs]

Brad it does get real close. Probably within a 1/4". My set up might be slightly different than yours as I have a fluid drive 4 speed and the bell housing is different. I think you could remove some metal from the underside of the brake pedal . As I have said mine has functioned quite well for over 20000 miles.

Jeff

[bkahler]

1 hour ago, Jeff Balazs said:

Brad it does get real close. Probably within a 1/4". My set up might be slightly different than yours as I have a fluid drive 4 speed and the bell housing is different. I think you could remove some metal from the underside of the brake pedal . As I have said mine has functioned quite well for over 20000 miles.

Jeff

 

20,000 miles in a pilot house is impressive

 

I don't know that I'll live long enough to be able to accomplish that feat!   If I remember right the pedals are different between a 4-speed and a fluid drive.  That might explain some of the difference.   

 

Thanks!

 

Brad

[bkahler]

I think I found a winner!  The Dorman M390378 that I bought from Amazon for the 97-06 Wrangler looks like it's going to work.  As luck would have it needed a slightly modified adapter plate so I fabricated one this afternoon.  Currently it's made from 3/8" aluminum plate but I think I'll use 1/2" for the final version.  I'd like the extra thickness for the 5/16-18 bolts that hold the MC to the plate.  More depth means more thread engagement.  The reservoir doesn't come close to the steering column or the pedal. 

 

There are some definite differences between the Wrangler MC and the Cherokee MC.  The Cherokee reservoir is 5-1/4" tall from the centerline to the top of the high part of the reservoir and 4-1/2" at the low end.  The Wrangler is only 3-1/2" from centerline to the top of the reservoir.  That difference right there was all I needed to get a lot more pedal travel.  The pedal actually runs into the firewall pad on the right edge where it angles inward.   At rest the pedal is about 10" above the firewall.  Fully depressed it gets to within 1-1/4" of the firewall.  That equates to about 1-3/16" piston travel.   I think full piston travel is about 1-5/8".  I have no idea if not getting full stroke of the piston will matter but there's nothing I can do about that.   The pedal arm does contact the the top of the reservoir at full pedal travel but my guess is if the pedal travels that far I probably have other problems to worry about at that point ?

 

I will have to use socket head cap screws to mount the adapter plate to the bell housing or else countersink the holes and use flatheads.   SOHC will definitely work for the top two holes but the bottom one will likely need to be countersunk.  I'm still in the mode where I don't want to alter a new MC to make it work if I don't have too and I think even a SOHC will interfere with the bottom of the MC.

 

One other thing.  The depth of the Wrangler MC bore is deeper than the Cherokee so the end of my pushrod that I cut off will need to be welded back on ? 

 

Brad

 

 

 

[Jeff Balazs]

54 minutes ago, bkahler said:

 

20,000 miles in a pilot house is impressive

 

I don't know that I'll live long enough to be able to accomplish that feat!   If I remember right the pedals are different between a 4-speed and a fluid drive.  That might explain some of the difference.   

 

Thanks!

 

Brad

Well I drive it every day........and it is my only ride......so it has been fairly easy. I generally put around 100 to 125 miles on it a week.

It is funny but once you get used to driving one of these you don't really enjoy driving other stuff. 

Jeff

[CO54]

Glad the Wrangler MC worked for you!!!! One to keep in mind moving forward when there are clearance issues.  I'm still leaning towards the small booster/MC option for myself.  The vacuum is the issue with my planning, and possible execution.