My Willys 3A and 3B Community
TECH FAQ SECTIONS => Chassis, brakes and suspension. => Topic started by: patrickt on November 06, 2019, 06:13:58 AM
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Hello All !
My first tech post here. If you haven't read my introduction post yet, then let me start by telling you that what I have is the Japanese version of the CJ3B, a Mitsubishi-Willys from I would say, sometime in the 1950's. All kinds of mods were done to it, surely for reasons of practicality, given that the vintage car/jeep parts situation over here is relatively poor. It does look period correct for the most part, but I digress.
I just discovered why my brakes tended to be low on the first two times I pumped the brake pedal, in spite of it not having leaks and being bled well, it turns out that the wheel cylinder pistons on all four 9 inch drums were 1-inch diameter. I had no luck finding any rear 3/4 inch ones over here, so I have to get them over there.
I just recently saw someone with a CJ3A on the net, saying he had Wagner-lockheed # FD- 73791 1 inch wheel cylinders in Front (which is exactly what I have on All four drums). So I wanted to ask if anyone knows if the front and rear wheel cylinders on their CJ3A are interchangeable, having the same exterior dimensions, as well as the same diameters and distances between the two mounting holes and the bleeder valve hole ?
If yes, all I need to do is order two rear CJ3A 3/4 inch wheel cylinders, and I should be good to go. I don't know how to post pics yet, but can tell you that my FD-7379 look virtually identical to pics I've seen for the CJ3A, CJ2A, M38. Your help would be greatly appreciated. Thank you. Patrick
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I'm no expert, but if there are "no leaks", I would suspect "air" in the lines, or deteriorated fluid, and not the size of the cylinders as the "problem". Dare I suggest you bleed the brakes, check the fluid quality for deterioration, flush the lines, and then replace the fluid and bleed the brakes before changing parts? You may like what you have already with a properly working system, since you said it is already "not original throughout". Just my thought. Good Luck!
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The CJ3A uses 1" wheel cylinders in the front and 3/4" in the rear.
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Thank You both.
Unfortunately, I, as well as mechanics in the past have tried that approach, including using new 1-inch wheel cylinders (on all four drums), but to no avail. We even tried a bandaid approach by simply adjusting the brakeshoes closer to the drum, but no dice.
Which is why I decided to do a bit more reading and found out that most willys and mitsu-willys jeeps from this era had 1-inch wheel cylinders in front and 3/4 inch ones in the rear. And then I decided to do the math, and ended up pretty much with 1 inch front wheel cylinders and 3/4 inch rear wheel cylinders. Not trying to sound all knowing here, but in retrospect, it's frustrating (strange ?) that these mechanics were not aware of volume - size relationships and such, not just so all the wheel cylinders fill properly to get a good and high brake pedal feel on the first pump, but for better brake bias.
Bottom line I'm pretty sure is that I need 3/4-inch rear wheel cylinders. Which brings me back to my question, Are the CJ3A Front and Rear wheel cylinders physically interchangeable ? Like I said in my first post, all four of my drum brakes have Wagner Lockheed # FD-7379 1-inch wheel cylinders, the same Wagner-Lockheed part number that someone says he has on his CJ3A Front wheel cylinder. Because if the front 1-inch and rear 3/4-inch wheel cylinders are interchangeable, I will then order the rear 3/4-inch wheel cylinders. Anyone else please.
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Glad you posted here. Plenty of experts that no doubt will chime in.
I believe the 3A and 3B are the same. My Parts Manual (PM) shows different part numbers for the front and rear wheel cylinders. I don't have any specifications to verify the diameter (I'd ordered new wheel cylinders on my 3B so I just installed them without measuring) but noticed on a recent repair that in fact the vendors offer both the 1" and 3/4" kits so you may be on track with your assumption.
I would think that if the brake line threads will work (thread and flare style) then yes, it should attach.
And re-reading your post, all wheels cylinders are physically the same with regards to mounting: 2 mounting screws and one threaded flare fitting for the brake line (the brake backing plates . I believe the only difference is the piston diameter. Referencing the PM again, I see the backing plates are listed as the same part number (no difference between front/rear) so anything mounted to them whether front or rear would need to have the same dimensions, i.e shoes, cylinders.
Hope I'm not adding to the confusion.
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Of course 'you' have to be the one 'comfortable' with your brake system, regardless of other opinions. Agreed, brake cylinder size creates "bias". Do not agree that your calculations for 1" cylinders as the "problem", but that is just 'me'. For example, my DJ3A has 1-1/8" fronts and 13/16" rear cylinders on 9" brakes, with the "same" 1" piston brake master cylinder as yours and/or most models of Willys (ecept some MBs). The "volume" is limited to the total area of the hydraulic system, but the "sponge factor"/ soft pedal is typically (?) "in the fluid", or MC piston, once the lines and cylinders are "full". FYI... I found this link to Wagner's answer to "What causes a spongy brake pedal?"... https://www.wagnerbrake.com/technical/technical-tips/why-are-my-brakes-spongy.html
Also, from my experience, I found the "vent hole" in the MC cap on mine was "plugged" not allowing air above the fluid when the MC is in use creating a vacuum against the MC operation. It is a tiny hole as pictured here attached. Sometimes we over-complicate our thinking from basics.
Just trying to help from my experience and research. Hope something works for you. Brakes are important!!! Good Luck!
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I think Steve is on the right track. I believe the wrong size cylinders will only allow more mechanical advantage to the rear vs. the correct bias.
There's something else causing your pumping problem. I first lean towards bleeding. It can be done and if not careful, can still have air. I always bleed farthest first working towards the m/c and let it run until clear. Shoes out of adjustment would be the second thing. Pumping will move them into contact with a good hard pedal for braking.
If you have eccentrics like the Willys 3B, turn them until you get a slight drag. Then test the pedal. Regardless of piston size, you should have a hard pedal.
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Rus Curtis and Stevenkfl - thanks for both your replies ( and Thanks for the welcoming remark Rus). I will get back to you guys in a few hours. I live in a way different time zone, so...
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Ok I'm back. It has been my understanding that (everything else being the same), using a bigger bore master cylinder than stock normally results in less pressure output to the wheel cylinders, so in fact it's harder to push down and results in less pedal travel since a bigger bore can push a greater amount of fluid with less movement of the pedal.
I mentioned this because all this time, I thought I had a 1-inch bore m/c, when in fact what I have is an undersized 15/16-inch bore. Now, I understand as well that an undersized m/c will do the opposite, create a higher pressure output, which is nice of course, but result in a longer pedal travel, because of the smaller bore of the m/c, which takes longer to fill up the wheel cylinders.
I decided to check old notes I made from 10 years ago, and discovered that the jeep in fact only had an extremely undersized 3/4-inch m/c ! I now somewhat recall having to pump up the pedal like maybe 4 or 5 times, before the brakeshoes caught on firmly to the drum, a mere 2 or 3 inches away from the floor. As low as the pedal was, it felt firm and solid (as opposed to being spongy). I believe it was pulling a big water tank very, very slowly around some big private piece of land, hence the owner being satisfied with the dangerously low and slow responding brakes. And this was with the 1-inch wheel cylinders on all four drums.
I apparently changed the 3/4-inch m/c to what I thought was a 1-inch one, but was in fact 15/16-inch (still undersized). The pedal took less strokes this time (2-3 pedal pumps) to get the brakeshoes to firmly contact the drums, and was a few inches higher now ! In both scenarios of the 3/4-inch and 15/16-inch m/c's, there was no spongy feeling on the brakes.
Given what I experienced, I figure I can either find the correct 1-inch sized m/c, or get the smaller 3/4-inch rear wheel cylinders (cheaper to do) either of which should reduce the number of pedal pumps and get the pedal higher sooner, because the wheel cylinders will fill up sooner.
Rus Curtis - I checked a couple of Willys jeep online stores and saw that it was only the rear wheel cylinder of the CJ3B that looked like mine, and that the fronts were totally different looks wise, though as you said, the front and rear backing plates had the same part number. The pistons for the front by the way didn't seem to have the notch for the brakeshoes to mate with. Whereas the CJ3A wheel cylinders I saw had notched pistons for both front and rear, as well as the exterior looking identical to each other.
This being the case, I would still appreciate it if a CJ3A owner could please confirm if the front and rear wheel cylinders are interchangeable, same distances of mounting holes and bleeder valve ? Maybe you could verify as well if the front and rear backing plates have the same part number? That would be most appreciated ! Thanks again.
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There were 2 different versions of 9" Benxix brakes used on the 1945-1971 CJ's.
(excluding the DJ's and other Jeep models.)
The early type 9" Bendix brakes 1945-1953 and the late type 9" Bendix brakes 1953-1971.
The late type 9" Bendix brakes used 2 different types of front wheel cylinders and backing plates.
This last 9" brake change depended on year of manufacture, pre 1959 or post 1959.
What year is your application ?
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OLDTIME - As I said in my first post, some mods where done to my jeep by the previous owners, so I unfortunately don't have an exact year on it. You mentioned somewhere on the internet that early drums were mounted inboard of the hub flange, and that later ones were mounted outboard of the hub flange. I hope i dont sound too dumb, but when you talk about the earlier brakes mounted inboard, is this the one with the hub flange visibly sticking out of the wheel rims ? If yes, then that would be mine.
SteveKfl - I forgot to say, Thank You for the pics you attached.
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If you can upload pics then we can identify what we see.
Early 9" Jeep Bendix brakes have 4 shoe adjusting eccentrics vs. late type 9" Bendix which have qty of 2 shoe adjustments per wheel.
All 9" CJ brakes use 1" diameter bore master cylinders, 1" bore front wheel cylinders and 3/4" rear wheel cylinders.
And yes all 9" CJ Bendix have 1-3/4" wide shoes.
Early type shoes and late shoes do not interchange.
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Just took a peep, and saw only 2 eccentric adjusters at the top. I'm sorry as I still don't know how to load pics. I will have to learn...
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Here's a pic of my jeep and a rear hub (first time to try to post a pic)
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mmm, jeep pic didn't show. Let me try again.
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It's like 10pm over here, so I will just take off I drum tomorrow and send a pic of what it looks like inside. Though here is a picture I took from the internet of the back portion of a CJ2A, which looks exactly like mine.
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...using a bigger bore master cylinder than stock normally results in less pressure output.....and results in less pedal travel since a bigger bore can push a greater amount of fluid with less movement of the pedal.
.........I understand as well that an undersized m/c will do the opposite, create a higher pressure output, which is nice of course, but result in a longer pedal travel, because of the smaller bore of the m/c, which takes longer to fill up the wheel cylinders......
.....the jeep in fact only had an extremely undersized 3/4-inch m/c ! .....And this was with the 1-inch wheel cylinders on all four drums......
.....the rear wheel cylinder of the CJ3B that looked like mine, and that the fronts were totally different looks wise.......The pistons for the front by the way didn't seem to have the notch for the brakeshoes to mate with. Whereas the CJ3A wheel cylinders I saw had notched pistons for both front and rear, as well as the exterior looking identical to each other.
I follow your fluid mechanics and believe that is accurate. Correct sized parts will certainly help.
Oldtime has more hands-on than I do AND more reference material too! My library is just a few books so far (all I have on Mitsu's is just pictures and the 3B Page). I wouldn't think much difference between the 3A and 3B brakes (mostly the engine change over) and am speculating that the notch "may" be a manufacturer thing vs. what will work. I've seen the notches (and smooth pistons) but (again, speculating) don't believe them to be that important to actuate the brake shoes. Your shoes are still anchored the same way and travel is still limited within the drum.
On posting, you can use 3rd Party, i.e. Imgur or Flickr, or attach directly. There's supposed to be a gallery here but haven't used it yet.
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The wheel cylinder pistons with a notch are 1941-1953 design.
Front wheel cylinder = A-1484
Rear Wheel cylinder = A-6110
Master cylinder = A-556
You can also use 1953-1958 parts essentially the same excepting the flat piston head design.
Front wheel cylinder = 807356
Rear Wheel cylinder = 807357
Master cylinder = 805223
After 1958 they use L=R wheel cylinders at the front.
I have those available for sale OEM NOS from the 1960's.
See: https://stlouis.craigslist.org/atq/d/saint-charles-willys-jeep/7007697619.html
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RUS and OLDTIME - I will get back to you both, have to run to work (morning over here). Here's pics of my wheel cylinder.
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Pics
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another pic
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last pic of wheel cylinder
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Okay, just to be on the very safe side, i decided to take exterior measurements of my wheel cylinder using a simple vernier caliper. Obviously not as precise as a digital one, but good enough for my needs.
So may I ask if anyone who has access to his CJ3A (or 2A if you have one) 3/4 - inch rear wheel cylinder, can please check the same areas I measured on my wheel cylinder ? I would hate to order the wrong one, and have to pay international shipping fees, as well as restocking fees to return it to the seller (if they would even accept returns). I hope you guys understand... Thanks again ! Patrick
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#807356 = 1" Left + Right = Cast # FD 7228 (early 9" front)
#803639 = 1" Left = Casting #FD 9006 S2 (late 9" front)
#803640 = 1" Right = Casting #FD 9006 (late 9" front)
#807357 = 3/4" Rear = Casting #FD 7544 (all 9" rear)
The 1953-1958 CJ's used front cylinder #807356 with "S" tubes
All 1959-1971 CJ front axles with 9" Bendix brakes eliminated the "S" tube at the wheel cylinder.
Instead they use 11" flex hose attached at both sides of front frame.
The hoses thread direct onto the "rear ward angled" front wheel cylinder ports.
Hence RH and LH part numbers for the front cylinders only.
All 1953-1971 CJ's with 9" Bendix brakes use rear cylinder #807357
Got that ?
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Finally took off rear-right brake drum. Pics first, text to follow in a bit.
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I decided to include the axle shaft and hub flange.
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Drum off
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3/4 view
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Top view
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Adjusters
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Aft of Rear axle
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OLDTIME-
I understand some. I have those "S" tubes going to my front wheel cylinders. My wheel cylinders are notched.
Your extensive knowledge of even the minute details of parts and such is helping to support my belief of this being one of the earlier Mitsu-Willys jeep. Please see page 2 as well for the brake pics I just posted earlier. My apologies for some of the duplicate pics, internet over here tends to be erratic, so i sometimes press a button twice because it seemingly did not respond... Thanks again, and any other observation you might want to give regarding the pics is always welcome.
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Yes Patric .
These are the early design 9"Bendix backing plates and parts.
They are the same as used on MB, CJ2A and CJ-3A. 1941-1953.
Not the same design as used on CJ3B and later CJ's.
However you can definitely use the later part numbers for the 1953-1958 master and wheel cylinders.
This early 9" Bendix design uses 4 adjustment eccentrics per wheel as opposed to late 9" type with 2 adjustments per wheel.
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OLDTIME - I stand corrected saying I only had 2 adjusters/wheel, forgetting that the 2 anchor bolts were also adjustable. Thanks again.
RUS CURTIS - I suppose slotted pistons are just my preference. Maybe it's just because that's what i've dealt with my previous cars. Thanks again for your helpful insights.
EVERYONE- Thanks again for your help. Always a learning experience hearing from more experienced fellas.
Patrick
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If you can locate these they should have the slotted piston heads.
The wheel cylinder pistons with a notch are 1941-1953 design.
Front wheel cylinder = A-1484
Rear Wheel cylinder = A-6110
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PICTURES!! I SEE PICTURES!! THANK YOU!
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FANTASTIC !
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Great illustrations of the differences of your Mitsu and a Willys. I notice your shoe linings are the same size (front and back). The upper adjustments aren't the same eccentrics as I've seen in manuals or on my jeep. Yours appear to double as anchors for the shoes also. Interesting.
But if both sets of eccentrics will move the shoes out, following that adjustment procedure should give you the correct clearance inside the drum.
Good looking jeep, BTW!
I hope all the info being provided helps you zero in on the correct parts.
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All the stuff I'm learning from you guys is most definitely helping me out ! Yes, Oldtime did mention the supposed advantages of four eccentric adjusters. I plan on posting a few more pics about the other areas of the jeep in another thread. I realize there are (relatively) few Mitsu-willys owners out there, except Japan of course. Thanks for the compliment Rus, and "see you around".