76 CJ5 Master Cylinder

[brandenj09]

Hey guys, I'm a newbie, former lurker who's having a few master cylinder issues.

I have a 76 CJ5 that had a leaky MC so I took it off, but now I'm thinking they had the wrong MC installed. The Jeep is drum/drum, but it has a short reservoir up front and a long one in the back. The MC piston on the old one was hollow so the pushrod could fit in right. The only numbers I could find on the old one were 315 (I think) on the left and 2227181 on the right. Google seems to know nothing about this MC.

Anyways-I bought a new MC, but this one has the shallow MC piston, so the pushrod won't fit in like it should. I looked around various parts websites, but I can't find a drum/drum MC with a hollow piston with the brake line ports on the left.

So what's a better option? Buying a different MC that's drum/drum and hollow, buying a new pushrod, or buying the complete MC assembly (pushrod+MC)? I'm just starting on this CJ5 as a project, so I need a little seat time before I dig into to high $ upgrades.

 

[gert]

the new one looks like a drum/drum and the old one looks like a disc/drum I am going to guess you have manual brakes? I looked at Oriellys and it looks like they have the one you need to me BrakeBest Brakes 10-1489 - Master Cylinder | O'Reilly Auto Parts

 

[Torxhead]

You could try an adjustable pushrod. I like them as they provide a more accurate setting.

 

[brandenj09]

Yup-I have manual brakes (should have mentioned that). So I'm guessing the new one I already have is a drum/drum for power brakes. I should have double checked when I bought it knowing that the AutoZone near me is run by teenagers. I was looking at that Oreilly one and I think that should work. Kind of hard to tell how deep the hole is in the MC piston, but it's definitely worth a shot for $20.

There were a few other things that the PO did with the MC that seemed a bit off. The rubber boot was on the outside of the retaining cup, which seems wrong to me, and there was a gasket between the retaining cup and the MC. Seems like there wouldn't need to be a gasket there unless your MC is leaking. I think the brake lines look a bit newer, so I'm really hoping the same PO didn't install those too lol.

 

[IOPort51]

79 corvette drum/drum, disk/disk. should bolt up. available in manual and power. Power has bigger piston than manual. for drum/drum u=you need something for residual pressure.

 

[taylorwoodwork]

I also had the same problem with my 76 cj. I put a Dorman M56193. I did have to mount the lines on the other side which was no problem. Hope this helps.

 

[brandenj09]

Think I'll try the the BrakeBest one from Oreilly to start. If that doesn't work I'll have to try one of the other MC ideas or a new pushrod.

The Dorman MC kept on coming up in my searches, so every time I would stumble upon it I would think I finally found the right MC, just to notice that the ports were on the right side instead of the left lol. Moving the brake lines will probably be a last resort, but it's good to know that is an option.

So I actually haven't driven the Jeep yet-I got it with bad brakes, so I'm not sure how bad the brakes were before they went out completely due to the MC. Hopefully the pushrod that I have here is the right length, but I guess we'll have to wait and see.

What actually came stock for a master cylinder these years, ports on the left, right, or either? I remember reading the the 76 and 77 were just random parts thrown together, but I didn't think I would run into this problem right away.

Thanks for the responses-it helps a lot

 

[brandenj09]

Hmmm.... just got the MC from Oreilly and it looks like the pushrod won't sit flush with this MC either because its shallow just like the other one I bought.

So does the pushrod have to sit flush in the MC piston (where the ball part of the pushrod sits in the center of the MC piston)?

I could install it with the shallow design MC, but it would compress the MC piston a little bit, and I'm not sure if that would make is so the brakes would always be on a little bit. It wouldn't be much compression (maybe a quarter inch), and I'm honestly not sure at what point the brakes would actually be applied. Would this work or not?

Does anyone with manual brakes have a pushrod that looks like the one in the initial pic?

 

[gert]

Brakes should start applying around 1 inch of travel on the pedal, I have had that design of brakes on my old 71 Dodge Dart I do not think you want the pushrod compressing the master cylinder tho I'm not for sure if it would work or not being partially pushed in.


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[brandenj09]

Well looks like bending the brake lines and using the Dorman unit is the best way to go then. Never messed around with bending brake lines before.

I'm still really confused why all the manual drum master cylinders on parts websites have the shallow piston dimple. I thought CJ manual MCs had different style pushrods that required the deep piston hole to work properly?

 

[gert]

Well looks like bending the brake lines and using the Dorman unit is the best way to go then. Never messed around with bending brake lines before.

I'm still really confused why all the manual drum master cylinders on parts websites have the shallow piston dimple. I thought CJ manual MCs had different style pushrods that required the deep piston hole to work properly?

i have not looked at manual brake jeeps to be able to tell you one way or another. My manual drum brake experiences are from my 71 and 69 Dodge Darts years ago and I really didn't pay a lot of attention to the back of the pistons then, I did just go look at one of my disc MCs from my Dodges and it has a deep piston. I was hoping some of the guys with the earlier Jeeps would chime in. Bending lines is not to bad by hand if you have enough slack to twist it around. Be cautious to not cross thread the MC by having the lines at an angle from not twisting them enough Good luck let us know how it turns out

 

[mriplaybass]

For making bends in brake lines that are not radius specific, you can't beat these bending pliers.
Eastwood Brake Line Forming Tool Pliers - Brake Line Bender - Brake Tubing Forming Pliers

I am not looking to start a debate over using something other than steel or stainless for brake lines, so I will just pass along some information.

I have been using nickel/copper line. It bends like warm butter, and is approved for brake use. I discovered that it is actually OEM on several European made vehicles. An auto parts store recommend it to me a few years ago, and I have been using it ever since. Cost is about 50% more, but well worth it.

 

[brandenj09]

Thanks for the info guys! I was actually looking at that brake line bending tool and it looked pretty useful. Don't think I would risk bending it by hand. Never heard of the Ni/Cu lines-that's news to me.

Only thing I am thinking of now is that if none of the parts stores have something that is drum/drum with a deep MC piston with left hand ports then this pushrod (and the MC that was initially on here) was probably not the right fit 76 CJ5 . So now I'm second guessing changing over to right side ports since the pushrod might not be the right length. Looks like it might not grant full motion to the brake pedal, but I never got to drive this CJ5 since I got it with no brakes.

Going back to square one-is the stock pushrod that would should go with a shallow piston manual MC shaped like this? https://www.summitracing.com/parts/ssb-a1726/overview/

 

[gert]

Thanks for the info guys! I was actually looking at that brake line bending tool and it looked pretty useful. Don't think I would risk bending it by hand. Never heard of the Ni/Cu lines-that's news to me.

Only thing I am thinking of now is that if none of the parts stores have something that is drum/drum with a deep MC piston with left hand ports then this pushrod (and the MC that was initially on here) was probably not the right fit 76 CJ5. So now I'm second guessing changing over to right side ports since the pushrod might not be the right length. Looks like it might not grant full motion to the brake pedal, but I never got to drive this CJ5 since I got it with no brakes.

Going back to square one-is the stock pushrod that would should go with a shallow piston manual MC shaped like this? https://www.summitracing.com/parts/ssb-a1726/overview/

Such a shame that you are having to go through all this just to get the correct replacement MC....... since the push rod is to long grab a grinder and take a little off the end of the push rod at a time til it fits the new MC would be my thought. Or lightly drill the back of the MC piston to get the push rod to fit a little better. just another thought to ponder

 

[phaques]

You've probably sorted this out by now, but the deep well cylinder is how the longer pushrood is held in place. If you just use a shallow well cylinder, and shorten the pushrod, you basically have NOTHING holding your pushrod in place. The boot for the shallow well MC has a fitting that holds the pushrod in place. the boot for the deep well MC does not. If that pushrod drops off the shallow well MC, you have no brakes.

 

[cglax6]

+1 on the NiCopp lines. I replaced all of my brake lines with it and it was a breeze. Bends easily by hand...just need to rent a double flaring kit from the part store and you'll be good to go. You can re-use your old fittings.

Take a look at The Jeep Guy website. He offers the corvette style MCs and that's where I got mine. I have power brakes, but there's an insert in the piston that you can take out that should accommodate your longer push rod. Give him a call or shoot him an email before you buy to make sure.

Good luck!