Brake question

[SGT1775]

When I'm going down a hill and I apply the brakes, it feels like the wheels lock up and I just slide. I'm new to drum brakes so I really don't have a clue what to look for.


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[Don Cavey]

I am going to ask a lot of questions so we can get a feel for what is going on.

Are the brakes stock, single master cylinder and drum brakes front and rear?

Are the wheel cylinders in good condition, not leaking on the shoes?

Good lining on the shoes, no metal to metal?

Are the rear locking up and not the front?

Sorry for the cross examination. Maybe we can get to the bottom of this problem. The M715 brake system is very basic and conventional.

Thanks!

[SGT1775]

There is a single m/c and from what I understand it is a stock system. I've only had the vehicle for a couple weeks and have not had any time to open the wheels up. Spent most of the two weeks just making sure it ran properly. Still very new to dealing with brakes and not sure I would know what to look for even if I did start looking at them.

Worst case scenario. The cylinders are all bad and say the lining needs to be replaced. Would it be easier/more economic to do a disc break conversion or to refurbish the original system? I'm not a purist, I would like to keep as much stock as possible but I also want dependable brakes.


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[Don Cavey]

There are differing opinions about this and that is not to say only one way is the best.

When I got my truck, the brake pedal was on the floor. So, I knew that I had work to do. I removed each wheel and brake drum one at a time. Some of the cylinders had leaked fluid all over the shoes; other shoes were OK. At the time, I did not know that the wheel cylinders being sold were Chinese. I bought two left and two right pair. I replaced the steel lines to each wheel. It's not hard at all and if you don't have a double flare tool and/or tubing bender, you can just buy lengths of tubing. I felt that this was important since much of the tubing was severely rusted. (I have had to replace the tubing to the rear of my '96 Grand Cherokee two times; the fuel line one time already)

I also replaced the three flexible lines that go from the frame to each front wheel and frame to differential. One wheel at a time they were brought up to original spec. Not a tremendous amount of money spent but when finished, I knew what I had.

Last, the master cylinder was replaced with an NOS one from Saturn Surplus. I disassembled it and cleaned it with alcohol and reassembled it with clean, new brake fluid.

It went well, and the truck stops well and in a straight line.

Fast forward, I checked my wheel cylinders two or three years later and found that those bloody Chinese wheel cylinders were leaking!! So, in the mean time, I had found some NOS Wagner-Lockheed left side wheel cylinders. I rebuilt them before using with new USA manufactured 1-1/16" seals because the ones in the cylinders had a set in them. I also rebuilt the Chinese right-side cylinders with new USA manufactured seals. That was a year ago and I need to check them again. (BTW, there seem to be NO right side NOS Wagner-Lockheed wheel cylinders out there, only Chinese from New Star or whatever their name is)

Anyway, rebuilding the original design components is easy because it matches the information in the TMs. You can change to a split system (dual MC with separate front and rear circuits) but not being an automotive engineer, I was unwilling to change design and suffer the results if not balanced etc.

There is one place where you may have a problem when removing the brake drums. After removing the wheel, the drum is still held on by three countersunk screws. They can be a bugger to get out. I was lucky and they eventually came out after a lot of PB Blaster and swearing. Heat would help but my torches were kaput. Reassemble with anti-sieze or wheel bearing grease so they will come out easier next time... There will be a next time! Many will tell you to mark the position of the drum and replace it in the same orientation or it will drag or pulsate. I was unaware of this and have no idea if mine went back the same way. In any event, I had no problem and I have not seen that in the TM. Just sayn'.

Others have converted to disc brakes but that will cost you way more than simply bringing what you have back to the original design. However, that is my opinion and you are free to explore other options. It just worked and worked well for me.

[SGT1775]

Wow, I appreciate the informative reply. I definitely have some things to consider as far as the brakes ago. I am also taking into account that maybe I'm just not used to driving with drum brakes. Due to my schedule and finances I have to prioritize my to do list for this vehicle to make it road ready. Currently the brakes work, just not as well as I would like. My electrical is kind of the same but I am trying to wire it for the road. Turn signal is my current headache. Headlights are another although I am not planning any night driving anytime soon. I found out that my tail lights do in fact work and that the brake lights work only if I position the switch halfway between two selections. It's fun but it would be a lot more fun if I could drive it around town instead of my neighborhood. Again, thank you for all of the information. Hopefully I will have it sorted out shortly.


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[Don Cavey]

Here is a picture of my left front brake after working on it.

http://i1067.photobucket.com/albums/.../M715Brake.jpg

[Don Cavey]

Here is a picture of my left front brake after working on it.

Try this. The short shoe is to the front and the spacer block between the top od the shoes has an arrow. It points to the front of the vehicle.

[292farmer]

dont for get to adjust pedal free play mine i got with no brakes, opened all wheels everything new...the free play was like an inch and 1/4 got it up too 1/2 inch everything works better now.

[Von]

The E-350 wheel cylinder swap is pretty easy. Easy to find parts and it'll work with the rest of your existing hardware if it's all good.

I had replaced one of my wheel cylinders a couple of months ago and just did the other 3 while the truck is down for wheel bearings, kingpins and install lockers.

Hardest part was elongating the mounting holes. First one I did with a hand file (2 hand files, broke one) and that took about an hour. The other three I used my Dremel and a cutting bit, took about 30 seconds per hole.

I had also bought some late 60s C30 brake shoes and was going to modify those to fit but all my shoes are in pretty decent shape. So I'll just leave those on a shelf till later. I bought the springs for them too.

[SGT1775]

Thanks


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