Brake issues 1967 Imp 1404

We are in the first year of using our new 1967 1404 Imp. We're amateurs so excuse any obvious beginner comments. Our right brake has always required pumping and excessive force to get it to work. We tried a new kit for the cylinder and had no improvement. So, we bought a new cylinder, and it works a little better, but unless you pump it back and forth quickly and build up some pressure in the line it will go back to being very loose. Any ideas or is there any additional info that i can provide that might be helpful in diagnosing our problem?

Welcome to the Forum! I bought an Imp about three years ago and have found the Forum to be a valuable source of knowledge, encouragement, and foolishness.

From your description is isn't clear to me if you've got a hydraulic problem (master cylinder or slave cylinder) or a mechanical one (weak brake band). If you're not leaking brake fluid from either cylinder then I'd be inclined to think your hydraulics are OK. Plus, you've already replaced half the system, so there's less left to fail.

For the brake bands, you can try cinching up the adjustment nuts on the rear end. Look for a couple levers on each side of the rear end that stick up above the top. Tighten up the nuts on the right side and see if that makes a different.






If that doesn't work then you'll need to take a peek inside of the rear end to see how the brake bands look. This isn't rocket science, but it does take a little more effort and preparation. Buy a pail of transmission fluid, pop the back cover off, and see how things look.



Allocate a day for the work the first time you do this, but subsequent trips into the rear end will only take a couple hours (you'll get speedier with experience). There are linkages inside that will allow you to further tighten up the brake bands. Photos below show how I use a 6' steel rod to lever the brake bands tight enough so that I can slip the pin back into place.




If you decide that the brake bands are kaput then you can get them rebuilt at Spryte Improvement -- Pat will take good care of you.



The steering system on an Imp really is pretty simple. If you've ever rebuilt brakes on a car then you have all the knowledge and experience you need to do the job. Dive in, and if you get stuck on something, don't be shy about asking for help.

Ron

Can air in the hydraulic brake lines be the problem, requiring the repeated pumping of the steering handle? It sounds like the pedal pumping needed in an auto, if there's air in the brake lines.

undy said:

Can air in the hydraulic brake lines be the problem, requiring the repeated pumping of the steering handle? It sounds like the pedal pumping needed in an auto, if there's air in the brake lines.

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That could be or you may have a ball hanging up in the master cylinder for that side. Could be a torn cup also. I would start at the slave and try to bleed it first.

Yeah we already replaced the whole cylinder that's giving us probs. maybe we haven't bled it properly?? We just pumped it rapidly about 10 times and then held it back while the valve was opened in the rear to let the air out. We did this multiple times. I'm leaning toward issues with the brake straps in the rear like 'cloudcap' suggested.

What you've described is not proper brake bleeding technique. You need a can of brake fluid, a small jar (baby food is perfect) and a length of hose that will fit over the nipple on the slave cylinder. Top off the master cylinder, put the hose on the slave cylinder nipple, and put the other end of the hose in the jar. Open the nipple on the slave cylinder, have someone in the cab pull the stick all the way back, close the nipple, and then have them release the stick. Repeat. When you stop blowing bubbles in the jar then you're finished. Basically, you're pumping fluid and air through the system (from the master out through the slave) till the air is gone and you have nothing but fluid. Note that it is critical that you close the nipple valve before releasing the stick. Be sure and top off the master between pulls or you'll run it dry and have to start over again. Probably only takes three or four good pulls to bleed the system. This is way easier than opening up the rear end, so it is best to do this first.

Ron

RigbyRaider said:

Yeah we already replaced the whole cylinder that's giving us probs. maybe we haven't bled it properly?? We just pumped it rapidly about 10 times and then held it back while the valve was opened in the rear to let the air out. We did this multiple times. I'm leaning toward issues with the brake straps in the rear like 'cloudcap' suggested.

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cloudcap,
I think you missed one small detail in your explanation: Fill the baby food jar 1/2 full of fluid before you start, to prevent air from getting pulled back into the hose.
(Please Note: You guys absolutely have more experience at this than I do. I'm just relating my auto-related experiences to this. Forgive me if I go off on the wrong direction.)

You're right. I tend toward the lazy side, so I usually just pump a little fluid into the jar from the master cylinder. It accomplishes the same thing and it also flushes a little more of the old fluid out of the system. But The Book says that you're supposed to start with fluid in the jar.

Also, be sure and keep the loose end of the hose below the surface of the fluid in the jar -- that allows the fluid to act as a one-way valve keeping the air out of the system. Closing off the nipple valve does most of the work, but having the end of the hose beneath the surface helps. It tends to be a two-handed operation -- holding the jar/hose in one hand and using the other to manage the wrench on the valve.

Ron

undy said:

cloudcap,
I think you missed one small detail in your explanation: Fill the baby food jar 1/2 full of fluid before you start, to prevent air from getting pulled back into the hose.
(Please Note: You guys absolutely have more experience at this than I do. I'm just relating my auto-related experiences to this. Forgive me if I go off on the wrong direction.)

Click to expand...