Loss of pedal with Full Left turn.

[Gacannon]

My 28 ford PU suffers from a brake problem that has been there day one. I have 30K miles on it and it brakes fine except for one situation. Full left turn, and the pedal goes to the floor. Oh yes, I have replace the master cylinder three times but finally figured out that it was always occurring with the full lock turn to the left. Last week, I swung around to park in a parking space on the other side of the road that was angled of course the opposite direction. Ended up knocking over a garbage can and jumping the curb. No damage done, but when I pressed that pedal to the floor, its always a panic situation.

Disc's on the front and drums on the rear. Dual master cylinder for disc / drum setup with 3 psi and 10 psi checks in the lines accordingly. Braking is very good. No power, manual brakes with a six to one lever setup.

No leaks in the system and reservoir was checked for fluid every time the problem happened. Always full to the top. Master cylinder located at frame level in the standard position.

Jack the front end up, rotate the wheel to full left lock and presto, you loose the pedal. Not so on a right lock turn. Never loose pedal during normal driving, only with a full left lock position. If you get close to left lock, you will start to loose the pedal but its right at the end of the wheel movement. DOT braided brake lines in front and no other flex lines in the system.

So both static (just sitting there) and rolling (1 mph) the problem will duplicate every single time.

Since I never have to fill the reservoir, fluid is not escaping the system. Something is swelling or expanding to take a good shot of fluid extra which leaves my pedal on the floor. 1" master cylinder.

the flex lines do not seem to be swelling or elongating.

Maybe someone has see this before. I searched the web and found comments on the flex lines causing the problem. One thing is for sure, the problem is repeatable every single time on a full left lock turn. Has never occurred in any other situation. Three mastercylinders later, the light bulb finally went off about the full left turn. Yea, it was every time it did it in the past. Logic said see if it will repeat static. Heck yes it will, every time.

I know its sounds impossible, but guys its doing it and its repeatable 100% of the time and only happens at full left lock turn.

give me some more ideas. For now, no full left turns, but that stinks.

Bob in Ga.

 

[Sam_Fear]

Jack it back up, get under it, and keep looking. If you aren't loosing fluid, somewhere you are gaining space. Since it does it on jack stands, it has to be in the front, not the rear. Check both sides (all the way to the M/C if you have too) while a helper pushes the pedal and turns the wheel.

 

[Bonehead]

Jack it up under the axle, and not the frame. So it stays where the suspension should be as if it were on the ground.

 

[Dirtyrat]

I'm trying to think about how this would play out if you were hitting a slider style caliper, if by moving the caliper on the sliders, if it would create more space to take up with the pads... Is there a chance you are hitting the caliper at full lock?

 

[Gacannon]

Reply

I will get a friend over to help check things out. I need someone to push the brake pedal while I really look close. As far as the disc caliper hitting anything, I will check that also. Logic says fluid is going somewhere and taking up space. I have never had a problem like this. Probably something simple, but it sure is getting by me.

Will check it out further today and post back what I see. Amazing how it is repeatable every time. There is a flex line on the rear end feeding the tee on the rear axle housing also, but it surely does not move when I jack up the front axle. I will look at it also however because something is causing the problem. will be interesting to find out what it is.

I see many posts on the web for the same condition as mine. Some good post reply's indicate the flex lines swelling or expanding some how. Mine are not kinking at all when the wheel is turned full lock. They do not have any sharp turns or anything.

I appreciate the help. I want to get this fixed and probably put in a safety valve on the system to automatically shut off a bad front or rear circuit. I do not have that right now, just master cylinder, steel lines, residual valves, flex lines and brake assemblies.

thanks

Bob in Ga.

 

[Old Iron]

I'm trying to think about how this would play out if you were hitting a slider style caliper, if by moving the caliper on the sliders, if it would create more space to take up with the pads... Is there a chance you are hitting the caliper at full lock?

X2 [cl

 

[Gacannon]

Solved

The banjo head on the left caliper was hitting the shock mount on the front axle. There are signs of fluid leakage at the banjo, not much, but some signs. It took a hard left turn full to lock to make it hit, but I believe this is what has been causing my problems. There is quiet a bit of force on the steering linkage and the bolt that goes through the banjo fitting was hitting.

I will grind the shock mount to clear the banjo fitting. Evidently, it was leaking with a hard left turn. By the time I discovered I had no brakes, I was usually straightening out so it did not suck air, only leaked fluid as I never developed a spongy pedal. The right side clears with no issues.

I will post one more time when I have made the modification and checked the operation. I appreciate the help guys.

Bob in Ga.

 

[bob w]

This same problem just happened to Tator, here on RRR on his Chevy powered VW. He added a steering stop to prevent the contact.

 

[Dirtyrat]

How about adding a steering stop for safety?

 

[Dirtyrat]

This same problem just happened to Tator, here on RRR on his Chevy powered VW. He added a steering stop to prevent the contact.

you posted that just before I did [cl[cl[cl

 

[Gacannon]

That fixed it

I attached two files on the car. One showing the banjo fitting hitting the shock mount on the front axle.

I never saw this. I scratch built the hot rod, bare frame up. I worked on aircraft for many years so I have a trained eye. In this case, you do not see the problem unless the wheel is full lock. I missed it and I have had issues with it from day one. Cost me three master cylinders and a lot of mistrust of the brake system because of the loss of pedal.

Just goes to show that building from scratch takes a good eye for problem areas and potential problem areas. The loss of fluid, which did occur, was very small and only every once in a great while. I never missed the fluid because it was such a small amount. So one of my statements was incorrect. Secondly the area of the banjo fitting is obscure, but there were tail tail signs of leakage at that point.

Thanks for the help Guys. My ride is about as good at it gets now. Drives great, handles great and STOPS GREAT all the time.

Bob in Ga.

 

[Gacannon]

Steering limiter

Ok, grinding the shock mount clears the banjo fitting, but the post that mentioned the steering limiter is making some real sense now. Something is going to hit somewhere to stop the wheels from turning. I guess the steering box has enough lock to lock movement to force the situation.

Steering limiters. Not an area I am familiar with.

What are the methods used to mechanically limit turning?

I believe I need this modification to mechanically stop the steering at some point.

Suggestions welcome

Bob in Ga.

 

[Sam_Fear]

 

[Sam_Fear]