Bump braking and a thank you.

S

Simonpie

Senior Member
First the thank you. I've pretty much been a lurker here because I can almost always find my answers in old posts. Thanks to you all I've fixed my ****** shifting (worn lever ball), set my model B timing, and learned to just buy a manual and read it. Handy!
Now my question. Do stock model A's, in decent but used condition, experience bump induced braking? I recently had a pothole jump out in front of me and the car let out a shriek like brake squeal from the right rear and it felt like someone stabbed the brakes for a quick instant. The brakes don't normally squeal. My foot was off the pedal. Throttle off. Everything went back to normal and I don't see obvious problems. The car is a speedster body, but the brakes are all stock. The suspension is all stock except 1 leaf pulled from the rear and the front shocks are dry friction. The rear feels similar to a stock A for stiffness. The steering column is rotated up a bit, but the shaft comes out the same place. Stock steering arm. The car handles well, no wobble, brakes work OK. I recently replaced some worn levers and bushings and the emergency brake linings, then adjusted per manual.

Ideas? Possibly I'm off base with the brake idea, just gut feel and hard to reproduce. I'm not overly worried, but it seems a corner, bump, and brake stab all together could really bite me.

Simon
 
Possibly something loose in the emergency brake assembly, so it gets engaged by the bump? Mine is very sensitive and locks up a rear wheel easily.
 
If you jack up the rear of your car by lifting on the differential; you should not feel any difference to your brakes. Spin them they will move. Now lift the back of your car by using the frame. Try to spin your wheels. Chances are they are tight. This is what happens when hitting the pot hole. The brake rods are pulled on to compensate the suspension. Hope this helps. Jeff
 
I had that occur once, and found it was the brake rod, which was bent a bit, catching on the shock absorber. I suggest checking clearances on the brake rods.
 
Thanks guys. None of the shock setups are stock. Someone cut off the balls in the rear, I assume for an attempt at hydraulics. I'll dig in and review the clearances for the shocks to the brakes.

Simon
 
I'm resurrecting this thread because I found some answers.
I had it happen again and it essentially locked up just while sitting there. On teardown, I had a bent e-brake backing plate. Probably an effect rather than a cause.
First observation, it wasn't any shock interaction, but it was a couple of non-stock items.
When I got the car, it didn't have any anti rattler springs. Since there wasn't any rattling, and the regular brakes returned and turned off the light just fine with no after-marked booster spring, I just let it be. Now I realize that my parking brake lever, when released, has no real spring to it. When hit a bump, the inertia in the lever can activate the brake.
Problem 2, I only had 1 spring inside each hub on the parking brake loop. That's all that's shown in the manuals, but the Snyder's parts list says 2 per side and someone pulled a wheel and looked and there were 2.
I'm waiting for parts, but hopefully all is solved.
 
Here's a picture of a correct rear brake setup.
 

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