Packard Forum Index » Pre-War (1899-1942)

I am adjusting the brakes on my 1929 640 Phaeton and have run into a problem that has me stumped. I have the Bendix Packard brake adjusting information and have been following it. With the car on jack stands and the brake applied, when I turn the wheels to the left, the left wheel is locked, but the right one will turn. When I turn the wheel to the right, the right wheel is locked and the left one turns. Per the instructions, I have adjusted the front brakes so that with the brake applied with 50 pounds pressure they both turn with equal resistance. I can't figure what is causing one wheel to lock up when the steering wheel is turned. The front brake system is the type that uses a Perrot shaft. Any ideas or suggestions.

That really doesn't make any sense, they shouldn't lock up just because they're being turned. It would likely be that the shoes are cranked too far out.

I have a '29 633 and the brakes are a constant source of irritation. That Bendix brake suppiment they put out looks nice but it doesn't solve the problems real world. With my car, I've found that having the car jacked up and adjusting the brakes doesn't do a whole lot of good, because when she goes back on the ground the trajectory of the brake rods changes and everything you just adjusted goes right out the window.

I've gotten now to where I just adjust them with the car sitting on the ground and use trial and error to get them about right. They are FAR from synchronized with each other and the back two do a lot more work than the front two on my car, but, they work a lot better now than when I got it.

Following the manual to the tee, I adjusted mine about a year ago with all four wheels off the ground, set her back down, and both rear wheels wouldn't roll forwards - the brakes locked instantly going forward, but going backwards, they were fine. I gave up using the suppliment after that! Back off the rods a bit, that should solve the problem, but, it's a rather unusual one. Good luck!

I have been struggling with the problem of the left front brake locking up when I make a left turn and the right locks up with a right turn. I have partially disassembled the front brakes and have found the problem, but not the cause. when I turn the wheel to the full left, the arm on the Perrot shaft (The arm that the cable fastens to) rotates forward about 10 degrees, increasing the pull on the brake cable. This is with the cable completely removed from the arm, so the movement is not caused by a movement of the cable. I have removed the outboard ball joint (fastens to the backing plate) of the system and there is no slop or problem there. The simple turning of the wheel outward is causing the Perrot shaft to rotate. It has been suggested that I loosen the brake cables. I have tried this and when loosened to the point that the wheels do not lock, I have no front brakes. Any ideas on what could be causing this?

I have a 533 which has a brake equalizer, which is similar to your 640. Your front end equalizer may need some lubrication.

Gar

Gar

I doubt that that is the problem as the rotation of the Perrot shaft occurs when the steering wheel is turned without the brakes being applied. I am not sure what you mean by an equalizer. Where is it located?

I think I have found the problem. The brake cam housings that mount on the backing plates are obviously left and right sided. What is not so obvious is that the cams themselves are also right and left sided. The cylindrical slot in the inboard side of the cams is at roughly a 90 degree angle from the cams. They are not exactly 90 degrees different. With the cam in a perfectly vertical orientation, the cylindrical slots are not perfectly horizontal. The slots should angle slightly up from front to back. Mine were reversed, causing the rotation of the Perrot shaft on turning of the steering wheel.

Well done. That is an excellent detail to file away and save a lot of grief.

The confusing thing is that both the right and left cams have the same number cast into them. In going thru my spare parts, I found some cams that have the same number cast into them, but also have R and L cast into them. The number does not correspond to the numbers in the parts book.

That solution begs the question: Is the axle on backwards? Don't laugh, because I have seen it done.

"Oh gee, it's on backwards. I got it!. Let's just switch these arms."

Jim:

Here is a pic of the equalizer.


Does you car have a trunion spring on the drivers side?

Also, my understanding is that Drv Frt brake shoes should be slightly smaller than the Pas Frt.

Gar

Attach file:

---

  Screenshot_20221218_035532.png (373.46 KB)