Front Brake overhaul Update

Overhauls updated since 05/30/07

This is an update to the front brake overhaul page that reflects things that I've learned since putting up that page.

The most important thing I've learned is that the indian-made spiders are junk. Apparently tolerance and finish and finish are new concepts to the indians.

The lack of finish or control of dimensions resulted in one wheel that would lock up solid whenever any amount of brake pressure was applied. It would stay locked up until the vehicle was allowed to roll backward.

After taking the wheel and brake drum off several times, I decided to pull the whole brake assembly off, take it back to the shop and look things over in an orderly manner. One thing quickly became evident - again - and that is, NEVER THROW AWAY OLD PARTS. At least until you're absolutely positively sure that the new parts work OK.

The basic problem I found was that the critical shoe back-seating radius on the spider AND the length of the guide tangs were so far off that the shoes were jacked up such that whenever brake pressure was applied, the shoe wedged between the drum and the cylinder and locked the wheel.

The solution was to machine the spider to more suitable dimensions. The old OEM spider provided known-good dimensions. Ideally the spider would be chucked up in a lathe and the important radii turned to perfection. Lacking such luxuries, I substituted the next best thing - an angle grinder, a wheel of suitable width and a stable hand.

This photo shows the old spider on the left vs the new spider on the right. Note the various arrows. Note how sloppy the radius where the shoes mate is. Note how the guide prongs hold the shoes off the seating radius. Note the general sloppiness.

This photo shows how the shoes are supposed to fit. Note the arrows. Note that the prongs don't touch the inside of the shoe.

This photo shows how much discrepancy there is in size between the old and new spiders. The caliper has been set to the radius of the new part. As is evident, it is way too large.

Here, the cylinder has been masked to protect it from grinding debris. The arrow points to the part that will be radiused.

This shows the radius after it has been ground to the proper dimension. The finish work was completed with a file after this photo was taken.

This shows the prongs after they've been ground. Ideally they should be ground to a radius centered on the center of the axle opening. As a practical matter, close is good enough.

This photo shows the "after" fit. The arrows show the important points.

The above photo is more of Glenn's at Assembled Parts collection of Citi and Commuta Cars