Brake and Clutch Tips


Tech Tip # 1 – Brake Bleeders
After hearing several conversations about them, I decided to try speedbleeders. These are the actual “speed bleeders” vs. Russell or other makes.  The label warns that they are made from soft steel so they are easy to remove if they break.  My experience was that they are SO soft that between the soft steel and the thread sealant used, there was no “feel” for when they were tight.  Pumping the brakes with the bleeders closed (or so I thought) resulted in fluid dribbling or spraying out onto the new paint.  Tightening them further in some cases shut them off, but in examining them I found that the threads were stripping.  In exasperation I took them all out and replaced them with originals. I like knowing when the are closed.  I also used a hand vacuum pump to initially bleed the system, but air enters around the bleeder and it is often difficult to know if you have all the air out. I know some have solved this by putting teflon tape on the bleeders, but it is pretty easy to get a piece of this in the bleeder. The vacuum pump helps evacuate the system, but the old-fashioned pump and hold method is still  necessary to do the best job bleeding the brakes.

Tech Tip # 2 – Spindle Nut Wrench
Pick up one of our Spindle Nut Wrenches (also known as Bearing Nut Wrench) if you are going to work on the brakes or any bearing/axle work.  For the little bit they cost, they make the job much easier and won’t leave filings in your bearings and chipped up bearing nuts that result from using a chisel.  They fit both the Chevy and GMC spindle nuts.

Tech Tip # 2 – Clutch Replacement
Clutch free-play is determined by the clearance between the throw-out bearing and the fingers. The throw-out bearing is pulled away from the fingers by the return spring. As the disk wears, the fingers protrude more from the pressure plate and the free play available becomes less. When there is no more free-play, the throw out bearing will be riding on the fingers and the clutch disk, at a minimum needs to be replaced. No adjustment will make any difference. If you keep driving, the clutch will start to slip and/or the throwout bearing will wear out.

Free-play does not matter until there is no more when replacements of the disk is required. What IS important is how much the pressure plate spring-disk is flexed. It should only be flexed the amount necessary to release the clutch plus a little more. If you adjust for the free-play amount, when the clutch disk is new, you will be way over bending and over stressing the pressure plate spring disk. If you adjust it to just barely release as the pedal touches the floor, you will not be over stressing the clutch AND the clutch will have the same release point for most of the life of the clutch.

While we are talking about the “GMC clutch”, there is also miss-information about rebuilding the pressure plate. If you machine the pressure plate, you have to do it in known thickness increments AND you have to ADD known thickness shims behind the pivot points for the diaphragm spring. Again, most of the manuals for the CCWK/DUKW do not mention this. Failure to do so results in the diaphragm spring fingers stick much farther out of the housing, decreasing pedal efficiency and rendering it pretty much junk! (thanks to Steve Keith – aka Dr. Deuce for this submittal)