Nuts, Bolts, and Studs

By Mike Palermo Jr.

In engine building, there are two goals that you strive to obtain, Power and Reliability. No matter how strong the engine is, you still need to finish the race to pick up your trophy.

Three areas come to mind that I believe deserve special mention:

Rod Bolts... If one of these highly worked units should fail for any reason, you are in for a very bad day. If the connecting rod is properly machined, (making certain that the surface the bolt head sets against is flat and square to the bolt), then all you have to do is use the proper bolt. This is simple... if the bolt head displays the VW logo, it is good. If not, it is junk, and you need to throw it out before it trashes your engine. I suggest replacing rod bolts every rebuild. If you don't rev past 6500 rpm, you should be OK with every other build.

Cylinder Head Studs... Here we have the Good, the Bad, and the Ugly. There has been an increasing number of broken studs. I heard of at least six failures at the '92 Runoffs. If you happen to have an engine sporting gold colored head studs... replace them now... these are the worst units out there. If they are the dull gray issue, you may wish to gamble on these 'till your next rebuild, and then change over to a better set. I strongly recommend the VW factory studs. I have these studs black anodized to help prevent rusting, and when I install them, I warranty them for life.

Gland Nuts... Most flywheels are secured to the crankshaft by a number of high grade bolts. Even the later model VWs use a 5 bolt pattern. This spreads the load over a larger area and secures the assembly more effectively. Our engines rely on one central hollow bolt that doubles as the pilot bushing for the transmission main shaft. The flywheel and crank are also joined by four 8mm dowels to assist in transmitting torque to the wheels. In heavier applications (such as drag racing, and off-road) it is common to beef up this area with more and larger pins, flanges, etc. This hasn't proven necessary in FV as long as the mating surfaces, holes and pins are in good condition. It is very important that the surfaces are both flat and square to the centerline of the crank. If not, you will at least have an oil leak, and at worst have a 12lb. flywheel that is being forced to oscillate from its intended rotational path. This will result in a vibration that can ultimately break the crankshaft. Another important consideration in this area is the gland nut. Because of the nature of the assembly, much is demanded of this unit. It is important that you use a quality unit. I have seen some very low quality nuts out of Brazil, that simply refuse to tighten! These pieces have "DC" stamped on the, and should not be used. Stay with a good German manufacture, and you should be OK.

Any questions, feel free to call, and good racing to all!!

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