In 1901 Oldsmobile’s curved dash runabout was the best selling car in America and Ransom Eli Olds had a problem. He couldn’t build engines fast enough. He needed a second source.
Olds turned to one of Detroit’s premier machine shops, Leland and Faulconer. Henry Martyn Leland accepted the challenge and, in his own way, duplicated the runabout’s engine. Now Olds had a second problem. Neither vendor could manufacture all the engines he needed, and Leland’s engine was significantly more powerful (3.7 horses rather than 3.0 – times have changed). Today, marketing would offer Oldsmobiles with Leland’s production as a sports model with special paint and a higher price, but Olds rejected Leland’s offering, and Leland founded Cadillac to use it.
In 1901 most machine shops employed ‘fitters’. Their job was to file mating parts until they could be assembled. A big shop might have hundreds, all scraping away. Leland and Faulconer, relying on more accurate machining, had none. And the closer tolerances they worked to, not some magic improvement to Olds’ design, was what boosted the performance of their Oldsmobile engine.
I am reminded of this when I see hand-fitted synchronizer clutch and hub sets offered with great fanfare. Points for effort to be sure but, if the quality of the parts being assembled were high to begin, would all this toil and trouble be necessary? And is the product worth the premium? Or is it Olds and Leland in reverse?
We need to look at how synchronizer clutches and hubs are, or could be, made.
Synchronizer clutches are usually broached. if the broach is well made and maintained this technology produces consistently uniform splines concentric with and parallel to the broaching axis, accurate in dimensions and, given material of good quality to broach, consistent from blank to blank. With good prints to work to, if reasonable attention is paid to the broaching and care is taken in handling, most manufacturers can deliver a usable blank to the furnace. Good or bad, heat treatment is where the magic happens.
Heat treatment is an art. The design, condition and operation of the furnace, how and to what percentage of its capacity it’s loaded. the shape and material of the parts to be heat treated, and how they will be quenched after, all contribute to the shape and dimensions of the final product. All that can be said with certainty is that the heat treated product will be different than the blank.
‘Quenching’ – plunging the hot part into oil or water – distorts thin irregular sections, sections of different thickness cooling at different rates and shrinking more or less. For example, the faster cooling ‘small’ end of ‘Muncie’ synchronizer clutches shrinks more than the ‘flange’ end. This is why less expensive ‘Muncie’ synchronizer clutches assemble more readily from the flange end –they have tapered splines with a smaller inside diameter at the small end.
‘Muncie’ synchronizer clutches, which have radial sections thin relative to their diameters, are also likely to fall out of round.
‘Plug quenching’ – the installation of a hardened plug into the clutch bore prior to quenching – minimizes these side effects of heat treatment, but most aftermarket manufacturers skip this ‘extra cost’ step. Euroricambi, Auto Gear’s Italian source, does not. And because plug quenched clutches share the loads more evenly from spline to spline and along each spline from front to back, Auto Gear’s synchronizer clutches perform better and last longer than the competition.
Compared to the synchronizer clutches, because the thin sections under the overhanging clutch splines of the Warner design synchronizer hub makes conventional heat treatment impractical (they would distort badly and become brittle), ‘Muncie’ four-speed synchronizer hubs are spared most thermal distortion in manufacturing and are therefore relatively easier to make.
Which is not to say, however, that there aren’t challenges – the clutch and mainshaft splines must be uniform, concentric and parallel. When they’re not, someone fitting poorly manufactured hubs against equally poorly manufactured synchronizer clutches can sometimes find a pair that will shift, for at least a short time until the several high spots wear away.
Euroricambi, Auto Gear’s Italian source, uses ‘nitriding’, a minimally distorting process, to provide each synchronizer hub with a tough wear resistant skin. After delivery, Auto Gear’s vibratory tumblers polish them, eliminating the burrs and hard corners even the most careful and diligent hand work misses. Together, these two ‘extra cost’ operations assure synchronizer hubs that, from piece to piece, are consistent in form and dimension. When used with Auto Gear synchronizer clutches, Auto Gear synchronizer hubs supply the highest performance available this side of true ‘selective fit’ assembly.
And how we can obtain true selective fit is a story for another day.
So, if in 1901, Henry Martyn Leland knew that he couldn’t file his way to Quality, why are we still fighting this battle? Because junk, and the fast buck to be made misrepresenting it, will always be with us. And sometimes, you don’t actually get what you pay for.