The Speedtech ExtReme & ATS AFX Spindle Manufacturing Process

ver wonder how a part like a forged aluminum spindle is made? What takes aluminum to that level of grain structure and strength? What makes it better than a common cast spindle and why is a forged spindle a bit extra cost over cast? Read on to find out why…

Like most spindles, cast components are typically formed by pouring molten metal into a sand mold and afterwards getting some final machining. Since this process is relatively inexpensive, quick and easy to do it’s often the choice for high production parts, but there are a few draw backs. While a cast part is relatively strong, the mold can experience some shift and therefore cast parts can have greater tolerances. This means less precision and less consistency. On top of that because the metal is simply poured into the mold it’s not possible to compact the molecules super tightly together, leaving some strength out of the equation. To make up for this weakness, often heavier metal compounds have to be used, for example iron instead of aluminum.

A forged part is a completely different concept, and with Speedtech ExtReme and our ATS Tall AFX forged aluminum spindles you get an end result that is lighter than cast iron, stronger than cast iron or even billet aluminum and much more consistent with ultra tight precision machined tolerances.

The forging process for each of our spindles starts out in at an aerospace parts manufacturing plant in Texas, USA. A length of 6″ round billet 7075 Alcoa Aluminum gets trimmed to specific lengths as seen at right. That section is then put in a large hydraulic press and under great force is compacted into a much more dense slug measuring less than 1/3 it’s original length. Once density is verified and passes inspection, things really start to heat up!

After compression, the billet slugs are then heated to over 800 degrees to a glowing red. The slug is placed in a special forging hammer and then pounded several times with over 2,000 tons of force into a preliminary top and bottom mold. When the slug has achieved an acceptable shape it is then removed and dipped in an acid bath to remove any scale and impurities.

After cleaning, the preliminary shape is heated again to over 800 degrees and placed back into the hammer. This time a second, more refined mold will create the spindle’s final shape. With over 2,000 tons of force the spindle is pounded again and again until it matches the mold. Along with forming the final shape, this pounding condenses the metal structure even more, this is one of the main reasons why forging is stronger than casting parts. Before moving to the next step each part is checked for dimensional accuracy.

Once cooled the extra flash around the spindle is trimmed off. The final process is heat treating, which involves heating the forging to 870 degrees for 2.5 hours. and then water quench to 140-160 degrees F. After this cool down the tempering process starts by heating the forging to 225F for 7 hours and then 350F for 9 hours. This process creates an exact level of material hardness and strength and achieves the T-73 condition. Grain structure is verified and each individual part is checked by undergoing very thorough strength testing to ensure it will stand up to the abuse of daily street and race driving.

Upon arriving at the Speedtech facility machine shop we carefully CNC machine all working surfaces of the spindle to exact specifications. The spindle is then assembled with genuine GM C7 Corvette heavy duty bearing and hub assemblies, and then packaged ready for delivery to you. At Speedtech we are dedicated to taking performance to the ExtReme, and are serious about providing parts that are reliable and perform beyond our customer’s expectations. Our forged spindles are no exception, and that’s why they’re number one in the industry.