randys blog
Things To Consider In Circle Track & Road Racing
COST The main thing to consider when building a rearend for any type of racing is strength and durability. After spending tens of thousands of dollars on the engine and transmission, why skimp on cheap rearend parts? OIL COOLERS Any rearend that transfers a lot of power will get hot. The only way to make the rearend live is to keep the oil from deteriorating and keeping it cool. The best way to keep the oil cool is to pump it through a cooler system that has adequate oil flow and air flow. This requires a pump, a system to turn the pump, oil lines, extra oil volume (and often an external sump), a good radiator, and ducting or placement for adequate air flow through the radiator. The difference in bearing and gear life with or without a good cooler system is amazing. SYNTHETIC OIL Some people do not like using synthetic oils. We have found that differentials without an oil cooler last far longer and have a much smaller chance of burning up the gear-set when synthetic oil is used. Crude oil is a lot cheaper, and works well if it does not get too hot, but synthetics work a lot better for rearends without a cooler. SAFETY WIRED BOLTS Safety wired bolts are not easy to work with. They take longer to assemble and the bolts are expensive to buy or drill. However, having a bolt back out costs a lot of time and money, especially if it costs points or a win. Ring gear bolts are the most important for safety wiring, but some insist on wiring the main cap bolts and pinion support bolts as well. LOCTITE Use red Loctite on all ring gear bolts, all pinion nuts, main cap bolts on severe duty use, and on pinion support bolts on severe duty use. Always clean the bolt and hole threads with a non-oily cleaner (brake-clean spray works well) before applying the Loctite. Put a drop or two on the end and it will work its way up the threads as the bolt is inserted. PINION BEARING PRELOAD SPACERS A crush sleeve works great for most street cars and production vehicles, but a race rearend should always use a solid spacer and shims. A spacer machined from billet steel is far superior to one cut from tubing. The best 9″ Ford spacers use two pieces cut from billet that enclose the shims completely and keep the bearings from wearing down the fragile shims. The pinion yoke should not be re-installed after removal when a crush sleeve is used. When using a solid spacer, the pinion yoke can be removed and installed over and over without affecting the bearing preload. HIGH QUALITY TIMKEN BEARINGS There are a few manufacturers other than Timken who make good bearings, but Timken has always been the most consistent and has always been the standard that others are judged by. It is also cheap insurance to install new bearings any time the old bearings show wear or heat damage. USE THE RIGHT TOOLS Tools set man apart from the rest of the animal kingdom. Using the right tools not only makes the job easier, it also ensures the rearend is assembled correctly and completely. A good, solid tool for turning the side adjusters is absolutely necessary. It takes about 150 ft lbs of torque to tighten a 9-inch Ford adjuster correctly. Any less will allow the ring gear to flex away from the pinion and the gear-set will not live as long. An accurate and easy-to-read dial indicator is necessary for properly measuring the backlash. An accurate inch/lbs torque wrench is needed to set the pinion bearing preload correctly. VITON HIGH TEMP PINION SEAL These pinion seals are best for racing. They are made from Viton® Fluoroelastomer, well known for its excellent (400°F/200°C) heat resistance. Their exceptional mechanical stability makes them ideal for severe operating conditions. MAINTENANCE OF A RACE REAREND The main thing a race rearend needs to live is good lubrication. Hot, dirty oil will end the life of a rearend faster than just about anything else. Cleanliness when assembling the rearend is essential to long life. Dirt, dust, metal filings, and any number of other foreign debris will affect the rearend life. A good rearend mechanic keeps their bench and work area free of any dirt or contaminants that can affect the rearend. This may seem obvious, but I see the issue of cleanliness missed more often than not. Bearings are more important to gear life than most mechanics realize. When it comes to the time and money to replace bearings, most people would choose not to go through the trouble. There are many things that can damage a bearing and lead to failure, even if the bearing doesn’t LOOK bad. Heat is probably the biggest killer of bearings in a racecar rearend. Scratches during assembly can lead to premature failure. Pinion bearing preload is VERY critical and either too much or too little can lead to bearing and/or gear failure. Whenever the pinion support is removed or the rearend is disassembled, the pinion bearing preload should be measured (with an accurate inch pounds wrench) and adjusted. Popular Resources: Limited Slips: Gov-Lock vs. Yukon Dura Grip Identifying Borg Warner Transfer Cases Limited Slips vs. Differential Lockers vs. Spools
When Just A Hammer Won’t Get The Job Done
Setting up a differential involves a lot of measuring, disassembly, reassembly, adjusting, and re-measuring. Aside from the tools needed to assemble and disassemble a differential, a good mechanic needs the right tools for making accurate measurements. Having the right tools makes the job far easier, while the wrong tools can make the job miserable, if not impossible. When working on a differential you will need a wide variety of special tools. If you do not have the tools you need, they can often be rented or borrowed. If you want to learn to build differentials or plan on building them on a regular basis, then investing in good tools is definitely worth the money. Using the correct tools, such as the ones listed below, will not only save you time but also prevent parts from being damaged. Dial indicator Genuine gear marking compound and a clean brush Calipers or a micrometer Bearing puller Bearing press (or access to one) Three foot long breaker bar or strong impact gun Pinion nut socket Six point cross pin bolt wrench Pry bars for removing the carrier case 48 oz plastic dead blow hammer Assorted brass punches Center punch or number stamp for marking main caps Foot pounds torque wrench Inch pounds torque wrench A good bearing puller is needed when removing the carrier bearings, and especially when the carrier shims are located between the side bearings and the carrier case. There is not any way to consistently set the backlash correctly without a good dial indicator. Gear marking compound is sometimes difficult to find, but always worth finding. Dial calipers can be found on many tool trucks and hardware stores. A good inch pound torque wrench is an expensive investment for a single installation, but it is worth finding. A foot pound torque wrench CAN’T be used for setting the pinion bearing preload as it is not accurate at settings that low. There are some tools that are not absolutely necessary. Bearing race drivers, for example, are not really necessary. A good bronze bunch (about 7/8″ dia x 12″ long) works well for driving bearing races in and out. Just be careful to remove any chips prior to assembly. Old inner and outer bearing races can be used for driving in seals and guiding on bearings during press operations. An old cross pin shaft can be ground to a point on one end and used for driving out the pinion shaft without damaging the threads. It is very important to accurately measure backlash, pinion bearing preload, and bolt torque. If any of these adjustments or torques are not correct, it could lead to early parts failure. Now that you are ready to dig in and build your own differential, remember that using the right tools will save you damaged parts, as well as time and frustration. Popular Resources: Diagnosing Noise (Part 1) Ford 9 Inch Differential Information Four Critical Ring & Pinion Settings
Ford 9 Inch Differential Information
The Ford 9″ axle is a semi-floating, drop-out with a GAWR up to 3600 lbs and is one of the most popular axles in automotive history. Ford began production in 1957 and stopped production in 1986 though many after market companies still produce this rear end. FEATURES The Ford 9″ has a stamped housing with axletubes welded on each end and nothing else. This makes the rearend easier to service because of its removable centersection that houses the gearset. This removable gear case houses a differential unit that the ring gear bolts onto. What sets the Fo rd 9″ apart from other high performance and heavy duty solid axles is that access to the differential gears is not through the rear center cover, which is welded to the axle housing, but through the center cover on the pinion side of the axle where the drive shaft connects. FORD 9″ BENEFITS The Ford 9″ has a number of benefits over its competition, here are just a few of them. In a Ford 9″ swapping gears is supremely easy as it has a removable third member. This is even more important if for dual purpose vehicles. A Ford 9″ also makes axles easy to install or remove as Ford designed the axle to slide out by yanking four bolts per axle flange for the 28- and 31-spline axles. An added plus for the Ford 9″ is an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. Ford improved tooth contact in the Ford 9″ by locating its pinion gear lower on the ring gear. This strengthens the rear end assembly but results in a minor loss of power to drive the gears. A Ford 9″ can save you money if the worst should happen. At some point no matter what axle you buy, that axle will break if you are doing something rough. With a Ford 9″ if the axle breaks inside the housing, the axle retainer keeps the axle in place, where in other types the axle would slide out potentially causing massive sheet metal damage. The Ford 9″ also has the widest variety of ratios on the market, so no matter what you have chances are excellent a Ford 9″ can work with it. Check out some of the parts we have to go with your Ford 9″ 28 spline, 31 spline, or 35 spline. Popular Resources: Limited Slips: Gov-Lock vs. Yukon Dura Grip Identifying Borg Warner Transfer Cases Limited Slips vs. Differential Lockers vs. Spools