randys blog
What Does “Complete” Really Mean?
Have you ever had to call around town on a Friday to find pinion shims or a crush sleeve so you could be on the trail for the weekend? Working on a rear end is hard enough with the right parts, and can be downright impossible with the wrong parts. A good installation kit can make the job a lot easier and save hours of frustration. Every distributor claims to have the best installation kits available. I have seen a number of items labeled “Installation Kit” or “Master Kit” that didn’t deserve to be named as such. Since there is really no established standard, the terms will always be used loosely and it is up to the customer to put the sales person through the drill of explaining what is in each kit, in detail. There are many good questions to ask when ordering. Does the kit include good instructions? Does it include ALL of parts necessary to rebuild or setup the rear end completely? Are both pinion and carrier bearings included in the kit, and are they the highest quality available? Many kits use cheap import bearings and seals. If the salesperson is not certain what kind of parts their kit uses, ask them to open the box and see. Many kits do not include useful carrier and pinion shims. This is due to the cost of making good shims. Are there just enough shims for one adjustment, or does the kit contain enough shims to setup the rear end from scratch? In my opinion, a complete “Installation Kit” includes: both pinion and carrier bearings, a crush sleeve or preload shims, enough pinion depth shims to set the depth without having to reuse any of the original shims. For most applications, a complete set of carrier shims. A high quality pinion seal, an OEM quality pinion nut, a gasket or silicone for the cover, Loctite® or thread locker for the ring gear bolts and pinion nut, an instruction manual with pattern diagrams and details that really help, and real gear marking compound. (If you are looking for gear marking compound in a handy tube, try GM part number 1052351.) It really doesn’t matter which parts a supplier includes in their installation kit, as long as they explain, in detail, what the kit contains. There are many high quality kits out there. Ask a lot of questions and don’t take “I’m not sure” for an answer. Remember, this is your rear end we are talking about. Popular Resources: Limited Slips: Gov-Lock vs. Yukon Dura Grip Identifying Borg Warner Transfer Cases Limited Slips vs. Differential Lockers vs. Spools
Calibrating Speedometers
Changing gear ratio or tire size can lead to an out-of-calibration speedometer that leaves you guessing how fast you are really going. Calibrating a speedometer is usually not as hard as people make it out to be. In many cases all you need is an accurate standard of speed or distance, the right equations, and some basic math.There are actually two ways to calibrate a mechanical speedometer. The ratio of the drive and driven gears in the transmission (or transfer case) can be changed, or you can install a reduction or overdrive calibration box between the cable and the driven gear. The simplest method is possible when only the speedometer driven gear needs to be changed. In some cases, the driven gear is not available small enough or large enough to complete the calibration, and the drive gear on the transmission output shaft must be changed. This is not easy due to the fact that the tailshaft of the transmission (or transfer case) must be removed to access the drive gear. An alternative is to install a custom made “calibration box” between the cable and the driven gear. This is a simple bolt-in procedure and the parts can be found at your local speedometer shop or by mail order. If the vehicle has an electronic speedometer, calibration is not so easy. Ford trucks with an LED odometer use the differential ABS ring to signal the speedo. Changing the gear ratio in these trucks does not require re-calibration. However, changing the tire size does require re-calibration by a professional. General Motors trucks with an electronic signaled dash must be calibrated by changing a chip in the dash. This can be done with parts from GM, but once again I would recommend calling a professional or making a trip to your local speedometer shop.