Editing Straightening a rear end housing

Here's how to make a fixture and rack for straightening a rear end housing. ==Building a straightening table== The straightening fixture pictured below is an old gas cylinder cart, bought at a garage sale and the top cut off. A 6" X 6" I-beam was then welded to the cart. You don't need a cart, any sturdy legs will do, The cart just happened to be handy and had nice wheels so we could wheel it around the shop. [[Image:Axle_straightening_table.jpg|frame|none|A gas cylinder cart, converted for straightening rear end housings.]] To prevent any mishaps involving slippage and gravity, common jackstands are cut up to wrap the leg of the I-beam. The bottoms were notched, and a slice made at each corner to get the stands fitted to the I beam.[[Image:Modified_jackstands.jpg|frame|none|Basic inexpensive jackstands are modified to wrap the I-beam for stability.]] A straight bar is necessary. This hardened and chrome-plated bar is about five feet long, and 1.5" in diameter. It's available from McMaster-Carr for about $115.00. Alternatively, an old length of scrap steel shafting can be used. V-blocks and a dial indicator can be used to verify that a used bar is straight. Smooth, round and straight is best. You could use 1" round bar but the accuracy will suffer. One of the manufacturers that sells these alignment fixtures uses 1 11/16" bar. Bigger than 1 3/4" and the bar will be too big to handle. [[Image:Hardened_bar.jpg|frame|none|A hardened and chrome plated steel bar.]] ==Making the inserts== Then, make some inserts. These are about 2" long, as to provide some load bearing area to lessen wear caused by repeated use. For this application (10-bolt Chevrolet), the ID is 1.504", and the OD is 2.894". [[Image:Making_inserts_in_lathe.jpg|frame|none|Making the inserts in a lathe.]] Another insert was made with the same 1.504" ID, and dimensioned to slip-fit into the housing end. This same set of inserts and matching bar can be used as an alignment aid when narrowing rear end housings. The inserts are then clamped in the bearing saddles, and the bar slides through them. The fit should be nice -- the bar should slide through easily, but with no noticeable play. [[Image:Straight_bar_in_inserts.jpg|frame|none|The straight bar, in the inserts.]] ==Measuring== The housing end insert slides over the bar, and indicates how much the end of the housing is bent out of alignment. [[Image:Housing_end_insert_slid_over_bar.jpg|frame|none|The housing end insert is used to indicate the alignment of the housing.]] Hold a ruler on the tube, to see where it's bent. In this case, it's bent at the areas that were welded by the previous "builder". [[Image:Finding_housing_bend.jpg|frame|none|A ruler is used to see where the tube is bent.]] ==Heating and bending== Next, rig a chain at the point of bend, and put a 12-ton bottle jack under the end of the axle. To prevent bending the center casing, attach the rear cover. [[Image:Bottle_jack_and_chain.jpg|frame|none|A bottle jack and chain are used for bending.]] Then, jack up the housing into perfect alignment with the housing end insert, and heat a band all the way around the tube, until it's red-hot. Let the tube cool while it's still supported by the jack. [[Image:Heating_the_axle_tube.jpg|frame|none|Heat a band all the way around the tube.]] [[Image:Red_hot_band.jpg|frame|none|A red-hot band indicating proper and even heating of the tube.]] In this case, when the tube cooled, the housing end was only a few thousandths of an inch off, and was easily bent into alignment cold, using only the bottle jack. This housing was initially out by almost 1/4" on one side, and 3/16" on the other. Now, the housing end slips on with minimal effort. [[Image:Insert_fits_properly.jpg|frame|none|The housing end slips on with minimal effort.]] ==Related information== *Moparts.com: [http://www.moparts.com/Tech/Archive/race/16.html Narrowing a Rear Axle Housing] *Hotrodders Bulletin Board: [http://hotrodders.com/forum/straightening-rear-end-housing-109642.html Straightening a Rear End Housing]

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