Why replace rack-and-pinion steering rather than rebuild it

Overhauling a power rack is not a job for the novice. Special tools are required to remove and install internal seals. The tools are expensive and may not be cost justified for a shop that only does an occasional rack. For a do-it-yourselfer, the tools could end up costing as much as a new or remanufactured rack.

It is tricky to get seals properly positioned. If a seal slips or is damaged during installation, the rack will leak. For that reason alone, many professional mechanics won't waste their time trying to rebuild questionable racks.

Operating pressures within a power rack generally do not exceed 100 psi when the wheels are in the straight-ahead position. In an easy turn, the pressure can increase to as much as 300 psi and it goes up to 700 psi in a tight turn. The highest pressures are usually encountered when parking. If the wheels are up against a curb or if the steering wheel is turned hard against the stop, internal pressures can climb to 700 to 1,400 psi. This is why anybody who overhauls a rack better make sure the seals don't leak.

Time is another important factor to the professional installers. Anything that makes their job easier and faster is money in their pocket. If given a choice, most avoid doing repairs the old fashioned way because overhauling certain components in the shop slows them down and takes too much time. That's why many components (like starters, alternators, front-wheel drive driveshaft assemblies, even brake calipers) are often replaced with new or remanufactured units rather than overhauled in the shop. The same is true for racks.

Time is money... and at $40 per hour it doesn't take long for a mechanic's time to add up. By the time a mechanic spends $25 to $30 for a seal kit and several hours overhauling a rack (assuming it can be overhauled), he can end up spending as much of his customer's money as if he had bought a replacement rack in the first place.

Another reason why installers and do-it-yourselfers do not rebuild their own racks is because some racks are not rebuildable - at least not with a seal kit alone. If the teeth in the center of the rack are worn or damaged, a replacement rack bar can run $100 to $150.

If the housing is worn, distorted, cracked or otherwise unusable, a new housing can cost upwards of $125. If the control valve is bad, it will cost $150 to $250 to replace - if you can find the parts. Individual component parts for racks are not readily available in the aftermarket because everyone knows it is cheaper and smarter to go with a new or remanufactured rack if the original rack needs to be overhauled.

Rebuilders can often salvage worn aluminum spool valve housings by boring out the housings and installing a stainless steel sleeve. The sleeve not only restores tolerances, but also prevents the wear problem from reoccurring. In that respect, a remanufactured rack may actually be better than the original. Most rebuilders also pressure test their racks after reassembly to make certain they function correctly and do not leak.

One mistake installers should avoid when replacing a rack is not flushing out the power steering pump and lines to remove all traces of old fluid. Flushing is a must because it removes contaminants that could ruin the replacement rack. The system also needs to be purged of air by cycling the steering slowly back and forth until there are no more air bubbles in the fluid.

Related items that may also need replacing include rack mounts and steering input shaft coupling. If the coupling donut is deteriorating with age, it needs to be replaced. Metal swivel couplings also need to be checked for rust and binding. Do not forget to include new power steering fluid (follow manufacturer recommendations as to the proper type of fluid).