Swapping to rack and pinion steering
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| + | ==Introduction== | ||
| + | Swapping to a rack and pinion (R&P) steering system from other set ups has become a commonly performed swap and a sometimes necessary part of vehicle steering and suspension modifications to older vehicles. Often clearance is gained for engine and exhaust placement and an improved steering feel can also result. | ||
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==Turning radius== | ==Turning radius== | ||
| − | Many cars suffer from poor turning radius after an R&P install. There are 2 basic reasons. Either the rack was placed too far left and interferes with the wheel, or no adjustment was made to the steering arms. On a typical RB type steering box the Pittman arm has a “throw” of 7 inches, side to side. It is usually connected to steering arms effectively measuring 7 inches long | + | Many cars suffer from poor turning radius after an R&P install. There are 2 basic reasons. Either the rack was placed too far left and interferes with the wheel, or no adjustment was made to the steering arms. |
| − | Changes to the steering arm can affect the steering geometry and introduce bump steer. So, if you are going to address this issue, (some people don’t) do it before the rack install. | + | |
| − | There are two acceptable methods of dealing with this issue. The preferred method is to replace the steering arms with shorter ones. On the 41 Pontiac upgrade covered in the wiki | + | On a typical RB type steering box the Pittman arm has a “throw” of 7 inches, side to side. It is usually connected to steering arms effectively measuring 7 inches long (The 7 inches is measured from the center of the steering arm mount, where the king pin or ball joint pivots the spindle, to the center of the outer tie rod where the steering pivots). Typical Cavalier racks have 6 inches of throw and originally connected to the upper strut in a manner that represents about 5 ½ inches from center of the strut to the center of the tie rod. Connecting the rack to the original arms causes a loss of nearly 20% of steering angle. It is strongly recommended that this be dealt with before installing the rack. |
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| + | Changes to the steering arm can affect the steering geometry and can introduce [http://www.longacreracing.com/articles/art.asp?ARTID=13 '''bump steer''']. So, if you are going to address this issue, (some people don’t) do it before the rack install. | ||
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| + | There are at least two acceptable methods of dealing with this issue. The preferred method is to replace the steering arms with shorter ones. On the '41 Pontiac upgrade covered in the wiki [[1937-1957 Buick Oldsmobile Pontiac suspension upgrade]] the original '65-'70 Chevy steering arms were replaced with a set from a '55-'57 Chevy. | ||
[[Image:Chevelle_arm_vs_chevy_arm.jpg]] 55/57 Chevy arm compared to 65 Chevy arm. | [[Image:Chevelle_arm_vs_chevy_arm.jpg]] 55/57 Chevy arm compared to 65 Chevy arm. | ||
There is a difference in mount width between the BOP arms and Chevy arms, so they won’t work on BOP without the Chevy spindle upgrade. If you are unable to find shorter arms for your application, bending the originals is the next option. You will find mixed opinions on this issue. Some will insist that heating and bending steering arms compromises their structural integrity and should never be done. Others warn you to be sure they are forged and not cast arms. Bending forged arms is OK, bending cast is not. | There is a difference in mount width between the BOP arms and Chevy arms, so they won’t work on BOP without the Chevy spindle upgrade. If you are unable to find shorter arms for your application, bending the originals is the next option. You will find mixed opinions on this issue. Some will insist that heating and bending steering arms compromises their structural integrity and should never be done. Others warn you to be sure they are forged and not cast arms. Bending forged arms is OK, bending cast is not. | ||
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