LS swap steering: shaft and box clearance by chassis

How we put this guide together

Of the 2,012 LS swap questions we pulled from forum threads, 32 were about steering: headers hitting the shaft, the rag joint touching a primary, pitman arms against the alternator, and which box or rack to run with the LS pump. Steering is the place where a swap that looked done on paper stops fitting. Below is why it happens, the order we check things, the fixes from cheapest to most work, and what each of our 36 vehicles needs.

Step 1: Understand why the LS crowds the steering

The LS itself isn't wider than the small-block it usually replaces (24 in across vs 26 in for a 350). The problem is what hangs off it:

• The driver-side header runs right past the shaft. On almost every front-steer and box-steer chassis the steering shaft drops from the column, past the driver-side head, to the box or rack at the frame. LS exhaust ports point the primaries straight at that spot. A swap header is bent around it, which is why each one fits only one chassis and one engine position.
• Engine position moves the problem. An inch forward, back or to the side changes which primary meets the shaft. Some kits move the engine on purpose: Vorshlag offsets an E36 drivetrain toward the passenger side, CX shifts the E46 engine sideways to keep the factory shaft. More: engine mounts and swap kits.
• The rag joint is the fat part. A factory flex coupling (rag joint, or guibo on a BMW) is much bigger around than the shaft, and it usually sits low, right where the collector and primaries are. Replacing it with a U-joint is the most common fix.
• Low-mount accessories hit the linkage. On some chassis it's not the shaft but the pitman arm or center link against a low-mount alternator or compressor (2nd-gen F-body, G-body, early Nova).
• The pump has to talk to the box. LS pumps use metric O-ring fittings and their own pressure. Older GM boxes take flare fittings, and imported racks want the pressure they were built for.

Step 2: Check it in this order

Do this with the engine on its final mounts and the headers you'll actually run.

1. Mount position. Confirm the engine sits where the kit says. A header can't clear a shaft if the engine is half an inch off the spot it was drawn for.
2. Header choice. Read the header's fitment notes for steering. Some route a primary around the stock shaft (S10), some need a swap shaft (Fox and SN95 with AJE or Team Z K-members, E36, E46 with Sikky), some list right-hand-drive cars as not covered.
3. Clearance at full lock and under load. Turn lock to lock and look at every joint. Then rock the engine on its mounts with a bar: under torque it rolls toward the driver side, so a gap that looks fine parked can close.
4. Heat. Allow real air space between the shaft and a primary; a shaft near a header gets hot enough to cook a rubber joint. Wrap the shaft or use a heat sleeve where it runs close.
5. Accessories against the linkage. Turn full lock both ways with the accessory drive on and look at the pitman arm, center link and tie rods.
6. Pump to box. Note the fittings and the pressure your box or rack needs before you buy lines.

Step 3: Fix it, cheapest first

1. A small dent in the primary. Where a header just touches the shaft (Tacoma, some C10 and A-body setups), a smooth dent in one tube is the accepted fix and costs nothing in power.
2. Replace the rag joint with a U-joint shaft. A rag joint is only meant for a straight connection, and it's fat (the common GM coupler is close to 3 in long and wider than that across). A telescoping or collapsible shaft with U-joints is thinner and often deletes the clash by itself. Borgeson's 000315 is one example for G-body, 3rd-gen F-body and early S10. Keep the shaft collapsible in a street car.
3. Reroute the shaft. U-joints and a support bearing let the shaft go around the header instead of through it. Aim for about 15° at each joint; up to 30–35° on a single U-joint is the limit, and a double U-joint takes up to about 70° where one joint would bend too far. Three or more U-joints, or a very long run, need a support bearing near the middle joint so the shaft can't flop. Use at least a 3/4 in shaft on a street car, and match both ends: column spline or double-D size, and box or rack spline.
4. Pick a header that clears. Sometimes the cheaper fix is a different header, or cast swap manifolds, rather than re-engineering the steering. More: headers and exhaust by chassis.
5. Change the box or rack. On GM classics a quick-ratio box (Borgeson's 800130 on F-bodies, its 12.7:1 box on C10s and A-bodies) bolts in and often fits better with headers; pre-1977 GM cars need a new rag-joint connector and manual-steering cars need a power pitman arm. Some swaps change the rack: an E30 with the Sikky kit takes an E36 rack, a 240Z or E39 keeps its rack but needs the right shaft. On some trucks and F-100s the front end changes completely (Mustang II style kits with a power rack).
6. Move the engine. Last resort: a different mount position. It changes headers, pan and driveline too, so it's a whole-plan decision.

Step 4: Plumb the pump to the box

• GM boxes: older boxes take inverted-flare fittings; the LS pump needs adapter fittings or a hose made for it. On C10s the stock LS truck pump bolts to the factory hoses once its check valve is converted to SAE fittings. A C4 keeps its rack with a C5 pump or a single adapter fitting.
• Import racks: match the GM pump's pressure and flow to the rack. Revalved pumps exist for some (Porsche 944), line kits for most (Sikky, V8 Roadsters, Fueled Racing). The wrong pressure can shear a pump's input shaft or make the steering darty.
• Big tires: on Jeeps and Toyotas the steering load comes from 35–40 in tires, not the engine. Hydraulic assist is the fix, and it needs a pump that can feed it.
• Pulley alignment: a pump on the wrong accessory spacing won't line up with the belt. More: accessory drive guide.

Step 5: Measure before you buy a shaft

Write these down with the engine and headers in place:

1. Column output: most American columns end in a 1 in or 3/4 in double-D, or a 1 in-48 or 3/4 in-36 spline. BMW used several columns, so measure yours and count splines.
2. Box or rack input: GM power boxes are mostly 3/4 in-30 (the 605 and 1978-up 800 series; pre-1977 800 boxes are 13/16 in-36), GM racks 5/8 in-36 or 3/4 in-30, Corvette racks from 1984 a 17 mm double-D, Ford boxes and Mustang II power racks 3/4 in-36, BMW 17 mm-54. Count the splines on yours.
3. Straight-line distance from the column end to the box input with the wheels straight.
4. Where the shaft has to bend to clear, and the angle at each bend.
5. Whether the column is collapsible, and whether the shaft needs to be.

A steering shop or the shaft maker can build from those numbers. When you assemble it, slide each shaft into its joint only as far as the inside edge of the yoke, and lock smooth-bore joints with roll pins rather than welding.

Common mistakes

• Buying headers before checking the shaft. The header decides the shaft, not the other way round.
• Checking clearance with the engine at rest. Under load the engine rolls. Check it rocked on its mounts.
• A U-joint past its angle. It binds, wears fast and feels notchy. Add a joint or a support bearing.
• A solid shaft in a street car. Keep a collapsible section.
• Mismatched splines. Measure both ends before you order.
• Forgetting the pitman arm. A low-mount alternator or compressor can hit the linkage at full lock even when the shaft clears.

Find your vehicle in the table below for the steering parts and checks that apply to it.