Symptoms
Wandering steering, a box that visibly moves on the frame when someone turns the wheel, or hairline cracks running from the steering-box bolt holes. Big tires and hard wheeling make it worse.
The fix, step by step
- Unbolt the steering box, swing it aside and clean or blast the rail inside and out, because cracks often show only on the inside.
- GMSquareBody members drill a stop hole at the end of each crack, gouge it out, weld it, grind it flat, and only then add reinforcement.
- Offroad Design's weld-on repair kit wraps the outside and bottom of the rail.
- A bolt-in brace ties the box to the opposite rail and is good insurance on an uncracked frame.
- Some members also replace loose front-crossmember rivets with grade 8 7/16-inch bolts.
Tools & part numbers
- Welder and grinder
- drill and bits
- socket set
- torque wrench
- magnaflux or dye penetrant for hidden cracks
Where to buy the parts
Offroad Design weld-on frame repair kit, 1973–91 GM trucksOffroad Design ↗Amazon ↗
Offroad Design bolt-in steering box frame brace, 1973–91 4WDOffroad Design ↗Amazon ↗
Steering gear (box), 1987 BlazerRockAuto ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Chevrolet K5 Blazer (1973–1991) parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.