Motor mounts and frame stiffeners

[jpeater]

The Scout II frames are fully boxed and extremely strong - mostly. The area around the steering box is notorious for cracking due to the longer pitman arms and lack of a front cross member under the engine to help distribute the load. To address the cracks you can either grind them out and reweld, plate the frame with some steel or both. To keep the cracks from coming back a few IH specific vendors have developed what is commonly referred to as a 'straight steer' brace. The brace connects the driver and passenger side frame rails just in front of the engine, in line with the steering box. Typically they is made of 1/2" plate that is designed to bolt on the frame then drop under the lower engine (crank) pully and rise back up to bolt to the frame on the opposite side. They are relatively simple to install as Scout II's were made in right hand drive versions and have the appropriate holes in the passenger side frame rail, minus the anti-crush sleaves.

After an inspection of my frame I found I did not have any cracks so that was a good start. I had planned to move the motor back about 1.5" to get more clearance for a Mark VIII style electric fan but not enough to upset firewall to engine clearance. I starred and thought for a while and figured I could kill two birds with one stone. Here is a rough step by step to what I did:

Using some angle iron and old bolts I made a jig that would index the front engine mounting plate bolts in reference to a set distance from the front of the frame. Using a 7" grinder with a cut off disc I cut the engine mounts off the frame and cleaned everything up with an angle grinder and some flap discs.




Using the old motor mounts as a template I made two new ones from 1/4" plate steel, bending the ends using my press and brake. The motor mounts are not symmetric so one was made longer than the other so the front of the mounts would be in the same location on both sides. I did this so I could tie the motor mounts into a straight steer style brace to make them even stiffer.



Next I grabbed some poster board and traced out the front frame rails and marked the locations of the steering box mounting holes. Once I cut it out and confirmed everything looked good I transferred it to some 3/16" steel plate. Notice that the ends of the stiffeners are not square, I angled them and opposed them inside and out to ensure I was not creating any weak or stress concentration point in the frame that would attract a crack for fatigue the frame any. I drilled the holes for the steering box and clamped both inner and outer frame stiffeners using the holes as a reference. I drilled a pilot hole through the stiffeners and frame at the front of the motor mounts to use as a guide for the hole for my modified straight steer brace then proceeded to drill the 1 3/4" hole through inner and outer stiffeners and the frame on both sides.

With two short pieces of 1 3/4" tubing and the bolts for the steering box in place I clamped everything to the frame and located the motor mounts 1.5" back using my jig and tacked the mounts to the inner stiffeners. I pulled the stiffeners off and finished welded them up then clamped it all back on and tacked the stiffeners to the frame and ensured everyting measured out right for the engine to it back in. The diagonal piece that was cut from the rear of the mounts was used as a gusset under the mount to add more strength. I then began the long process of welding everything up, 20% duty cycle is a killer.