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Installation Instructions for IF-3739CP Mustang II IFS for 1937-1939 Chevy

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IF-3739CP Mustang II IFS for 1937-1939 Chevy

Chassis Engineering Installation Instructions for IF-3739CP Mustang II IFS for 1937-1939 Chevy

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1. Remove the original front cross member by drilling out the rivets. Straighten the frame lips where the new IFS cross member and strut rods will sit. Make sure to remove all the rivet heads that may interfere with fitting the IFS. Grind heads flush with the frame.

Note: You can reuse the radiator support by cutting it free from the cross member and leaving it attached to the frame. Alternatively, we also offer a replacement radiator support, AU-2254 (link).


2. Clamp the new lower cross member in place using the dimensions displayed below.

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The steering mounts on the cross member go to the front. On some frames, some mounting holes may line up, depending on the model of the car.

3. Place the coil spring pods over the frame and line them up with the lower cross member.

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The pods will only fit one way, the taller side goes to the front.If the pods are flipped, the bolt holes will not line up.

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Note the slope of the pod to find the tall side.

Check for clearances between the frame and your new parts. Correct any interference problems you may find.

At this point, we recommend to do a tire-centering check. To do this, assemble the A-arms and spindle on one side, without a spring, and install a wheel. Visually check for centering.

In the (unlikely) event of a miss, the cross member can be moved slightly (up to a 1/2"). Wheel centering shouldn't be a problem, but it is always better to check.

4. Drill the eight vertical holes through the frame lips using the cross member as a drill guide. Install the bolts.

5. Drill the side holes (8 total) through coil spring pods and the new cross member. Install the bolts.

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The cross member, frame and pods should now be firmly attached to each other.

6. Strut rod brackets are next. Put the brackets in place under the frame and insert a bolt in the center brace to cross member tube. Now fit the bracket to the frame and locate the point that the bracket fits the frame best. Do both sides. 

Compare the measurements and make them both the same. Brackets will fit the frame exactly only if the frame is straight and the mounting surface is flat.

7. Drill through the strut brackets and frame lips while keeping the bracket in alignment. Install the bolts.

8. Install components from 1974-1980 Pinto/1974-1978 Mustang II to complete the installation.

Manual steering is recommended. Use Pinto strut rods, no Mustang strut rods. Use a new strut rod bushing set. See Ford ot Front-End manuals for installation instructions covering A-arm, strut rods, springs, shocks and lineup specs. Cut your coul to 12" height. (Chassis Engineering coil springs are sized properly).


9. Chassis Engineering has springs available in 25lb increments, link


10. To adjust the height, first take off all the weight off of the springs. This means jacking up the front wheels of the ground and possibly unhooking the shocks.


Caution: To prevent injury be sure to use jack stands to support the car anytime you may be working under it.

Loosen 1/4" locking set screw and turn height adjuster to new position. The adjustment can be used for different springs. For correct geometry, the lower A-arm should be parallel to the ground. Line up groove in threads and re-tighten locking set screw.

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11. The final step, after height adjustment is to have the front end aligned to Pinto specs.

once a "fresh" car with a new IFS gets some good road miles, it may become necessary to once again adjust the IFS spring pods due to normal settling of the new front coil springs.

The lower control arms must maintain a "parallel to the ground" stance for good geometry and prolonged ball joint life. When making such an adjustment remember to loosen the set screw and add a little anti-seize compound before turning down the spring adjuster.

Removing the shock and use of a spring compressor will also aid in this procedure.

To aid in adjusting your IFS, we offer the IF-0000W adjustment wrench (link).

Afterwards, reinstall the shock and tighten the set screw.

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