Front Frame

During the 1999-2003 Major Upgrade, the Morgan Front Frame was replaced with a custom designed version that performed the same function as the original, but was stronger. Below is a front view photo (with the suspension attached), and the following Sketch #1 shows more detail.


The upper and lower crosstubes consist of middle sections made of 1 ½ in. OD x 1/8 in. wall steel tubing, and outer ends that were cut from the Morgan front frame. The Morgan outer ends have 1 ¼ in. OD tubes and were inserted and welded into the larger middle section tubes. The vertical plates on each side were cut from 0.12 in thick steel plate, and bent to match the chassis. They were doubled at the front to reinforce the area where the tubes pass through and where the front frame bolts to the chassis. Holes were drilled in the vertical plates and the middle tubes were fitted and welded. The center area is reinforced with an X-shaped web cut from 0.12 in. steel plate and welded on the plane through the centerline of the tubes. The tubes were positioned so the stock length kingpin is used and the stock caster angle is retained.

The outer ends were positioned so the kingpins, when viewed from the front, are vertical, when a nominal bottom kingpin plate is fitted. In other words, the nominal Kingpin Inclination Angle (KPI) is zero. The stock Morgan KPI is two degrees. With a sliding pillar suspension having forward facing steering arms connected by a tie rod, a KPI greater than zero will cause a slight Toe Out condition under hard braking (both wheels moving upward relative to the chassis). This effect is eliminated.

Also, the outer ends were positioned so the lateral distance between the vertical kingpins was 37.5 inches, which is less than original, moving the kingpins inward. This distance, when combined with the offset axle of the custom spindle and using a six inch wide wheel with ½ in. negative offset results in:

A. Front Track of about 50 inches, and
B. About 3/8 in. clearance between the coil spring and a 205×15
Hoosier Speedster tire.

Changing the bottom kingpin plate will slightly alter these values.

The Morgan Tension Rods were replaced with 3/8 in. UNF Grade 8 threaded rod. The lower attachment is a threaded clevis which is bolted to a ¼ in. thick steel tab welded on the front frame, and the upper attachment is the same as on the Morgan front frame.

Front Frame

Sketch 2 is a top view of the lower part of the custom Front Frame, showing the lower crosstube with the Morgan outer ends, the vertical plates and doublers, and the web. The front portion of the Forward Supports is also shown. These supports are described in the Roll Bar Structure section. They attach to the Front Frame with ½ in. AN bolts through rod ends and custom Attachment Fittings, which are also shown on the frame and in a detail sketch. The fittings were machined from 1 ½ in steel rod and have a 0.875 in. diameter “nose” that fits tightly in a hole drilled in the vertical and doubler plates to assist load transfer. They were welded around the OD on the inside and around the “nose” on the outside and ground flat. The hole for the rod end was drilled undersize and finished after welding. The following photo shows the lower end of the right side Forward Support.



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s