Preventing Scuttle Shake On A Big Healey

If you have any questions regarding this modification, please feel free to contact either Keith or Bill:

Keith Pennell writes:

Having had a BJ8 for many years and driven a number of big Healeys, I have experienced varying degrees of shake in the front end. I vowed to solve this in the major restoration of my BJ8 in 1991. The front end was rebuilt and so I assumed that front end was not then the cause of the problem. Numerous truing and balancing of wheels over time helped considerably, but did not completely eliminate the trouble as there was always that "low level" vibration at highway speed. The tires were never shaved although this may have helped.

Upon aquisition of the BN7 in 1993 I decided that I was going to attack the problem more aggressively. I had heard and read the opinion that the big Healeys' vibration was inherrent in the superstructure and that there was even a harmonic at certain frequencies characteristic of the chassis.

It seemed to me this motion must be a lateral one in the scuttle structure as I could not see how the motion could be in the fore/aft or vertical directions. Upon examination of the scuttle I ruled out certain cross bracings from scuttle to inner sills and/or main rails as
something was always getting in the way - the engine! Therefore, the only logical possibility seemed to be to reinforce the transmission box as I call it - the roughly box-shaped part of the scuttle above the bell housing.

I had the idea of welding in some angle iron with small gussets in the two corners in this box. (The gussets were never added as later they seemed to be an overkill.) I discussed the idea with John Vrugtman whose opinion I value very much. We also considered welding a plate cut to fit to the vertical portion of the box. I still liked the angle iron solution best. In running this idea past the list, I received a return from Bill Bolton who had performed this same mod to more than one car already. Boy, great minds run in the same gutter!!! Thanks to Bill. The one significant suggestion he added was to weld solid the box on the cockpit side which I did. If one looks there are only a few small welds there originally.

Here are the before and after shots of the mod. Sorry for the quality of the pictures as I am not a photographer.

The angle iron is 3/4 stuff salvaged from a real estate sign frame! This view is a before picture taken from an angle below the front crossmember. Welds were on both edges of the angle and roughly 1 inch long and laid every 2 inches. On the passenger's side the piece runs from the main rail all the way up and and a relief cut is needed at the solenoid hole. The angle is welded hard to the top of the main rail. To me this is the weakest link in the mod but I could not come up with a satisfactory way to attach the angle iron better on this side. Maybe someone else can.

This is the finished version. On the cross piece two cutouts had to be made to allow for the mounting of the accelerator linkage cross shaft brackets. The cutout amounted to about 7/8 x 3/8 for each. Note that little of the mod will be seen once the car is finished. If one is so motivated the open spaces could be filled with a bead of seam sealer to dress up the mod and keep out debris/water.

On the driver's side the angle runs from the bottom of the main rail up. Some cutting in the angle is needed for the tunnel opening and because the footwell face is not flush with the inside surface of the rail. There the iron is welded solid to the rail.

This view shows the painted driver's side.

This view shows the upper corner, driver's side. The cutout for the linkage bracket is visible near the top center of the photo.