Posts Tagged ‘shock absorber mounting angle’

Installing the Rear Shocks in 1929 Ford with C4 Corvette IRS

Saturday, March 27th, 2010

Installing the Rear Shocks                   

Now it came time to figure out how to mount the rear shocks.  I am using the modified C4 Corvette IRS composite mono spring in the rear of my 1929 Ford Hot Rod.  To control the bounce, shock absorbers will be added to the suspension.  Without any pre-made plans and instructions in hand on how to build this car, everything including the shocks has a bit of trial and error element in the design and build.  I had a set of new gas charged Munroe Shock absorbers bought for my 1988 Cobra Mustang convertible.  Unfortunately, the Cobra convertible was stolen.  This happened in broad daylight, out of a highly visible area in the parking lot at the College I am employed at.  Sometime between 9 and 11am in the morning, somebody wanted the car more than my wife and I did.  Somebody took the car and never returned it!!  This will be another story later on.  As a result, the shocks I purchased never did get used.  Realizing that the Cobra convertible and the 1929 Ford roadster would have a similar weight for the rear of the cars, I thought it might be a good idea to use these shocks in the hot rod. 

1929 Ford Hot Rod - C4 Corvette IRS first attempt at mounting the shocks.  The angle of the shocks was too great.  At this angle the benifit and working abiltiy of the shocks would be greatly reduced and undesirable.

1929 Ford Hot Rod - C4 Corvette IRS first attempt at mounting the shocks. The angle of the shocks was too great. At this angle the benifit and working abiltiy of the shocks would be greatly reduced and undesirable.

My first attempt at mounting the shocks was less than desirable.  The look was not right and the angle of the shock was too great.  Shocks work best when they can be mounted as close to a vertical position as possible.  If not, a shock absorber damping correction factor will need to be applied.  For example, if a shock is mounted 15 degrees from the vertical position, then the shock will be 93 percent effective.  When the shock has a 35 degree mounting angle, then it will be 66 percent effective.  I had just too much of an angle and the shock just did not work very well.  There was just a bit too much bounce in the suspension.  This was not too much of a problem.  It is a good thing that I only tack welded the brackets to the frame.  The upper shocks mount brackets were easily removed.

1929 Ford Hot Rod - C4 Corvette IRS lower shock mount.  This piece was made from 2 inch square stainless steel tubing.  I will end up place a spacer in between the shock mount bracket I made and the receiving end on the wheel assembly.  This will help improve the angle of the shock and provide me with frame clearance at the top end.

1929 Ford Hot Rod - C4 Corvette IRS lower shock mount. This piece was made from 2 inch square stainless steel tubing. I will end up place a spacer in between the shock mount bracket I made and the receiving end on the wheel assembly. This will help improve the angle of the shock and provide me with frame clearance at the top end.

For my second attempt, I decided to move the upper rear shock mounts closer to the frame rail.  The mid section of the shock did not have enough clearance and was hitting the lower edge of the frame.  I already had made a lower shock mount out of 2 inch square stainless steel tubing.  A small spacer between the stainless steel mount and the actual mount on the C4 Corvette lower aluminum shock mount was all I needed.  Now there was just enough clearance and the shock did not hit the lower part of the frame rail.

1929 Ford Hot Rod - C4 Corvette IRS upper shock mount in its final position.  With the extra spacer at the bottom of the shock moving bottom of the shock in towards the center of the chassis and the upper shock mount up against the frame rail, the shock is in a more vertical and desired position.  This even looks better then my first attempt.

1929 Ford Hot Rod - C4 Corvette IRS upper shock mount in its final position. With the extra spacer at the bottom of the shock moving bottom of the shock in towards the center of the chassis and the upper shock mount up against the frame rail, the shock is in a more vertical and more desirable position. This even looks better then my first attempt.

1929 Ford Hot Rod - C4 Corvette IRS upper shock mount in its final position with the shock installed.  This will work much better now and give me good shock perfermance.

1929 Ford Hot Rod - C4 Corvette IRS upper shock mount in its final position with the shock installed. This will work much better now and give me good shock performance.

1929 Ford Hot Rod - C4 Corvette IRS right upper shock mount finished.  You can also see the center mount for the rear end.

1929 Ford Hot Rod - C4 Corvette IRS right upper shock mount finished. You can also see the center mount for the rear end.

1929 Ford Hot Rod - C4 Corvette IRS left upper shock mount finished.  This picture also shows one of the rear body mount and the mount I developed for the rear control arms.

1929 Ford Hot Rod - C4 Corvette IRS left upper shock mount finished. This picture also shows one of the rear body mount and the mount I developed for the rear control arms.

The upper mount in my opinion looks substantially better now and the shock is in a more vertical position.  With a few sand bags in the trunk and my 250 pounds, bouncing up and down on the back end of the 1929 Ford hot rod seemed to give me the right kind of movement and damping effect I was looking for.  Everything was welded into place permanently.  My next step will be to place the rear sway bar on the chassis.  Come back next week for more information on how I did this.

Share