Archive for March, 2010

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.

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The Rear Suspension for the 1929 Ford Roadster – Part 1

Saturday, March 20th, 2010

The Rear Suspension for the 1929 Ford Roadster – Part 1

One of my design goals was to use as much of the C4 Corvette suspension as possible. On the rear of my 1929 Ford Roadster hot rod, I thought that I would try using the original C4 Corvette composite mono spring. The only problem is that the 1986 Corvette is a fair bit heavier than what the 1929 Ford Roadster will be. With the spring installed on the 29 Roadster and the body on the chassis, there was not much movement in the suspension, no matter how hard I jumped up and down on the back of the roadster. Not having too much to loose, I decided to narrow the composite mono spring. A bit of masking tape was laid down along the edges of the spring. This was used to mark cutting lines on. I started cutting a ¼” to ⅜” off each side of the spring. My first cut was made on my large 20” wood band saw. Forgetting that the composition of the Corvette mono spring is very abrasive, my blade only lasted about a minute and only managed to make a very small cut in the spring. The band saw blade was ruined. Then I realized the better option for cutting the composite Corvette spring would be on my metal cutting band saw. This worked out much better. After removing the first strips off each side of the spring, I mounted it back on the car and checked the spring rate. This continued this routine for sometime. I eventually stopped when the spring was approximately the same width along the length of the spring. Still, this provided me with a very stiff spring rate that was totally unacceptable. Taking a close look at the composite spring, I decided that I could make the spring thinner in the middle section of the spring. I did this using my 6” stationary belt sander using a 24 grit sanding belt. To keep the dust down, the shop vac up connected to the belt sander. The dust from the spring is very hazardous and I did not want to breathe in the dust.

C4 Corvette composite mono spring.  Masking tape is use to scribe lines onto for easy visibility while make the cut on the bandsaw.

C4 Corvette composite mono spring. Masking tape is use to scribe lines onto for easy visibility while make the cut on the bandsaw.

C4 Corvette composite mono spring. Ready to be cut on the bandsaw.  Material must be removed by equal amounts on both sides.  This will provide the same spring rate for each rear wheel.

C4 Corvette composite mono spring. Ready to be cut on the bandsaw. Material must be removed by equal amounts on both sides. This will provide the same spring rate for each rear wheel.

Finally after a full day of this, I finally achieved the spring rate that I needed for the 1929 Ford Roadster. This should be fine and safe for the roadster. I took some of the castings that I cut off and tried to break them by bending them into extreme shapes. Not one of the pieces broke. If this does turn out to not work out once the car is on the road, I have made provisions to install coil over shocks on the back of the 29 Roadster. The true test will be when the car is on the road.

The modified C4 Corvette composite mono spring installed on the 1929 Ford Roadster.  The spring was cut so that the spring was the same width for the entire length of the spring.  I also removed a bit of material from the center section of the spring to make it a bit thinner.  This gave me the desired spring rate for my hot rod.  The edges still need to be smoothed off before this modification is considered complete.

The modified C4 Corvette composite mono spring installed on the 1929 Ford Roadster. The spring was cut so that the spring was the same width for the entire length of the spring. I also removed a bit of material from the center section of the spring to make it a bit thinner. This gave me the desired spring rate for my hot rod. The edges still need to be smoothed off before this modification is considered complete.

Next week I will start installing the C4 Corvette sway bars onto the 1929 Ford Roadster hot rod frame.

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