Tech Question - Trans Am Build Dates

Q -Mike,

I have a 70 Trans Am without A/C. I looked up the front springs on your web site and saw that the build date of my car determines if I use spring number MC1222 or MC1294.

I don't know the exact day of manufacture but the car was made in February. What are the differences in the springs? - Mike

Mike,

It was not uncommon that car manufacturers would make running changes during a model year. Many times the build date was not that critical, however, and just your luck, this time it is because there is a rather large difference in the springs.

The MC1222 has an inside diameter of 4.080 Inches with one square end and one tangential end.

The MC1294 has an inside diameter of 3.625 Inches and both ends are tangential.

Bottom line, the springs are not interchangeable due to the inside diameter and end type.

The cup on the A arm holds and locates the spring and the end type locks the spring in place.

There are 2 ways to figure which spring you need. 1st is by the Body Number Plate. The last code numbers on the left side of the plate, just above the rivet hole is the build date.

The numbers is the month, February is 02, and the letter is the week of the month.

A=1st week, B=2nd week, C=3rd week, D=4th week, E=5th week.

With any luck yours will be clear as to what time of the month.

If the code falls right around the 10th of the month then you will have to use the 2nd way to determine the correct spring.

This means taking one of the springs out.

The cup on the A arm locates the spring and because different strength springs can use various wire sizes the inside diameter of the spring is the important measurement.

The easiest way finding the inside diameter is to measure the outside diameter and the wire diameter.

Once these are known subtract 2 times the wire size from the outside diameter to get the inside diameter.

I hope this has been clearer than mud and helps you.

Mike