I am doing a Rebuild on my 1967 904. I have Mr. Toms book and it has helped a lot, I am actually using his recommendations from the appendix, but I still have a question about the single apply spring. I have a 5 disc front drum, but I have 3 springs, 1 from the 67, 1 from a 69, and one from a 999 which is where I got the steel 4 pinion planetary's. I have been all over looking for questions about this spring with no luck.
Is one any better than the other?
Yes I know of the aftermarket multi spring but that is not my question.
Thanks in advance for reading..

Measure the wire diameters first.

Then the free lengths.

If they are the same wire diameter and close in free length then they are probably the same springs rates.

They were color coded in the plant so the builders could select the correct spring front the BOM for that can clutch.

If you have a valve spring tester you can test them in a vice for spring rate too.

It’s not which is better but which is required to match h the front servo lever and spring rate there - it affects 2-3 shift timing.

Thanks
I have a 4.2 lever. The 999 spring is yellow, the other 2 are orangeish......how do I determine which is best for me?

Use orange spring/5 discs along with the 3.8 lever. You can try the 4.2 but install 4 discs. Install the inner KD servo spring and find an orange outer spring for the KD servo.

Yellow spring is for peanut motors and 2.5 lever.

Ok thanks, I will see if I have a 3.8 lever.

http://www.atiracing.com/products/trans/904/index.htm

ati makes a replacement single wound spring for the 904.....

TF904 Reverse Wound Direct Drum Spring 20 bucks....

Thanks for the assistance. Hopefully I can see how good a job I have done here soon.... stupid virus