Technical Rear spring perch model a

I'm putting a bronco rear end in model a chassis. The factory spring was to wide for my rearend it was in the way of backing plates. I ordered a brand new main leaf that is 2 inches narrower on each side. So a total . In theory do I just move the spring perches in two Inches also or do u think that new spring being shorter and stronger it may vary. I took the main spring apart and it's right at 4 inch total compared to old spring. Or is there another way to make sure the perches are where I need em.

 

The manufacturer of your main leaf should be able to tell you what the perch center should be?

 

Placing the spring perches at the right width is always a crapshoot. If your car weighs a little different than the "design" car the spring width will be different at rest. Use the manufacturer's recommendations, but if the car is much lighter or heavier than a stock A, I might adjust a little inward or outward (with your 4" also).

 

Anyone know the stock dimension, I have asked with replies anywhere from 46.5 to 49.5

 

Mine are at 49.5 which is stock. Yours should be at 45.5 given that your spring is 4" narrower.

 

think it's gonna be perfect.

 

Building a 29 roadster. Here is chassis. 10 inch kickup in rear 4 in front