Hot Rods Rear model a spring perch dimensions

Hey guys. Just mocking up my rear on my model a. I have a model a rear crossmember and spring. I’m mounting the spring behind the axle on a Ford 8” rear.

Everything I’m finding in here seems to be the dimensions for spring over/stock which is 49.5”. The issue is my rear width backing plate to backing plate is 49”.

What am I missing here? Any help would be great.

Here’s some pics of my chaos.


Sent from my iPhone using H.A.M.B.

 

Unless Henry Ford made your spring, how do you know it's the same measurement? Looks like a new spring to me, with lots of arch.

 

you will need to put a load on to see what you have. right now, naked, the shackle angle looks correct. get the fat girl next door to sit on it and see where you end up

 

49.5 is correct, the spring has to be spread when installing it. It looks like you bolted the spring in place and set your perches to it unloaded, that won't work very well once weight is applied. You'll have to put the perches as close to the backing plates as possible and see where you're at but I think a new housing and axles is in your future. I made the same mistake way back in the day.

 

You can simulate a lot of load with a couple of ratchet straps / tie downs. No need to disturb the overweight girl next door. I'd suggest you gusset the brackets beforehand though.

Looks like there could well be a lot of clearance over the axle - was that intended?

As mentioned by Pocket Nick, the spreading of the spring on installation - you'll know whether you did this or not as it's a heavy and quite daunting experience. I use ratchet straps and you've really got to work them hard to be able to get the shackles in. At rest they remain under a lot of tension! Hence the aforementioned gusset.

Narrower springs are available - Posies and SoCal - couple of inches or so narrower. Depending on the axle width it is likely that the shackles will need to me perilously close to the brake backing plates, and I'd say much closer than yours appear to be. Indeed, it looks to me like you could move your brackets outboard by 1 1/2" or so per side. This will likely put you in the ballpark with the existing spring. You know about that from the workout when refitting the spring. Did I mention the gussets?

Chris