Speedway Motors high arch spring mounting

I was looking at rear spring mounts at Speedway Motors and clicked on their installation instructions for the high arch rear spring and was surprised at what I read. I have read here that generally Model A spring perches at mounted around 49" while Model T's are an inch closer. Speedway's spring is only five leafs and 39" from eye to eye but they say mount the perchs from 44" to 47" depending on sprung total weight of the rear of the car less rear end and tires. Has anyone followed these instructions? I can see a light weight car, like a t bucket, not needing as much spring tension as a heavier 32' Ford but moving the perch mount up to 5" seems extreme. Weight to width is below.

500lbs = 44"
750lbs = 45"
1000lbs = 46"
1250lbs = 47"

 

Don't buy that spring. Wait for the next swap meet in your area and pick up a Model A rear spring. You'll be happy you did.

 

Thats the spring i am using on my T. I put the pearch mounts at 44' even thought it should have been a little wider, but my rear end is so narrow i had to move them in so i could get a fitting on the wheel cylinders. The car hasent been running yet but the rear suspention seems to work good even with every thing mounted engine, trans, body.....

 

Looking through old posts and thought I would do a fallow up to help someone in the future. I put my T's rear perches at 44" per speedways instructions ,car was 500 give or take, spring was not under near enough tention. My rear spring was bottomed out on my spring perchs. I wouldent get the high arck spring again, seemed it sat way too high than it should have and could have gone lower with stock A spring. Hope this helps someone.

 

Want the truth..?? Dont buy from Speedway...theres more then enough people on here who sell springs and can give you a STRAIGHT answer.Contact Todd from Posies..( I did,awesome guy to talk to...KNOWS his stuff..) also call Pete and Jakes or other dealers on here.I for one will never buy from Speedwad again,more of a hassle to send stuff back because the crap they sell is junk.I save my money and buy from guys listed here.

 

I'm using speedway's spring and axle brackets on my roadster.I mounted them at the recommended width and they came out fine.Dont forget you have the length of the two shackles to figure in.So with a 39'' spring,46" mounting distance,and 4" of shackles{2" per side}you are only spreading the spring 3"
T-roadster-love that avatar!!!

 

I been using the A spring and crossmember from So-Cal on the last few buggy rear Quick Change rears I've done. Did one in my last roadster and it worked fine.