Spring plate angle - '71

BK911 · BK911's Garage

Using stock torsion bars, the Ferch method says I need the spring plate angle around 37 degrees. At this angle the spring plate blocks the rear bottom torsion plate mounting bolt hole, and wont allow the installation of the bolt.

Should I keep this bolt out until some weight is on the car?
Maybe this is the reason for the removable thick washer / boss thingie?

I dont remember this being an issue before.

Flieger · Flieger's Garage

That sounds fine to me. I have been running with only three bolts on one side because there is a broken off tap in one of the holes for some reason.

mcaterino · 02-07-2012, 05:11 PM

I recall the same issue. I just torqued down the three I could do, then jacked the spring plate up (I don't remember if it was before or after attaching to the banana, shouldn't matter), and then stuck the last one in there.

Mike

Porboynz · Porboynz's Garage

The perfect height for my 1972 with the stock torsion bars refitted was when the spring plate obscured half the mount bolt hole. I simply fitted 3 bolts then jacked up the end of the spring plate until I could fit the 4th bolt, don't forget the spacer.

jpnovak · 02-08-2012, 08:14 PM

Yep, the load is distributed fine with 3 bolts until the car is on the ground. You can always put a jack under the trailing arm and "load" it higher to clear the bolt. That is usually the last bolt installed on the rear suspension work.

ddubois · 02-09-2012, 05:13 AM

I just finished installing new ER front bushings and resetting my spring plate angle on my 71. I was previously at 31 degrees and decided on 35 (euro) using the Ferch calculator. I think 37 would be a bit high. I ended up with 26" fender lip height with my 195/75-14 tires. I was able to easily put in the 4th bolt by simply jacking the plate before connecting to the swing arm. Also, I left all four cover bolts loose, jacked up the plate, then tightened all four with the plate jacked. My reasoning was that I wanted the plate bushings locked down in the normal position assuming they don't rotate relative to the body and plate once seated. I bonded the bushings to the plates using Permatex 16B black silicone adhesive and let them cure for several days before installing.