I had a nagging idea that since the SA strut inserts are longer, the strut housing may be longer in a favourable way (like providing a better roll center).

Luckily I have an extra set of 79 struts and 85 GS struts kicking around. I measured them both with a tape measure: bottom of spring perch to strut tube top, bottom of perch to hub, bottom of perch to bottom of tube.

They appear to be externally identical. Has anyone else measured these struts that can confirm or deny my findings?

 

the SA tube is like 14" long and the FB is like 12.5"

 

Is that external dimensions? I realize the strut cartridges are shorter for FB's.

I suppose the difference could be from a couple places:

1. I measured with the hub and brakes attaches, so the strut tube section of te strut assembly for the SA may sit deeper in the hub casting than the FB.

2. My SA struts have tokico blues in them and the person who fitted them modified the strut tube to fit FB cartridges.

Anyone have any ideas which may be the case?

 

#2, or you just have 81-82 struts in there.

if you have SA and FB strut tubes next to each other its a pretty obvious difference

 

Must be 2, the struts have wedge brakes on them and welded-all-around spring perches. When I have a chance I'm going to measure the '79 struts that are on my '81(former owner liked his SA better).

This brings my initial curiosity back; is the additional SA strut tube length in a place that changes the suspension geometry (between perch and hub or hub and ball joint) or is it above the spring perch?

 

SA strut tube length is about 15 3/4" Spring perch is about 4.5" down
FB strut tube is about 15" Spring perch is the same 4.5" down as the the SA.

Just measured.

As far as the FB Tokicos in the SA strut housings: I needed to put a spacer on the bottom of the housing for the FB struts to fit the housings properly.