1982 850 forks and a 1979 GS 1000

[jknappsax]

I'm looking at a set of 1982 GS 850 forks (tube diameter 37 mm) to see if I can use them to convert my bike to dual front disc brakes. I did a search, but did not find any kind of interchange list. The tubes should slip into my triples, but I don't know how the length is compared to my forks. The tubes on the 850 forks have some pitting, and I'm wondering if I can just change the lower to get the tabbing for the second caliper on the right side. Anyone have any insights? Thanks.

[Grimly]

I'm doing exactly the opposite - putting GS1000 stanchions onto an 850. The GS1000 tubes are ~17mm shorter, iirc. Apart from that, no problems with interchange of the lowers between them - the GS1000 forks I bought were single-disced and they're now fitted with GS850 twin-disc lowers. Remains to be seen how much of an effect the slight loss of height has, but in your case you'd be gaining that 17mm instead.

To avoid that; if your GS1000 stanchions are still unpitted, use the 850 lowers on them.