Your '77 forks are unique. They were the 1st year for the 35mm forks. Their damper rods, tubes, and springs differ slightly from the later models. If they are still original, you should find a preload spacer already in there (about 40mm long). To stiffen them up, you could just replace that with one maybe 15 to 30mm longer. Another option would be to install the later adjustable caps. They would add an additional 36mm of preload at their lowest setting, each step up adding another 10mm .....
The oil weight spec for your forks is 20. All the later versions speced 10 weight. This may be due to the beveled holes in the damper rods. I spoke with an engineer buddy of mine and he told me beveled holes flow more .....
I feel the tubes and damper rods in the '77 forks are of a higher quality than the later ones. Notice how the '77 damper rod shines in the pic above - it's polished. They also mount that fiber wiper ring in a separate metal ring that 'floats" on the rod. The fork tubes retain the bottom bushing via a snap ring where the later tubes simply crimp it in place.
If your springs are stock, they should be about 472mm long. This is 10mm shorter than the later model springs.
I did a lot of experimenting last summer to see what the best fork assembly I could come up with was using all stock parts. I combined '77 tubes and damper rods with '78-on springs, adjustable top caps, and top out springs. I also Minton modded the damper rods. This "hybrid" set works quite well but the springs are still a bit soft. I either need to add some more preload or maybe try some heavier oil (or maybe both).
The oil weight spec for your forks is 20. All the later versions speced 10 weight. This may be due to the beveled holes in the damper rods. I spoke with an engineer buddy of mine and he told me beveled holes flow more .....
I feel the tubes and damper rods in the '77 forks are of a higher quality than the later ones. Notice how the '77 damper rod shines in the pic above - it's polished. They also mount that fiber wiper ring in a separate metal ring that 'floats" on the rod. The fork tubes retain the bottom bushing via a snap ring where the later tubes simply crimp it in place.
If your springs are stock, they should be about 472mm long. This is 10mm shorter than the later model springs.
I did a lot of experimenting last summer to see what the best fork assembly I could come up with was using all stock parts. I combined '77 tubes and damper rods with '78-on springs, adjustable top caps, and top out springs. I also Minton modded the damper rods. This "hybrid" set works quite well but the springs are still a bit soft. I either need to add some more preload or maybe try some heavier oil (or maybe both).
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