My twin-shock swingarm arrived yesterday. It’s not quite the bolt-up replacement I was hoping it would be, but it will work if I decide to go that way.
Compared side-by-side, the DT175 swingarm is negligibly longer than the YZ, but the width between the axle plates is the same. I will need to enlarge the axle slots for the larger Suzuki rear axle, however.
A bit more significantly, the pivot bushing sits just a couple centimeters further out on the right-hand side:
This really surprised me, because I thought I’d verified that all the pivot hardware was the same. I should have paid closer attention. Here’s the cross-reference screen I was looking at:
If you look closely, it lists the 1976 YZ125C (my swingarm), but then specifies at the end of the line that it’s actually referring only to the two prior model years, ’74(A) and ’75(B). I assume this is because all three years were originally included together on the same microfiche card. In reality, the two swingarms use different inner bushing sleeves.
The good news is that the swingarm does bolt up, and will work fine with very minor modifications.
I either have to remove a bit of the DT175’s pivot tube to fit my existing YZ parts, or tweak the pivot bolt and spacers to match the new swingarm’s dimensions. I’m leaning toward altering the swingarm because 1) I already purchased a brand-new YZ inner bush, and 2) that would give me the option of swapping between the two suspension configurations fairly effortlessly at any future point.
I finally trimmed the rear mounting boss on the crankcase halves for clearance. I had been putting this off for a while now, but it was going to be necessary regardless of which swingarm I go with. Fortunately, it was fairly quick and painless: I just clamped each half in the drill press and used a hole saw to make the cut. The pilot bit wasn’t boring into anything, so the teeth on the hole saw chattered a bit as I started the cut, but overall it worked fine.
I like the idea that I can still resurrect the monoshock configuration at some point. I’ve already done the majority of the hard lifting on it; the only outstanding issues are carburetor placement and getting a shock with acceptable damping/spring rates. Since those could turn out to be fairly significant sticking points, for right now I’m glad to have a simpler, more straightforward alternative.
