Frankenstein 550

[Normandy10]

Recently acquired, 1975 GT550. Front end, wheels, disc brakes and swing arm I think from a 600 or 750 Katana. Swing arm was modded for twin shocks, and pushed the wheelbase out to about 62”-63”, and rear seems pretty low. Trying to get back to better geometry. Picked up an Ohlins set-up with ride height adjustment rod from a Hypermotard 1100 EVO, looks like it will be an easy one to resto back to monoshock, but need a dimension, like from the center of the rear axle to the center of the upper rear shock stud so I can build the monoshock mount accordingly, would like to set the stock rear height in the middle of the Ohlins adjustment range. Anybody out there with a stock 550 that could pull a tape measure and let me know that dimension? Most appreciated,

[Craig380]

Hi and welcome.

The back end of the triples always sat pretty low anyway. On my old GT380 I put longer shocks on to raise the rear and sharpen the steering, it worked well.

Because your frame and suspension is so heavily modded, you might be better served just setting the bike the way you want it. The original 550 shock length won't mean much as you already have a longer wheelbase, and forks are probably a different length from the lower triple to the axle too.

[Normandy10]

626CDF86-6926-4FDD-980A-12CA6E954AB9.jpeg

The stock shock length does me no good as the swing arm is not stock. Distance from the axle center to a benchmark on the rear frame, such as the upper rear shock mount stud will give me the original height of the rear of the frame, which affect the rake of the front end. Just looking for a starting point so I know how high to build the mounts for the Ohlins set up.

[Normandy10]

534EB376-B6A0-4960-A62C-689FCBF228C2.jpeg

[Normandy10]

Couple views of the Ohlins mocked in place so I can fab mounts.