We’re excited at the potential the addition of a new pipe unleashed in our Sportster project bike. The Vance & Hines RSD Slant Exhaust
gave the 2004 1200 Custom a much-needed boost in both aesthetics and performance. It was the first step in resurrecting an old Sporty, out with the old, in with new. Its old parts weathered and worn, it was nigh time to hot rod it up.
As we look to improve the all-round performance of the ’04 Sportster, updating the suspension on the back end was a priority. The old sticks were soft, slow to rebound and quick to compress. It didn’t take much to blow through the stroke on the back end. Throttle up to around 85 mph and the bike started to get a little loose. We also wanted the Sportster to continue to be able to ride two-up, and the shortcomings of the springs with a passenger aboard quickly become exacerbated.
To remedy the situation, we sourced a set of Progressive Suspension
970 Shocks for Sportsters. The twin tube arrangement features a main chamber with a big deflective disc valved main piston and a piggyback reservoir with a high pressure gas chamber. A deflective disc valved compression piston serves as the interface between the two. With a forged aluminum body, 6061 aluminum tube, and heavy duty spring, the 970s are constructed to last.
The Progressive 970 Series Shocks feature a two-chamber system connected by a deflective disc valved compression piston. They are adjustable for both preload and compression.
Gotta love being able to reach down and dial in compression with a few simple clicks.
Progressive says the 970 series feature a “high pressure gas monotube design with deflective disc damping routed through two unique circuits.” This means the big piston has discs on both sides to move the oil. The discs have small perforations in them so they flex when the shock compresses and rebounds. As it flexes, it moves oil from one side of the piston to the other. The full floating piston separates the nitrogen gas charge from the oil.
Peeking at the installation instructions, the install should be fairly straight forward. The bike’s rear end needs to be jacked up so the rear tire is off the ground. The Progressive directions defer to the bike’s service manual to remove the stock shock. This is as simple as removing two bolts, the lower locknut first and then the top. Swapping out one shock at a time is recommended, the second one acting as a support and standard measurement. Problem is, the new 970 Series Harley Shocks we’re installing are 13-inch, 1.25-inches longer than stock. This means we had to drop both sides in order to line the new ones up. The stock mounting bolts are retained for use with the shocks. The top bolts currently on our Sportster are 'Frankenbolts' and combine with a spacer to stick out over an inch. We suspect they’re leftover from the saddlebag set-up the prior owner had on the bike, but we didn’t have replacements at the time of install, so back on they went. That will change shortly.
Before tightening down the new shocks, we ran through a quick list of checks. First was tire-to-fender clearance, followed by making sure they cleared the frame, belt ,belt guard, and calipers. A little Loctite went on the upper shock bolt while both top and bottom were tightened down to 45 lb-ft. With the new shocks in place, we hopped on the bike to sample the stock settings before adjusting the sag. The factory settings were way too soft for a 220-pound rider, so we loosened up the locking ring with the spanner wrench supplied with the kit and gave it a few clicks in to firm it up. The beauty of the 970s is they allow riders to dial in compression, too, which is even easier thanks to a hand-adjustable knob on the piggyback reservoir. We took the Sportster out for a few laps around the block before bringing it in a few clicks, too.
The differences between the worn-out stock shocks and the Progressive Suspension 970s are night and day. The old shocks were still in their stock settings and we doubt anybody touched them since they were put on the bike. With the new Progressive sticks, the back end no longer feels squirrelly. It used to feel a little loose when we got on the throttle but the new shocks keep it more inline and composed. The dreaded potholes we unavoidably encounter during our daily commute on I-5 no longer punish our spine as what formerly blew through the stroke is now a quick flex and spring. The taller shock jacked up the back end like a lifted Nova and gave us more turning clearance, too. After we put on the new pipes, we began scraping on right hand turns, something we didn’t do with the old exhaust. By lifting the back end of our
Quick and easy two-way adjustability, preload and compression, is one of the 970s strong suits.
bike, we’ve gained side-to-side clearance. The new shocks have given us a bike that dips down lower and feels more stable doing it. It’s stability at higher speeds has also greatly improved.
To say we’re impressed with the Progressive Suspension 970 Sportster Shocks is an understatement. It definitely rides more like the hot rod we’re envisioning. At $999.99, they’re coming off of Progressive Suspension’s top shelf. But it’s OK to splurge every now and then, especially when the performance gains are ten-fold. Add ease-of-use to the equation and the ability to quickly dial in the ride to personal preference and you’ve got a winning combo. Now we can’t wait to get the Progressive Suspension monotube fork lowering kit on the front, too.
Find Progressive Suspension 970 Series Piggyback Shocks at the Motorcycle Superstore
- MSRP $899.99.