Tusk spring compressor

[firstyammerha]

I purchased one of these last week to compare to Bluntlunchboxes AlphaMoto compressor that he mentions in the CBR600RR shock swap thread. I applied it to a GSXR 1000 shock  spring that I believe to be in the mid 400lb./inch rate range with the intention of swapping the FZ07 spring for it. The compressor worked fine but did have me breaking a sweat cranking down on it. Made me think of those twin shock bikes of old and their 80-100 pound rate springs. No compressor needed on them! Moved to the FZ shock and applied the compressor to it and got about five minutes into compressing that spring when one of the two jaws which hook onto the spring wire popped out of the steel channel that it rides in. Struggle ensues to disengage the compressor from the spring but I was able to release it. At first I thought the tool was out of commission but I was able to bludgeon the jaw back into the channel and blacksmith hammer the channel back into shape so the jaw was contained in it again. I reapplied the tool to the  spring and it held up long enough to get the FZ spring off the shock and let me place the GSXR spring on the FZ shock. The tool is pretty beat up and I am asking for a replacement. My thought is that this tool needs to be beefed up to work on springs in the 500lb. + range and should be marked with limitation information. The Suzuki upper spring collar matched up to the  Yamaha shaft and upper eye really close so that I don't worry about the spring coming loose. The Yamaha lower spring seat is narrower than the od of the Suzuki spring but using a Suzuki spring seat on top of the Yamaha spring seat fills in the gap. Suzuki uses a threaded body on this GSXR shock to adjust preload while Yamaha uses a ramp preload adjustment method.   

[blackout]

Yah, the FZ07 spring is quite stiff at around 625 lbs/inch.  It needs a stiff spring because of the poor motion ratio of the linkage setup.  Not a big deal, just needs a stiffer spring than many bikes.  I know a racer who runs a 550 and 575 lb/in spring on his BMW S1000RR.

[shinyribs]

I have that same compresser and the sheet metal guide frame is a joke. Waste of material, and a false sense of security IMO as it prevents you from being able to stabilize the tool properly. Due to the spiral shape of a spring the two hooks can't stay parallel to each other anyway.

 

I jerked the sheet metal off and binned it. Just use the tool and hold the bottom hook with a wrench to stabilize the hook from twisting. Done over a dozen shock rebuilds like this and no issue so far. 

 

 

[Cruizin]

Tusk makes some great generic parts, and some not so great generic parts. 

[blackout]

Unfortunately, this is how I had to remove the spring.  A plate is required that has a hole sized so that the spring hat fits through but the spring does not and can be compressed by the shop press.

 

Part of the problem with the Nitron shock was that the shock body had limited threads to remove more preload.   Other shocks I'm sure have more threads available.  The Nitron needed this tool to safely preload the spring during assembly.  Not what I am used to when dealing with race car shocks during those days.

[firstyammerha]

I'm going to investigate other methods of removing and installing springs since this is one of my "things". A bench hydraulic setup would be great. The GSXR spring worked great on a 30 mile ride yesterday soaking up short 3" tall heaves in the pavement that caused the fork to send a sharp shot to my handlebars. The bike rolled in and out of a long shallow pavement depression without harsh bottoming or kicking my butt off the seat. The shock bumpstock showed that I used full travel during the ride.The only drawback was the tendency to slide the rear end out in a long gentle sweeper under power. A little more stiffness might be a good compromise, like 450lbs. Think I'll try the FZR600 spring next. It's 492lbs. by my spread sheet.

[firstyammerha]

Blackout, you couldn't turn the preload rings down and off the body threads? That is how I removed the GSXR spring from its shock body. Once the spring was lowered to the bottom eye, there was space to allow removing the upper spring seat/collar. I had a Nitron R1 a few years ago but never needed to change the spring. It was practically right out of the box-a little less preload and a couple more clicks on the damper adjustment wheel set it right for me.