MikeG Posted July 30, 2007 Share Posted July 30, 2007 I got my Penske and installed it yesterday. It was built with a 1000lb Hyperpro spring and seems to work very well. Came directly from Penske through GMD Computrak. I don't know how much preload it has--might have more preload than Traxxion uses with their 1300lb spring. I guess there are different ways to achieve the same results. The rides and handling is very good--took away all the sharp edged bumps, but still taut. Good product no matter who you buy from. MikeG Link to comment Share on other sites More sharing options...
shayne Posted August 1, 2007 Share Posted August 1, 2007 I got my Penske and installed it yesterday. It was built with a 1000lb Hyperpro spring and seems to work very well. Came directly from Penske through GMD Computrak. I don't know how much preload it has--might have more preload than Traxxion uses with their 1300lb spring. I guess there are different ways to achieve the same results. The rides and handling is very good--took away all the sharp edged bumps, but still taut. Good product no matter who you buy from.MikeG My understanding is that different preload does not change the spring rate. Spring rate is a separate issue. Link to comment Share on other sites More sharing options...
MikeG Posted August 2, 2007 Share Posted August 2, 2007 The force a spring exerts is equal to K multiplied times x, where K is the spring constant(lbs/in), and x is the deflection from it free length. As you squeeze a spring the force goes up linearly until you reach it's elastic limit, where it permanently deforms. If you deflect a 800lb/in spring by 1", it will take 800lbs to do it. If you preload a spring by 1", then deflect it another 1", the total deflection will be 2" and the force will be 1600lbs. That is why you add preload when you ride with a passenger. So, preloading a spring does not change it's spring constant, but it does increase it's force for additional deflection. MikeG Link to comment Share on other sites More sharing options...
shayne Posted August 5, 2007 Share Posted August 5, 2007 That is what I meant, I don't have the technical ability to explain it though. :wheel: Link to comment Share on other sites More sharing options...
Guest Posted October 28, 2007 Share Posted October 28, 2007 Guys: I have been going through the same dilemna myself this week concerning my shock spring also. I have a Penske double adjustable shock on my VFR that Traxxion set up for me a couple of years ago. They installed a 1400# spring on it when I ordered. I was a really big guy at the time. Luckily, I've lost about 40-45# in the last year and the rear end of the VFR is getting to ride a little rough. I'm down to 245 now. I've been wondering if it is time to go to a lighter shock spring. I've talked to Traxxion, RaceTech, Lindemann, and indirectly to AfterShocks. Phil has recently been involved in a motorcycle accident so he is not getting to put as much time in the shop as normal. I talked with Sarah in his shop. They all agreed (with the exception of RaceTech), that a 1250-1400# spring is the correct spring. I spoke with Jim Lindemann Friday and he suggested that I try the "10/20" test. If the bike has the correct spring on it, it should have 10 mm of static sag (without the rider) and then an additional 20 mm sag when the rider climbs aboard. If you get those numbers, you have the correct spring. As you guys get to know me through my posts, you will learn that I have a propensity for thinking some things to death. I do enjoy the tinkering and modifiying my bikes just about as much as riding them. One thing I've been thinking about concerning this subject: Is Racetech/Lindemann/Aftershocks/Traxxion too race oriented? As an analogy, do you think that even though both types of bikes are out and out race bikes, don't you imagine there is a completely different setup for an Isle of Mann type bike vs. a MotoGP bike? The Isle of Mann doesn't look near as smooth as Laguna Seca. I live the metro Atlanta area. I've either raced or done track schools at Road Atlanta (both original and current), Savannah, and Jennings in this area. I can tell you for a fact, those tracks a lot smoother than the roads and highways of north GA (Highway 60, Wolf Pen Gap Road, etc). We run one tire setup/pressures for track days vs. the street. Would we not do the same with spring rates and compression/rebound rates? One thing I will say for Traxxion. Mike is the man to deal with. Calling a spade a spade, Max runs the business but Mike is the one really doing the work. Don't mean to step on your toes Max, but I've spent a ton of money with you guys over the years and that is my impression. One last thing and I will shut up. Fork springs are a more apples to apples thing to compare from one bike to another. Due to mechancial linkages, moments, pivot arm lengths, etc. you can't make the same comparion of bike X needs an X # spring and bike Y needs a Y # spring. If the linkages are engineered differently, you're comparing apples to oranges. For instance, Mike built my Penske for my VFR with a 1400 # spring. He built the Penske for my ST1300 with a 1000 # spring. Springs are relatively cheap. Hyperco springs can be purchased from a racecar oriented website like Performanceshock.com for $75-85 each. They have a ton of different length, diameter, and stiffnesses available. Penske shocks seem to use 2.25" id springs either 6 or 7 inches long. Springs on a Penske are a piece of cake to change. Takes maybe all of 5 minutes and absolutely no special tools. That is, once you get the shock off the bike. Time to shut up and get the metric tape measure out. "Oh honey, could you help me in the basement for a few minutes?" I'll report my results. P.S. Good luck to Phil Douglas. Hope you heal up well and soon. Link to comment Share on other sites More sharing options...
Guest Posted October 28, 2007 Share Posted October 28, 2007 From Pete's wife: "Oh shit, are we going to see if you're sagging again or whatever?" Link to comment Share on other sites More sharing options...
Guest Posted October 29, 2007 Share Posted October 29, 2007 One last thing I forgot to add about the Penske shock. Spend the few extra dollars and get the Torrington radial bearing that fits between the preload adjuster and the spring. With a 1200-1400# spring, there is a lot of friction there. You will wallow out the adjustment holes in a hurry trying to turn the preload collar if you don't have the radial bearing. They'er not all that expensive and worth every penny. Makes turning the preload collar as smooth as butta. Link to comment Share on other sites More sharing options...
Guest Posted October 29, 2007 Share Posted October 29, 2007 OK, did the Jim Lindemann measurements. I have 4 mm of static sag (no rider) and 31 mm of dynamic sag (with me on board). I think I will try a softer spring. Based on what another member of similar weight has said he is running, I am going to try a 1250# spring. Link to comment Share on other sites More sharing options...
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