Yamaha Truly Unlimited UTV - Rustfish Racing 2921

kornfed

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Looks like this is going to be a good thread with some interesting conversations...going to have to stick around a bit...i will probably learn something...always enjoy when i get to learn the easy way!
Funny. Yes always good to learn the easy way. Hopefully we get this pretty close to sorted day one. We are not going to have any testing time before UTV Worlds. It is a mad dash to get it on the ground. Still waiting on some parts and there is a lot of work to get done. Who would of thought a custom 1 off car would be hard to finish in 10 weeks. YIKES...!!!
 

kornfed

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Ok here is the next round that has the front end being brought to the chassis. I had a quick chat with Will and there are a couple of elements he wanted to point out. There is less than 1/8th inch on the bump steer tolerance. The anti dive geometry is very slight in the suspension, but he has put castor and rake into the bulkhead. This is used in larger cars and keeps the dive to a minimum. Also with the dual shocks, there is a lot of variability so it will ride very neutral. Again, testing will be key here. The guys are doing final CV angle calcs and wheel travel calcs next. We think we know, but want to make damn sure. Don't want to break the 31 degree no go zone.

Will get this detail and pass it along as we go. Enjoy and let us know what you think... Remember, see something, say something. :)


IMG_0872.jpg IMG_0875.jpg IMG_0876.jpg IMG_0877.jpg
 

kmb760

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Holly Molly! Are the front axles being exposed before the lower A-arms going to be a issue
 

kornfed

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Good point, picture of the mock up we have here doesn't show it too well, but the approach angle keeps the arm pretty much aligned with the axle. It will be a little exposed at the end, but not that much. Also we have a material we use that is super tough that will go in front of the boots. Talking with Will, he thinks it will be fine. He just said Kent needs to keep it out of the rocks, it's not a jeep. :)

Here are a few more pictures and some information. The CV angles are 27 degrees on the rear and 30 on the front. The rear has some room to expand, but we are going to limit the travel and the angle at this time. Once we get some data from testing, we can move it up. Right now we are at 22" all around for wheel travel.IMG_0879.JPG IMG_0880.JPG IMG_0881.JPG IMG_0882.JPG
 

badassmav

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Dave, the craftsmanship is highly impressive! Everywhere. The effort put in is evident. Ok, there's your "attaboy", 'cause the car is really looking badass!
Really curious with all the effort put forth, why the stock engine and rear diff cradles were still used. I'm sure time played a part in that decision. Likewise, given the commitment set forth towards the front a-arms, it surprises me to see the use of the OEM spindles, and maintaining the rear steer configuration. It's been my experience when building around a rear steer layout, that there was always a sacrifice to be had either in the ackermann effect, or bump steer. In said configuration, desirable ackermann usually places the outer steering knuckle location too far inboard to accommodate good bump steer geometry. Then, move out the knuckle position to minimize bump steer, and lose ackermann. The positive thing that comes from rear steering bump steer, is that the tires bump inward, again adding directional stability and less wandering in the fast, deep rollers.
With that being said, I never had the luxury of using an interactive application (like Solid Works or similar) to calculate the possibilities, then run motion studies and be able to modify a design before it hits the shop floor. I also never used a center steer rack. If you say all is good, then all is good. I do however, have serious doubts that the integrity of the OEM front spindles and articulating joints will suffice consistent class 10 type performances without letting you down more often than you would like. Curious to see how that plays out.
Saw the new pics. I am in favor of exterior-spun alternators such as you are running, but have rarely seen one running off of the driveline that didn't either break or throw belts while under hard breaking . Being that you are an open book with your hard spent efforts (and thank you again for your grace), I will be happy to share the solution we found to keeping the drive belt on, and in one piece. I expect I may be preaching to the choir here, so excuse me if I come across as insulting your fabricators' intelligence.
I know many of the top truck and buggy teams were implementing this technology , at least when I was involved in the sport.
So, for the lay-mans out there; UTV's usually need to add aftermarket charging devices like an alternator to supplement the output wattage of the factory magnetos, which were only putting out 400-600 watts in my day. Simple math says watts/volts=amps. Therefore a 600 watt magneto divided by 12 volts, only supplies you with 50 amps of available power to run your entire car. Maybe that's ok in short daytime races. But once you add in cooling fans, Parker Pumpers, robust fuel pumps etc., you quickly use up all available power and die (and you still haven't addressed your lighting needs). Since UTV's normally do not have exterior belt drive systems on their motors, one must look elsewhere to attach an aftermarket charging device, such as an alternator. Usually, it is somewhere on the driveline. (unless your Badass Johnny Angal, and build your own setup to run off of the crankshaft!) Truck teams run these devices off of their drivelines as not to rob any hard earned horesewpower from their motors. It is more efficient to take advantage of leverage provided via gear ratios, so usually, it's on the driveshaft. The problem lies in when the driver locks up the brakes, the driveshaft immediately stops turning, along with the wheels/ tires. Well, no one told the alternator that was coming up. The alternator pulley wants to continue rotating while the belt attached to the locking driveshaft does not. SNAP, or FLING it goes!
The solution is not to run a v groove belt that will slip, but run a cog belt/pulley system that will not slip, and have a free wheeling pulley installed on the alternator. Similar to the rear hub on your bicycle, that when you stop pedaling, the crankset doesn't keep rotating with the rpm of the rear wheels.

Ok, back to you Dave. I also had to add a sturdy tensioner in the way of an idler pulley to preload the drive belt enough so that when it plays the mediator between stopping or continue on rolling, there is enough slack to absorb the immediate energy loss in the belt without ripping teeth off of the cogs, or flinging it off of the pulley. I can forward to you the equation I came up with to calculate pulley diameters considering alternator output at a given rpm, gear ratios of the tranny and diffs, and engine rpm. Just need to be wary okf the belt tension, and the driving shaft seal and bearing ability to withstand it. I think I used a tensioner off of a 4.0l Ford Ranger.
Oh, one correction: We ran a 4 or 5 groove serpentine belt, not a cog type.
Sorry, I don't mean to hijack your thread. Just saw an opportunity to educate any one wanting to follow the depth of your thread. I like it that you're not secretive about what you are building, and you are modest enough to listen to input. After all, no one is breaking down any doors here. Like an old boy told me when I would patronize him in my early days, "It ain't nothin' that hadn't been done before".
 
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zambo

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At what point does a desert car stop being a UTV and start being something else entirely?
 

badassmav

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I think that transition already happened around 2013 when the 3 major mfgr's all offered long travel, wide-stanced cars. At that moment, they became machines designed and purpose built, and marketed for a different use. They were no longer made for use on the farm, or elsewhere in agriculture, or even on the greens for that matter. The visionaries convinced the bean counters to go all in, and look where they landed now. I think Polaris had around 4 billion dollars in sales the year these monsters changed shape. Joey can jump in and add clarity here. Yet, there is still the hard core "golf cart" accusers out there, with their heads SO FAR UP THEIR ASS they can't see the light shining on their blind faces! Golf cart-WALMART!
 
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kornfed

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Dave, the craftsmanship is highly impressive! Everywhere. The effort put in is evident. Ok, there's your "attaboy", 'cause the car is really looking badass!
Really curious with all the effort put forth, why the stock engine and rear diff cradles were still used. I'm sure time played a part in that decision. Likewise, given the commitment set forth towards the front a-arms, it surprises me to see the use of the OEM spindles, and maintaining the rear steer configuration. It's been my experience when building around a rear steer layout, that there was always a sacrifice to be had either in the ackermann effect, or bump steer. In said configuration, desirable ackermann usually places the outer steering knuckle location too far inboard to accommodate good bump steer geometry. Then, move out the knuckle position to minimize bump steer, and lose ackermann. The positive thing that comes from rear steering bump steer, is that the tires bump inward, again adding directional stability and less wandering in the fast, deep rollers.
With that being said, I never had the luxury of using an interactive application (like Solid Works or similar) to calculate the possibilities, then run motion studies and be able to modify a design before it hits the shop floor. I also never used a center steer rack. If you say all is good, then all is good. I do however, have serious doubts that the integrity of the OEM front spindles and articulating joints will suffice consistent class 10 type performances without letting you down more often than you would like. Curious to see how that plays out.
Saw the new pics. I am in favor of exterior-spun alternators such as you are running, but have rarely seen one running off of the driveline that didn't either break or throw belts while under hard breaking . Being that you are an open book with your hard spent efforts (and thank you again for your grace), I will be happy to share the solution we found to keeping the drive belt on, and in one piece. I expect I may be preaching to the choir here, so excuse me if I come across as insulting your fabricators' intelligence.
I know many of the top truck and buggy teams were implementing this technology , at least when I was involved in the sport.
So, for the lay-mans out there; UTV's usually need to add aftermarket charging devices like an alternator to supplement the output wattage of the factory magnetos, which were only putting out 400-600 watts in my day. Simple math says watts/volts=amps. Therefore a 600 watt magneto divided by 12 volts, only supplies you with 50 amps of available power to run your entire car. Maybe that's ok in short daytime races. But once you add in cooling fans, Parker Pumpers, robust fuel pumps etc., you quickly use up all available power and die (and you still haven't addressed your lighting needs). Since UTV's normally do not have exterior belt drive systems on their motors, one must look elsewhere to attach an aftermarket charging device, such as an alternator. Usually, it is somewhere on the driveline. (unless your Badass Johnny Angal, and build your own setup to run off of the crankshaft!) Truck teams run these devices off of their drivelines as not to rob any hard earned horesewpower from their motors. It is more efficient to take advantage of leverage provided via gear ratios, so usually, it's on the driveshaft. The problem lies in when the driver locks up the brakes, the driveshaft immediately stops turning, along with the wheels/ tires. Well, no one told the alternator that was coming up. The alternator pulley wants to continue rotating while the belt attached to the locking driveshaft does not. SNAP, or FLING it goes!
The solution is not to run a v groove belt that will slip, but run a cog belt/pulley system that will not slip, and have a free wheeling pulley installed on the alternator. Similar to the rear hub on your bicycle, that when you stop pedaling, the crankset doesn't keep rotating with the rpm of the rear wheels.
Ok, back to you Dave. I also had to add a sturdy tensioner in the way of an idler pulley to preload the drive belt enough so that when it plays the mediator between stopping or continue on rolling, there is enough slack to absorb the immediate energy loss in the belt without ripping teeth off of the cogs, or flinging it off of the pulley. I can forward to you the equation I came up with to calculate pulley diameters considering alternator output at a given rpm, gear ratios of the tranny and diffs, and engine rpm. Just need to be wary okf the belt tension, and the driving shaft seal and bearing ability to withstand it. I think I used a tensioner off of a 4.0l Ford Ranger.
Oh, one correction: We ran a 4 or 5 groove serpentine belt, not a cog type.
Sorry, I don't mean to hijack your thread. Just saw an opportunity to educate any one wanting to follow the depth of your thread. I like it that you're not secretive about what you are building, and you are modest enough to listen to input. After all, no one is breaking down any doors here. Like an old boy told me when I would patronize him in my early days, "It ain't nothin' that hadn't been done before".
Ok so lot here and want to take the time to answer. I will do it in sections that I know and then get with Will tomorrow and get more detail.

First I will go over the driveline alternator. We have a similar set up in the Rustfish 1992 car. It is an alternator that is used on LS power and also used in Trophy Trucks with a free wheel pulley. We had Brian Deague do the design and work with Will on how to lay it out. We use a 4 grove belt and a tensioner out of a corvette. Works like a charm. We have never lost a belt and it is still running along. Actually on the original belt. You are spot on with your description of the issues. The new set up is a little simpler in the Yamaha and the space is a little tighter. Time will tell if this works. We are doing an additional bracket and will adjust the tensioner when we get to the final tuning.

On the drivetrain mounting, yes time was the consideration and we did some clever mounting and brackets to support the components. We are going to CAD the Chassis so the next one will be chromoly end to end. Most the stock stuff is just to hold the components and is reinforced. Perhaps phase 2 will get some added structure to deal with the power. Kind of a test and learn deal here.

On the OEM spindles that was a bit of a surprise to me as well. Two things played into that. First we have been talking with some folks and they had stated the stock ones have been very strong. Second was the CAD guy did the original design using the stock spindles. He said that the design with the new arms and Uniball angles worked perfectly. It would have been an option to increase the height of them, but with 22" of travel, it worked. Now when we move to the next phase, POWER, I am sure we will need to revisit the spindles and the CVs, but for now I think we are good. Again we will see.

The rear steering design is something I will have to discuss with the designer. This is a bit of a black box to us. This is what I know. The design has 1/8 inch bump steer tolerance. It accounts for Ackerman and the bulkhead rake, canter align to the anti dive geometry and it has 22" of travel at 30 degrees of CV angle. I have seen it cycle and it tracks really well. I guess this computer stuff works. We will see.

I like your point about it ain't nothin' that hadn't been done before. These techniques are well known and applied to many cars. This is hopefully the next evolution of the UTV as we come to the Unlimited 1 liter class era...

Phase 1, bring a truly competitive, unique and next level vehicle to the UTV World Championships. Phase 2, bring a monster to V2R... ;-)


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zambo

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I think that transition already happened around 2013 when the 3 major mfgr's all offered long travel, wide-stanced cars. At that moment, they became machines designed and purpose built, and marketed for a different use. They were no longer made for use on the farm, or elsewhere in agriculture, or even on the greens for that matter. The visionaries convinced the bean counters to go all in, and look where they landed now. I think Polaris had around 4 billion dollars in sales the year these monsters changed shape. Joey can jump in and add clarity here. Yet, there is still the hard core "golf cart" accusers out there, with their heads SO FAR UP THEIR ASS they can't see the light shining on their blind faces! Golf cart-WALMART!
Was that intended to answer my question? Perhaps I didn't phrase it correctly so let me retry. At what point would you tell somebody that the vehicle they want to enter in the UTV race isn't really a UTV and belongs in another class?
 

kornfed

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At what point does a desert car stop being a UTV and start being something else entirely?
I think this car is going to be a 1 liter race car that could be the formula for the UTV of the future. You take the actual off-road racing fabricators, like real ones and build something that takes into consideration all of the learnings from real off-road racing.

I think the manufacturers see this. Arctic Cat got RG involved. We are building a race ready Yamaha platform. Not invited by Yamaha, but who knows. I am sure Polaris and Can Am have something cooking with someone with real racing pedigree. It is inevitable. These things will evolve and desert racing fabricators are the natural brain trust to make it happen.


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zambo

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I think this car is going to be a 1 liter race car that could be the formula for the UTV of the future. You take the actual off-road racing fabricators, like real ones and build something that takes into consideration all of the learnings from real off-road racing.

I think the manufacturers see this. Arctic Cat got RG involved. We are building a race ready Yamaha platform. Not invited by Yamaha, but who knows. I am sure Polaris and Can Am have something cooking with someone with real racing pedigree. It is inevitable. These things will evolve and desert racing fabricators are the natural brain trust to make it happen.


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I dig the passion around here but you guys are giving me philosophical answers to what should be a straightforward question. Is any car with a 33" tire and a 77" track width and a 1 liter motor allowed to run as an unlimited UTV? Can you really run a car that, other than the engine and transmission, doesn't have a single UTV part on it?
 

kornfed

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I dig the passion around here but you guys are giving me philosophical answers to what should be a straightforward question. Is any car with a 33" tire and a 77" track width and a 1 liter motor allowed to run as an unlimited UTV? Can you really run a car that, other than the engine and transmission, doesn't have a single UTV part on it?
So this has been asked a lot lately. Here is my opinion. There are 6 or 7 complete six figure custom race cars in UTV now. Our Rustfish 1992 is a complete one off custom race car. It is fully custom and shares almost nothing with the RZR it is based upon except a few parts. It is almost like this new car. A little more stock, but not much. Is it still a UTV? According to the rules, yes.

The answer for this car and others like it is the Pro Unlimited UTV class. We are examining the rules and this car will meet those requirements. If BITD says it is a UTV, it is a UTV. The stock powertrain seems to be the baseline. If we had no restrictions, we would do a 1 liter power plant from a motorcycle and use type 1 parts from a 1600 or 930 from a 10 car.

Philosophically, I don't know, but we are going to build something that is really fast and falls within the rules. If we make this work and it dominates then maybe they will create a new class. Or hopefully the manufacturers will take up the challenge and this will just be an evolution for the sport. Pro Unlimited should be where people push the envelope and do crazy things.

We shall see...


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badassmav

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I'm just impressed on how quickly you guys are turning around so much labor. Probably a smart thing to wait til phase 2 to go all badass on the steering and spindles. Then, to have phase 2 ready for V2R, well that's quite the sharp curve to navigate. Good luck on that one. Come V2R in our rookie year, we were still ironing out vapor lock, charging, and exhaust issues.

When I decided on our build there was just no other option but all in, namely front steer conversion, and heavily modified spindles, it took our 10-11 week project, and made it a 13-15 week project. Yep, 3 extra weeks just to modify a couple of spindles, and relocate the steering rack. I was able to get away with using the stock spindles, but mounted on the opposite side of the car. By applying proper prep, then pre and post weld heat manipulation, and relocating the steering knuckle and ball joint positions, I physically and geometrically got exactly what we needed. One lesson learned was in trying to keep the stock brake caliper mounts, and respectively swapping sides with the stock calipers like i did with the spindles. Brake performance and life was severely reduced as the solid leading slider pin now became the trailing one, and the flimsy trailing pin had no business playing the role as the leading pin. Ended up running oem calipers off of the massive Renegade atv that were designed to be mounted in the position I modified the Maverick spindles for. Based on the pics, your stock spindles seemed to have enough beef to work with. The cost of all custom built spindles was prohibitive, as we had no machining or turning capacity, and would have to send everything out. Kinda hard when hand building everything to spec out drawings for precision spindles.
Off subject, are you going to be able to keep the motion ratios of the external bypass shock under 1.5?
 

kornfed

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I'm just impressed on how quickly you guys are turning around so much labor. Probably a smart thing to wait til phase 2 to go all badass on the steering and spindles. Then, to have phase 2 ready for V2R, well that's quite the sharp curve to navigate. Good luck on that one. Come V2R in our rookie year, we were still ironing out vapor lock, charging, and exhaust issues.

When I decided on our build there was just no other option but all in, namely front steer conversion, and heavily modified spindles, it took our 10-11 week project, and made it a 13-15 week project. Yep, 3 extra weeks just to modify a couple of spindles, and relocate the steering rack. I was able to get away with using the stock spindles, but mounted on the opposite side of the car. By applying proper prep, then pre and post weld heat manipulation, and relocating the steering knuckle and ball joint positions, I physically and geometrically got exactly what we needed. One lesson learned was in trying to keep the stock brake caliper mounts, and respectively swapping sides with the stock calipers like i did with the spindles. Brake performance and life was severely reduced as the solid leading slider pin now became the trailing one, and the flimsy trailing pin had no business playing the role as the leading pin. Ended up running oem calipers off of the massive Renegade atv that were designed to be mounted in the position I modified the Maverick spindles for. Based on the pics, your stock spindles seemed to have enough beef to work with. The cost of all custom built spindles was prohibitive, as we had no machining or turning capacity, and would have to send everything out. Kinda hard when hand building everything to spec out drawings for precision spindles.
Off subject, are you going to be able to keep the motion ratios of the external bypass shock under 1.5?
Motion Ratio? Dude who are you? ;-)

Do you race with us? I gotta see this Mav...

You have seen the shock mounts for the rear, 1.5 should be easy. They are loooong... Just need King to get them to the shop. How hard can it be. ;-)


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kornfed

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I figured it out... Hey Reid... Ok I now know what is going on. ;-)

I saw Marc a few weeks ago at Plaster with Airdam. Good to catch up. Hope you are well. Keep the questions and input coming. ;-)


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Rynomx785

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Off subject, are you going to be able to keep the motion ratios of the external bypass shock under 1.5?
First, bad ass build kornfed and I am thoroughly enjoying all the tech talk. Thank you for being open with everything.

Second, since this is a learning thread, :) How much preload is too much with an extreme motion ratio like on the front of a stock 1K or Turbo? I know I have heard on motion ratio that is 1:1 (or close to it) that your spring rates are correct when you have have to run 2-3" of preload to get to ride height. I was also to told that to divide by the ratio on higher ratio setups. So given a RZR is really close to 2:1, that would make the proper preload somewhere in the ballpark of 1-1.5"? Would you say that is correct Reid?
 
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CSG

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First, bad ass build kornfed and I thoroughly enjoying all the tech talk. Thank you for being open with everything.

Second, since this is a learning thread, :) How much preload is too much with an extreme motion ratio like on the front of a stock 1K or Turbo? I know I have heard on motion ratio that is 1:1 (or close to it) that your spring rates are correct when you have have to run 2-3" of preload to get to ride height. I was also to told that to divide by the ratio on higher ratio setups. So given a RZR is really close to 2:1, that would make the proper preload somewhere in the ballpark of 1-1.5"? Would you say that is correct Reid?
Personally I don't like any pre-load or very little so I am curious to hear some other peoples opinions on this.
 
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kornfed

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First, bad ass build kornfed and I am thoroughly enjoying all the tech talk. Thank you for being open with everything.

Second, since this is a learning thread, :) How much preload is too much with an extreme motion ratio like on the front of a stock 1K or Turbo? I know I have heard on motion ratio that is 1:1 (or close to it) that your spring rates are correct when you have have to run 2-3" of preload to get to ride height. I was also to told that to divide by the ratio on higher ratio setups. So given a RZR is really close to 2:1, that would make the proper preload somewhere in the ballpark of 1-1.5"? Would you say that is correct Reid?
Thanks for the nod. Bad Ass seems to be the theme here. :)

We have been talking about the preload a lot on our 1992 car and we have it fully sorted. It flies, but not without a lot of tuning. A lot. If anyone has seen this car move over whoops, it is impressive. Now, that being said, preload adjustment can cause a lot of weird side effects. One of the guys we are partnering up with has a new Can Am X3. This thing is awesome. We took it out and realized that they had remove some preload from the car when it was delivered. Davey had used a Cam Am tester while he waited for his car and it was spot on. But his newly delivered car was not working as well.

As it turns out, Can Am had removed some of the pre-load to lower the front end. We don't know why, but once we brought the car back up, added back preload, we came back into the sweet spot for the valving and spring rate. When you move around the preload, you do a couple of things, you move the timing for the secondary spring engagement which can have impacts on the valve to spring interactions. From the factory, cars are usually tuned pretty well. They know how this works. Then guys go and add preload and the cars jump all over the place.

I would say that if you have a stock vehicle, do not mess with the preload unless you really know what you are doing. You will coil bind and mess up valve and spring interaction. This will kill the ride. If you are going to buy a kit, talk to the builder about your vehicle weight and driving style and have them set it up. Or have a shop that specializes in the tuning do the work.

Reid will probably have a lot more to say, like diagrams and math, but this is the jist. :0)
 

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