I hope you've stumbled upon this post at just the right time. A big, fancy box of coilovers has arrived at your door, and now you're wondering, 'How the hell do I set these up properly?' The internet is full of information, but much of it is only half-right or flat-out wrong. Who can you trust, especially for something as seemingly simple as setting ride height? Well, fear not! As a car enthusiast, engineer, and damper expert, I understand the struggle of trying to find trustworthy sources amidst a sea of conflicting advice. That's precisely why I've written this blog post, which focuses specifically on spring preload and ride height adjustment. In my research, I was surprised by the amount of misinformation coming even from the coilover suppliers themselves. This problem is exacerbated by the reduced available stroke that many coilovers come with, especially those designed for extreme lowering. So, let's dive in and clear up the confusion once and for all using basic data and calculations for verification.
The focus of this post is on coilovers that offer independent spring preload and ride height adjustment with the use of any linear racing springs on the market. If your coilovers only have a threaded spring seat adjuster and stiffer OE style springs, the problem is much easier and won't be covered here. I also want to highlight the variables that you should be thinking about throughout this process. These are:
First, let's review what I believe, based on a reasonable amount of internet searching, is the most common advice you'll find on how to set up coilovers. The gist of it is that, no matter what spring you selected or were provided, you apply 5-10mm of preload or just enough to keep the spring from moving around at full rebound then set your full rebound damper length to lock in this preload. You can find this in the BC Racing written instructions as well as here, here, comes so close but not quite, here, I think this "Dr." gets it but doesn't realize it and designed around it for some good shock travel reasons, and finally this is completely fucking wrong.
The same info seems to be presented endlessly and it all misses a key tuning parameter available to you when you have independent preload and ride height adjustability. That is of course tuning how much of your total stroke is used for jounce/bump/compression and rebound/extension at your ride height position.
So what are they doing? You can use the pic below to help visualize it. By putting 5mm of preload (left strut in pic example) in at the full droop position regardless of spring rate and then put the vehicle on the ground the wheel will compress an amount equal to ("Unsprung mass" / "Wheel rate") - "Preload travel".
What is my made up preload travel term? As I'm sure you're aware, when you preload a spring 5mm, the spring exerts a force and you have to impart an external force greater than that preload force to compress the spring any further. "Preload travel" is the amount of spring preload compression MEASURED AT THE WHEEL. I'm subtracting this from the equation above because the mass of the vehicle has to overcome this preloaded wheel before the mass starts to move the wheel up relative to the chassis. The solution to the above equation is now your available rebound travel AT THE WHEEL from ride height position and this is only tunable with independent preload adjustment.
At this point all the "experts" say you're good, just thread the body in or out to fix your ride height or thread your spring perch up or down with rear decoupled suspensions (different spring and damper motion ratios) like the BMW.
So you're ride height is set, maybe you even went through corner weighing, but how much friggin bump and rebound travel do you have? When I started this journey with my set of BC coils, I realized I had no friggin clue. I'm a professional racing and active damper designer. This is wildly unacceptable and I couldn't believe the companies peddling these products have nothing to say on the topic, as if they don't know...
Can you imagine an example where a set of coilovers was installed without any thought about this, the ride is harsher than the customer wanted, they complain like hell all over the internet, maybe even swap springs to a softer rate only to find its the same or worse? Countless examples... truly incalculable. Well when you have little to no preload at full droop you're more likely than not to have far less bump travel and far more rebound travel at ride height than a proper setup would which is not ideal for street driven cars.
Here's an actual example based on the rear BMW F30 and I'll go over the setup calculator in more depth on Youtube so please subscribe to get notified if you enjoy or benefit from this content. I am also working on building it into the website with the help of ChatGPT so you can use it for free whenever you need.
BMW F30 Rear | OEM | BC Racing Bad | BC Racing Good |
Spring Rate (lbs/in) | 426 | 672 | 672 |
Spring preload (in) | 1.391 | 0.195 (5mm) | 0.499 |
Total shock travel (in) | 6.157 | 5.118 | 5.118 |
% of total stroke for bump @ RH | 55 | 46 | 55 |
Bump travel @ Ride Height (RH) (in) | 3.386 | 2.379 | 2.815 |
Rebound travel @ RH (in) | 2.771 | 2.739 | 2.303 |
Well hooooly shiza. Who wants more rebound travel than bump travel on a lowered street car?????????????????????????????????????????????? Did you realize what you were getting when you followed their instructions? That's a 0.436" reduction in bump travel from where the car could and should be and you can tune in more bump travel if you want (city folk)! The situation is even worse on the front where you have a higher mass, maybe a lower wheel rate, and a motion ratio closer to 1.
Seriously, what a fuck up at the industry level. With these highly adjustable dampers, the extra preload AFFECTS NOTHING ELSE (almost). It just places your rod correctly in the damper at RH and the threaded damper body can handle achieving desired ride height as usual. Hell, look at the OEM preload amount. We all know how dangerous OEM springs are to remove without a spring compressor. That is because they preload the shit out of soft springs to get the wheel rate they want at the ride height and bump/rebound travel they want. The only difference is they're designing everything as a non-adjustable package to work together so they don't need spring preload adjustability to get the bump and rebound travel where they want it.
Here is a post I found by Andre, the owner of HPAcademy from down unda...
So what is affected by adding more preload to your coilover besides the pain in the ass it can be to install correctly? Well I've now found out with my BC kit. I intentionally bought their default suggested springs to assess the ride my future customers have knowing I'll be swapping to different rates I want later. The supplied springs in the rear are 200mm (7.87") long and 12kg/mm. The total spring travel I would need to accommodate with 0.499" of preload plus full bump travel is 4.080". BC doesn't provide data on their springs so I have to go off of what is typical and usually the spring travel limit is around 55% of its overall length. That would mean this spring has 4.33" of usable travel. This is too close for comfort with a cheap-loose-tolerance-no-data-provided Taiwan/China spring. The 55% is a highly variable estimate and I would still be operating near coil bind which is a higher stress in the spring than necessary. An actual 8" spring with travel data would be better though Swift states at this spring rate and 8" length you have 3.6" of travel! So a 9" or 10" is probably required and since the stock springs are around 12" long I should be able to accommodate that.
So there you have it. Everyone is installing their coilovers wrong and its not just clickbait. I honestly can sit here imagining so many happy faces of people reading this, adding preload and resetting ride height to an otherwise unchanged vehicle, and completely changing how harsh their ride is. This simple change will:
Thanks for your attention. If you enjoyed this and got some value out of it please let me know and follow me through whichever medium you prefer to see more in the future. The calculator will be available at some point but it needs to be cleaned up to make it more user friendly.
]]>Hello 2022! It's been too long since the last update but it has been a wild year with covid things, house things, and day-job things. I'm finally getting settled down and focusing on growing PdV again as I prepare to move into a new house with a much better workspace. Today, I want to catch up on the brake rotor project. I'll paste the relevant OKRs as we go but the entire updated list is at the bottom.
The brake rotor project is getting bigger and more real so a new Objective 4 has been added to the list. It's pretty simple, copy Objective 2 (wheel product line) for a new brake rotor line. I'm particularly excited about this project because of the uniqueness of the product.
The one massive problem I have not been able to overcome yet is getting the Wilwood calipers on the stock BMW MPerformance rotors. The thickness of the BMW rotors and recommended rotor thickness from Wilwood do not align. My dream of staged upgrades was dead, until I finally had a simple thought that honestly took way too long to have. I might be able to include titanium brake pad shims to improve performance and adapt the Wilwood calipers to the thinner BMW rotors. Eureka!
The math is as simple as it gets.
The same analysis is done on the rear and even more space is available while needing 1.5mm shims per brake pad to fit the OE rotor to the Wilwood caliper.
As far as I'm aware as of this writing, no one sells everything listed at this price point;
The work isn't done but enough of it is to say that I am going to achieve this target. My next step is to get a rear knuckle on the CMM so I can design the caliper bracket. That's it.
I've reached out to a friend that used to work at Performance Friction. I'm hoping to close this task out very soon.
I'm so happy this is going to be possible. For roughly $2,000 a race ready brake package for all four corners will be available for the first time. For another roughly $2,000 you can add all four full floating rotors. That is less than a front only Stoptech STR60 kit and you'll have lower maintenance costs per season.
Here are some pictures for the giggles from a trip up to my day-job where I spent personal time in the inspection lab.
Manual inspection has its place...
CMM fun! Hand measurements have gotten me by but now I've got the good data.
Playing with the laser marker
Rockwell hardness tester to ensure material specs were met..... they weren't :(
Just for record keeping, the entire list of project objectives is below.
OK, so the critical wheel FEA step is complete. According to industry standard I'm taking my wheel design well above and beyond what any other wheel designer would do except for suppliers of professional racing cars, which I'm on par with and ultimately is the quality/strength level I want to target for the business.
Cheap rebuildable coilovers. Done. BC Racing is perfect so far. I'm currently seeking out local shops with a shock dyno to help with all the tuning I'll be doing so I don't have to buy a dyno.
On to the good stuff. I have been hyper-focused on the F30 front brake kit so in this post I'll cover a couple things.
Unbeknownst to some (dare I say many), a race car does not stop faster with 8ft rotors and 34 piston calipers. For the Volvo S60R and BMW F30, Brembo 4 piston calipers and big rotors are standard with exception for some BMW models. Sticking to the readily available 345 to 380mm rotor options seems reasonable. So what do I really want to achieve?
The intent was always to use Wilwood calipers but not Wilwood rotors. I didn't know about their lug drive system at the time. Sourcing the bobbins or whatever system you want to use, was a surprising task at first. I am confident I just didn't find the right source online to sell me copious amounts of floating rotor hardware. People need replacements right?
Well I'm glad cause when I dug deeper into the Wilwood catalog I discovered the lug drive system which is, to be honest, fucking awesome. Zero bolts required, no safety wire needed, and no expensive bobbins or other hardware. For $20 a rotor you get a big ass retaining ring and some steel inserts.
Young engineers, perk up! How do I design my rotor hat to work with their floating hardware when I know tight tolerances are involved? I bought one of their rotor hats that had 12 "lugs" and took very accurate measurements of all 12 lug features. Pretty simple and I'm highly confident after considering the average, max, min, median, and standard deviation I'll nail the fit on the first try even if it means my tolerances are a little tighter than whatever Wilwood has on their drawings.
Rotors done. For now, my rotors are aligned with the stock rotor centerline but I am considering moving it away from the wheel as much as possible to improve caliper clearance.
This is the important bit and required some research to be safe. My customer's lives are in my hands after all! Safety is of course the under-appreciated aspect of engineering I hear about from other engineers seeking fame/fortune/gratitude. ;)
So I read some books and research papers with sweet titles like "Brake Design and Safety", "Braking for Road Vehicles", and one particularly interesting one called "FEA Analysis and Correlation of Thermo-Mechanical Deformations of a Disc Brake Rotor".
Side note for engineers, read that last paper and make sense of the section with figures 12-15. I verified it with my own FEA but unfortunately can't package the lug drive rotor to mount on the inboard rotor face without moving the caliper closer to the wheel and there is no room for that. The benefit of not extending the rotor hat of course is the reduced cost of hogging out a smaller billet of aluminum.
To summarize, a vehicle's stopping power is obviously based on tire performance and there is a force balance between the tire and the brake pad, the pedal and the calipers, as well as between the front and rear systems that needs to be considered. So now I have that Matlab script. Fun stuff!
At this point I can say I have some system requirements and those need to drive component requirements. An important one would be how much torque is applied to the caliper bracket based on the pad pressure/friction requirement and the moment created by the offset of the rotor centerline to the caliper's radial mounting bolts? Then go a level deeper to find that the stiffness of the caliper and the radial bolt pretension is so important to the bracket itself, you can't easily and accurately analyze just the bracket in a component level FEA in Solidworks. That isn't a terrible thing, I want to verify and instruct on assembly bolt torques that are safe and can be verified in an assembly level FEA.
I hope by now it is abundantly clear that I'm trying to discuss the engineering process as much or more so then what I'm designing, why, and how many cool colors it can come in. If you are enjoying this please comment and let me know.
Below is a list of rotor and caliper combinations to help sort out my options and ensure I can set and meet certain design targets. If you compare the M sport and M performance data you'll notice some variation in the calculated bias and ratios on what is for all intents and purposes an identical car. Take that variation and then assess how Stoptech modified the system for their kits and you start to see what can change and by how much to maintain a properly functioning brake system.
So now I have 3 Wilwood options to move forward with and ultimately every customer will as well. Base and M sport guys can save some money by going with FNSL6R calipers. They just have to decide if they want to maintain the stock pedal characteristics or move toward something that might improve pressure modulation and make heel/toe maneuvers a little easier.
The issue with the two other FNLS6R options with 381mm rotors is, the FNSL6R caliper is not supposed to be used with rotors larger than 355mm. I'm still looking into this but assuming that's true then a different, more expensive caliper is required called the Aero4. The Aero4 is a serious caliper yet can still come with piston dust seals if you wanted. The Aero4 combo would increase torque a lot and reduce piston area, perhaps too much. Some testing is required but its potentially a killer racing package for less then $2500.
In terms of caliper bracket design, I think I'm good to go on the FNSL6R version. Stress levels are low at unrealistically high max torque, like under 120MPa low for 6061-T6 which is perfect.
For the nerds that might be reading this, my sim setup was an assembly (most parts hidden in pics) with a dummy steel (for stiffness) caliper, the bracket with steel spacers, and dummy knuckle mounts that were fixed in space. Preloaded bolts were used with global contact, no penetration, and 0.2 friction coefficient.
Bolts were used but the final design will have studs which makes caliper installation a bit easier and I think makes for a more professional look.
I've rambled on long enough. I do want to end with one bling bling progress pic. Almost all of my current F30 projects are fully detailed and assembled in CAD now.
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Personally, this is what I've been most excited to get into. I started this process the same as many before it, scholarly article research. These papers can be fountains of priceless information, never underestimate what you can learn from a grad student. Also, never trust a grad student.
There are two clear benefits and one gaping hole to the research done so far. First, many papers I've found have fatigue related data and analyses that will greatly inform and improve my designs. Second, occasionally you can find research that had real funding behind it for physical testing verification and some commercial partnerships to better inform the research. I was lucky enough to find exactly that after a lot of searching/reading. Finally the gaping hole. What if everything I'm reading from these grad students does not align with what industry professionals do? Does real experience developing expensive products blow up certain assumptions?
I'll tackle that last bit first. I hired a contractor with experience as the simulation engineer and engineering manager at a wheel company you have heard of. I'm not fucking around, it was worth it and the work is ongoing as I write this. So problem solved! Now as far as what to do with the research data? I believe it will refine and improve what I'm learning from my contract engineer. Full disclosure, I'm a little surprised at the low sophistication inputs and boundary conditions required in FEA to pass physical SAE/TUV testing often on the first attempt. That tells me the wheels are over-designed due to the way they're simulated which is fine by me for my first design.
Now onto the real content I want to share. SAE J2530 is the guiding document for aftermarket wheel certification in the USA and is very similar to the VIA specification. What I've come to find out is there is a lot of room for interpretation on the variables involved to achieve a specific wheel load rating. I'm going to explain my process in detail.
In order to certify a wheel to a specific load rating the manufacturer needs to pass three tests based on the stated load rating for the specific wheel design. These are the dynamic cornering fatigue, dynamic radial fatigue, and impact tests. So what goes into choosing a wheel load rating?
The bare minimum cornering test torque for a vehicle per SAE is based on two main factors. 1) GAWR or gross axle weight rating divide by 2. That is the maximum weight allowed per axle divided in half to provide a number per wheel. 2) Maximum tire radius for the wheel being tested. Another important factor is the coefficient of friction for the tire which SAE sets as 0.7. As an example, the bare minimum for an F30 BMW with a GAWR of 1161kg should have a wheel load rating of at least 580kg (1279lbs).
580kg is reasonable for a daily driven car with all season tires. But what should I design to if I wanted to allow for any tire including racing slicks on a track? Well then I could assume (and then validate with testing) a higher coefficient of friction. Lets say our customer's racing tires are upwards of 1.3.
This is more straightforward. It is a rolling fatigue test with no camber so friction isn't a factor. It's purely wheel load times a load factor which is there to accelerate the test. However, lets assume I'm designing for an SCCA track car and maybe my customer has a big ole wing that generates 600lbs of downforce. This would be a conservative approach and I'm going to add that force to the radial force for the test AND THEN correct the wheel load rating based on the aero assumption.
"F_aero" shows a small increase in the radial force and I can then correct the wheel load rating "Wsae" to capture that increase in the wheel load rating.
So aero bumped my wheel load rating from 580kg to 634kg. Not a crazy jump up but worthwhile added safety margin. Now I can go back to the cornering load calc using this new "Wsae_final" force and solve for the coefficient of friction required to achieve the same cornering force as the "Mrace" equation with the assumed coefficient of friction equal to 1.3. I know it gets a little confusing here.
So, "Msae_final" uses the new higher wheel load "Wsae_final" and is the same result as the earlier "Mrace" with the race tires. The actual coefficient of friction required to make all this magic work is 1.17.
If we compare the same 634kg wheel load rating based on the SAE standard 0.7 coefficient of friction:
What I've just walked through is an argument I'm making that the cornering fatigue test, which factors in the vehicle weight, aero, wheel size, and now reasonably high friction is representative of the customer I'm targeting. I can also say the same for the radial fatigue test. What the hell does this mean? Well, it now comes full circle to that marketing nightmare I mentioned. I've outlined a reasonable way to design a seriously strong wheel with a load rating barely over the minimum required.
The next question for me is, what would my equivalent wheel load rating be if I solved for that using the very high cornering load and the SAE standard 0.7 coefficient of friction?
992kg or 2,188lbs! That's a wheel that sounds like it'll stand up to the 12hrs of Sebring! What's the problem? Throw that wheel rating back into the radial fatigue test calc and you would have to design a wheel to withstand over 1 million cycles with 24,320 Newtons (5,467lbs) acting on it. That doesn't make any sense.
Kudos if you made it this far. Someone tell me I did something wrong before I start spending money and have to hop on the marketing strugglebus using my "equivalent wheel load rating".
If you're interested in the wheel designs I'm working on, keep an eye on this page. https://www.pdvmotorsports.com/pages/pdv-forged-wheels
]]>The obvious issue with designing a wheel is fitment. If I'm going to achieve Objective 2 (creating a product) it needs to be capable of fitting more than just my own car. Once I locked in the overall wheel and tire size to 18x9 +30 with 255/35-18 tires, a specific meaty tire combo that fits all corners without wheel spacers, I needed to concern myself with brake caliper clearance.
Fortunately, Brembo is great about supplying just enough data to CAD up some clearance volumes. (See here) There are a lot of BMWs, the Volvo S60R, and plenty of other cars that come with stock Brembos so the data is available. The caliper model was not available but all of the rotor options were. That provides the stock offset from the spindle or rotor hat face to the rotor centerline. Head on over to any caliper supplier with dimensioned drawings and you have yourself a clearance volume. For the F30, I did that for Stoptech, Dinan, and Wilwood and I'll be able to physically check clearance on my car.
Now I've got enough information to select my rim halves. With the proper model setup...
... I can just click a drop down list and switch my rim half lengths to see what clears all of the calipers. I wanted the longest outside rim half I could fit because for a given overall wheel width that would mean a shorter inner rim half. The shorter the inner rim half is, the stiffer the whole wheel assembly will be up to a point.
Seeing all of the fitment issues that can come up, I saw an opportunity to make a new product I've been wanting to make for a long time. Fully floating brake rotors. With my own design I could change the rotor centerline position and give myself more room for larger calipers or a longer outer rim half. It could also be an inexpensive performance oriented option over sourcing larger BMW components from other models. The one item missing I'll have to physically measure myself to determine rotor offset is of course the upright, you can't go too far. Nevertheless, I also know how expensive BBK's are and there aren't a lot of options for the F30.
I'm guessing right now I'll need to come in under $1800 retail for a front kit to be successful. I don't think it needs to be an all out 20"-wheel-required 10 piston caliper. Find a good front/rear balance, increase thermal mass and torque as much as possible, full floating lightweight rotor hat, quality but not overpriced American made replacement parts with a racing pedigree. Sounds nice.
Wilwood is without a doubt cheaper than pretty much every brand out there. Calipers come from forgings with radial mounts, pistons have dust boot options, brake pad compounds are expansive enough, and replacement rotors are relatively cheap. I think this brand can help make this happen.
Below is a space claim sweep of the Wilwood Forged Narrow Superlite 6 piston caliper (light greyish), stock Brembo 370mm rotor (dark grey), and the initial PdV 355mm floating rotor assembly (blue). Not pictured is the 340mm rotor on my F30 which has the same rotor centerline position. Since its a square setup, the same process occurs on the same wheel with the 4 piston caliper for the rear.
It seems sourcing the floating rotor assembly hardware from AP Racing or Brembo isn't easy. I am going to start out with my own design for now and keep looking.
I need to actually build a brake system calculator before I freeze anything but I started documenting whats out there. For starters I'm going to target the M performance in terms of bias and what I'll call a front/rear torque ratio which is 62.3%/37.7% and roughly a ratio of 1.072 which is just a comparison of front and rear pad radius from axle centerline.
A similar setup from Wilwood results in the following:
Front
Rear
So I'm developing wheels, brake components, and shocks but doing it the PdV way, which is to say I design, engineer, source, assemble, and ship. There is no PdV machine shop, no CNC coding in house, no anodizing baths. I rely on trusted manufacturers from my history in the professional racing market as much as possible to ensure quality whenever possible.
In the case of the wheels, they will not be 100% Made in the USA. Mostly due to US manufacturers simply costing so much just for the raw material and often requiring minimum order quantities of 50 or more. A barrier to entry that makes no sense for a one off first prototype and I will never stock and machine in-house. So if this turns into a significant product line one day and the competitors or trolls don't like what I have to say you can reference this blog and know the truth, I don't care and the product speaks for itself. So what if the raw material comes from somewhere else in the world when I can send samples off to a lab to periodically verify material properties? Perhaps there will come a time when I can transition from foreign suppliers and be able to afford 50+ wheels per order. One can dream but if you search your favorite wheel supplier followed by "bill of lading" you may be surprised at what you find they're ordering. That is actually how I start searching for reputable foreign suppliers!
With that said, as much as possible will be made in the USA which will inevitably mean more design work on my part, higher (and sometimes redundant) expenses, longer lead times, etc. This whole project is really a tale of two parts, the wheel rim and the wheel center. The wheel rim requires little engineering and could be from an Asian supplier but I've found a Californian spun forged supplier that seems to make a great product, in a lot of sizes and styles, and has no minimum quantity with reasonable pricing. The wheel center is a different story I'm going to cover in more detail.
With any worthwhile project of some complexity, a plan is needed. A list of objectives and key results (random book suggestion) will kick off a series of efforts in market research, design, costing, etc. I'm not going so far as to develop a Gantt chart but writing some things down is certainly necessary. This blog is part of that effort.
The PdV brand aligns with my personal feelings toward performance car modifications. Generally, they should be highly engineered for performance and at a quality level I expect when shipping to a professional race team. So an expansion of Objective 1 above would be to design the lightest possible wheel for a given design to pass SAE certification with UTQG 200 tread wear tires on a full weight F30. Lower quality wheels may pass VIA or SAE testing but do so with 400+ tread wear tires. The higher wear rating usually means stiffer sidewalls which distribute loads better into the wheel and are therefore easier to pass the tests. I hope my wheels are chosen by serious racers and so I need to cover my ass. Full weight, 200 tread wear.
In the next post I'm going to get into the actual wheel design and supply chain. For now, I can share two wheel center designs. I feel like some added detail and complexity is needed for PdV-01 based on a few other designs I've seen lately and really liked. The back face is nearly locked in with exception for some minor tweaks from FEA so making a template of the back face to confirm fitment will be the next step. I'm not yet a big fan of PdV-02 and if its my creation I better be, so we'll see how I can improve that.
PdV-01
PdV-02
Real simple. I settled on BC Racing. They have pretty good quality structural parts, they're completely rebuildable, inexpensive, fairly popular already, and they sell components right on their website so I can buy just what I need instead of the whole kit. I've started reverse engineering a set and designing some of the important hydraulic bits. Below is a preliminary layout for a rear S60R. A few length changes and baddabingbaddaboom I'll have a rear F30.
The first issue I'm tackling is the bleed adjuster. I never ever want a simultaneous compression and rebound adjuster like BC has. I'd rather have a true single adjustable damper and rebuild if necessary until I'm happy. So I'm going to be inserting a check valve in my own needle jet assembly (next pic below). A new needle design to mate with this part will be next on the agenda that will improve the range and linearity of bleed adjustment.
In addition to this, I have a few sizing tweaks to make a lower friction floating piston as well as a high flow and double digressive piston design. I've already developed the pistons for one of my day-job projects and they'll drop right on to the BC shafts and bodies with minor changes.
For the lower body caps that come with rubber bushings like the S60R models, I'm going to press that out and press in a spherical bearing assembly to match the upper mounts and improve damping hysteresis/response.
Longer term, I'd like to swap out their oversized 18mm rods and shaft bearings to reduce friction and rod force. Perhaps add a compression adjustable piggyback assembly. We'll see how popular this becomes which I know will be highly dependent on my tuning but the target is to be better than KW V2s for less $$$.
The design specs are as follows for the front strut:
The design spec for the rear shocks:
I can't fully fund everything necessary to build up stock before making these available for sale. I will be running a group buy with a large deposit required. I'm thinking $700 will keep it to serious buyers only. I do have at least 5 already saying they're committed.
Needless to say, I'm extremely excited. Once the first design is complete I'm not sure how far this will go. It won't be difficult to change a few things and adapt the shocks to different cars so keep that in mind if you reading this and you are in need of some quality dampers for your new R-design or old 850R.
If you have any questions/feedback or would like to express interest please feel free to email me at pdvmotorsports @ gmail.com
]]>Feel free to peruse this research paper on the underhood temps of several vehicles in several scenarios but I’ll summarize.
Idle @ 1000RPMs – 75C/167F (no convective heat transfer!)
Flat road at 60MPH – 30C/86F
Hill at 70MPH – 65C/149F
The equation for such a thing is
Tin = 70F + 460 = 530 deg R
Pin = -5 psig + 14.7 = 14.2 psia
Pout = 14.5 psig + 14.7 = 29.2 psia
Pout/Pin (compression ratio) = 2.056
Assume an awesome compressor efficiency of 78%
So,
a very efficient compressor running at a relatively low compression ratio outputs air that is significantly hotter than the test vehicles underhood temps in all scenarios by a minimum of 44 deg F. Insulating this heat energy with silicone tubing instead of aluminum is a bad idea and can contribute to early onset “heat soak” of your intercooler and will most assuredly increase intake air temp post intercooler as well.
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Often this equation is written in terms of specific work and specific volume, where the above equation is divided by the mass of the substance.
Like the integral of F·ds, the area under the P-V curve represents the work.
Courtesy of Wiley.com
Initially, I was going to develop parts that would increase horsepower for our caRs so the name was appropriate and I love the use of nerdy references. The products I have in mind are more expensive to develop than the drivetrain and suspension parts I decided to develop first so I had to reprioritize. I think it worked out better in the end as my expected product lineup will create a better performing car overall. So the slogan "Integrated Designs" was born from the integral sign in the equation. I will go ahead and pat myself on the back for that bit of cleverness.
6spd MT Part # 31256008 (45 teeth on each end)
As per the above mentioned angle gear compatibility list, the angle gear side of both collars are identical in diameter and tooth count. The transmission side is of course drastically different and the GT collar is actually thinner than the angle gear side.
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5spd Auto and 6spd Manual
2003-2009 S60 & S60R
2003-2007 V70, V70R, XC70, & XC90 2.5L
2003-2006 XC90 2.4T (diesel)
2001-2006 S80
6spd Auto
2006-2007 S60R/V70R
*Always verify the correct part number with your Volvo dealer*6spd Auto]]>