veris Posted October 30, 2018 Report Share Posted October 30, 2018 The rule book has the following on final drives: Rear end gear ratios are open to all OEM differentials available for that year, make, and model or chassis generaton (excluding specialty high-performance models not listed on the VPI table). What is the points cost to running a different final drive then reflected above? Is that considered a different differential so 25 points? Or not allowed? In the event I wanted to run a LSD off a car on the VPI list and a different final drive is that still 25 points or something else? Thanks. Quote Link to comment Share on other sites More sharing options...
Ron_e Posted October 30, 2018 Report Share Posted October 30, 2018 A non-OE diff is 25 points, diff must come from any vehicle on the list. Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 30, 2018 Report Share Posted October 30, 2018 I think he's looking for clarification on the differences between the differential itself and the final drive gearing, which is a good question.The wording is somewhat inconsistent about what parts it is referring to. Quote Link to comment Share on other sites More sharing options...
veris Posted October 31, 2018 Author Report Share Posted October 31, 2018 ABR-Glen precisely. The current rule set does not explicitly cost [off chassis] final drive changes. My assumption is that under the current/2019 rules a new final drive outside the chassis generation would be considered a differential swap; 25 points. A LSD [from a car on the VPI list] is also considered a differential swap; 25 points. What happens if you do both? 50 points doesn't make sense as you aren't running two differentials... Which means in theory it would be 25 points for a differential change that includes both a [VPI List] LSD and [off chassis] final drive swap. I'd like confirmation on interpretation before finishing my 2019 plans. Thanks. Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 31, 2018 Report Share Posted October 31, 2018 40 minutes ago, veris said: What happens if you do both? Find a vip listed diff that has it all, declare a diff swap for 25 pts and enjoy. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 Not trying to complicate things but a 2019 rule could require that both improvements be acknowledged and accounted for. 1 Quote Link to comment Share on other sites More sharing options...
veris Posted October 31, 2018 Author Report Share Posted October 31, 2018 7 minutes ago, mender said: Not trying to complicate things but a 2019 rule could require that both improvements be acknowledged and accounted for. Which 2019 rule? I quoted the 2019 rule book. Quote Link to comment Share on other sites More sharing options...
Ron_e Posted October 31, 2018 Report Share Posted October 31, 2018 2 minutes ago, veris said: Which 2019 rule? I quoted the 2019 rule book. Don't forget to look through all of the ratios offered for both manual and automatic, you should be able to find an applicable ratio somewhere. You can also select a winter package option. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 22 minutes ago, veris said: Which 2019 rule? I quoted the 2019 rule book. If you're going to do a final drive ratio that isn't available in a diff from a car from the VPi list, you may have points charged above the 25 point diff swap or not be allowed to run it. If that describes what you're planning, you should check with a tech person first. Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) 3 hours ago, veris said: The rule book has the following on final drives: Rear end gear ratios are open to all OEM differentials available for that year, make, and model or chassis generaton (excluding specialty high-performance models not listed on the VPI table). What is the points cost to running a different final drive then reflected above? Is that considered a different differential so 25 points? Or not allowed? I read it as not allowed unless you swap in a diff that had your desired gear ratio as a factory option but I've been wrong before. Edited October 31, 2018 by mender Quote Link to comment Share on other sites More sharing options...
veris Posted October 31, 2018 Author Report Share Posted October 31, 2018 Open refers to free/ 0 points. It doesn't state other final drives not being allowed. Or certainly is not clear... Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 Specifically, the "free" part is for a gear ratio that was a factory (OEM) option in that diff. If you swap in a different diff, it also has to have an OEM gear ratio but one that can in that diff. For example, if you want a 4.30 gear and the only car it came in from the factory was a Miata, you have to swap in that Miata diff. Is that helping? Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 31, 2018 Report Share Posted October 31, 2018 10 hours ago, mender said: Specifically, the "free" part is for a gear ratio that was a factory (OEM) option in that diff. If you swap in a different diff, it also has to have an OEM gear ratio but one that can in that diff. For example, if you want a 4.30 gear and the only car it came in from the factory was a Miata, you have to swap in that Miata diff. Is that helping? I think veris and I would define the diff as the component that takes the torque from the ring gear and splits it between the two wheels, it could be open, or LSD of various types etc. It doesn't have any gearing per se or a housing or anything else to attach it to the wheels. If the rules mean to imply that the "diff" includes the final drive gearing and the housing and ??? it could stand to be made more clear. This is another place where some well chosen examples would do wonders. In practice, I suspect that you'll be able to run any combination of diff/final drive/housing/??? that was factory offered in your chassis for free and 25 points total if any/all of those come from outside of that as long as it's on the VPI list. That's just my guess, looking forward to official clarification. 1 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 31, 2018 Report Share Posted October 31, 2018 Your guess is the right answer. Splitting hairs on a topic that has never been discussed is overkill,do we really need clarification on everything? 1 Quote Link to comment Share on other sites More sharing options...
enginerd Posted October 31, 2018 Report Share Posted October 31, 2018 2 minutes ago, ABR-Glen said: I think veris and I would define the diff as the component that takes the torque from the ring gear and splits it between the two wheels, it could be open, or LSD of various types etc. It doesn't have any gearing per se or a housing or anything else to attach it to the wheels. If the rules mean to imply that the "diff" includes the final drive gearing and the housing and ??? it could stand to be made more clear. This is another place where some well chosen examples would do wonders. In practice, I suspect that you'll be able to run any combination of diff/final drive/housing/??? that was factory offered in your chassis for free and 25 points total if any/all of those come from outside of that as long as it's on the VPI list. That's just my guess, looking forward to official clarification. That does make a little more sense now. When I hear “differential” I think of the 80 lbs cast iron housing and everything in the middle. The wording of the new rule did not make much sense to me. I thought “why are they talking about diff ratios.. why not just say “any differential from year / make /model is usable regardless of trim package or transmission””. Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) My usage: Rear gear ratio = ring and pinion ratio Gear carrier = houses the side gears, LSD components if applicable and supports the ring and pinion Centre section = removable housing that holds the gear carrier (Ford 9", Chrysler 8.75") on a live axle. On an IRS, also includes the stub axles/output flanges Differential = live axle housing that includes the centre section, axles, and brakes; IRS centre section Edited October 31, 2018 by mender Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) I guess I'm a drivetrain nerd or something. What do you guys think about FWD cars then, they don't have the components that this rule is referring to at all? they just have a "transmission"? "Technically" an AWD transaxle may have multiple differentials, a "rear end" with a spool doesn't have a differential at all. I'm not trying to pick nits here, but since the rules don't have definitions for these things I guess we have to think about how they could be interpreted. Edited October 31, 2018 by ABR-Glen 1 Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 31, 2018 Report Share Posted October 31, 2018 20 minutes ago, Team Infiniti said: Your guess is the right answer. Splitting hairs on a topic that has never been discussed is overkill,do we really need clarification on everything? Splitting hairs? This is a new rule, no? On a solid axle car, how many parts can be lumped under what you consider a diff? Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) 8 minutes ago, ABR-Glen said: I guess I'm a drivetrain nerd or something. What do you guys think about FWD cars then, they don't have the components that this rule is referring to at all, they just have a "transmission"? "Technically" an AWD transaxle may have multiple differentials, a "rear end" with a spool doesn't have a differential at all. I'm not trying to pick nits here, but since the rules don't have definitions for these things I guess we have to think about how they could be interpreted. Different rule, same intent: "Transmission/ Transaxle swap: 25 pts for any transmission/transaxle swap from a vehicle on the VPi list, adapters included" Edited October 31, 2018 by mender Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) 14 minutes ago, mender said: Different rule, same intent: "Transmission/ Transaxle swap: 25 pts for any transmission/transaxle swap from a vehicle on the VPi list, adapters included" The "free" part is new"ish" though, I know it was being applied that way in 2018, but never in the rules, correct? This also seems like it could have some VPI implications if there were differences in values between cars that can now share these components freely. Edited October 31, 2018 by ABR-Glen 1 Quote Link to comment Share on other sites More sharing options...
mhr650 Posted October 31, 2018 Report Share Posted October 31, 2018 23 minutes ago, ABR-Glen said: Splitting hairs? This is a new rule, no? On a solid axle car, how many parts can be lumped under what you consider a diff? Unlimited based on the design. If it bolts to the suspension and the wheels bolt to it that is your differential. 1 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 31, 2018 Report Share Posted October 31, 2018 1 hour ago, ABR-Glen said: Splitting hairs? This is a new rule, no? No, not a new rule. 1 hour ago, ABR-Glen said: On a solid axle car, how many parts can be lumped under what you consider a diff? If its on the vpi list, all internal components right down to different lug pattern. 1 hour ago, mhr650 said: Unlimited based on the design. If it bolts to the suspension and the wheels bolt to it that is your differential. This Quote Link to comment Share on other sites More sharing options...
mender Posted October 31, 2018 Report Share Posted October 31, 2018 (edited) 3 hours ago, ABR-Glen said: 1. The "free" part is new"ish" though, I know it was being applied that way in 2018, but never in the rules, correct? 2. This also seems like it could have some VPI implications if there were differences in values between cars that can now share these components freely. 1. Yes, somehow it was implemented before a rule was made. Hope to see a lot less of that in the future. 2. Yes, but how would you apply it? Essentially another freebie which used to be 25 points, so cars that needed the swap before and would have gotten 25 points added on should have 25 points added to their VPi? Edited October 31, 2018 by mender Quote Link to comment Share on other sites More sharing options...
Alchemy Autosport Posted October 31, 2018 Report Share Posted October 31, 2018 5 hours ago, ABR-Glen said: I think veris and I would define the diff as the component that takes the torque from the ring gear and splits it between the two wheels, it could be open, or LSD of various types etc. It doesn't have any gearing per se or a housing or anything else to attach it to the wheels. If the rules mean to imply that the "diff" includes the final drive gearing and the housing and ??? it could stand to be made more clear. This is another place where some well chosen examples would do wonders. In practice, I suspect that you'll be able to run any combination of diff/final drive/housing/??? that was factory offered in your chassis for free and 25 points total if any/all of those come from outside of that as long as it's on the VPI list. That's just my guess, looking forward to official clarification. I very much agree with this interpretation. Not that my opinion matters but its also how I read it as well. 1 Quote Link to comment Share on other sites More sharing options...
veris Posted October 31, 2018 Author Report Share Posted October 31, 2018 ABR-Glen I agree. A diff could or could not include final drive. I can argue it both ways, but would lean towards non gearing related. Additionally, in a fwd car, the final drive is equivalent to the rear end gear ratios. Technically how the rule is written wouldn't allow a fwd ratio change even if available in the chassis generation. I'm sure the rule wouldn't be enforced that way, but that is how it is written. Really, I think this playing with free gear sets should be stopped and non oe gear ratios should be charged some point value. If you open the transmission you use points. That said, that isn't in the cards for 2019 so direction would be appreciated. Preferably public so everyone is playing off the same rulebook [interpretation]. 1 1 Quote Link to comment Share on other sites More sharing options...
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