klutched Posted August 15, 2021 Report Share Posted August 15, 2021 Hey guys, currently running factory abs/speed sensor on the pinion of my S15 diff in my R33. Have used a factory 2 wire sensor and wired it up to my G4+ GTR plugin into a digital input. Get speed readings fine but am only getting readings to 130-140km/h. Have just counted and have 24 teeth on the pinion. It's setup on a 275/60r15 (28.2" roughly). Does the it just max out the frequency hence why its not reading over 130-140km/h? Whats my best option to fix this? I'm planning on putting an abs hub on the front to pick up my front undriven wheel speed so I can setup up a traction control strategy. I believe they are 46 teeth and I will be running it with a cherry sensor. I believe I'll have to grind the teeth down and have it as 23 teeth but unsure if this will just result in the same outcome topping out around 150km~. Thanks Quote Link to comment Share on other sites More sharing options...
Adamw Posted August 15, 2021 Report Share Posted August 15, 2021 If there are 24 teeth on the pinion and the diff ratio is say 3.5:1, then that is equivalent of 84 teeth at the wheel. Way too much for the G4+ DI frequency limitation of 500Hz. One of these will divide the frequency by 8: https://shop.vems.hu/catalog/hall-p-162.html klutched 1 Quote Link to comment Share on other sites More sharing options...
klutched Posted August 15, 2021 Author Report Share Posted August 15, 2021 5 hours ago, Adamw said: If there are 24 teeth on the pinion and the diff ratio is say 3.5:1, then that is equivalent of 84 teeth at the wheel. Way too much for the G4+ DI frequency limitation of 500Hz. One of these will divide the frequency by 8: https://shop.vems.hu/catalog/hall-p-162.html Hmm yeah ok, would it still be the same even if I used a cherry sensor? I assume then if I use the abs pickup on the half shafts and bring them down to a 23 tooth setup would be ok being after the diff gears? Quote Link to comment Share on other sites More sharing options...
klutched Posted August 17, 2021 Author Report Share Posted August 17, 2021 Ok so I've decided to use the ABS pickup on front and rear with cherry hall sensors. They are a 46 tooth ring so I will need a frequency divider for hall sensors. Can anyone recommend one? Quote Link to comment Share on other sites More sharing options...
Adamw Posted August 17, 2021 Report Share Posted August 17, 2021 klutched 1 Quote Link to comment Share on other sites More sharing options...
klutched Posted August 24, 2021 Author Report Share Posted August 24, 2021 On 8/15/2021 at 6:04 PM, Adamw said: If there are 24 teeth on the pinion and the diff ratio is say 3.5:1, then that is equivalent of 84 teeth at the wheel. Way too much for the G4+ DI frequency limitation of 500Hz. One of these will divide the frequency by 8: https://shop.vems.hu/catalog/hall-p-162.html Was doing some thinking/calcs, I run a 3.69 diff gear which would mean 88.56 counts per tyre rotation. So when I move the pickup to the axle with 46 teeth per tyre rotation I will get almost double the speed (1.92x). 275/60r15 circum. is about 2233mm, 500hz/46teeth=10.87 rotations per second. 10.87 rotations x 2233mm=24272mm/second = 87.38km/h. Doesn't seem right when I get 140km/h atm with the 24teeth on the pinion. Quote Link to comment Share on other sites More sharing options...
Adamw Posted August 24, 2021 Report Share Posted August 24, 2021 The 500hz limitation we quote is very conservative, it depends how many other interrupts various other functions are using. In a typical basic install they will often go to about 1500hz. But something like a 8cyl sequential setup with 8 channels of knock, individual cylinder fuel trims, 4 vvt cams, 4 wheel speeds etc will have less capacity. Quote Link to comment Share on other sites More sharing options...
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