Inaccurate Tachometer?

***TitaniumTT*** · 07-20-2010, 08:45 AM

There is alot of accurate information here regarding the inaccuracy of the stock gauges. Fact of the matter is that the stock tach, as Ted pointed out is eay off. I was seeing ~4-500 rpm difference compared to the S-AFC and the Autometer tach that I was using to test the accuracy as well much like the sentwo.

Your speedo is also off. I've said it before that I've never seen an accurate stock speedo. Don't know why companies do this but I've seen stock speedo's off by as much as 10%. Hell, I went from a 225/75/15 tire (28.28") to a 31", a difference of ~10% and my speedo up to about 70 FINALLY became accurate. After 70 the speedo actually shows slightly slower than what the GPS/police radar will show. Something to be aware of.

Other points of concern are how the speedo works, there is a spring involved, springs do fatigue, and the fact that tires are always slipping or rotating at different RPM's will cause reading's to jump around as well.

The most accurate way to get readings is not going to be from an analog gauge, but rather from high quality electronic sensors, really sheilded wiring, and digital displays.

Things the RX8 has. Can anyone comment on the accuracy of the the RX8 gauges?

infernosg · 06-06-2012, 10:49 AM

Thread revived!

Quote:

Originally Posted by TitaniumTT

The most accurate way to get readings is not going to be from an analog gauge, but rather from high quality electronic sensors, really sheilded wiring, and digital displays.

I'm halfway there. The tach is now being run by a Haltech but I'm still using the stock speedo cable until I rig something up for a Hall effect sensor or the like. Too bad I didn't jump on those trigger wheels being sold a while back. I'm not sure about a digital display but one day the car will have a custom instrument cluster.

infernosg · 12-04-2013, 07:38 AM

Quote:

Originally Posted by infernosg

I'm halfway there. The tach is now being run by a Haltech but I'm still using the stock speedo cable until I rig something up for a Hall effect sensor or the like. Too bad I didn't jump on those trigger wheels being sold a while back. I'm not sure about a digital display but one day the car will have a custom instrument cluster.

I'm now working on the custom gauge cluster. I'm using analog gauges and the tachometer is still going to get its signal from the Haltech but I need to identify a source for the speedometer. I can theoretically use any signal for the speedometer as long as it produces between 4000 and 200000 pulses per mile. Some options I'm considering:

1. Keep the mechanical speedo cable and isolate the speed output from the stock cluster and use it as a signal source.
2. Hall effect sensor + trigger/magnetic pickup wheel on the driveshaft (there are some pre-made options out there that look like they'll work).
3. Hall effect sensor + trigger/magnetic pickup wheel on a front wheel hub (a la TII ABS sensor)
4. Use FD VSS (will this even work in a N/A transmission?)

Thoughts?

07-20-2010, 08:45 AM	#1
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	There is alot of accurate information here regarding the inaccuracy of the stock gauges. Fact of the matter is that the stock tach, as Ted pointed out is eay off. I was seeing ~4-500 rpm difference compared to the S-AFC and the Autometer tach that I was using to test the accuracy as well much like the sentwo. Your speedo is also off. I've said it before that I've never seen an accurate stock speedo. Don't know why companies do this but I've seen stock speedo's off by as much as 10%. Hell, I went from a 225/75/15 tire (28.28") to a 31", a difference of ~10% and my speedo up to about 70 FINALLY became accurate. After 70 the speedo actually shows slightly slower than what the GPS/police radar will show. Something to be aware of. Other points of concern are how the speedo works, there is a spring involved, springs do fatigue, and the fact that tires are always slipping or rotating at different RPM's will cause reading's to jump around as well. The most accurate way to get readings is not going to be from an analog gauge, but rather from high quality electronic sensors, really sheilded wiring, and digital displays. Things the RX8 has. Can anyone comment on the accuracy of the the RX8 gauges? __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**