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The T5 apps mentioned got straight-at mainshaft VSS bosses in the late 80s and mid 90s respectively. Even so, a non-straight-at m.s. VSS was used in speedo-gear tailhousings in late 700R4 and early 4L60E models. Maybe there are others like that. Like you said, the external seems easier, but internal will be safe from debris.
:beer: to a good discussion.
Oh and only back-to-back testing with and without VSS validates "good drivability." Which, I have done on all types of ECM and PCM GM swaps I have done.
Yeah - the Stang T5's (85-95 anyhow) have a worm-type drive gear and the speedo cable gear is kind of like a ring gear -- has to go over or under to work; can't go straight in.
Gonna ride this one out and do what it takes to come up with external target for the stock sensor so the computer gets the signal it's expecting. Then I can use Dakota's CRC-1000 cruise unit that takes the speed signal as modified by the ECU.
Same topic - slightly different angle, I've been researching the number of pulses per mile that this 17 tooth reluctor will generate. For 2010 Corvette with 325/30/19 rear tire and 3.42 rear gear - I get 43,966 pulses per mile; for Camaro with 275/40/20 rear tire and 3.45 rear gear - I get 41,215 pulses per mile. Since I have much shorter tires (similar rear gear) on my car, the same 17 pulse per driveshaft revolution nets 48,109 pulses per mile (235/45/17 and 3.55 gear). Anyone see any reason that I can't drop down to a 15 tooth target -- that puts my pulses per mile at 42,449 -- right in between the Corvette and Camaro.
From your comments, I'm guessing you're using an 06+ ecu that requires the BCM for cruise.
If you cant get the external reluctor set up, this might solve your problem.
"The CRC-2000 variation features a discrete VSS input (4,000 PPM)"
I believe that uses the DD pass thru VSS from the speedo output. If splitting the output to both ecu and Cruise doesn't work, you could piggyback 2 VSSs together, one feeding the ecu, the other the CC unit.
And I agree with jmd on testing with and without. I've done that with 2 swaps with similar results.
I spoke with Dakota just yesterday Gary about whether or not they thought that would work. Pretty tough to get a reasonably coherent answer about a (truly) technical question out of them. They didn't seem to think splitting the signal would work. Furthermore, since the ECU uses the VSS input to generate a 4000 pulse/mile signal for the factory cruise, they hadn't considered what might happen if their new 2000 unit was set up with 1) the direct 4000 pulse/mile signal coming from driveshaft magnets AND 2) the ECU was receiving the same signal and trying to send an output to the cruise control. There were simply too many unknowns to try that route - which is another way of saying that I'm overcome with 'this might work' solutions, mostly of my own making. The one route I know will work is to send the ECU a 41,000 pulse/mile sine wave signal and let it generate/send the 4000 pulse/mile square wave signal to the cruise so Dakota's CRC-1000 will work as designed. Just a matter of fashioning a reluctor and reading it. Staying the course....
BCM = Body control module. Earlier Gen motors didn't need the BCM for cruise control, just a GM cruise lever.
Yeah, I could see the combo being problematic.
I would seriously consider the differential yoke mounted reluctor. It's a proven mod. While the trans yoke doesn't move much, the sensors are pretty sensitive. Even JTR recommend trying to get their reluctor as flat as possible. Be sure to check out the installation pdf on Jags that run, looks pretty simple to make yourself.
Yeah, the DD module is designed to eliminate the need for the BCM.
A top mounted VSS on the trans would probably be preferable. I would imagine the JTR diff mounted collects a lot of crud that would eventually affect it.
Be sure to post some pics and let us know how it works.
I've been running a diff mounted VSS for the past 10 years without any issues. First with a 7727 ECM when I was running a V6 now with the 0411 I'm running with my LS4, FYI.
Looks like 4 teeth -- what are you using the VSS signal for?
Yes, 4 teeth. Right now just to give a signal to the PCM. But I'm going to be adding cruise in the near future. The guy who did my tuning adjusted the parameters to account for the 4 tooth signal so the PCM is seeing my actual speed.
I forgot to mention I'm using a Ford T5 with a cable to drive my stock speedometer.
The "tune" to remove the VATS, certain emission controls, etc., comes with the ECU/harness I'm buying. The other changes don't. I can specify a manual trans (17 tooth) ECU. 'Spose I should've said I'm trying to avoid the second tune....
Thanks to you guys and a couple of other friends for gently encouraging me to look at the other end of the car for the reluctor location. Decided that by the time I'd figured out if my cute little teeth would work, I could just make a reluctor for the pinion of the rear end. 15 teeth makes the pulses per mile with my shorter tires about the same as the Corvette or Camaro ecu I'll be using - within a couple of percent. So if I ever do actually need the signal for an accurate speedo (for example) I'll already have it. Lots of fun with protractor today - templates, then sheet metal. I'll do some grinding on it to even things up and test fit tomorrow.
In case anyone pulls this up as a reference -- here's where I ended up. A 9 tooth instead of 15. About 1/16" gap between VSS and toothed wheel. Seems to be giving the ECU what it needs to prevent occasional stalls when rolling up to a stop and declutching at the last minute.
03-11-2016, 06:12 PM
