Speedo recalibration - change the actual speedo used and recal via Tunercats?
03-30-2009, 12:24 PM
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Speedo recalibration - change the actual speedo used and recal via Tunercats? A little background. 1994 B-body LT1 with 1994 F-body T56 installed in 1987 Mazda RX7, using TunerCats to tweak my $EE PCM file.
The RX7 speedo is cable driven, so I need to replace the speedo with an electric. I want to maintain stock looking gauges, so I am looking to swap out the guts behind the face instead of the easy VDO/Autometer option (and save $$.. it has been done with a VDO behind stock face but it's a bit of work and $120.. whereas used clusters are $20)
The layout of the RX7 speedo doesn't match the layout of a Z28/Formula/Impala/Caprice so I have looked to other Mazdacars and I have found 2 possible donor speedos so far, a 1990 Mazda 929 and a 1994 Mazda 626. Layout and configuration are very similar to the RX7. Using the 929 as a start, it has written on the face "1026 rev/mile". I believe the T56 takes 2000 or 4000 per mile... not to mentiont he 929 has like 6 wires to the speedo that I need to sort out..
Questions:
1. Can I change the VSS output from the PCM to the speedo independantly from the VSS to PCM signal? i.e. the driveline is all GM with 4.10 gears and 235/40/17 tires.. the PCM needs to know those things so it has an understanding of the actual speed of the car. However, I want to also output less revs/mile to the speedo so a Mazda unit can be used.
2. If I can do it, how would I figure it out?? Page 34 of the Tunercats manual here: http://www.tunercat.com/tnr_desc/tnr_manual.pdf has a tool for it, however I am sure that assumes stock speedo output. So while that will help me correct the VSS to PCM part, it won't help me fix the PCM to Speedo part. I see the following parameters:
Speedometer Scalar
Speedometer Scalar, Fraction
Speedometer Scalar, (Scan Tool)
Speed Pulses Per Driveshaft Revolution
Time Between Pulses For 'Stop'
But I have to assume that is to correct he input speed to the PCM...yes/no?
Help appreciated!
Wallyman
The RX7 speedo is cable driven, so I need to replace the speedo with an electric. I want to maintain stock looking gauges, so I am looking to swap out the guts behind the face instead of the easy VDO/Autometer option (and save $$.. it has been done with a VDO behind stock face but it's a bit of work and $120.. whereas used clusters are $20)
The layout of the RX7 speedo doesn't match the layout of a Z28/Formula/Impala/Caprice so I have looked to other Mazdacars and I have found 2 possible donor speedos so far, a 1990 Mazda 929 and a 1994 Mazda 626. Layout and configuration are very similar to the RX7. Using the 929 as a start, it has written on the face "1026 rev/mile". I believe the T56 takes 2000 or 4000 per mile... not to mentiont he 929 has like 6 wires to the speedo that I need to sort out..
Questions:
1. Can I change the VSS output from the PCM to the speedo independantly from the VSS to PCM signal? i.e. the driveline is all GM with 4.10 gears and 235/40/17 tires.. the PCM needs to know those things so it has an understanding of the actual speed of the car. However, I want to also output less revs/mile to the speedo so a Mazda unit can be used.
2. If I can do it, how would I figure it out?? Page 34 of the Tunercats manual here: http://www.tunercat.com/tnr_desc/tnr_manual.pdf has a tool for it, however I am sure that assumes stock speedo output. So while that will help me correct the VSS to PCM part, it won't help me fix the PCM to Speedo part. I see the following parameters:
Speedometer Scalar
Speedometer Scalar, Fraction
Speedometer Scalar, (Scan Tool)
Speed Pulses Per Driveshaft Revolution
Time Between Pulses For 'Stop'
But I have to assume that is to correct he input speed to the PCM...yes/no?
Help appreciated!
Wallyman
03-30-2009, 12:42 PM
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Why not get the adapter to run cable?
Something like this
http://www.shiftworks.com/tailhousing.htm
I know that's not quite what you wanted, but just tossing out options.
Something like this
http://www.shiftworks.com/tailhousing.htm
I know that's not quite what you wanted, but just tossing out options.
03-30-2009, 12:56 PM
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Why not get the adapter to run cable?
Something like this
http://www.shiftworks.com/tailhousing.htm
I know that's not quite what you wanted, but just tossing out options.
Something like this
http://www.shiftworks.com/tailhousing.htm
I know that's not quite what you wanted, but just tossing out options.
I'm shooting for least cost while maintaing stock look.. and if I can get the programming sorted, that cost is a used $20 cluster.
I've seen tailshaft conversions for $300-$500, the Cable-X box for $300, the VDO electric speedo for $120... but I'm cheap and I think somehow it can be done for minimal cost. The trick is purely in the pulses per mile (and finding a speedo that fits. If only the sweep of the GM stuff was more 270* instead of 210* I would just use a stock GM 140mph+ speedo out of a LT1 car and be done with it, but it's not that simple.
Wallyman
03-30-2009, 06:38 PM
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This must be pretty much the same thing as that Cable-X box.
http://www.hawksthirdgenparts.com/el...ometerbox.aspx
Even the 3rd Gen, like a 95, uses a cable driven speedo?
Only help I can provide is like my 93 is electronic, but is supposedly still considered mechanical :\ I really don't know, since after peaking in my BIN file I've found a VSS Pulse table, but we still use gears to run the speedo accurately...
http://www.hawksthirdgenparts.com/el...ometerbox.aspx
Even the 3rd Gen, like a 95, uses a cable driven speedo?
Only help I can provide is like my 93 is electronic, but is supposedly still considered mechanical :\ I really don't know, since after peaking in my BIN file I've found a VSS Pulse table, but we still use gears to run the speedo accurately...
03-30-2009, 08:27 PM
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This must be pretty much the same thing as that Cable-X box.
http://www.hawksthirdgenparts.com/el...ometerbox.aspx
Even the 3rd Gen, like a 95, uses a cable driven speedo?
Only help I can provide is like my 93 is electronic, but is supposedly still considered mechanical :\ I really don't know, since after peaking in my BIN file I've found a VSS Pulse table, but we still use gears to run the speedo accurately...
http://www.hawksthirdgenparts.com/el...ometerbox.aspx
Even the 3rd Gen, like a 95, uses a cable driven speedo?
Only help I can provide is like my 93 is electronic, but is supposedly still considered mechanical :\ I really don't know, since after peaking in my BIN file I've found a VSS Pulse table, but we still use gears to run the speedo accurately...
No clue on the 3rd gen, honestly. Probably, but no idea.
Yup, that don' help.
Wallyman
03-30-2009, 08:37 PM
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[QUOTE=Wallyman;11342192]No clue on the 3rd gen, honestly. Probably, but no idea./QUOTE]
So wouldn't that be the place to start? If they have electronic speedos then you'd just have to take the guts from it, like you wanted to do with another GM unit.
I'd also think that you'd find your answer on one of the RX7 swap forums. There seemed to be a couple based on results I noticed when I was trying to find stuff for you.
So wouldn't that be the place to start? If they have electronic speedos then you'd just have to take the guts from it, like you wanted to do with another GM unit.
I'd also think that you'd find your answer on one of the RX7 swap forums. There seemed to be a couple based on results I noticed when I was trying to find stuff for you.
