Speedo off
Thread Starter
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Joined: Oct 2008
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From: Red Oak TX
I did a gear calculator and this is what it said, Reuse your current drive gear: GM # 8640517 - 17 tooth, red
New Driven Gear: GM # 25513049 - 42 tooth, green
New speedometer sensor: GM # 10456092
(These parts are ideal for a 25.9 inch tire. At 60 mph, your speedo will read 59.8 MPH.)
does anyone know if this is right?
New Driven Gear: GM # 25513049 - 42 tooth, green
New speedometer sensor: GM # 10456092
(These parts are ideal for a 25.9 inch tire. At 60 mph, your speedo will read 59.8 MPH.)
does anyone know if this is right?
Team Owner
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Ideally with original tire specifications your information is correct. Those are GM production specifications for the trans/ratio/tire combination.
If you've access to a GPS I'd likely do a speedometer check with it or maybe some measured miles before I assumed and started buying parts!
All '93 A4's used the same internal drive gear so your work will be all external and quite simple!
If you've access to a GPS I'd likely do a speedometer check with it or maybe some measured miles before I assumed and started buying parts!
All '93 A4's used the same internal drive gear so your work will be all external and quite simple!
Thread Starter
Intermediate
Joined: Oct 2008
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From: Red Oak TX
Well i think its has 3.07 gears someone wrote 3.07 on the back of the rearend. Anyone know how many times the driveshaft turns with 3.07 gears so i can count driveshaft to see what gears i have?
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
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You could check your SPID/RPO label in the console for the original axle ratio which I'm guessing would have been a 2.59 and assuming the 3.07 is present now your speedo would be something near 18.5% high or at 60 read 70+.
I would think you could drive some "measured miles" at 70 MPH and you should knock them off in 60 seconds! If you'd rather I'd guess at 60 MPH on speedo with present gear package the miles would click off in 70 seconds!
I've never attempted to do a gear check in this fashion but it seems it would be a "valid" check!
Post the 3 digit RPO codes from your SPID label on the console door that start with a G and original axle ratio could be confirmed! If your label is missing post the last 8 digits of the VIN Pxxxxxxx.
I would think you could drive some "measured miles" at 70 MPH and you should knock them off in 60 seconds! If you'd rather I'd guess at 60 MPH on speedo with present gear package the miles would click off in 70 seconds!
I've never attempted to do a gear check in this fashion but it seems it would be a "valid" check!
Post the 3 digit RPO codes from your SPID label on the console door that start with a G and original axle ratio could be confirmed! If your label is missing post the last 8 digits of the VIN Pxxxxxxx.
Last edited by WVZR-1; Oct 4, 2009 at 09:05 PM.
Thread Starter
Intermediate
Joined: Oct 2008
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From: Red Oak TX
Ok i was under the car today and got the numbers stamped in the housing and they are 605491-3 10163872 3.45 it looks a dana 44, my car is a auto it should have the dana 36 with 2.59 gears is this a good or bad thing?
Last edited by nobull66; Oct 5, 2009 at 10:14 PM.
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I'd consider that a definite + !!!!
That could be the reason for the "3.07" being written in the rear. When the PO had the D44 done he realistically retained a very flexible A4 ratio.
Have you tried any of the measured miles?
If the rear is a 3.45 and the PO didn't do the speedo gears I'd think at 60 mph on the original gears a mile would be something at 79 seconds.
Post your speedometer readings at maybe 1000, 1200, and 1500 RPM's in 3D gear(1 to 1) along with your tire size and you could do some calculations based on the tach being correct. The tach frequently is in error!!
I still like the GPS for a simple speedo check!
That could be the reason for the "3.07" being written in the rear. When the PO had the D44 done he realistically retained a very flexible A4 ratio.
Have you tried any of the measured miles?
If the rear is a 3.45 and the PO didn't do the speedo gears I'd think at 60 mph on the original gears a mile would be something at 79 seconds.
Post your speedometer readings at maybe 1000, 1200, and 1500 RPM's in 3D gear(1 to 1) along with your tire size and you could do some calculations based on the tach being correct. The tach frequently is in error!!
I still like the GPS for a simple speedo check!
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From: Red Oak TX
In 3D gear RPM's 1000= 25-27 mph, 1200= 34-36 mph, 1500= 47+, 2000= 61-63 pop in o/d at 2000 and rpm drop to 1400 at 61. In o/d 1500 rpm= 65+ mph and the speedo feels like its running about 10+ mph faster the hole time. Does that sound like 3.07 or 3.45 gears? Rear tire size 285/40/17
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For your situation you could use this calculator for comparisons:
http://www.f-body.org/gears/
Plug-in your tire size, the 93-97A4 and the axle ratio. I don't believe this is adjusted for any "rolling radius" but for your requirements you could check against the results. I don't use this calculator frequently but it looks like it should answer your questions!
If your car still has the 2.59 speedo gears you should see about an 18% error if your rear is a 3.07. Your posted #'s are a little "erratic" but I believe if you did the correction for 3.07's you'd be where you need to be! I'd bet on the 3.07 in the D44
http://www.f-body.org/gears/
Plug-in your tire size, the 93-97A4 and the axle ratio. I don't believe this is adjusted for any "rolling radius" but for your requirements you could check against the results. I don't use this calculator frequently but it looks like it should answer your questions!
If your car still has the 2.59 speedo gears you should see about an 18% error if your rear is a 3.07. Your posted #'s are a little "erratic" but I believe if you did the correction for 3.07's you'd be where you need to be! I'd bet on the 3.07 in the D44
Melting Slicks
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