Speedometer Gear Replacement?
Thread Starter
Intermediate
Joined: Feb 2006
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Speedometer Gear Replacement?
How difficult is it to replace the speedometer gear on a 1992 700R Auto transmission? I would like to know how accessible it is. Is the exhaust in the way? Do you have to drop the X member and exhaust.
Thanks
Bruce
Thanks
Bruce
Burning Brakes
Joined: Feb 2008
Posts: 988
Likes: 7
From: Sarasota Fl
To change the speedo drive gear, you will need to remove the rear exhaust at the least, remove the driveshaft, remove the c- beam or unbolt it so you can unbolt the rear extension housing. To remove the rear extension housing, you must unbolt 4 bolts that connect to the rear of the tranny, but to access one of the bolts, the speedo sender must be removed (1 little bolt). Then you can either break the plastic gear with a chisel and a hammer, being careful not to scratch or damage the output shaft or the clip for the speedo drive gear.
Then slide the new one on, the dealer will sell you a gear that is easier to come off, try this site for the better version of the drive gear : http://www.transmissioncenter.net/sp...__va.htm#700r4.
If you have 2.59 s in the rear, you will need the red one. Call that website's contact (if they have one) and ask about it. Or call your dealer and have them tell you the color/tooth number. For my '91 with the Dana 36 and 2.59 gears (both stock), I needed the red 17 too gear. It looks like its $11 on that site. Then slide it on with the beveled side on first (IMPORTANT) and clip it on.
If I have time later today, I will post some pics of how to remove it, pics of the bolts, and pics of the gear and its clip.
Jonathan
Then slide the new one on, the dealer will sell you a gear that is easier to come off, try this site for the better version of the drive gear : http://www.transmissioncenter.net/sp...__va.htm#700r4.
If you have 2.59 s in the rear, you will need the red one. Call that website's contact (if they have one) and ask about it. Or call your dealer and have them tell you the color/tooth number. For my '91 with the Dana 36 and 2.59 gears (both stock), I needed the red 17 too gear. It looks like its $11 on that site. Then slide it on with the beveled side on first (IMPORTANT) and clip it on.
If I have time later today, I will post some pics of how to remove it, pics of the bolts, and pics of the gear and its clip.
Jonathan
Thread Starter
Intermediate
Joined: Feb 2006
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Thanks very much for the information. How difficult is it to just replace the sensor unit and gear? I think I will try and just replace the speedometer sensor and gear first. If that doesn't work then I try and do the drive gear.
Thanks
Bruce
Thanks
Bruce
Burning Brakes
Joined: Feb 2008
Posts: 988
Likes: 7
From: Sarasota Fl
I wouldn't change the sensor though unless I knew it was the problem. Check the wiring for damage and replace if necessary (connector is only $4 at ecklers). I know the gear attached to the sensor is much tougher plastic than the drive gear on the outut shaft too. So check connections and teeth of the gears before throwing parts at it - I know the speedo sensor is over $100 and would only replace if I diagnosed it as the problem.
Jonathan
Team Owner
Joined: Sep 2003
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The more important question! What are you trying to accomplish?
Thread Starter
Intermediate
Joined: Feb 2006
Posts: 44
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My speedometer is reading around 80 mph and my actual speed is 70 mph. It reads about 15% higher than it should. I think I have a 3:07 rear. I am hoping that I can fix this by simply changing out the gear to a gear with more teeth.
Good to hear that I may only have to remove the rear exhaust to get at the sensor.
Thanks for the info and recommendations.
Bruce
Good to hear that I may only have to remove the rear exhaust to get at the sensor.
Thanks for the info and recommendations.
Bruce
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
You may get away with just changing the driven gear if you have 3.07's
Try this calculator.
http://webpages.charter.net/khasting...peedocalc.html
Courtesy of Central Coaster.
Try this calculator.
http://webpages.charter.net/khasting...peedocalc.html
Courtesy of Central Coaster.
