I changed over to a 3.55 gear and swapped the speedo gear based on the chart that Resto50 had on their site. While driving to the track(roughly an hour and 15 min away) I was doing 60 by my speedo and a few buddies behind me called and asked why I was going so slow, turns out my speedo is rougly 9-10mph off. With most of my trip going to the 1/8 and 1/4 track being mostly highway I need to get it fixed. What if I put the stock speedo gear back in, would that make my speedo read even faster or slow it back down? I have a 275/40/17 on the back, not sure how much of a role the tire plays in this, but I figured id point that out. Thanks
Question About Fixing Speedo
- Thread starter 92GreenGT
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ryan218
In just 10 years, I'll be old enough to drive!!!!
So based on that site im guessing T5's have 8tooth drive gears? It says my best match is a 6tooth drive gear and 17tooth driven gear. It says the highest ratio with the 8T drive gear and 21tooth driven gear is .381 while I need a .353 ratio, couldnt I use a higher tooth gear than 21 with my 8T drive gear to equal close to my desired .353 ratio? Sorry, never messed with this before so if im way off, please correct me. Thanksjrichker said:
The 23 tooth gears tend to be difficult. Some guys have no problems, while other guys find they chew up and last 3 months.
Here's some more sites to look at:
http://www.geocities.com/mgnedell/notchback/tech/speedo.html
See http://www.corral.net/tech/gearcalc.html for more help
Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 1%-3%. The drawback is that it isn't cheap.
Please excuse the typo (their's, not mine) in the following picture - it should read Custom ratio adapters, not Custom radio adapters.
See http://www.gaugeguys.com/ratioadapt.htm for more info.
Here's some more sites to look at:
http://www.geocities.com/mgnedell/notchback/tech/speedo.html
See http://www.corral.net/tech/gearcalc.html for more help
Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 1%-3%. The drawback is that it isn't cheap.
Please excuse the typo (their's, not mine) in the following picture - it should read Custom ratio adapters, not Custom radio adapters.
See http://www.gaugeguys.com/ratioadapt.htm for more info.
Ive got the 23 tooth speedo gear in my car, here is the one I ordered and installed.
http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-17271D 1&comp=LRS
Surely it shouldnt be that far off just becuase of tire size should it?
http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-17271D 1&comp=LRS
Surely it shouldnt be that far off just becuase of tire size should it?
WhiteFizzo
Founding Member
I just borrowed a hand held GPS unit that tracks speed over land. After a few trips to work, I know that my speedo reads about 7mph too fast on average. So, whatever the speed limit is, I drive 10 mph faster according to my speedometer. 55 mph zone, 65 mph on speedo, Im going approximatley 58 mph. I've done this for a few years and I have yet to get any tickets. Besides, people are always hauling *** around here so I really don't worry about getting any speeding tickets.
