MC-71 Posted May 31, 2009 Share Posted May 31, 2009 Can anyone tell me how many teeth are on the drive gear inside the 400 transmission? This is the gear that drives the speedometer gear. I'm trying to figure out what speedometer gear I need for a combination of a 350 engine, 400 tranny and 3.31 gears. I gave up years ago and got it close enough. Now they have all the right gears. There are 13 different gears listed in the NPD Catalog. Thanks Carl from Connecticut Quote Link to comment Share on other sites More sharing options...
Phil Posted May 31, 2009 Share Posted May 31, 2009 I think we need to know how tall your tires are too. Quote Link to comment Share on other sites More sharing options...
MC-71 Posted May 31, 2009 Author Share Posted May 31, 2009 My tires are 26.6 they are 245-60-15. Are you going to give me the answer now????? Thanks. Quote Link to comment Share on other sites More sharing options...
Ian Posted May 31, 2009 Share Posted May 31, 2009 Carl start here http://www.tciauto.com/Products/TechInfo/speedo_gears.asp Quote Link to comment Share on other sites More sharing options...
MC-71 Posted May 31, 2009 Author Share Posted May 31, 2009 Ian. Thanks. I have the formula but I need to know how many teeth are on that drive gear. That means I will have to open the tranny. I guess I'll have to wait. There are too many combos. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 31, 2009 Share Posted May 31, 2009 there are different drive gears, the only way you'll know is to get into the trans Quote Link to comment Share on other sites More sharing options...
Phil Posted May 31, 2009 Share Posted May 31, 2009 Sorry Carl I could only show you the formula. Quote Link to comment Share on other sites More sharing options...
Ian Posted May 31, 2009 Share Posted May 31, 2009 Can't you just take the speedo cover off to see what color the drive gear is? I am going to have to do the same thing now that I changed the rear gears too. Quote Link to comment Share on other sites More sharing options...
502ci Posted May 31, 2009 Share Posted May 31, 2009 That means I will have to open the tranny. I guess I'll have to wait. It's been 7 years since I changed mine out, I remember talking to a tech and they squared it away in no time...and swapping out the gear was a piece of cake, took like minutes. Bill Quote Link to comment Share on other sites More sharing options...
DavidTX Posted May 31, 2009 Share Posted May 31, 2009 By using the chart it is easy enough to see what driven gear you need. It takes less than 5 minutes to install/attempt to install it. If it will not work, you will then have to change the drive gear. That will probably require a Transmission repairman to drop the driveshaft, remove the tailshaft and replace the drive gear. I bought my drive gear at Autozone to have it installed. I think I did have to special order the driven gear. Quote Link to comment Share on other sites More sharing options...
MC-71 Posted May 31, 2009 Author Share Posted May 31, 2009 Check this out. www.chevelles.com/shop/speedo.html I think they have the gear chart backwards. But good info. Quote Link to comment Share on other sites More sharing options...
FASTSS454 Posted June 15, 2009 Share Posted June 15, 2009 Pull the speedo driven gear and housing out and find out what color gear is in there then post it and I'll look in my parts book and tell you how many teeth it has. Quote Link to comment Share on other sites More sharing options...
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