I have a 74 mav that I will be putting a 3-speed auto with auto overdrive trans in. I was going to put in 4/11 rearend but since I will be driving it on the highway also I think I am going to go with 3/75. How do I measure the rear end to see what inch I have? How can I tell the gear ratio that I have at this time? Do I just change the gears or do I need to change the whole rearend? Does anyone have 3/75 gears that they want to sell? Rearends is something that I haven`t messed with? Thanks, Maverickdad
Your rear end is an 8 inch unless it has been changed, which I doubt. As far as changing the gears, you only need to change out the center chunk and swap gears. Hope this helps, and I am sure more people can help you with more specific questions as I haven't personally done the swap yet. -Corbin
Most mavericks have an 8" rear end. It is an easy swap to change the 3rd member. I shouldnt take more than 2 hrs the first time you do it. Check out Ebay there are usually rebuilt 8" 3rd members. here is a used 3rd member with 3.80 gears http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33731&item=2429098867
To roughly determine what gear you have now. Jack the car up in the air, support it safely, make a mark on the drive shaft and one on the tire. Have someone slowly rotate the tire for one revolution while you or someone else counts of many times the drive shaft turns.... example: if the drive shaft turned 3 1/2 times for one wheel revolution you have a 3.55 gear. Its not a science but it will get you close. As far as what rear end you have. It is more than likely a 8 inch, unless someone changed it. Easy way to tell if it is a 9 inch is to crawl under the car and try to put a socket and extention on the 3rd member bolts on the bottom left side of the case. If you can get the socket and extention on it, then its "not" a 9 inch. To change the gears you need to pull the 3rd member. To do that, jack the car in the air remove the drive shaft and take the tires off. Then look behind the "stud" plate that is part of your axles(that thing your tires where mounted to) . There are 4 bolts that hold your axle on. There is a little hole in which you will have to line up to get a socket on it(I think it is a 1/2 inch bolt) so you will have to spin it to line up with each bolt to remove each of the 4 bolts. Take those four bolts off each side and pull your axle out, then remove the bolts on your 3rd member. Remember to have a drain bucket with you, cause when you loosen the bottom bolts, it could get messy Remove all the bolts and the 3rd member is ready to come out. You might want to support your 3rd member with a floor jack, depending on your size and strength those 3rd members can be a hand full. Good luck.
You need to jack up both rear tires. Otherwise the drive shaft will turn over twice as fast. Because of the spyder gears, this method dont always work correctly. The drive shaft sometimes wont turn at all. If the rear is original, there should be a tag on one of the center section bolts that will have the ratio on it. If your buying used gears or new gears, count the number of teeth on the pinion and divide it into the number of teeth in the ring gear.
Count the teeth on the ring gear and pinion gear, then divide the number of the ring gear teeth by the number of pinion gear teeth and that's your ratio. Typical gear ratios for the 8-inch Ford are: 2.79, 3.00, 3.40, 3.55, 3.70, and I "think" 4.10. A lot of times, the gear ratio code is on that sticker on the inside driver-side door jamb. Then just look up the code in a Chiltons manual. My bet it that you currently have a 3.00:1 rearend...
