We need some help with this one. We have a 170 (2.8) and a 9" rear end that is apparently geared way to low. We haven't taken the carrier out yet, but we can't get much above 55....It's really whining hard pushing past that. (69.5 170 with auto) We see that the 2.8 should have something like a 3.08 ratio for the rear. With out 9" 5 lug 28 spline, we aren't seeing a 3.08 gear set for that. Just for 8.8. The size we see for the 9" is the 3.50 gear set. Will this work to get us highway speeds in our 9" rear end with the 2.8, or is there a better ratio to use? Never worked on swapping the pinion and gear out before, so any heads up will be appreciated.
Why's there a 9" rear in a small six banger car anyway ? Nine inch gear sets mostly are even numbered. They started with 2.47, then 2.50, 2.75, 3.00, 3.25, 3.50, 3.70, 3.91, 4.10, 4.30 and so on. You need something like at least 3.50's for that, 3.70's even better. Just look in Summit Racing's website to see the ratios available for a 9" rear. There's about twenty at the least.
what did the 9" come out of? a lot of the 6 cyl. 8" gears were 2:79. a 69.5 also had...7.5 rears... ...Frank...
Not exactly sure, It was in the car when we bought it, and like everything else we've discovered working on this vehicle, the guy who had it just cobbled everything and anything together...... We new something was up when we found a 5 lug set up on there, when we picked up the car....I'm starting to think the guy might have pulled it out of one of the numerous pickups he had laying around his yard.....
If you want to go down the highway, you need something around 3.00 gears. 3.50 gears are pushing it, and not what I would consider a highway gear. 3.00 and 2.75 are really common 9" gears. Should be able to scare one up pretty easy, as a whole chunk, that way you aren't stuck setting up gears. That is a job best left to those who know what they are doing! If you get a chunk, just drop it in and go. Sounds to me like you got a 4.11 gear in there.
Well, we think so, but we have no tags or anything on it to identify....I was just looking at kevinstangs 9inch website, and I am starting to think it may be the 8" as I think I can get a socket on the bottom bolts...... I will check again after work.........
Snap some pics, that'll straighten it right out. You can also see how many rotations of the driveshaft it takes to spin a tire 1 complete turn. Jack it up in back, block the wheels, put it in N, mark the tire with chalk or something, rotate the driveshaft by hand... count the turns of the shaft. If it takes just over 4 turns, it's a 4.11. If it takes 4 and a third turns, it's a 4.30. Etc... so on.
If you can get a socket on the two bottom retainer nuts, it's definately an 8" rear. :16suspectWasn't sure about the 4.10 ratio Dave
What if it turns 1 3/4 turns for one revolution of the wheel? I was counting it that way for the old 9 inch in my grandpa's '57 Ranchero. Being that it was an old drag car, I was expecting it to have a decent gear in it. But for every one revolution of the wheel, the pinion only went around went around 1 3/4 turns. :16suspect dschrodt, It sounds to me like you may have an 8 inch out of a Mustang II in your car. Some of those came with around 3.50 gears. It may also be a Maverick 8 inch with the center chunk out of a Mustang II in it. I see you are in Ellijay. My grandparents live near Murphy, NC just north of Blue Ridge, and I store 7 of my 8 Mavericks at their house. I go through Ellijay all the time on hwy. 515 going to their house, just went through this past Sunday and will be going again next weekend. If you find that your car really does have a gear like that in it, and you are looking to put a more highway friendly gear in, I would gladly trade you a 2.79 or 3.00 chunk for the one in your car. I could help you swap it out too. I'm looking for a gear like that for my Spider.
Jamie, Just a quick check last night after work, at it appears to be a true 9". I can't get a socket on the bottom bolts. We did try turning the shaft, and it did take 4+ to get a rotation. Could be 4:11. I will double check that again though. No wonder we can't get anywhere with our 170..... I am calling around looking for a 9" w/3.00 or less gearing, at least I'm guessing that is what we need. If we can find a whole chunk to just swap that would be cool. If you have something like that we can use, and you want the 4:11, we'd be more than happy to trade. Yes, we live off Whitepath just past the North Georgia Auto Auction on 515 almost to Cherry Log....
