Im new to this forum but it seems like every time I am searching for info on my build this site pops up near the top. I have a 62 Falcon and am doing a complete rebuild front to back. When i purchased the car it came with most of the parts for the mustang II install, an old (74 i think) 9" rear end (not installed), and a set of wheels and tires. I have already installed the mustang II front end and am now moving on to the back end of the old girl. I am having the rear end rebuilt and re-geared and am starting the install on the 4 link i picked up. Ive got all the old rear suspension, axle etc... removed already and have mocked up the new wheel and tires just to check that they will fit. Its snug and I may end up rolling the fender edge in more just to be safe. My real question is this: when starting from scratch like I am now, how do you determine how wide to make the rear end housing? I can get a fairly accurate measurement between the wheels and I just ordered a disc brake conversion kit so i will be able to measure the width of the brake set up. Then I plan to subtract that number from the overall width wheel to wheel. I just wanted to run this plan by everyone to see if i am on the right track. I have kept the stock rear end just in case i need to measure it for anything but I don't feel confident on just winging this deal and was hoping some of you folks that know a lot more about this than I do can help me out.
sounds like you are on the right track - so, with the new tire/wheel set-up bolted to replacement rearend everything fits within the wheel wells when mocked up under car? disc brake kit dimensions posted online to use for calculation? of course, will need to allow for installing/removing tires once all is said & done - post some pics of everything under rear to help others help you
i don't currently have the new (old) 9" put together yet. I am waiting on the disc brake kit to show up and then I can mount them and get a "current" or pre narrowed measurement. currently I just have the new rear wheels and tires sitting in the wheel well so that I can get an idea of what the wheel base will need to be but that's as far as I've gotten. As I said Im waiting on the brake kit. I also need to finish the install of the 4 link suspension. Ive got the axle housing sitting on stands and the stock axle is sitting in garage as well. I just don't think I can pull a measurement off of the stock axle since the new wheel and tires are so much larger/wider. I will post some pics here in a minute.
One caution; first-gen non-V8 Falcons have somewhat flimsy body structure. Ford basically used the same thickness metal as the fenders etc for the frame rails, rockers, etc. When Ford added the V8 in '63, the V8 cars got much thicker gauge metal for all those, plus adding torque boxes to tie the frame rails and rockers together. Subframe connectors are definitely recommended, as well as reinforcing all suspension attachment points. Seal-welding all the flanges (rather than just the factory spot welds) will also help with increasing body structure strength.
Measure your stock rearend WMS to WMS (wheel mounting surface), that'll give you your stock measurement. Try to keep your new rear setup at that width. Size your wheels (backspacing) to fit your wheelwells.
@ crazy steve, thanks, ya I noticed that "flimsy steel" when I was working on the front end. my mustang II required me to box in the frame rail where the new crossmember and upper shock mount attach. I also purchased the sub frame connectors to go with the 4 link kit. 4 link also boxes in the frame where upper crossmember attaches. But yes, I was pretty surprised at how thin the frame rails were.
@evintho my fear of keeping the stock width on the car is that I will be VERY limited on the tire/wheel size i can put on. Is it critical to maintain that stock width?
Ray. you are on the right track. Set the car at ride height and position the wheels and tires in the wheel well openings and make sure to check clearance of the tires in the openings in regards to upward travel of the tires under suspension compression. a lot of people miss this part and wonder "what the hell!" the first time you hit a bump. Measure between the wheels and you have your finish axle width and then assemble your rear as you planned with the brake rotors installed and measure that and subtract one from the other and you have the amount you need to narrow it. This is the way I have always done it. I did run into a situation early on where the outfit that built an axle for me when I told him the finish width including the brake rotors and that he needed to build it minus the thickness of the rotors and he misunderstood and made the axle flange to axle flange width the finish width and when I installed the brakes the rear end ended up being almost an inch to wide. So now I always find my finish width and deduct the thickness of the rotor hats and give them the flange to flange measurement and then there is no room for error. I hope I described it so you know what I mean. Larry
so I took a quick measurement on my stock rear end and WMS to WMS is 56". inside wheel to inside wheel as I have them mocked up is 51 5/8. eek
@one bad 51 merc... without having the rear end completed and wheels mounted and everything mounted up to 4 link, how do i ensure that i am allowing for suspension travel? I am thinking that the way its mocked up now will have to be pretty close to the ride height required to accommodate my desired wheel tire setup (as seen in pics). it looks pretty mean, and I'm not super into the really low stance that is popular on TV these days anyhow. If I rolled the fender edge in further and did something similar with the wheel well on the inside that tire should tuck up there just about perfect and i could even lower the rear end a bit more.
Ray as long as the tire can move up and down and there is room for possible body roll when making a turn are your big concerns. Sometime it is hard to figure out how much clearance you will end up and what modifications you will need to make . I try to get an inch to inch and a half of clearance on each side of the tire. sometimes you have to step in the rails and mini tub or old school and radius the wheel openings ala gasser style. Good luck and keep us posted. Larry
What are the planned for the car: drag race, street, road race, gymkhana etc.? All these uses have serious influence on all that one bad 51 Merc spoken about. Sent from my XT1710-02 using The H.A.M.B. mobile app
By example...road race... nostalgia ol school, needs lots of room for big tires, turning and body roll. Car eating tires and not the asphalt will kill the cookie jar. Sent from my XT1710-02 using The H.A.M.B. mobile app
mostly just a cruiser, nothing crazy.... at least not often. but want the option if you know what i mean. @koolbeans...i LOVE what you did with that! how did you modify the fender and quarter like that? I have some body repair to do on both quarters and something similar, probably little smaller flare. Did you use the flare off of another vehicle or are those custom?
Determined what tires, ride height, what room was needed for wide wheels and tires and their movement. Then zit wheeled the outer metal fenders. Then hand rolled and hammered a lip about 3/4" wide around the circumference. Then used cardboard pattern paper and made the shape wanted then translated to metal. The metal was then spot welded to the formed lip. The outer edge then had a 3/16 gas welding rod tacked to the edge. This became the edge welded, hammered, formed and strengthen the flare shape. Final finished with bondo. Geeezus, didn't realize all the work at the time. Sent from my XT1710-02 using The H.A.M.B. mobile app
Forget all about the stock rearend, it has no bearing on the situation once you change wheels, tires and suspension system. You just slide your tires under the car and put them where you want them. Block them from rolling. Get the side clearances you want and put the body at ride height. Measure between the back of the wheel mounting flange to wheel mounting flange, subtract your brake thickness at the hub flange and you have your answer for mounting surface width. What you next need to decide is where you want the pinion. Measure from either wheel mounting surface to the centerline of your tranny tunnel. Make sure not to flip those dimensions or you will have a mess getting the driveshaft in the tunnel! Those are the numbers the rearend housing builder will need to get the correct offset and axle lengths. SPark
The Falcon is a historical and very kool car. Keep in mind when it came out in 1960, we didn't have all the instant now computers. It was hand drawn back then and the idea of the cars platform probably started several years earlier. And it became the platform for the Mustang, Couger, and many other Ford cars. Interesting read on Wikipedia. Sent from my XT1710-02 using The H.A.M.B. mobile app
If you are wanting to change rear wheel wells , I have helped I the past using a Volvo Wagon front fender and an early Mustang front fender . I would love to build a Falcon gasser with FE Power .
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