anybody help me out what does most of the guys run on a 1940 Ford coupe for a rear end width wheel to wheel. I have a 58" now and it looks to narrow with 15x7 with 3 1/2 back spacing. the guy that is doing my chassis said he uses a 56" wheel to wheel can any body give me a idea. Body is off the frame now so it makes it harder for me to calculate ,
I used a 9" Ford cut down to Maverick width 56" I used 4 1/2 " back spacing on the wheels & they were rubbing on the inner fenders 235 - 70 15 tires Used 1/2" spacers Cured the problem I would think with 3 1/2" back spacing your rear end at 58" would be a little wide
Mine has a nine-inch rear from a '59 Ford. About 57 1/2 wide outside to outside. Either your current setup or the one recommended by your chassis guy are in the ball park, and will work with tires that are not too big. If you want to put big skins on the back, either axle will require a good tape measure and willingness to get wheels with exactly the right backspacing.
do you know, how wide of rim you used, I had a 15x7 3 1/2 back spacing it looked like it was sitting in to far. that was on a 58" wheel to wheel rear axle
I used a 9" Bronco,,58" You might think about a different back spacing on the rims or use spacers,but with the body off the frame your just guessing. HRP
View attachment 2971352 View attachment 2971351 FYI: The stock 40 Ford rear end measures 59 1/2 in. wheel mounting surface to wheel mounting surface. Here's a photo of a 40 with stock rear with 15 x 6 rims (Total width is 7) with 7:60 x 15 tires. Backspacing is 4 in.
In the old days if someone was throwing a later rear under them the '57 Ford rear was the rear of choice for a lot of fellas and they are @ 58" flange to flange. You may have to adjust your wheels accordingly. Hope that helps a little bit.
My 40 coupe measures 66" from inside the outer fender lip to the other inside lip. I measure the outermost edge of the tire mounted on the rim to be used to the mounting surface of the rim x2 and subtract this measurement from the total 66" . Decide how much space you desire between tire and fender lip. subtract that from your total so far. Then what is left is the width from drum mounting surface to the other drum mounting surface. Subtract the thickness of your drums where they mount to the axles and you have axle flange to axle flange width. If you are going with pretty wide tires you have to figure how much inside tub and maybe frame narrowing you have to do.
These charts will help. http://www.carnut.com/specs/rear.html and http://www.roadkillcustoms.com/hot-rods-rat-rods/Rear-End-Widths.asp#axzz3i9WHCHGW They show drum to drum wheel mounting surface distance to wheel mounting surface distance - which is what you need to know. A 9 inch rear is overkill if you are running a flathead. Use an 8 inch rear, which can take a lot of horse power also looks better and gives your car a better ride. Stay away from the Lincoln Versaile rears as they are over priced, have highway gears and there are almost no spare parts available for them. You might want to consider using a Ford 8.8 in. rear. They are 59.5 in. like the stock 40 rear and have disc brakes on the later models. Plus many come with Traction-Loc gears. In these rears the pumpkin is not centered like the original 40 but you can have the rear narrowed if that is critical to you. By critical, I mean that since the 8.8 rear has a large offset it might hit your 40 tunnel. There are guys using this rear in 40 Fords. I personally would use a narrowed 8.8 since they are plentiful, are not expensive as 9 inchers, look good under your car and have nice gearing so you won't have to rebuild your rear. Plus, they have disc brakes. Do some research on 8.8's. I think you will be happy. Here's a start. Maybe others will chime in. http://www.jalopyjournal.com/forum/threads/shortening-the-ford-8-8-rear-end-quick-question.793153/
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