Real simple. Mount up the tires you are going to use on the wheels you are going to use. Now position them under the chassis (frame) with the clearance you need. Measure the distance between the mounting surfaces of the wheels. this is the flange to flange measurement you need for the rearend. Seeing how economical it is to get axles shortened and resplined i always narrow a rearend to fit every car I build. It's just one of those things that make the final look of the car right on. Frank
thanks for the ideas. i dont have the body or wheels yet (hope to get the body this weekend) and have a line on a ford 8.8" out of a 70's or 80's f-150. dont want to get too narrow. i have had axles cut & resplined years ago but dont know any local shops that will still do it.
Theres a shop in Redwood city (Rearend Specialties I think) that I've had a couple done at. Housing and axles where around $300 - 350 if I remember right.
they were (or still are) in santa clara. they did the ones on my '40 willys coupe & my dads '55 chevy p/u, but that was years ago. i thought they told me they dont de them anymore due to liability reasons.
I had one narrowed there about three years ago. I think they send the axles out to be resplined. Your problly right about Santa Clara.
To get the best price and quality job done on axle shortening/resplining contact Moser Engineering in Indiana. I send them axles with instructions on length and spline configuration and have them back in about a week. Their turnaround for resplined axles is approximatly 24 hours from receipt of the axles to sitting on the dock to be picked up by UPS. While you are at it have them change the bolt pattern if you need that done and install new bearings. I can't get 1 bearing for a 9" Ford axle and have it pressed on for what they charge for a pair of them installed. Good people and precision work done in a timely manner. Frank
I got nothing at stake here but I second using Moser for axle work, I had them weld up new style bearing ends to 36 ford axle housings and shorten and spline axles to fit , They were quick and helpful and very professional. I'd use them again in a minute.
I used a 65 Chevy II V8 (5 lug) rear axle in a stock fendered 27 roadster without narrowing. I had 15X7 Tru-spokes. The tread was completely covered by the stock rear fender. Not easy to find but maybe cheaper than narrowing one. If you decide to narrow a 9", get the measurements as Fab32 said and then call Moser to find out what rear to buy. If you buy the rear first, you may end up having to buy CUSTOM axles.$$$$ He saved me money by telling me to buy a wider rear than I thought I needed to get axles that could be shortened to the length that I wanted.
You need to know what wheels and tires you are going to use. On my Roadster I used a 8.8 out of Fox body Mustang, its 58-3/4" wide. I'm using 7" wheel with 4-1/4" back spacing. I would have gone 1-2" narower if I didn't have this one already to keep it really tight to the body. Currie is pretty good too if you decide to buy new, they got me a really narrow 9" setup with axles within a couple of days.
You'll need one at least 61" wide if the thing is going to be low... but if you're still unsure, measure the width of the body where the tires will come closest to it... add two inches (or more) overall clearence (and inch/ inch and a half per side is good), then measure the overall offset (including tire bulge) of your rims... add them all together and you get the width rear end you need... Sam.
Hey Tim if you have the wheels it would be a good decision to mock up the rear before deciding on the rear end width...! You'll need to know what ride height (because the bottom part of the bodies are slightly narrower than the top), Need to know the offset of the wheels and the overhang of the sidewalls of the tires past the wheels! Mock it up and measure the inside of the wheel flanges and that should be your desired rear end width...! From there you can look up cross refference books on the different differential dimensions to find a close fit..., or you could dump a boat load of cash on a New Differential...!! I've seen many people channel cars and find out that they have too narrow of a rear end and then they have to use spacers to get the clearance needed!! Remember..., the desired width for the differential is really determined by the wheels you're going to use at the desired ride height!
thanks for all the help guys. i hope to get the body this weekend, and have a line on a pair of '40 wheels. i know how to make up an adjustable mock up axle, so i will wait & mock it up. i am using the yellow "bad news" '27 coupe as a model for mine, but mine will have a 392 hemi & auto, be channeled 3" z'ed front & rear. cant wait to start fabbing it up!
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