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47 Chevy Coupe

3K views 5 replies 5 participants last post by  capngrog 
#1 ·
I'm building a 47 chevy coupe that i bought disassembled. I've got most of what i need but, i ended up getting a 70's sub frame that's wider than i wanted to use. If i narrow it, how much can i take out and still fit a small block in?
 
#2 ·
You are going to get a lot of people suggesting you use a MII instead of the 70's sub frame; but before the MII was popular these were the way to go for a new independent suspension. Narrowing it will not be a problem as a small block would fit in the stock frame with stock suspension. I don't suppose you will be narrowing it less than the original frame.

I am sure there is someone on the board who has done this. I saw it done several times about 15 years ago but because I didn't have a Chev I didn't take much notice. I don't remember them talking about narrowing it though.

I do remember someone talking about narrowing one for a 37 Ford. If I remember they may have redrilled the mounting points for the A arms? Sound plausible?

I also remember an article in one of the magazines of that era doing a narrowing on a camaro subframe for a ??? Maybe someone the board will remember that and give you more information.

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#3 ·
Hey Conrad. You did the same thing I did with my 41. I know what you are going through.This is what I came up with. First, is it a front or rear steer sub? I have a friend with a rear steer and he took a slice out of the center of the crossmember and all was well. I can contact him to find out how much. If memory serves, he also bought narrowed a-frames for it. If it is a front steer, like mine was, the steering box will require a notch in the radiator support without narrowing. Narrowing will put the box in the radiator. And the box is almost out to the roll pan, so you will really have to do some fancy relocating of the radiator. You could convert to a rack. And you will probably still need narrowed a-frames. This is a chunk of changes from the factory design of the sub. Depending on how good you are with stuff like Ackerman, anti-dive angles, etc., you will either end up with a very nice riding and handling car or a nightmare. I looked at the expense and the risk and decided to buy a salvage yard frame and put a MII in it. Good luck. Keep us posted on how things are going.
 
#4 ·
I have done that two times. I took two inches right out of the middle. I would be afraid to go any more than that. I have heard that the later GM mid-size cars (early 80's) were narrower than the earlier ones. I prefer the subframe over the MII in these cars. Just my opinion.
 
#6 ·
47 Chevy C0upe

This past fall I purchased a built 1947 Sedan Delivery. The build was completed in 1997 and included a (reportedly) 1974 Camaro subframe welded to the stock Sedan Delivery frame (the Sedan Delivery is built on a passenger car frame, not a truck frame). I didn't do the work, but have a hand drawn diagram of the alignment geometry the builder used, plus some construction photographs (it was a body-off build). I'm no expert, but it appears that the Camaro front clip was not narrowed for the build. By the way, my '47 Sedan Delivery drives "straight and great". If you're interested, I can mail you what I have on this particular modification.

Cheers,
Grog.
 
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